3. To my family, Patricia, Lora, and Cynthia, for their love; h To Henry, Warren, Paul, and William, who represent the next generation; hTo the memory of Anthony R. and Roberta B. Ronzio; h And to people everywhere who want to learn more about their health and the fascinating world of nutrition.
5. ACKNOWLEDGMENTS Nass Ordoubadi, M.D.; and John Hibbs, N.D., pro-T o complete this encyclopedia, I drew on the support of many friends, colleagues, students,and family. The concept for the book originated vided me with unwavering support. Jonathan Wright, M.D., generously offered the use of hisfrom stimulating early morning conversations with extensive collection of reprints on nutritional med-Jeff Kelly, Ph.D., Lendon Smith, M.D., and Lisa icine. Elizabeth Wales’s advice during the evolutionMeserole, N.D., R.D., provided valuable sugges- of this work proved to be invaluable. Patriciations in the early stages of this work. Denny Han- Ronzio, M.Ed., has been a constant source of inspi-nem; Loren Freeman; Amy Nystrom; Kathlyn ration throughout. Her enduring love and supportSwann, L.Ac.; Gary Buhr, N.D.; Ralph Golan, M.D.; made this book possible. vii
6. INTRODUCTION ers were once believed to be inevitable conse-T he average American consumes an estimated 50 tons of food in a lifetime. This staggeringamount of food represents the sum of daily quences of aging. The health revolution also has changed ourchoices each of us makes regarding the type, thinking about how the body functions. There isquality, and quantity of foods. These critical less emphasis on distinct organ systems and morechoices in turn reflect a complex interplay of focus on integration—seeing the body as a whole.many factors, including family upbringing, reli- Extensive research has documented this mutualgious or philosophical beliefs, as well as practical interdependence, particularly among the brainmatters, such as the cost and availability of foods (nervous system), hormones (the endocrine sys-and beverages. Importantly, Americans are tem), and defenses (the immune system). Forincreasingly selecting food for health reasons. example, we cannot understand digestion withoutThey are increasingly aware that food choices pro- considering the effects of hormones, immune cells,foundly affect health, the quality of life, and even and nerves of the digestive tract.longevity, and they realize that the explosive Americans face many challenges and oppor-growth in medical costs requires attention to tunities to improve and maintain health. Over-nutrition and food to prevent disease and even nutrition and excessive daily calories and,promote optimal health. consequently, obesity and overweight are consid- This change represents a “health revolution,” ered a major public health concern. We now real-based on advances in the science of nutrition. It is ize that prolonged emotional and physical stresseven changing the outlook of health professionals. can deplete the body of critical protective nutrientsThe old model of curing disease and ameliorating and impair important functions of the body.symptoms is seen as incomplete. We now realize Chronic exposure to potentially damaging chemi-that disease prevention is the foundation of good cals in food, water, and air reduces the body’s abil-health. This new model of health care emphasizes ity to fend off infections and cancer. The beneﬁts ofthe importance of personal choices and lifestyle even modestly increasing regular physical exercisemodiﬁcation, especially the critical role of diet in are well established, yet we are tugged in manymaintaining health. Inadequate nutrition is linked directions by commitments that limit the time weto some of the most profound diseases of the last can spend for self-care.half-century. We now understand that incorporat- Healthy lifestyle choices, including eatinging speciﬁc nutrients and eating appropriate foods wisely, can lead to a more productive and person-can reduce the risk of chronic degenerative diseases ally satisfying life. As one of my clients put it, “Iand, in some cases, treat or slow their progression. can’t change my job, I can’t change my kids, and IArthritis, senility, cancer, obesity, coronary heart can’t change the way my spouse is, but I candisease, high blood pressure, osteoporosis, and oth- change the way I eat and how much I exercise.” By viii
7. Introduction ixmaking informed choices about diet and lifestyles, and many other chronic degenerative conditions.we can level the environmental playing ﬁeld so Global issues such as world hunger are relevant.that we can feel better about ourselves and live I have sifted through thousands of scientificmore active and fulﬁlling lives. papers and carefully evaluated recent advances in Patients and consumers are increasingly more nutrition, food technology, and pertinent medicalwilling to ask questions. They want to be better breakthroughs. My analysis and synthesis of thisinformed, and they feel empowered when they information is based on 40 years of experience astake greater responsibility for their own health and a biochemist with a keen interest in humanthe health of their families. Making wise choices metabolism, nutrition, and clinical laboratoryrequires facts, yet the amount of nutrition infor- practice, and as a biomedical researcher and pro-mation available to consumers can be overwhelm- fessor.ing. The basic issue lies in deciphering this Why a second edition of The Encyclopedia ofmountain of information without becoming lost in Nutrition and Good Health? The dramatic growth ofthe maze. We hear advice from talk shows, maga- nutrition research over the last decade has had azines and newspaper articles, a vast assortment of huge impact on health care and public health pol-books, food advertisements, personal experience icy. I have incorporated much new information byby family and friends, in addition to health profes- expanding the number of entries to more thansionals. The often expressed sentiment, “Since 1,800 and updating approximately 30 percent ofeverything causes cancer (or is fattening), why the original text. For readers who wish to explorebother?” reﬂects vast consumer frustration. key topics, I have included dozens of up-to-date After working with many clients and teaching references to the medical and nutrition-related lit-nutrition for many years in settings ranging from erature. Use of botanical preparations has increasedfamily programs to graduate school courses, I saw dramatically, and, therefore, I have described morethe need for a basic sourcebook to serve as a one- herbs and botanical preparations. In addition, thestop introduction to the world of nutrition. The encyclopedia now provides a glossary of commonEncyclopedia of Nutrition and Good Health can provide medical terms and, as a further aid for consumers,the keys to unlocking nutrition facts. My aim is to I have included summaries of food labels anddemystify scientiﬁc concepts without sacriﬁcing dietary guidelines.accuracy, so you, the reader, can grasp the essential Nutritionists and health care providers of manyideas quickly and easily. I have eliminated much of disciplines agree that diet and a healthy lifestyle arethe scientiﬁc jargon that can hinder the under- the mainstays of health. However, opinion isstanding of fundamentals. divided on amounts of speciﬁc nutrients needed for This encyclopedia is objective; it does not advo- optimal health. Furthermore, because of researchcate particular vitamin or diet plan. It does not pro- limitations, we still do not have a complete picturemote “cure-alls”; indeed, no single food or of the roles played by speciﬁc nutrients or supple-supplement can guarantee health or prevent dis- ments in use. For example, do results of animalease. The Encyclopedia of Nutrition and Good Health is studies extrapolate to humans? Do clinical observa-up-to-date and comprehensive. It provides current tions based on a small population of white, middle-information on speciﬁc foods and nutrients such as aged males extend to women, elderly persons, or tovitamins, minerals, fats, carbohydrates, and pro- different ethnic groups? Sometimes there are dif-teins. I describe many herbs and plant products ferences of opinion among experts on how to inter-now being widely used, in addition to detailing pret research findings when several differenteach nutrient—how it works in the body and how hypotheses can explain the observations. This isit impacts health. The encyclopedia is more than a natural and inevitable as the science of nutritionsupplement guide. Here you will ﬁnd a discussion progresses. Yet such controversy can be confusingof many food-related conditions, including eating and frustrating. Where there is disagreement in thedisorders, obesity, addiction, weight loss and man- scientiﬁc literature, I have taken the middle groundagement, food sensitivities, diabetes, aging, cancer, in describing pros and cons.
8. x The Encyclopedia of Nutrition and Good Health Only your physician is qualiﬁed to diagnose and is on lowering cholesterol levels, managing hyper-treat health conditions. Please consult your physi- tension, preserving bone density, losing weight,cian for any medical problems you may have, boosting immunity, or combating the effects ofrather than relying on self-diagnosis and self- environmental pollutants. Consider The Encyclope-medication, and before using any supplement. dia of Nutrition and Good Health your nutrition trans-Supplements may alter prescribed treatments and lator and stepping-stone on your pathway tocould interfere with medications, so expert medical wellness.advice is essential. Armed with new facts you will be able to ask Yours in health,more questions of your health care providers and Robert A. Ronzio, Ph.D., C.N.S., F.A.I.C.become better informed about your speciﬁc condi- Houston, Texastions or health objectives—whether your concern
9. Aabsorption Generally, the passage of liquids into Accent The trade name for MONOSODIUM GLUTA-solid materials and of gases into liquids and solids. MATE (MSG). MSG, a common FOOD ADDITIVE, isIn terms of nutrition, absorption refers to the pas- used as a FLAVOR ENHANCER.sage of substances into body ﬂuids and tissues.Digestion is only the ﬁrst step in the assimilation of acerola (acerola cherry, acerola berry) Acerolanutrients. This chemical breakdown of food parti- fruit is a product from the Caribbean and is one ofcles releases AMINO ACIDS, GLUCOSE, FATTY ACIDS, the richest natural source of VITAMIN C. AcerolaVITAMINS, and MINERALS, which must then be juice contains nearly 40 times more vitamin C thanabsorbed by the intestine in order to be used by the orange juice. Acerola extract is sometimes added tobody. Nutrients enter cells lining the intestine (the natural vitamin C supplements. Because of its veryintestinal mucosa) and then are drawn into under- limited availability, the amount added to supple-lying cells, where they may enter either the lymph ments is usually very small; an acerola-enrichedor bloodstream for distribution to tissues through- vitamin C preparation may contain as little as aout the body. Tissues absorb nutrients from blood tablespoon of acerola extract per barrel of vitaminvia capillaries, the smallest blood vessels. Gases, C powder.too, are absorbed. Blood becomes oxygenated inthe lungs by absorbing oxygen from inhaled air andreleasing carbon dioxide that was absorbed from acesulfame-K (acesulfame potassium; Sunett)tissues. This non-caloric, ARTIFICIAL SWEETENER tastes Absorption requires a disproportionately large approximately 200 times sweeter than table sugarsurface area to meet the body’s needs. Consider the (SUCROSE) and lacks the bitter aftertaste of SACCHA-total area of the small intestine, which is a highly RIN. The United Nations Food and Agriculture Orga-specialized absorptive organ. Though this tube is nization endorsed acesulfame-K as a satisfactoryonly about 20 feet long, it has a highly convoluted artiﬁcial sweetener in 1983. Acesulfame-K wassurface. Furthermore, the cells lining the surface, approved in 1988 by the U.S. FDA as a sugar sub-VILLI, are covered with microscopic, hairlike projec- stitute to be used in packets or as tablets and now istions (MICROVILLI) that dramatically increase the approved for use in chewing gum and in powderedabsorptive area to a quarter the size of a football drink mixes. Unlike ASPARTAME, acesulfame-K canﬁeld. The microvilli move constantly, to trap nutri- be used in cooking because it does not break downents and partially digested food, which is further at oven temperatures. Blending Sunett with otherdigested. The upper regions of the small intestine, low-calorie sweeteners creates a beverage with athe lower DUODENUM, and upper ILEUM, are most more sugarlike taste than one sweetened with anyactive in absorbing nutrients. Other regions of the single low-calorie sweetener.gastrointestinal tract carry out limited absorption: The Center for Science in the Public Interest hasThe stomach absorbs some ALCOHOL, glucose, ions, raised questions about Sunett’s safety, saying a fewand water, and the colon absorbs primarily water tests on rats indicated a possibility of cancer, al-and minerals. (See also DIGESTIVE TRACT; MALAB- though this was not proof that the sweetener couldSORPTION.) cause cancer. The Calorie Control Council counters 1
10. 2 acetaminophenthat the safety of acesulfame potassium has been it is readily oxidized by the heart and brain for theconﬁrmed by more than 90 studies, and it is production of ATP, the energy currency of cells.endorsed by a committee of the World Health Though small amounts of ketone bodies are nor-Organization. Theoretically, it would not be mally produced by liver metabolism, an excessiveexpected to be absorbed by the body. Nonetheless, buildup of acetoacetic acid and its derivative, BETAsome studies suggest that large doses raise blood HYDROXYBUTYRIC ACID, in the blood (ketonemia)CHOLESTEROL levels in diabetic laboratory animals can occur during excessive fat breakdown, whenand increase the number of lung and mammary the liver cannot completely oxidize massivetumors in other animals. amounts of fatty acids released from fat (ADIPOSE TISSUE). Conditions conducive to excessive ace-acetaminophen See ALCOHOL-DRUG INTERACTIONS. toacetic acid production include STARVATION (pro- longed FASTING), crash DIETING, uncontrolled DIABETES MELLITUS, and chronic ALCOHOLISM.acetic acid A fermentation product of wine. Ketone body production serves an importantDuring fermentation, certain bacteria produce role in the physiologic adaptation to starvation.acetic acid by oxidizing alcohol when exposed to With prolonged starvation, the blood levels ofair. VINEGAR contains 4 percent to 6 percent acetic ketone bodies rise, and more of them cross theacid, which gives vinegar its characteristic sour BLOOD-BRAIN BARRIER to be taken up by nerve tis-taste. As vinegar, acetic acid is a common ingredi- sue, where they are burned for energy. Conse-ent in food preparation. quently, the brain requires less blood glucose One of the simplest organic acids, acetic acid (blood sugar) for energy at a time when this fuel iscontains only two carbon atoms. It is classiﬁed as a at a premium. The sustained build-up of ace-weak acid because it is only partially ionized, toacetic acid in the blood (KETOSIS) can acidify theunlike strong mineral acids, such as hydrochloric blood, leading to metabolic ACIDOSIS, and alteracid. the acid-base balance of the body, a potentially Acetic acid plays a pivotal role in metabolism. To dangerous condition. (See also ELECTROLYTES; FATbe metabolized, acetic acid must be activated as METABOLISM.)acetyl CoA, in which acetic acid is bound to a car-rier molecule, COENZYME A, which is in turn derivedfrom the B vitamin PANTOTHENIC ACID. Metabolic acetone The simplest ketone. Ketones are anpathways that oxidize fatty acids, carbohydrate, important class of organic compounds. Acetone is aand amino acids for energy, all yield acetyl CoA, volatile compound that forms spontaneously bythe common intermediate by which carbons from the breakdown of the KETONE BODY, ACETOACETICthese fuels enter the KREB’S CYCLE to be oxidized to ACID. Unlike its parent compound, acetone is acarbon dioxide. Alternatively, acetyl CoA can be metabolic dead end and cannot be metabolized forused as a building block. It forms saturated fatty energy production. Its occurrence is a sign of severeacids, cholesterol, and ketone bodies. Nerve cells and prolonged imbalanced carbohydrate and fatcan use it to form the NEUROTRANSMITTER, ACETYL- metabolism. Acetone has a characteristic sweet,CHOLINE. Tissues combine acetic acid with amino ether-like odor, which accounts for the characteris-sugars to form a family of sugar derivatives like N- tic breath of individuals with uncontrolled DIABETESacetylglucosamine and N-acetylgalactosamine that MELLITUS. Acetone and ketone bodies are excretedhelp deﬁne recognition sites on the surface of cells in urine under conditions promoting extensiveand blood group speciﬁcities, such as the A, B, O, mobilization of fat stores, as STARVATION and meta-and Lewis blood groups used in blood typing. bolic disorders. (See also ACETOACETIC ACID; FAT METABOLISM; KETOSIS.)acetoacetic acid (acetoacetate) The most preva-lent of the KETONE BODIES, which are acids pro- acetylcholine One of the best characterized NEU-duced by the liver. Acetoacetic acid is a useful fuel; ROTRANSMITTERS. This family of brain chemicals car-
11. acid 3ries nerve impulses between individual nerve cells CELIAC DISEASE, diabetes, lupus, myasthenia gravis,(neurons) and between neurons and muscle cells. rheumatoid ARTHRITIS, and some forms of cancer.Acetylcholine is involved in memory, in processes Limited stomach acid production, not theassociated with thinking, in muscle coordination absence of stomach acid, is termed HYPOCHLORHY-and in many other functions. Nerves that secrete DRIA. It is not as severe a condition as achlorhydria,acetylcholine are called cholinergic neurons. An although unless corrected, the ensuing malabsorp-electrical impulse traveling down such a neuron tion syndrome can have similar, detrimental long-liberates acetylcholine, which then ﬂoods across range effects on health. In either situation patientsthe gap (synapse) separating the neuron from an may be advised to take supplemental hydrochloricadjacent cell, where it binds to its neighbor. A acid in the form of BETAINE HYDROCHLORIDE or glu-bound neurotransmitter in turn triggers an elec- tamic acid hydrochloride with meals to enhancetrical impulse or other reaction in the receiving digestion. These supplements should be used withcell. Acetylcholine is destroyed by the enzyme medical supervision because of the danger of over-cholinesterase, which clears it from the synapse dosing. (See also ACID; GASTRIC JUICE.)and prepares it for the next impulse. The brain synthesizes acetylcholine from acid A large family of compounds that taste sourCHOLINE, a nitrogen-containing ethanol derivative, and can neutralize bases to create salts. Strongand acetyl CoA, an activated form of acetic acid. acids like hydrochloric acid (STOMACH ACID) andTherefore, administering choline, or the phospho- sulfuric acid (battery acid) give up all of their pro-lipid LECITHIN, a dietary source of choline, might tons in water and lower the pH, the effectivebe expected to increase brain acetylcholine levels. hydrogen ion concentration. A pH of 7.0 is neutral,This strategy has been used in clinical trials to that is, neither acidic nor basic, while pH values lesstreat TARDIVE DYSKINESIA. Up to 50 percent of than 7.0 are considered acidic. Exposure to strongpatients in mental hospitals suffer from this condi- acids tends to damage cells and tissues. The stom-tion, characterized by uncontrolled twitches of ach is the only organ normally exposed to strongmuscles of the face and upper body. This is a side acids, but it is protected from injury by a heavyeffect of certain tranquilizers and antipsychotic mucous layer.drugs, which may cause a deficiency of acetyl- In contrast to strong acids, organic acids are clas-choline in critical regions of the brain. (See also siﬁed as weak acids because they donate only aSENILITY.) portion of their hydrogen ions, lower the pH to a lesser degree, and are less dangerous to tissues.acetylsalicylic acid The chemical name for Many compounds in foods are weak acids, includ-ASPIRIN. ing CITRIC ACID, ACETIC ACID, and TARTARIC ACID. Several weak acids are used as FOOD ADDITIVES, including benzoic acid, CARBONIC ACID, and alginicachlorhydria A condition resulting from the lack acid. As food additives and recipe ingredients, weakof STOMACH ACID. DIARRHEA, stomach discomfort, acids add tartness to foods. Weak acids are commonand bloating are common symptoms of achlorhy- intermediates, products of cellular processes thatdria, which has serious effects. It can lead to MAL- sustain life, including LACTIC ACID, KETONE BODIES,NUTRITION, even when the diet is well balanced, PYRUVIC ACID, acetic acid, FATTY ACIDS, SUCCINICbecause achlorhydria drastically reduces the efﬁ- ACID, citric acid, even the nucleic acids DNA andciency of DIGESTION. A chronic MALABSORPTION syn- RNA. GLUTAMIC ACID and ASPARTIC ACID (two com-drome leads to deﬁciencies of VITAMIN B12, CALCIUM, mon AMINO ACIDS) are classiﬁed as acidic aminoIRON, and other nutrients and sets the stage for acids, and are more acid than most.chronic FATIGUE, OSTEOPOROSIS, ANEMIA, and serious In the body, weak acids characteristically haveinfections. Although causes of achlorhydria are lost all their hydrogen ions and exist as a family ofunknown, lowered stomach acid production is anions (negatively charged ions) classiﬁed as “con-associated with anemia, stomach inﬂammation, jugate bases” because they have been completely
12. 4 acidemianeutralized by the buffer systems of blood. In the burning pain near the stomach. Typically, thisblood, lactic acid exists as its anion, lactate; ace- occurs an hour or so after a heavy (fatty) meal andtoacetic acid (a ketone body) as acetoacetate; citric is often relieved by taking ANTACIDS or by drinkingacid as citrate, and so on. Often the names of acids MILK. Acid indigestion is the most common gas-and their anions are interchanged in nutrition lit- trointestinal complaint in the United States; one inerature. (See also ELECTROLYTES.) 10 Americans suffer daily attacks. The pain associ- ated with acid indigestion is caused by STOMACH ACID backing up into the ESOPHAGUS, the region ofacidemia The condition in which blood becomesacidic. (See also ACIDOSIS.) the throat connecting the mouth with the stomach. Acid indigestion can be caused by air gulped when swallowing large bites of food, which canacid-forming foods Foods that create acidic keep the passageway open. Some food allergiesresidues after they have been broken down by the and food sensitivities may trigger acid indigestionbody. Protein-rich food, such as EGGS, MEAT, and by relaxing the sphincter muscles that normallypoultry, produce acidic residues when oxidized for seal off the stomach juices from the esophagusenergy. The combustion of sulfur-containing amino after eating. Although the stomach lining is pro-acids tends to acidify the body (acidic residue). In tected from acid by mucus, the unprotectedcontrast, fruits and vegetables make the body more esophagus is irritated by repeated exposure toalkaline or basic. They contain magnesium, cal- acid.cium, and potassium salts of organic acids, which To prevent acid indigestion, patients should eatyield an alkaline residue when oxidized. Fruits are slowly and chew food thoroughly, avoiding foodsaccordingly classiﬁed as alkali-forming foods, even and beverages that cause adverse reactions. Com-though juices and fruit taste acidic (sour). Excre- mon examples include fatty foods, CHOCOLATE, COF-tion of organic acids (potential renal acid load) can FEE, CITRUS FRUIT, and alcoholic beverages. Alsobe calculated for various foods based on their con- patients should consult a physician for any chronictent of sodium, potassium, calcium, magnesium, stomach pain because what feels like acid indiges-chloride, phosphorus, and sulfur. Choosing more tion may actually be inadequate stomach acidalkaline foods may ameliorate osteoporosis, (HYPOCHLORHYDRIA). Patients should seek immedi-autoimmune conditions such as rheumatoid arthri- ate medical attention if experiencing a crushingtis, and chronic inﬂammation. (See also ACID.) pain in the middle of the chest that extends to theRemer, T., and F. Manz. “Potential renal acid load of foods left arm, since these symptoms could indicate a and its inﬂuence on urine pH,” Journal of the American heart attack. Dietetic Association, 95, no. 7 (July 1995): 791–797. acidophilus (Lactobacillus acidophilus) A speciesacidiﬁers Common additives that increase the of the bacterium Lactobacillus that produces lacticacidity (lower the pH) of foods and beverages. acid by fermenting LACTOSE (milk sugar). ThisAcidiﬁers provide tartness and enhance ﬂavors of organism in the upper intestinal tract forms a sym-processed foods. The increased acidity inhibits the biotic relationship with its human host. Other acid-growth of microorganisms; thus acidiﬁers act as producing bacteria, including BIFIDOBACTERIA, arepreservatives. Certain acidiﬁers can also retard predominant in the lower intestine. Acidophilus isspoilage by acting as antioxidants, preventing a member of the normal intestinal microﬂora, thechemical changes due to oxygen. This group of so-called friendly bacteria that produce nutrientsadditives includes ADIPIC ACID (adipate), TARTARIC like BIOTIN and VITAMIN K. Acidophilus and otherACID (tartrate), benzoic acid (benzoate), and CITRIC Lactobacillus species help balance the digestive sys-ACID (citrate). (See also ACID; FOOD ADDITIVES.) tem by maintaining conditions that inhibit the growth of yeasts like CANDIDA ALBICANS, as well asacid indigestion (heartburn, esophageal reflux, potentially dangerous bacterial species. Withoutgastric reﬂux) A condition characterized by a beneﬁcial bacteria to control them, such oppor-
13. acrylamide 5tunistic microorganisms can multiply rapidly, lead- hydrogen ions. Prolonged acidosis requires medicaling to a full-blown infection. attention because it slows down many vital func- A variety of conditions can drastically lower or tions, including nerve transmission and heart mus-eliminate the intestinal acidophilus population. cle contraction. Symptoms of acidosis includeTreatment with broad-spectrum antibiotics (such as nausea, vomiting, DIARRHEA, headache, rapidtetracycline) imbalances gut microecology because breathing, and, eventually, convulsions.these antibiotics destroy both benign and disease- Two forms of acidosis are recognized: metabolicproducing bacteria. More generally, an unhealthful and respiratory. Metabolic acidosis can occur whenlifestyle and a diet high in SUGAR and PROCESSED metabolic acids accumulate excessively. For exam-FOODS also adversely affect beneﬁcial intestinal ple, when the body burns FAT at a high rate, thebacteria. liver converts FATTY ACIDS to KETONE BODIES, acidic Acidophilus is a common food supplement that substances. This condition may occur during crashmay help repopulate the gut with beneﬁcial bacte- DIETING and FASTING or in a person suffering fromria to prevent hard-to-control yeast infections; to uncontrolled DIABETES MELLITUS or chronic ALCO-break down milk sugar for those with LACTASE DEFI- HOLISM. Excessive ingestion of acids, such as inCIENCY; to control travelers’ DIARRHEA; to relieve aspirin poisoning, also causes acidosis. MetabolicCONSTIPATION; to treat vaginitis (when administered acidosis can also result from vomiting or diarrhea,as acidophilus douches); and to decrease the pro- which cause excessive loss of ELECTROLYTES likeduction of potential CARCINOGENS by certain bacte- BICARBONATE and upset the acid/base balance.ria populating the gut. (See also CANCER.) Renal disease may prevent the kidneys from ade- quately correcting acid production.Rosenfeldt V., K. F. Michaelsen, M. Jakobsen, et al. “Effect of Probiotic Lactobacillus Strains in Young Respiratory acidosis can occur when breathing Children Hospitalized with Acute Diarrhea,” Pediatric does not adequately remove carbon dioxide. Shal- Infectious Disease Journal 21, no. 5 (May 2002): low breathing, associated with respiratory disease, 411–416. can cause excessive CARBON DIOXIDE in the lungs, in turn causing carbon dioxide blood levels to rise andacidophilus milk (sweet acidophilus milk) ACI- upset the bicarbonate buffer system of the blood.DOPHILUS bacteria are sometimes added to low-fat (See also BUFFER; FAT METABOLISM; KETOSIS; STARVA- TION.)MILK by the producer. Consumption of acidophilusmilk and of yogurt may help lower blood choles-terol levels. Milk and yogurt labels should specify acidulant A food additive that acidiﬁes preparedviable (active) acidophilus cultures, since PASTEUR- foods and beverages. Citric acid and sodium dihy-IZATION destroys acidophilus bacteria. drogen phosphate are examples. (See also ACIDI- FIERS.)acidosis The acidiﬁcation of the blood and otherbody ﬂuids. This condition can be due to acid accu- acrylamide A chemical used in making plastics,mulation or to the loss of bicarbonate buffering textiles, and dyes and in purifying drinking water.capacity from kidney disease. The pH of blood is Short-term exposure above safe limits (maximumtightly regulated; the normal range is between pH contaminant levels) set by the Environmental Pro-7.3 and 7.4. A drop in blood pH below pH 7.3, tection Agency (EPA) causes damage to the centralwhich corresponds to increased hydrogen ion con- nervous system. Long-term exposure can causecentration, could signal excessive acidity of the paralysis and possibly cancer. The chemical hasblood (ACIDEMIA). Homeostatic mechanisms (the been shown to cause cancer in laboratory animals.body’s regulatory system of checks and balances) In 2002 the World Health Organization (WHO)help prevent acidosis. Bicarbonate and serum pro- convened an emergency meeting of food safety andteins take up hydrogen ions to neutralize excessive health experts after a team of Swedish scientistsacid rapidly, while the kidneys more slowly com- reported that some starch-based foods, like potatopensate for acid production by excreting surplus CHIPS, FRENCH FRIES, and some BREAKFAST CEREALS
14. 6 ACTHand BREADS, contain high levels of acrylamide. The Markowitz, J. S., A. L. McRae, and S. C. Sonne. “Oralamount of the chemical found in a large order of Nutritional Supplementation for the Alcoholicfast-food french fries was at least 300 times above Patient: A Brief Overview,” Annals of Clinical PsychiatryEPA safe limits for drinking water. Additional stud- 12, no. 3 (September 2000): 153–158.ies in Norway, Great Britain, Switzerland, and theUnited States reached similar results. addiction and sugar Addiction to reﬁned CARBO- Acrylamide apparently forms in some starchy HYDRATES in general and to sucrose (table sugar)foods when they are baked or fried at high tem- speciﬁcally is a controversial topic. Proponentsperatures. Raw or boiled samples of these foods, believe that sugar has no effect on behavior, andsuch as potatoes, test negative for the chemical. that it has little effect on health other than pro-Research on the health effects of acrylamide in moting tooth decay. A government task force con-food is ongoing. For the time being, most health cluded in 1986 that typical sugar consumption doesexperts have stopped short of advising consumers not generally pose a health hazard. Critics contendto avoid the risky foods or change their cooking that sugar addiction is a common phenomenon.methods. Preferring sugar and sweets seems to be pro- grammed at infancy. A craving for sweets oftenACTH See ADRENOCORTICOTROPIC HORMONE. develops later in life, and in this sense sugar may be psychologically addicting. Compounding the prob- lem of deﬁning sugar addiction is the generaladdiction A chronic condition characterized by observation that related symptoms are ratherCRAVINGS for and uncontrollable use of a substance vague, including a change in mood or feeling shaky(often drugs or alcohol) despite negative physical, when abstaining from sugary foods.mental, or social consequences. People who suffer One hypothesis proposes that addicted personsfrom drug or alcohol addiction are often malnour- have a drive to achieve a sense of well-being and toished and may be either overweight due to an overcome depression. Some addicted persons seemincreased consumption of foods high in reﬁned to have an abnormal metabolism of NEUROTRANS-CARBOHYDRATES or underweight due to a loss of MITTERS, chemicals that carry signals from oneAPPETITE. nerve cell to another cell. A primary example is the Nutrition offers a powerful adjunct to recovery link between depression and low levels of the brainand restoring the body’s biochemical balance. A chemical serotonin and the correlation betweennutritional program for a recovering addict might high-sugar, high-fat diets, and high brain serotoninadvise: levels. Evidence suggests that eating certain sugary foods stimulates the production of brain peptides• establishing new eating patterns, including eat- (ENDORPHINS), which trigger pleasant feelings. It ing frequent small meals to stabilize blood sugar has been hypothesized that the formation of (GLUCOSE) and prevent HYPOGLYCEMIA endorphins may be abnormal in some individuals,• avoiding foods high in sugar or reﬁned carbohy- possibly triggering compulsive eating behavior like drates BULIMIA NERVOSA. (See also APPETITE; BLOOD SUGAR;• eating a varied, balanced diet of VEGETABLES, NATURAL SWEETENERS.) whole GRAINS, LEGUMES, FRUITS, lean MEAT, POUL- TRY, and FISH• avoiding or eliminating foods that contain CAF- additives See FOOD ADDITIVES. FEINE• taking daily supplements of certain VITAMINS and adenine A building block of DNA, the genetic MINERALS, such as GLUTAMINE, VITAMIN C, and blueprint of the cell, and of RNA, the cell’s mes- NIACINAMIDE. senger that directs protein synthesis. Adenine is also used to manufacture ATP (adenosine triphos-(See also ALCOHOLISM; ADDICTION AND SUGAR.) phate), the energy currency of the cell, as well as
15. adipose tissue 7several enzyme helpers (COENZYMES) required to adipose tissue (body fat, depot fat) Fat storage isproduce energy. These include coenzyme A, a specialized function of adipose tissue, and it rep-derived from the B vitamin pantothenic acid; FAD resents the major fuel depot of the body; it is as(FLAVIN ADENINE DINUCLEOTIDE) from riboﬂavin; and essential to normal function as any other tissue.NAD (NICOTINAMIDE ADENINE DINUCLEOTIDE) from Body fat serves other important functions: It insu-niacin. lates the body against low environmental tempera- In DNA adenine constitutes one of the four tures and serves as a shock absorber. Typically, fatbases that make up the alphabet of the genetic code stored in adipose tissue represents 15 percent to 20and it stabilizes the unique double helix based on percent of men’s weight and 20 percent to 25 per-the attraction and complementary bonding cent of women’s average weight. Women usuallybetween two parallel DNA chains. have more fat than men because fat is an important Chemically, adenine is a cyclic structure belong- energy reserve during pregnancy and lactation.ing to the family of purines. Adenine is synthesized Adipose tissue synthesizes fat after a high carbo-in the body from three amino acids (ASPARTIC ACID, hydrate meal in response to the hormone INSULIN.GLUTAMINE, and GLYCINE). Therefore, adenine is not During FASTING, STARVATION, or STRESS, a secondan essential dietary nutrient. (See also GOUT; GUA- hormone EPINEPHRINE (adrenaline) signals ADIPO-NINE.) CYTES (fat cells) to break down stored fat into FATTY ACIDS, which are released into the bloodstream.adenosine triphosphate See ATP. They are rapidly absorbed and oxidized for energy by muscles. In contrast, the brain relies on blood sugar to meet its energy needs.adipic acid (hexapedioc acid) A common FOOD The fact that an adult can consume approxi-ADDITIVE in vegetable oils, adipic acid prevents their mately two pounds of food a day (or 700 pounds ofoxidation and retards rancidity, thus acting as an food a year) with only small changes in body fatANTIOXIDANT. As an acidiﬁer, adipic acid adds tart- indicates how well the body regulates weight whenness to soft drinks, throat lozenges, gelatin desserts, the calorie intake matches the total body require-and powdered, fruit-ﬂavored beverages. Adipic ments.acid is readily metabolized and is considered a safe Of course, common experience suggests thatfood additive. (See also CHELATE.) body fat can increase. For example, fat accumula- tion often accounts for the weight gain of middle-adipocyte FAT storage cell. The adipocyte is like a aged Americans. Older people tend to EXERCISE lessballoon; it expands in size when fat is added and it and the metabolic rate slows with aging. An indi-shrinks when fat is depleted. Adipocytes form ADI- vidual’s optimal body fat at any age depends uponPOSE TISSUE, specialized for fat storage. The number many factors, including inheritance, body build,of adipocytes increases during early childhood and sex, and age. Standard HEIGHT/WEIGHT TABLES or theadolescence as the amount of adipose tissue BODY MASS INDEX can be used to estimate an appro-increases. At other stages in life, fat is deposited in, priate body weight for an individual.or released from, existing adipocytes. Stored fat Excessive body fat is not healthy for many rea-comes from the diet or the liver adipocytes take up sons. OBESITY carries with it the increased risk offatty acids from chylomicrons, which transport CARDIOVASCULAR DISEASE, HYPERTENSION, and somedietary fat in the blood, and from very low-density forms of CANCER. It is interesting to note that thelipoprotein (VLDL), which transports fat synthe- distribution of body fat plays a role in deﬁning thesized by the liver. Adipocytes also synthesize fat risk for heart disease. Abdominal fat (the “sparefrom blood glucose in response to the hormone tire” proﬁle) carries a greater risk for cardiovascu-insulin. Conversely, many hormones initiate fat lar disease than fat accumulated around hips andbreakdown in adipocytes: EPINEPHRINE, GLUCAGON, thighs (the “pear” proﬁle).GROWTH HORMONE, and ANDROGENS, among others. The general approach to losing fat stored in adi-(See also LIPOGENESIS; LIPOLYSIS.) pose tissue is exercising and eating low-fat, high-
16. 8 adrenal glandsﬁber meals, while decreasing caloric intake. Dieting the heart rate and the rate of breathing, constrictswithout exercise decreases muscle mass (not desir- blood vessels, and relaxes bronchioles (the small airable) as well as the fat in adipose tissue, and the passageways of the lungs). It stimulates the releaseweight regained after a crash diet is mostly fat (also of free FATTY ACIDS from fat stored in ADIPOSE TISSUEnot desired). Cycles of dieting and not dieting also and the release of glucose from glycogen. Thecause loss of muscle mass. Muscle burns more effects of norepinephrine resemble those of epi-ENERGY per pound than fat, so DIET cycling may nephrine, described above, although it is lessincrease the difﬁculty of losing weight perma- active. It, too, increases the liberation of free fattynently. The number of fat cells in adipose tissue— acids, stimulates the central nervous system, andthe storage bags themselves—cannot be lost by increases heat production. Norepinephrine in-dieting or exercise. The only way to lose fat cells of creases blood pressure by constricting blood vesselsadipose tissue is by LIPOSUCTION, a surgical proce- in most organs.dure. (See also FAT METABOLISM.) The function of the adrenal glands is severely affected by sustained, long-term stress. In early stages of adaptation to chronic stress, the adrenaladrenal glands Triangular-shaped glands at- cortex produces large amounts of cortisol. This cre-tached to the kidneys that secrete two types of hor- ates a highly catabolic state, in which muscle, fat,mones that regulate tissue metabolism and blood and glycogen are degraded, leading to chroniccomposition. The body’s two adrenal glands are FATIGUE. Stressed adrenal glands may be linked toeach divided into two parts. The outer cortex abnormal blood sugar regulation, to muscle proteinsecretes three classes of steroid hormones (adreno- breakdown, and to suppression of the immune sys-corticosteroids), each with a different primary tem. In later, extreme stages of adaptation tofunction. The GLUCOCORTICOIDS consist of CORTISOL chronic stress, cortisol production is depressedand corticosterone. Their function is to develop a when the adrenal cortex can no longer be activatedsustained response to stress. They increase blood by signals from the pituitary gland. Inadequate cor-GLUCOSE; stimulate the synthesis of liver GLYCOGEN; tisol in turn can lead to hypoglycemia (low bloodmobilize amino acids from protein; and stimulate sugar) and to chronic fatigue. (See also ENDOCRINEADIPOSE TISSUE to break down stored FAT and SYSTEM; HORMONE; HYPOGLYCEMIA, POSTPRANDIAL.)release free FATTY ACIDS into the bloodstream. MIN-ERALOCORTICOIDS (mainly ALDOSTERONE) direct thekidney to conserve SODIUM and water, and there- adrenocorticotropic hormone (ACTH) A poly-fore they play a key role in ELECTROLYTE and water peptide HORMONE produced by the anterior lobe ofbalance. ANDROGENS (such as testosterone) are ana- the PITUITARY GLAND and secreted to activate andbolic hormones that stimulate muscle protein syn- sustain the ADRENAL GLANDS. ACTH release fromthesis and decrease the rate of protein breakdown, the pituitary gland is regulated by the HYPOTHALA-leading to an increase in growth rate. Androgens MUS via a hormone, corticotropin-releasing factordevelop and maintain male secondary sex charac- (CRH). ACTH triggers the production of all steroidteristics, such as genitalia, enlarged larynx, hair hormones of the adrenal gland, where it stimulatesgrowth, and muscular development. Testosterone the conversion of CHOLESTEROL to steroid hormonemaintains the prostate gland, seminal vesicles, and precursors. ACTH also acts on ADIPOSE TISSUE tosperm production of the testes. mobilize FAT and to increase blood levels of FATTY The inner region of the adrenal gland, the ACIDS. Inadequate ACTH leads to atrophy of themedulla, is a major source of stress hormones. It adrenal cortex, while excessive ACTH causesfunctions independently of the cortex (outer hyperplasia, the excessive growth of adrenal tissue.layer). The medulla synthesizes a family of hor- (See also CORTISOL; ENDOCRINE SYSTEM.)mones (CATECHOLAMINES) that are derived fromTYROSINE: EPINEPHRINE (adrenaline) and norepi- adulterated food A food is classiﬁed as adulter-nephrine. Epinephrine is released when a threat- ated if it contains extraneous material, dangerousening situation is perceived. The medulla increases amounts of poisons or ﬁlth, or if it has been
17. aﬂatoxin 9processed or stored under unsanitary conditions. In Taras, Howard L., and Miriam Gage. “Advertised Foodsterms of food for interstate commerce, the U.S. on Children’s Television,” Archives of Pediatric and Ado-Food and Drug Administration monitors environ- lescent Medicine 149, no. 6 (June 1995): 649–652.mental contaminants, toxins from microorganisms,bacterial levels, and potentially harmful sub- aerobic A physiologic or cellular process requir-stances. Since it is impossible for food to be 100 ing oxygen. Cellular RESPIRATION is the aerobicpercent pure, tolerances have been set for each process by which oxygen diffuses into cells and istype of contaminant. Very hazardous materials can used in the oxidation of fuel to produce ENERGY.be ruled so dangerous that no amount should be The waste product of respiration is carbon dioxide.detected (a “zero tolerance”). (See also RISK DUE TO Aerobic also refers to the ability to function only inCHEMICALS IN FOOD AND WATER.) the presence of oxygen. For example, aerobic bac- teria that are potential pathogens (disease produc-adult onset diabetes See DIABETES MELLITUS. ers) do not ﬂourish in the intestine when the availability of oxygen is limited. (See also ELECTRONadvertising Billions of dollars are spent each year TRANSPORT CHAIN; OXIDATIVE PHOSPHORYLATION.)on advertising food, and much of this is focused onspeciﬁc markets. Food ads for breakfast cereals and aerobic exercise Sustained physical EXERCISEjunk food, for example, focus largely on the chil- involving moderate to high levels of exertion anddren’s market. Toys, comic books, giveaways, and characterized by increased heart rate and acceler-polished commercials can hinder young people ated breathing. Vigorous activity associated withfrom making independent judgments on how to hard work and athletic sports can raise the pulseeat a balanced diet. Instead, their choices may rely rate sufﬁciently to strengthen the cardiovascularon the direction of advertisers. TV advertising plays system. Conditioning refers to increased physicala prominent role, where cartoons featuring food endurance due to increased muscle mass and acommercials dominate children’s programming. strengthened oxygen delivery system, includingMost of these emphasize PROCESSED FOODS—low in heart, arteries, and lungs, as a result of aerobicnutrients and high in CALORIES, SUGAR, SALT, and exercise. (See also FITNESS.)FAT. The American Academy of Pediatrics (AAP)discovered that less than 3 percent of advertisingduring children’s programs focuses on healthful aerobic respiration See RESPIRATION, CELLULAR.food, such as fruit and milk. The AAP concludedthat there is a direct link between commercials pro- aﬂatoxin A mycotoxin, a family of toxic com-moting high-calorie food and health problems, and pounds derived from molds growing on foods andin 1991 recommended a ban on food commercials on grains used for animal feed. Aﬂatoxin is pro-geared toward children. duced by ASPERGILLUS, a storage mold that often The Better Business Bureau’s Children’s Adver- infests damp grains and nuts. Nuts such as PISTA-tising Review Unit was founded in 1972. Com- CHIOS, ALMONDS, WALNUTS, PECANS, and PEANUTS areposed of representatives from the media, ad susceptible to MOLD. Very low levels of aﬂatoxinagencies, and others, its goal is to monitor truth in often contaminate PEANUT BUTTER. Spot checks haveadvertising in radio, TV, and the printed word for shown that this contamination is usually below thechildren up to the age of 12, according to self-reg- U.S. Food and Drug Administration limit. In theulating guidelines. It will review material before it 1970s and again in the 1980s, hot drought condi-is publicized upon request. The group provides a tions caused outbreaks of mold in corn and, conse-forum for information exchange and relies on a quently, widespread aﬂatoxin contamination.panel of academic professionals to provide exper- Concern has focused on aﬂatoxin because it is atise on the impact of images on children. (See also potent liver CARCINOGEN. The amount of aﬂatoxinCONVENIENCE FOOD; EATING PATTERNS; FOOD ADDI- permitted by the U.S. FDA is 15 parts per billion,TIVES; OBESITY.) although levels as low as one part per billion can
18. 10 agarcause liver cancer in certain species of experimen- contraindication of beta-carotene supplementa-tal animals. As yet there is no compelling evidence tion.that aﬂatoxin consumption in the low amounts Other studies have found that older men andusually encountered in Western nations causes women who ate the most dark green leafy vegeta-cancer. In regions of Africa where peanut con- bles were less likely to develop the condition thansumption and consequently aﬂatoxin intake is very were those who ate the least amounts of those veg-high, population studies suggest a correlation with etables and carotenoids (a group of red, orange,liver cancer in humans. Recent epidemiological and yellow plant pigments that includes beta-studies have shown that ingestion of aﬂatoxin B-1 carotene). Two pigments in particular—LUTEIN andincreases the risk of developing liver cancer. The zeaxanthin—accounted for this reduction in risk ofrisk is even higher for people who are infected with advanced age-related macular degeneration.hepatitis B. In addition to increasing the risk of Scientists suspect that these carotenoids protectchronic diseases such as cancer, ingestion of aﬂa- the retina by ﬁltering out damaging light. Datatoxin B-1 can cause acute symptoms of aﬂatoxico- from the Baltimore Longitudinal Study of Agingsis, including vomiting, abdominal pain, and even also suggests that vitamin E helps lower risk.death. Consumers should avoid moldy, discolored, or aging The progressive decline over time in phys-off-ﬂavor nuts. Molds and fungi send out micro- iologic function, including reﬂexes, vision, hearing,scopic ﬁlaments beyond the immediate, visibly short-term memory and learning, physical strengthmoldy area and cannot be easily removed. Further- and endurance, DIGESTION, cardiovascular function,more, aﬂatoxin is not completely destroyed by and immunity. Although these changes often begincooking. Therefore moldy food (except cheese) in the mid-twenties, heart functioning, memory,should be discarded, rather than cutting out the and reasoning need not drop signiﬁcantly untilmold. (See also CANCER-PREVENTION DIET; FOOD TOX- very late in life.INS; FUNGUS.) Aging is commonly associated with chronic dis- eases. These include CANCER, diabetes, OSTEOPORO-agar An organic FOOD ADDITIVE that forms non- SIS, PERIODONTAL DISEASE, OBESITY, SENILITY,digestible gels. This extract from SEAWEED has no CARDIOVASCULAR DISEASE (STROKE, HEART ATTACK,odor or ﬂavor. It is used occasionally as a THICKEN- ATHEROSCLEROSIS, and so on), and AUTOIMMUNE DIS-ING AGENT in the manufacture of whipped cream, EASES (such as RHEUMATOID ARTHRITIS and SPRUE). AICE CREAM, JELLY, JAM, and MAYONNAISE, and to pre- growing body of evidence indicates that chronicvent frosting on baked goods from drying out. In diseases are not inevitable, but are related to manymicrobiology, agar gels in petri dishes are used controllable factors, including diet. The commonextensively to culture microorganisms for identiﬁ- expectation that decreased physical ability willcation purposes. accompany aging often leads to diminished exer- cise at mid-life or later, setting the stage for nar-age-related macular degeneration A progressive rowed arteries, elevated blood CHOLESTEROL, andimpairment of the cluster of cells at the center of heart and kidney disease.the retina (macula), which is responsible for cen-tral vision. This disease is the leading cause of irre- Possible Causes of Agingversible blindness in the United States. About a Genetic research has conﬁrmed that longevity is, inquarter of people over age 65 have this condition, part, genetic. Scientists discovered a speciﬁc genefor which there is no cure. mutation in yeast, SIR2, that dramatically short- However, the Age-Related Disease Study ened the organism’s lifespan. Researchers foundResearch Group found that the combination of that if the gene was doubled, the yeast’s lifespanBETA-CAROTENE, vitamins C and E, and ZINC slowed increased dramatically, but if a mutation was intro-the progression of age-related macular degenera- duced that destroyed the gene, the yeast’s lifespantion and vision loss. Smoking is considered to be a was curtailed. Cellular molecular theories of aging
19. aging 11are currently popular. According to these theories, annoying, forgetfulness need not be debilitating.genes limit a person’s life span, and there may be Because memory is selective, it will usually servegenes for longevity and predisposition to ALZ- the learning process throughout life. The mentalHEIMER’S DISEASE, cancer, and schizophrenia. The faculties of most older people remain functioninglongevity determinant gene hypothesis predicts when exercised and challenged by a commitmentthat a few key genes regulate the rate of aging of an to lifelong learning and activity. Furthermore,organism. Aging may be the result of the improper research suggests that people may be trained toreadout of genes occurring during aging. partially recover their mental function apparently Accumulated oxidative damage is another mol- lost during aging.ecular explanation of tissue aging; experts suspect Forgetfulness can be caused by depression, bythat the body gradually loses the ability to repair the use of alcohol, tranquilizers, and sleeping pills,damage caused by oxidation to genetic material, as by certain drug interactions and by any factor thatwell as to cellular machinery. The damaging agent decreases the supply of oxygen to the brain. Mal-is believed to be FREE RADICALS, highly reactive nutrition can also cause mental deterioration. Infragmented chemicals including extremely danger- this regard, antioxidants may be particularlyous forms of oxygen. Free radicals bombard tissues important because free-radical damage may play aand attack DNA, proteins, and cell walls. role in mental aging. Older experimental animals Senescence could be linked to the structure of fed antioxidants dramatically improve their mentalchromosomes. The tips of chromosomes are pro- performance with a concomitant decline in oxi-tected by structures formed of DNA and protein. dized brain proteins. Such experiments suggest theWith successive cell divisions, telomeres become buildup of oxidized protein, the result of free-progressively shorter, reaching a point at which radical attack, may cause brain cells to age.they can no longer protect the chromosome and Preventive medicine proposes that making wisecell division ceases. Because senescent cells are no lifestyle choices sets the stage for health later in life.longer able to protect organs and blood vessels, The following lifestyle choices increase the odds ofthey possibly contribute to aging. living longer: Drastically limiting caloric intake may slow theage-related physiologic decline in experimental • Avoiding cigarettes. Smoking can lead to cancer,animals and increase their longevity dramatically. cardiovascular disease, and emphysema.While this approach is a useful research tool, it • Taking care of all emotional needs to reduce theis an impractical approach to slowing aging in stress of daily living and thus strengthening thehumans. Few adults would volunteer to restrict immune system. Chronic stress leads to elevatedtheir CALORIES by 20 percent or more for a lifetime. CORTISOL, which suppresses the immune system.Investigators are trying to identify substances that • Keeping mentally active; individuals who usewill mimic the physiological effects of calorie their reasoning power retain it longer.restriction. • Exercising regularly to slow deterioration of sen- On the other hand, prevention seems a much sory and physical abilities. AEROBIC EXERCISE canmore feasible approach to counteract aging. It is increase ﬁtness and endurance throughout aestimated that only about 30 percent of aging char- lifespan.acteristics are genetically based. Consequently, • Eating wisely. A varied, balanced diet with min-how a person lives is the major key to a healthy old imally processed food is the foundation for last-age. Regular physical activity, continued social rela- ing good health.tionships, the ability to recover from losses, and afeeling of control over life are predictors of success- Nutrient Needs During Agingful aging. Elderly persons are prone to MALNUTRITION for sev- Aging and Memory eral reasons. They are more likely to eat alone andShort-term memory functions and the speed of so take less interest in meal preparation, and theyrecall often decline with aging. Although it is are more often disabled and immobile. Thus, they
20. 12 agingare less likely to eat properly. More than 30 percent adequate calcium declines progressively with age.of homebound older individuals may have difﬁ- The common experience is that the bodies ofculty in preparing their own meals. Low-ﬁber, elderly women and men remove calcium fromhigh-carbohydrate meals typify the diets of many their bones to meet their calcium needs. Supple-elderly persons. They use more LAXATIVES and med- mentation with calcium and VITAMIN D, or calciumications for long periods. Furthermore, many with low-dose ESTROGEN for post-menopausalelderly persons have periodontal disease and poor women, seems to be more effective in slowingteeth. Their senses of smell, taste, and sight decline, bone losses than supplementation with calciummaking eating less appealing, and STOMACH ACID alone. Normally, iron stores increase throughoutproduction gradually drops, decreasing nutrient adult life in men and in women after menopause.uptake even with an adequate diet. However, blood loss due to chronic ASPIRIN use and Evidence indicates that superior nutrition may bleeding ulcers can cause iron deﬁciency; 5 percentprevent unnecessary illness and disability from of elderly men are iron deﬁcient in the Unitedshortening a productive life. Therefore, experts rec- States. CHROMIUM stores in the body declineommend the following health decisions: steadily with age and this may contribute to the decline in the regulation of blood sugar. Chromium• Avoiding excess calories and ALCOHOL. Surplus assists in insulin action and helps blood sugar reg- calories regardless of their source are converted ulation in some diabetics. Low chromium is corre- to fat. Excessive body fat contributes to the risk lated with elevated blood cholesterol levels. of heart disease, hypertension, and some forms Vitamins Research suggests there may be of cancer. Besides carrying a risk of addiction, increased vitamin needs in elderly people; how- excessive alcohol can damage the liver, pan- ever, no deﬁnite proof that vitamin supplements creas, and brain, in addition to depleting the increase the life span has been offered. Many body of nutrients. elderly Americans obtain less than 50 percent of• Medical testing of stomach acid production. Low the Recommended Dietary Allowance of VITAMIN stomach acid production sets the stage for inad- B6. Medications such as penicillin, estrogens and equate digestion of nutrients. antihypertensive drugs interfere with absorption of• Making informed choices regarding nutritional this vitamin. Folic acid and vitamin B12 are less supplements. They can affect the quality of well absorbed in elderly persons, and the RDAs health of those who are nutrient deﬁcient, should be higher. Inadequate diet and decreased though eating wisely. uptake of fat-soluble vitamins probably account for• Choosing a diet based on DIETARY GUIDELINES FOR the increased need for VITAMIN A and VITAMIN E with AMERICANS as a foundation. A BALANCED DIET, aging, and extra vitamin E may boost immunity, one that provides adequate amounts of all nutri- thus helping elderly persons resist disease. Vitamin ents and FIBER from varied, minimally processed E has also shown promise in slowing decline in foods without excessive calories and FAT, is of mental functioning in the elderly. One study paramount importance. showed that people who took high amounts of vit- amin E had a 70 percent reduction in the risk ofRelatively little is known regarding speciﬁc nutri- developing Alzheimer’s disease. In another studytional needs of people over the age of 65, although researchers followed more than 2,800 people overmore research is being done in this area. Attention the age of 65 for three years. Those participantshas focused on three classes of nutrients as being who had the highest amount of vitamin E con-especially important in aging: minerals, vitamins, sumption showed the slowest decline in mentaland antioxidants. alertness. Vitamin D requirements may increase Minerals Diminished digestion and ABSORP- during aging because the skin gradually loses itsTION can lead to deﬁciencies of MAGNESIUM, IRON, ability to manufacture the vitamin. Patients withZINC, COPPER, and CALCIUM. Older persons probably hip fractures may be deﬁcient in vitamin D.need more than the current calcium RDA of 800 Another problematic nutrient for elderly peoplemg because the ability of the intestine to absorb is VITAMIN C, a versatile antioxidant. Consumption
21. AIDS 13may be low with diets relying on processed, over- Agricultural Marketing Service (AMS) A ser-cooked foods and lacking adequate fruits and veg- vice-oriented arm of the U.S. Department of Agri-etables. Vitamin C may protect against cataracts culture (USDA) that provides marketing services toand atherosclerosis. the agricultural industry. It facilitates marketing of The RDA for RIBOFLAVIN is believed to be too low agricultural products domestically and abroadfor elderly people. Geriatric outpatients can exhibit while promoting competition and fair practiceslow-THIAMIN levels and evidence suggests that RDA among U.S. food producers. Its six commodity divi-of this critical nutrient is greater for older people sions (cotton, DAIRY, POULTRY, FRUIT and VEGETABLE,than for middle-aged individuals. livestock and seed, and tobacco) employ specialists Antioxidants Several nutrients seem to protect who provide standardization, grading, and marketthe body throughout life against damage by free news services for those commodities.radicals, highly reactive forms of oxygen that can AMS also purchases a variety of foods that are inattack cells. Trace minerals like copper, SELENIUM, excess supply, including fruits and vegetables,and zinc, as well as vitamins C and E plus BETA- meat, poultry, EGG products, and FISH, in support ofCAROTENE, function as antioxidants. Together with the national SCHOOL LUNCH PROGRAM and other fed-vitamin A they also keep the immune system bal- eral nutrition assistance programs.anced. The immune system protects the bodyagainst bacterial and viral diseases and defendsagainst cancer. AIDS (acquired immune deficiency syndrome) Other ingredients in foods, especially fruits and The last stage of a disease that diminishes thevegetables, act as ANTIOXIDANTS. They strengthen body’s ability to fight off infections. The disease isthe body’s defenses and protect against cancer. caused by infection with the human immunodefi-These include FLAVONOIDS, PHYTOESTROGENS (ISO- ciency virus (HIV), which destroys the body’sFLAVONES), and ISOTHIOCYANATES. Many more IMMUNE SYSTEM by attacking the white blood cellsremain to be identiﬁed. From hundreds of studies, called T-cells. AIDS is diagnosed when HIV infec-it is clear that diets that provide ample fruits, tion progresses to a point at which either thelegumes, and vegetables protect against many of number of T-cells drops to dangerously low levelsthe degenerative diseases that commonly occur or the patient suffers a life-threatening conditionwith aging. As an example, middle-aged men and or disease. A number of lifestyle factors have beenwomen who eat plenty of fruits and vegetables are implicated in increased physiologic susceptibilitysigniﬁcantly less likely to experience cardiovascular to HIV infection: overconsumption of refineddisease and strokes. foods; inadequate diet and malnutrition; malab- More research is required to determine the opti- sorption; use of recreational drugs; repeated in-mal intake of anti-aging nutrients. Foods with anti- fections, including sexually transmitted diseases;aging nutrients include orange vegetables use of medications that weaken the immune sys-(CARROTS, SQUASH) and dark green leafy vegetable tem; blood transfusions; as well as STRESS and(CHARD, KALE, SPINACH) for vitamin A and beta- smoking. Relatively few carefully designed andcarotene. Fresh fruit like ORANGES, frozen citrus controlled clinical studies of nutrition and HIVjuices, and BROCCOLI provide vitamin C. VEGETABLE infections have been carried out to permit generalOIL, WHEAT germ, and nuts supply vitamin E, while conclusions.whole GRAINS, SEAFOOD, CABBAGE, ONIONS, and GAR- As a result of increased susceptibility to diseaseLIC provide selenium. (See also DEGENERATIVE DIS- due to lowered immunity, AIDS patients mayEASES; DHEA; SENILITY.) develop pneumonia, Kaposi’s sarcoma, and dis-Gutteridge, John M. “Hydroxyl radicals, iron, oxidative eases due to infectious agents, including the yeast stress, and neurodegeneration,” Annals of the New CANDIDA ALBICANS, Epstein-Barr virus, and herpes York Academy of Sciences 738 (November 1994): simplex virus. Poor nutritional status contributes to 201–213. these diseases. HIV-infected patients are more susceptible toagricultural chemicals See PESTICIDES. parasites, such as CRYPTOSPORIDIUM, a contaminant
22. 14 airline mealsin municipal water supplies. The recommendation beta-carotene. Vitamin C boosts immunity, helpsis to avoid all public tap water and to drink water protect against viral and bacterial infections, andthat has been boiled or ﬁltered. may decrease the risk of stomach, esophageal, and Weight loss characterizes HIV infection, but the cervical cancer. It increases blood antibody levelscauses remain ill-deﬁned. In AIDS patients this and supports the function of the THYMUS GLANDmay be due to MALNUTRITION or it may be due to and lymphocytes. Furthermore, vitamin C supportsthe lack of appetite (anorexia) associated with the healthy connective tissue and assists in woundsubsequent severe infections or cancer. Anorexia is healing. FLAVONOIDS are associated with vitamin Cworsened by DEPRESSION. Oral and throat yeast in plants and enhance vitamin C therapy. Manyinfections, early symptoms of depressed immunity, ﬂavonoids function as antioxidants and severalcan also compromise food intake. types may stimulate the immune system. GLUTA- There is no cure for AIDS; however, several THIONE supports the immune system and functionsnutrients, food-related materials, and ENZYME as a major antioxidant. N-acetylcysteine, a deriva-preparations boost the immune system and may tive of the sulfur amino acid CYSTEINE, can enhanceoffer protection against the risk of CANCER and glutathione levels.infection in some individuals with AIDS. Egg Lipids Mixtures of LECITHIN and other Trace Nutrients ZINC deﬁciency is common in fatty materials from eggs have been used withpatients with AIDS and may indicate trace mineral some positive results in small clinical studies.malnutrition or malabsorption. Zinc plays an Although there is a lack of strong evidence of itsimportant role in maintaining the immune system. effectiveness, these mixtures are still being used.Zinc inhibits an enzyme needed for HIV produc- They are apparently nontoxic, though long-termtion. SELENIUM deﬁciency may be part of the mal- effects are unknown.nutrition seen in AIDS patients. It is a COFACTOR for Herbs Several herbs, such as GOLDENSEALenzymes that serve as ANTIOXIDANTS. Selenium (Hydrastis canadensis), have been shown to enhancehelps protect against liver and colon cancer in several aspects of immune function. The mostexperimental animals, and clinical studies of the active component of goldenseal is berberine, aeffects of selenium supplementation on cancer pre- broad-spectrum antimicrobial agent effective invention are being carried out. Other vitamins and treating the severe DIARRHEA that is typically seenminerals, such as VITAMIN A, FOLIC ACID, VITAMIN in AIDS patients. Herbal treatment based on Chi-B12, and POTASSIUM, may be deﬁcient in some AIDS nese medicine is also being studied. Certain formu-patients. lations inhibit viruses and boost the immune Enzymes Megadoses of a variety of enzymes, system. Some research suggests garlic may enhanceincluding SUPEROXIDE DISMUTASE, are being used as immunity and help combat opportunistic organ-antioxidants. There is no clear evidence that their isms associated with AIDS, including Candida albi-use diminishes or prevents symptoms. cans, cryptococcus, herpes virus, and mycobacteria. Antioxidants Evidence suggests that HIV- Gasparis, A. P., and A. K. Tassiopoulos. “Nutritional Sup-infected patients have lower levels of antioxidants, port in the Patient with HIV Infection,” Nutrition 17,including VITAMIN C, CAROTENOIDS, COENZYME Q, nos. 11–12 (November–December 2001): 981–982.GLUTATHIONE, and selenium. Such oxidative stress Gramlich, L. M., and E. A. Mascioli. “Nutrition and HIVcan promote HIV replication and decrease immu- Infection,” Nutritional Biochemistry 6 (1995): 2–11.nity. Antioxidant nutrients may lower the risk ofcancer in the general population, and the same airline meals Over the years, airlines havemay be true for HIV-infected patients. BETA- revised the meals they serve in order to meet con-CAROTENE and carotenoids may lower the risk of sumer expectations for more healthful choices.many cancers, including those of the lung, bladder, Changes include more chicken and less beef andstomach, esophagus, and prostate. Beta-carotene fewer saturated fats, like coconut and palm oil.can increase the numbers of T-helper cells. Signiﬁ- On noncharter ﬂights passengers can choose fromcantly, the standard American diet is deﬁcient in up to a dozen special dietary meals. The requests
23. albumin 15must be made at least 18 hours ahead of the sched- Alar (daminozide) A chemical formerly used touled ﬂight. Religious meals include kosher, Hindu, improve the color, yield, and storage qualities ofand Muslim. For medical conditions, bland, diabetic, APPLES. It is not a PESTICIDE. Until the late 1980s,GLUTEN-free, low-CALORIE, low-CARBOHYDRATE, low- Alar was used on an estimated 5 percent to 10 per-CHOLESTEROL, low-fat, and low-SODIUM meals may cent of the American apple crop. It was also usedbe offered. Other options include a FRUIT plate, on CHERRIES and PEANUTS. Alar is a systemic pollu-SEAFOOD, strict VEGETARIAN, ovolactovegetarian, and tant, meaning it is distributed throughout the plantinfant, toddler, and child meals. First-class meals fol- and cannot be washed off. Because alar has causedlow the same nutritional standards. CANCER in experimental animals, experts worried Passengers on long ﬂights, especially those who that because young children drink more apple juicehave been diagnosed as having phlebitis, inﬂamma- for their body weight than do adults, they are moretion of the VEINS in the leg, or who have a history of susceptible to the potential risk.heart disease or stroke are considered at high risk of In 1989 Alar was withdrawn by the manufac-developing deep-vein thrombosis (DVT). A person turer, Uniroyal Chemical Company. The followingsuffering from deep-vein thrombosis has one or year it was formally banned by the EPA. Alar is stillmore blood clots in the body’s deep veins, often sold abroad, however. About 50 percent of applethose in the legs. Because constant air circulation in concentrates for apple juice comes from foreignplanes promotes DEHYDRATION, and this, coupled countries where Alar is widely used, and importswith prolonged sitting, increases the risk of DVT in may be contaminated by Alar.even healthy people, passengers should drinkplenty of ﬂuids, including water and JUICE, and albacore (Thunnus [germo] alalunga) A type ofavoid ALCOHOL, COFFEE, and TEA on long ﬂights. tuna with white meat. Albacore is characterized byAbout 4 percent to 5 percent of high-risk patients a large pectoral (side) ﬁn. One of the smallest tuna,may suffer DVT on ﬂights of 10 hours or more. albacore usually weigh less than 40 pounds (18 A brown-bag, carry-on meal is always an option kg). They are found near the surface of warm orfor those with special dietary needs or with food temperate seas throughout the world, where theysensitivities. feed on ANCHOVIES, SARDINES, and other small ﬁsh. Albacore have been called the “chicken of the sea”alanine (Ala, L-alanine) One of the simplest because their white meat is comparable to chickenAMINO ACIDS used to build PROTEINS. Alanine is in ﬂavor. Albacore is the highest quality cannedreadily formed in the body from PYRUVIC ACID, a tuna and is an excellent PROTEIN source. The fooddirect product of GLUCOSE utilization; hence, it is value of 3 ounces (85g) (packed in water): calories,classiﬁed as a non-dietary, essential amino acid. 135; protein, 30 g; fat, 1 g; cholesterol, 48 mg; cal- In addition to serving as a protein building cium, 17 mg; iron, 0.6 mg; sodium, 468 mg; zinc,block, alanine plays an important role in transport- 0.94 mg; vitamin A, 32 retinol equivalents; thi-ing the toxic waste product, AMMONIA, out of mus- amin, 10.03 mg; riboﬂavin, 0.1 mg; and niacin,cle. Ammonia is produced when muscle cells break 13.2 mg (See also FISH OIL.)down amino acids for energy. Cells couple ammo-nia with a simple acid called pyruvic acid to form albumin A class of water-soluble PROTEINS thatalanine, which is then released into the blood- are soluble in dilute salt solutions but are insolublestream. The LIVER next absorbs alanine and in pure water. Important members of this classremoves ammonia, which it rapidly converts to are serum albumin and ovalbumin. The LIVER pro-UREA, the ultimate nitrogenous waste of the body. duces serum albumin, the most plentiful protein inThe liver converts pyruvic acid back to glucose, serum. Serum albumin transports ions like CAL-which is released into the bloodstream. Blood glu- CIUM, free FATTY ACIDS, and fat-soluble materialscose is taken up by the muscle, where it is broken like BILIRUBIN through the blood. Serum albumindown to pyruvic acid, which is then ready to accept also helps buffer the blood. It is a highly chargedammonia and thus completes the cycle. molecule (polyelectrolyte) that cannot pass
24. 16 alcoholthrough cell membranes and thus helps maintain of the ingested alcohol is destroyed by ENZYMES inthe electrolyte balance of body ﬂuids. the stomach that are more active in men than in Ovalbumin is one of the most abundant proteins women; consequently, women generally have aof egg white. The Roman author Pliny recorded the lower tolerance to alcohol. The liver’s capacity toname of egg white as albumen. Ovalbumin is an destroy alcohol in the blood is limited, and whenexcellent source of sulfur-containing amino acids, the liver’s metabolic system is saturated, a fractionsuch as CYSTEINE, and this accounts in part for the of ethanol in the blood is destroyed each hour. Theexcellent food value of egg protein. (See also ELEC- remaining alcohol readily penetrates the blood-TROLYTES; LIVER.) brain barrier and interacts with the central nervous system. Alcohol can pass from maternal blood intoalcohol (ethanol, grain alcohol, ethyl alcohol) A breast milk; therefore, lactating mothers may wishcommon term for the simple alcohol ETHANOL, the to abstain from drinking.product of FERMENTATION. As a constituent of alco- Some studies suggest that a single alcoholicholic beverages, ethanol is the most common, and drink a day may slightly reduce the risk of heartlongest used, sedative. To produce alcohol, special attack and stroke in some individuals. Moderatestrains of yeast are incubated with CARBOHYDRATES alcohol consumption increases the level of HDL,of FRUIT juices and GRAINS together with other nutri- the beneﬁcial form of cholesterol that tends to pro-ents. Under ANAEROBIC conditions (in the absence of tect against heart disease. Alcohol also inhibitsoxygen), these microorganisms ferment sugar to platelet formation, which is required to form bloodethanol and CARBON DIOXIDE to obtain energy. The clots. Moderate alcohol use may also help preventimmediate product of the fermentation of grapes is age-related decline in reasoning and problem-WINE. When malted grains and hops are fermented, solving. The apparent beneﬁts decline after morethe product is BEER. Distillation, a process intro- than one or two drinks, however. The Americanduced in the Middle Ages, produces alcoholic bev- Heart Association does not recommend drinkingerages with a higher alcohol content. These include alcoholic beverages to prevent heart diseaserum, whiskey, liqueurs, and the like. Beer and wine because of the hazards of alcohol abuse.are perhaps the most popular beverages among Possible consequences of excessive alcohol con-moderate drinkers. A mug of beer (11 oz., 4.5 per- sumption including the following:cent), a glass of table wine (4 oz.) and a shot (jigger;1.5 ﬂ.oz.) of liquor (80 proof) contain about the Birth Defects and Mental Retardation in Infantssame amount of alcohol (9 to 13 grams.) Drinking during pregnancy can lead to FETAL Excessive consumption of alcoholic beverages can ALCOHOL SYNDROME.cause MALNUTRITION because alcoholic beverages Addiction Alcoholism is one of the most commoncontain little else besides CALORIES. A glass of red addictions.wine contains 88 calories; a bottle of regular beer, Intoxication Excessive alcohol can lead to a pro-146; and a shot (1.5 ﬂ. oz.) of whiskey (90 proof), gressive deterioration of mental functioning.110 calories. VITAMIN, PROTEIN, and MINERAL content Alcohol is a depressant and slows down the ner-of alcohol is exceedingly low, though wine may con- vous system, especially the brain. While moder-tain a signiﬁcant amount of IRON. For this reason, ate drinking can be relaxing, being intoxicatedalcoholic beverages are classiﬁed as low-nutrient means the control centers are blocked, whichdensity or EMPTY CALORIES. To the extent they are can lead to memory lapses, decreased coordina-consumed, they displace nutrient-dense foods. tion, loss of inhibitions, confusion, mood swings, The blood alcohol level is affected by the and depression. Most individuals will beamount of alcohol ingested. Water and juice slow adversely affected when the alcohol content ofthe absorption of alcohol, while carbonation the blood rises above a threshold value. Legalincreases the rate of uptake into the bloodstream. intoxication in the United States is often deﬁnedAlcohol taken with food is less intoxicating. How as having a blood alcohol content ranging fromalcohol is metabolized is another factor. A portion 0.01 percent to 0.02 percent, depending upon
25. alcohol-drug interactions 17 the state. (Normally, the alcohol content of the ple, the LIVER adapts to alcohol consumption by blood is negligible.) Drunk drivers contribute sig- increasing its battery of drug-destroying ENZYMES. niﬁcantly to trafﬁc fatalities in the United States. Because a heavy drinker may metabolize a sedativeAggravated High Blood Pressure Excessive alcohol rapidly, its effects could wear off sooner than in a consumption can worsen hypertension. non-drinker, leaving the heavy drinker underse-Increased Risk of Disease Alcohol injures the liver dated. Patients should read prescription labels (CIRRHOSIS), the pancreas (PANCREATITIS), and carefully before drinking, and inform dentists, the brain. It causes intestinal inﬂammation, physicians, pharmacists, and other health care pro- interferes with nutrient uptake and may viders if they drink. increase uptake of toxins. Heavy drinkers have Interactions include: increased risk of heart failure, and alcohol causes a dangerous enlargement of the heart. Analgesics Non-prescription pain killers, such as For this reason some researchers do not recom- Tylenol, that contain acetaminophen can dam- mend that anyone past the age of 50 drink alco- age the liver of those who consume several holic beverages. Alcohol increases the risk of drinks a day. ASPIRIN together with alcohol cancer of the esophagus, mouth, larynx, liver, increases stomach bleeding. and breast. Women who drink two to ﬁve alco- Antidepressants Monoamine oxidase inhibitors, holic drinks a day increase their risk of invasive AMPHETAMINES, and tricyclic antidepressants breast cancer 30 percent to 40 percent, accord- such as imipramine cause severe reactions and ing to the American Medical Association. Inva- increased sedation, if taken with alcohol. Taking sive cancer is the type most likely to spread to any one of several antidepressant drugs called other TISSUES or organs. selective serotonin reuptake inhibitors (SSRIs),Surplus Calories One gram of ethanol provides including Prozac, Paxil, and Zoloft, can increase seven CALORIES, almost as much as FAT. One beer the effects of alcohol, including drowsiness and is equivalent to 150 calories. One shot (1.5 ﬂ. impaired motor skills. oz.) of 80 proof gin, vodka, or rye whiskey con- Antihistamines Drinking after taking drugs like tributes about 110 calories that supply no other benadryl can lead to excessive drowsiness. nutritional value. Alcohol even increases the Arthritis Medications Indocin and other drugs pre- body’s need for vitamins. scribed for arthritis taken with alcohol can irri-Exposure to Sulﬁtes Wine contains SULFITE, which tate the gastrointestinal tract and may cause can cause reactions in sensitive people. (See also dizziness. ALCOHOL-DRUG INTERACTIONS; ALCOHOLISM.) Barbiturates Alcohol should never be combined with drugs like amytal or phenobarbital, whichHolmberg, L., J. A. Baron, T. Byers, et al. “Alcohol Intake is the most hazardous combination. The additive and Breast Cancer Risk: Effect of Exposure from 15 Years of Age,” Cancer Epidemiology Biomarkers Prev 4 effects of taking the depressants can lead to res- (1995): 843–847. piratory failure and coma.Menzano, E., and P. L. Carlen. “Zinc Deﬁciency and Cor- Diabetic Medications Individuals taking Diabinese, ticosteroids in the Pathogenesis of Alcoholic Brain Orinase, and other sulfonureas to treat diabetes Dysfunction: A Review,” Alcoholism, Clinical and Exper- will probably not be able to tolerate alcohol imental Research, 18, no. 4 (July/August 1994): because these drugs can make the user ill after 895–901. drinking alcoholic beverages.Smith-Warner, S. A., D. Spiegelman, et al. “Alcohol and Niacin Large doses of niacin taken with alcohol Breast Cancer in Women: A Pooled Analysis of Cohort can reduce blood pressure excessively. Studies,” JAMA 279 (1998): 535–540. Prescription Pain Killers Codeine and narcotics combined with alcohol cause increased sedation.alcohol-drug interactions ALCOHOL interacts Sedatives and Tranquilizers Combining alcohol andwith many medications. Drinking alcohol can alter tranquilizers such as Valium and Thorazine canthe way the body metabolizes drugs. As an exam- lead to oversedation and extreme drowsiness.
26. 18 alcoholismalcoholism A condition characterized by an un- support groups, rehabilitation programs, educa-controllable urge to drink, a tolerance to increasing tion, behavior modiﬁcation, vocational guidance,quantities of ALCOHOL, blackout episodes, and with- and exercise. Nutritional and medical treatment isdrawal symptoms during abstinence. Alcoholics fre- often recommended to remedy nutritional deﬁ-quently deny that they have a problem. ciencies and alcohol-related disorders and to speed The costs of alcoholism to society are enormous. detoxiﬁcation. A number of clinics treat alcoholismExcessive alcohol is involved in one out of 10 deaths by incorporating lifestyle changes affecting DIETin America and typically shortens the life span by 10 and EXERCISE, while eliminating CAFFEINE and nico-to 12 years. Alcoholism contributes to accidental tine. Alcoholics Anonymous (AA) can provide adeath, crime, violence, and abuse. According to the very strong support system for recovery. (See alsoNational Highway Trafﬁc Safety Administration, half ADDICTION.)of all fatalities due to automobile accidents haveoccurred in crashes in which the driver or pedestrian aldicarb (Temik; Carbamyl) A very toxic insecti-had been drinking. Estimates of the total cost of cide widely used on POTATOES, SOYBEANS, PEANUTS,alcoholism to society range from $65 billion to $117 and citrus crops for control of chewing and suckingbillion. Alcohol abuse occurs among young people insects. Aldicarb was assumed to break downas well as the elderly, encompasses people of all rapidly after application. However, tests show thatsocial and economic backgrounds, and women as it can persist in soil for years and contaminate cropswell as men. Children of alcoholics are more likely planted in the same soil later. Several instances ofto abuse alcohol and drugs. Individuals may be born aldicarb poisoning indicate the potential hazard ofsusceptible to alcoholism due to imbalanced body using this pesticide.chemistry; however, the social environment obvi- Symptoms of aldicarb toxicity include seizures,ously plays an important role. disorientation, blurred vision, and gastrointestinal Alcoholism leads to disturbances of the GAS- disorders. The EPA recently limited the use ofTROINTESTINAL TRACT: Excessive ethanol directly or aldicarb and directed states to determine areas sus-indirectly increases chronic intestinal inﬂammation ceptible to contamination and then to monitorassociated with MALABSORPTION, comprised diges- them, to assure concentrations do not exceed thetion, and “leaky gut,” in which the intestine more limits set by the EPA. Activated charcoal ﬁlters canreadily absorbs toxins and potentially harmful sub- remove aldicarb from drinking water. (See also PES-stances from food and microorganisms that the TICIDES.)body recognizes as foreign (antigens). This can setthe stage for FOOD INTOLERANCE and systemic effects. aldosterone A hormone of the adrenal glandsAlcohol affects the LIVER, where altered GLUCOSE responsible for regulating SODIUM in the blood. It isand GLYCOGEN METABOLISM, fat formation, and fat classiﬁed as a corticosteroid, a group of hormonesexport can lead to fatty deposits (FATTY LIVER). The synthesized by the adrenal cortex. Aldosterone isability of the liver to detoxify other potentially dam- the principal MINERALOCORTICOID, which directs theaging materials can also be compromised. KIDNEYS to conserve SODIUM by reabsorbing sodium The alcoholic individual faces profound health and water from urine. In the kidneys, aldosteroneconsequences in terms of MALNUTRITION, heart fail- stimulates the renal tubules to release POTASSIUMure, high blood pressure, damage to pancreas, liver, and hydrogen ions in place of sodium, thus increas-stomach and brain, and increased risk of CANCER of ing urine acidity. Mineralocorticoids also increasethe mouth and esophagus. Even moderate alcohol sodium reabsorption from sweat, SALIVA, and GAS-intake can cause birth defects if the mother drinks TRIC JUICES. Other steroid hormones, deoxycorti-during pregnancy. costerone, corticosterone, and progesterone, can Alcoholism is treatable; however, recovery also cause sodium retention, though they are muchdepends on the person’s willingness to accept help. less active.Individualized recovery programs work best and Stimuli that increase aldosterone secretionmay incorporate family counseling, psychotherapy, include SURGERY, anxiety, physical trauma, high
27. alginate 19potassium intake, low sodium intake, and diseases of algae (seaweed) Simple plants found in freshthe heart, LIVER, and kidneys. The pituitary hormone water and oceans throughout the world. Algae areACTH stimulates steroid hormone release from the largely undifferentiated and, unlike terrestrialadrenal glands. Aldosterone is also regulated by the plants, algal leaves and stems are composed of thekidneys in response to low serum sodium levels. The same tissue. Edible species are either grown or col-kidneys produce an enzyme, RENIN, which forms the lected along coastal intertidal zones. In Japan, sixhormone ANGIOTENSIN in the blood that stimulates types are consumed, and together they account foraldosterone release. (See also ADRENAL GLANDS; an estimated 10 percent of the country’s total foodANTIDIURETIC HORMONE; FLUID BALANCE.) production. Edible brown algae, which represent most of theale See BEER. edible seaweed harvested worldwide, include arame, hiziki, kelp, and kombu. Edible red algaealfalfa (Medicago sativa) A LEGUME used primar- include CARRAGEENAN (Irish moss), dulse, and nori.ily for fodder throughout the world. As a nutri- These “sea vegetables” are rich sources of MAGNE- SIUM, IRON, IODINE, and CALCIUM, and some are astional supplement, this plant is a rich source ofTRACE MINERALS, BETA-CAROTENE, ESSENTIAL FATTY rich in vitamins such as VITAMIN C, BETA-CAROTENE, VITAMIN E, and the B COMPLEX as the best cultivatedACIDS, VITAMIN K, and the B COMPLEX vitamins.Alfalfa contains signiﬁcant FIBER and is a rich sources. In addition, various algae are used com-source of PROTEIN (25 percent by weight). In Asia, mercially as sources of gums (AGAR, carrageenan,alfalfa leaves are used in the form of greens as a and ALGINATE). Carrageenan has the ability to formVEGETABLE. salt gels in milk products and is used to keep fats Claims that alfalfa boosts the IMMUNE SYSTEM from separating, and to thicken ICE CREAM. Alginicmay relate to its trace mineral content. It also has acid (alginate) in brown seaweed can bind toxicantibacterial activity, and there is some evidence metals in the body and speed their removal. Thesethat alfalfa can induce LIVER detoxifying enzymes algae can be added to SOUPS, VEGETABLES, SALADS, BEAN dishes, and GRAINS to add zest and boost nutri-that destroy toxins and pollutants. Alfalfa containsseveral classes of compounds, including SAPONINS, tional value. Their ﬂavor is neither ﬁshy nor salty.STEROLS, and FLAVONOIDS, which can affect the There is little information on toxic metal conta-body. For example, alfalfa saponins decrease blood mination of any domestic or imported seaweed.cholesterol levels in lab animals. Alfalfa may One study found very low amounts of arsenic, cad-reduce damage due to radiation, perhaps due to the mium, lead, and mercury in common importedANTIOXIDANTS it contains. Individuals who have varieties; the levels were well below limits set byheart disease, who are pregnant, who have a ten- the Food Chemicals Codex of the Food and Nutri-dency to clot easily or take anticoagulants should tion Board. Mercury levels were far below the lim-avoid alfalfa supplements because their vitamin K its set for ﬁsh.content may promote blood clotting. Avoid con-suming excessive amounts of alfalfa during preg- alginate (ammonium, calcium, potassium, andnancy and when breast-feeding, because it sodium salts of alginic acid) A food additivecontains substances with weak estrogenic activity. obtained from the giant kelp, a brown algae com- Alfalfa sprouts are a healthful alternative to LET- mercially harvested off the coast of California. Algi-TUCE because it contains beta-carotene, VITAMIN C, nate is a major constituent of the cell wall andand trace minerals at levels higher than those consists of polymers of acidic sugars Alginate isfound in iceberg lettuce. In contrast with most let- used by the food industry as a thickening and sta-tuce, alfalfa sprouts are not treated with PESTICIDES. bilizing agent because calcium alginate forms veryAlfalfa sprouts (100 g) provide 54 calories; protein, stable gels in water. It prevents jelly in pastries6 g; carbohydrate, 9.5 g; ﬁber, 3.1 g; fat, 0.4 g; cal- from melting during baking and provides smoothcium, 215 mg; iron, 2.3 mg; thiamin 0.13 mg; textures to ICE CREAM, YOGURT and CHEESE, CANDY,riboﬂavin, 0.14 mg; niacin, 0.5 mg. whipped cream in pressurized cans, and canned
28. 20 alimentary canalfrosting. Alginate also helps keep cocoa butter dis- resents an accumulation of hydroxide ions andpersed in chocolate milk. The red PIMENTO stuffed depletion of hydrogen ions, CARBON DIOXIDE, andin green OLIVES contains the most alginate (6 per- CARBONIC ACID. The body is exquisitely buffered tocent) of any food source. Alginate is not used in keep blood pH slightly alkaline, within a very nar-acidic foods and beverage such as salad dressings row range, 7.35–7.45. However, this equilibriumand SOFT DRINKS, because it forms sediment under can be shifted by loss of STOMACH ACID throughthese conditions. vomiting; by the consumption of alkaline medica- Alginate is on the GENERALLY RECOGNIZED AS SAFE tions such as those used to treat ulcers; and by(GRAS) list of the U.S. FDA. Short-term animal test- rapid breathing (hyperventilation), which rapidlying indicates the alginate is not absorbed by the decreases the body’s stores of carbon dioxide.body and is not toxic. Because alginate forms The body compensates for alkalemia andhighly charged gels in water, it remains to be deter- reestablishes normal blood pH by slowing the res-mined whether it can limit the absorption of min- piration rate (breathing); this increases the level oferals and other nutrients by the body. (See also carbon dioxide in the blood, which spontaneouslyFOOD ADDITIVES.) forms more carbonic acid. The KIDNEYS can com- pensate for elevated pH by excreting alkaline urine.alimentary canal See DIGESTIVE TRACT. (See also ALKALOSIS; BUFFER; ELECTROLYTES.)alimentation The physiologic processes by which alkali-forming foods See ACID-FORMING FOODS.food nurtures and maintains the body. Theseinclude chewing (MASTICATION), swallowing, and alkaline A solution with a pH greater than 7.0,digesting food. Alimentation also encompasses the which is considered neutral. Alkaline solutions areABSORPTION of NUTRIENTS (VITAMINS MINERALS, also called basic, as opposed to acidic. MILK, BLOOD,AMINO ACIDS, FAT, CARBOHYDRATES) by the intestine and EGG yolk are examples of slightly alkaline solu-and their use in CATABOLISM (energy production) tions. Solutions of BAKING SODA (sodium bicarbon-and in ANABOLISM (building cellular constituents). ate) and AMMONIA form mildly alkaline solutions. InThe term alimentary canal refers to the digestive contrast, the corrosive metallic hydroxides such ascavity running from the MOUTH to the anus. sodium hydroxide (lye, caustic soda) are very strong Artiﬁcial alimentation refers to feeding a patient bases and are very alkaline. They destroy TISSUE,artiﬁcially either by intravenous procedures or by a create burns, and are considered toxic substances.nasal tube. Forced alimentation is feeding a patientwho is unwilling to eat. (See also DIGESTION; HYPER- alkaline tide The slight rise in blood pH followingALIMENTATION.) a meal, when the BLOOD temporarily becomes more ALKALINE. When the STOMACH producesalitame A non-caloric ARTIFICIAL SWEETENER that hydrochloric acid (STOMACH ACID) for use in DIGES-is 2,000 times sweeter than sugar that has not yet TION, it removes a fraction of negatively chargedbeen approved by the U.S. Food and Drug Admin- CHLORIDE ions from circulation. Chloride is thenistration. This sweetener was developed to be safer replaced by BICARBONATE in the blood, which tendsthan ASPARTAME. Unlike aspartame, alitame does to raise blood pH. As the meal is digested, chloridenot contain phenylalanine and consequently ions are reabsorbed by the INTESTINE and againwould likely be safe for individuals with PHENYLKE- enter the bloodstream. In turn, bicarbonate is reab-TONURIA (PKU), a genetic intolerance to this amino sorbed and the pH returns to normal. The URINEacid. may become more alkaline during digestion as the body compensates for the change in blood pH.alkalemia A blood condition characterized byexcessive alkalinity (excessively high pH). A blood alkaloids A large, diverse class of organic com-pH greater than 7.4 is considered alkaline and rep- pounds prevalent in the plant kingdom that con-
29. allergy, food 21tain nitrogen and function as bases. Often alkaloids tible individuals. Prescription drugs (includingprofoundly affect the body’s physiology, and puri- penicillin), antisera, and constituents of infectiousﬁed alkaloids are even more active. Examples of agents (including bacteria and viruses, yeast, andpotent alkaloids include morphine, cocaine, qui- parasites) can be allergens. Physical agents, includ-nine, strychnine, nicotine, CAFFEINE (COFFEE), and ing radiation, heat, and pressure may also provoketheobromine (CHOCOLATE). Depending upon the inﬂammation, an aspect of the immune response.application and the dose, alkaloids may be used in In provoking an immune response, allergens typi-therapy or they may cause toxicity. Socrates was cally react with ANTIBODIES, protective proteinskilled by the alkaloid coniine that occurs in hem- formed by specialized cells of the immune system.lock. Eating quail that have eaten poison hemlock (See also ALLERGY, FOOD.)can cause food poisoning in humans. Alkaloidssuch as nicotine and caffeine are addictive sub- allergic rhinitis This condition refers to allergystances. Morphine and cocaine are controlled sub- symptoms associated with the chronic inﬂamma-stances due to their addictive properties. tion typical of hay fever: a perpetually stuffy, runny nose, sneezing, puffy bags and dark circles underalkalosis Excessive alkalinity (elevated pH) of the eyes, and a puffy face. Allergic rhinitis can leadbody ﬂuids caused by either an accumulation of to chronic earaches, especially in children, and toalkaline substances or a reduction in ACIDS. Alkalo- inﬂamed sinuses (sinusitis). It is more commonsis is thus more general than ALKALEMIA (alkaline among children, but can occur at any age. Allergicblood). Respiratory alkalosis occurs with hyperven- rhinitis is the result of a speciﬁc type of ANTIBODY,tilation, aspirin poisoning, abnormal brain func- IgE, which binds to mast cells, defensive cells of thetion, or inadequate oxygen supply, as may occur IMMUNE SYSTEM, to stimulate inﬂammation. There-during exertion at high altitudes. Metabolic alkalo- fore allergic rhinitis can be measured by a skin test.sis occurs with severe VOMITING due to losses of Nasal symptoms occur immediately after exposurehydrogen ions and chloride ions (STOMACH ACID); to common allergens, including pollen, animallosses of POTASSIUM due to diuretic therapy; and dander, house dust, mites, insects, MOLD, andingestion of BAKING SODA (or other alkaline sub- foods. Identiﬁcation of the offending substance andstances). Symptoms of both types of alkalosis reduced exposure are important; complete avoid-include shallow breathing, a tingling sensation at ance may be curative.ﬁngertips and toes, muscular cramps, and convul-sions. Like prolonged ACIDOSIS, alkalosis requires allergy, food An abnormal reaction of themedical intervention. (See also BUFFER; ELEC- IMMUNE SYSTEM to normally harmless foods. AnTROLYTES.) allergic response involves two aspects of the immune system: circulating ANTIBODIES and spe-allergen A substance or agent that causes an cialized attack cells. Each branch of the immuneallergic reaction. Allergens provoke the IMMUNE system can react to foods as though they were for-SYSTEM when it senses an allergen as a foreign sub- eign invaders. In contrast, other types of FOOD SEN-stance and overreacts. This “hypersensitivity” may SITIVITY such as LACTOSE INTOLERANCE do notbe immediate, when symptoms appear within min- depend on antibody reactions, nor do they involveutes to several hours after exposure, or it can be other aspects of the immune system.delayed, when symptoms appear hours after expo- Allergy patterns may change during a lifetime;sure or longer. old sensitivities may vanish, and new ones may At the top of the list of food allergens are DAIRY appear according to the health of the immune sys-products, PEANUTS, nuts (e.g., HAZELNUTS, CASHEWS), tem and to the amount of allergen exposure. Intro-GRAINS (especially WHEAT and CORN), SOYBEAN prod- ducing solid foods before an infant’s DIGESTIVEucts, CITRUS FRUITS, and SHELLFISH. The binders and TRACT is fully developed carries an increased risk ofother ingredients of vitamin supplements, as well the development of food allergies. Children areas HERBS and SPICES, can cause reactions in suscep- more likely to suffer from allergies than adults,
30. 22 allergy, immediatethough they often outgrow them. Individuals who lishes Cooking for People with Food Allergies. (See alsohave relatives with allergies are more prone to ALLERGY, IMMEDIATE; ALLERGIC RHINITIS; CHALLENGEdevelop food allergies themselves. Food allergies TESTING.)are more likely to occur with inadequate nutrition, Brostoff, Jonathan, and Linda Gamlin. Food Allergies andinfections, and physical and emotional stress. Food Intolerance: The Complete Guide to Their IdentiﬁcationFaulty DIGESTION and intestinal inﬂammation can and Treatment. Rochester, Vt.: Healing Arts Press, 2000.allow food ALLERGENS to penetrate intestinal barri- Walsh, William E. Food Allergies: The Complete Guide toers and enter the bloodstream. Understanding and Relieving Your Food Allergies. New Depending on how food allergy is deﬁned, esti- York: Wiley, 2000.mates of the prevalence of food allergies rangefrom 2 percent to 25 percent of the U.S. popula- allergy, immediate (immediate hypersensitivity)tion. Opinion is also divided regarding the predom- An inﬂammatory reaction responsible for the famil-inant form of food allergies. Those who consider iar hay fever, asthma, and hives due to exposure tofood allergy an uncommon phenomenon focus on an ALLERGEN. These symptoms seldom leave anythe readily observable, rapid systemic reactions to doubt as to their cause. The key lies within mastfoods. These generate hay fever–like symptoms cells, defending cells embedded in tissues, which(immediate hypersensitivity). Other research indi- carry a bound ANTIBODY (IgE) on their surfaces.cates that typical food allergies are complex Upon contact with an invader, mast cells releaseimmune reactions resulting in delayed hypersensi- inflammatory agents such as histamine andtivity. They frequently involve antibodies in the leukotrienes that evoke swelling, itchiness, copiousblood (IgG type), and symptoms develop over mucous secretion, and the spasm of muscles of thehours or days after consuming the problem food. intestinal tract and of air passageways (bronchioles).This delay increases the difﬁculty in relating a spe- Common materials often trigger fast-developingciﬁc food to sometimes vague symptoms. reactions: dust, pollen, animal dander, medications, The most common symptom of food allergy is disease-producing microorganisms, and pollutants.FATIGUE. Other symptoms range from those typical Seafood, milk, sulﬁtes, PEANUTS, and strawberriesof PREMENSTRUAL SYNDROME to HYPOGLYCEMIA, are a few of the food-related causes of immediateeczema, irritability, achy joints, puffy eyes with hypersensitivity. It may come as a surprise thatdark circles, or postnasal drip. Food allergies may immediate allergic reactions account for a smallproduce asthma in the respiratory tract; in the fraction of food allergies. Most food allergies are ofbrain, insomnia, mood changes, confusion, or the slow-reacting type.fatigue; in the gastrointestinal tract, INDIGESTION, Anaphylactic shock is the condition resultingirritable colon, CONSTIPATION, or DIARRHEA. from allergic reaction and affects the whole body A simple, proven method of coping with food quickly. It produces labored breathing, fever,allergies is abstinence. Avoiding the offending food erratic heartbeat, violent coughing, hives andfor several days to several weeks may allow the edema, even convulsions. This severe response canimmune system to return to normal. If symptomsrecur when the questionable food is eaten again, be life-threatening. Individuals who are susceptiblethat food is probably the culprit. ROTATION DIETS to severe allergy attacks may be advised to carryhave been devised to minimize exposure to aller- injectable medications (“bee sting” kits containinggenic foods. Because allergy-restricted diets can be adrenalin or other drugs). (See also ALLERGY, FOOD.)difﬁcult to balance nutritionally, those who havemultiple food allergies may wish to consult both a allspice (Pimenta ofﬁcinalis; Jamaican pepper) Aphysician and a nutritionist. Individuals with food spice prepared from ground, unripened, reddish-allergies often need to ﬁnd substitutes for common brown berries of an evergreen tree found in thefoods. A wide variety of food allergy cookbooks are Caribbean, Central America, and Mexico. Its namenow available to help plan delicious, nutritious derives from the observation that its aroma resem-meals. The U.S. Government Printing Ofﬁce pub- bles a blend of cloves, cinnamon, nutmeg, and
31. alpha linolenic acid 23juniper berries. Allspice is used to season sausage, sitive people, and pregnant women should not takesalt beef, pickle sauces, and marinades. aloe internally. Aloe vera skin gel may slow the healing of infected surgical incisions.almond (Prunus amygdalus) A cultivated, elon-gated nut with white meat and a brown skin. The alpha linolenic acid Chemically speaking, thisalmond tree resembles the PEACH, to which it is FATTY ACID has 18 carbons and a pair of doublerelated. The almond originated in Asia and was bonds. It cannot be synthesized by the body andknown to the Romans as the “Greek nut.” There must be obtained from the diet. A POLYUNSATURATEDare two varieties: the sweet almond and the bitter FATTY ACID, it is classiﬁed as an essential dietaryalmond, which has a stronger ﬂavor. nutrient. Alpha linolenic acid is the smallest of the Almond extracts are used to ﬂavor cakes and omega-3 family of polyunsaturated fatty acids, dis-pastries, and slivered or ﬂaked sweet almonds are tinguished by subtle structural differences in whichused in cakes, cookies, and pastry. Dried almonds the double bonds begin at the third carbon fromare served raw or roasted and salted. Nuts roasted the end. It is the building block of larger omega-3with coconut or palm oil dramatically increase acids, including EICOSOPENTAENOIC ACID andtheir caloric content and increase their SATURATED DOCOSOHEXAENOIC ACID (DHA), which in turn formFAT content. Almonds are also used as ingredients the PG3 class of PROSTAGLANDINS, hormone-likeof stufﬁngs and couscous, and they can accompany substances that decrease inﬂammation, decreaseFISH or POULTRY dishes (the garnish is known as blood clotting and lower blood CHOLESTEROL. PG3amandine). Almonds are a good source of CALCIUM prostaglandins help return the body to equilibriumand they are also rich in oil. Most of the oil is after physical stress or injury.monounsaturated and more closely resembles Omega-3 fatty acids are deﬁcient in the standardOLIVE OIL than typical vegetable oils like SAFFLOWER American diet, and this deﬁciency may be linked tooil, which are high in polyunsaturates. One ounce an increased risk of heart attacks and inﬂammation(28 g) of raw, sweet almonds provides 167 calories; associated with degenerative disease. Chronic,carbohydrate, 5.7 g; ﬁber, 3 g; fat, 14.8 g; protein, severe deﬁciencies impair vision, increase inﬂam-5.9 g; calcium, 75 mg; iron, 1.0 mg; niacin, 0.95 mation, and diminish learning curves in experi-mg; thiamin, 0.06 mg; riboﬂavin, 0.22 mg. mental animals. The utilization of alpha linolenic acid may be limited in some disease states. The ner-aloe vera A succulent plant with long pointed vous system and brain contain high levels of theleaves that produces a JUICE with medicinal proper- omega-3 fatty acids, and there is a positive rela-ties. There are hundreds of different aloe species. tionship between the content of these fatty acids inAloe extracts are a folk remedy, long used to treat the diet and vision and brain function. Pre-termmild burns, insect bites, abrasions, minor cuts and babies need DHA because their livers are notchaﬁng, fever blisters, poison ivy, and to relieve mature enough to synthesize it from alphajoint inﬂammation and allergic reactions. Research linolenic acid.has yielded mixed results. Most human studies Good dietary sources of the omega-3 fatty acidshave been uncontrolled. Evidence suggests that are limited. Breast milk contains omega-3 fattyaloe vera may help heal ulcers and gastrointestinal acids, suggesting their importance in an infant’sinﬂammation and ﬁght infections by boosting the growth and development. Food processing destroysimmune system. Although a 1985 U.S. FDA study or removes the omega-3s, and there are none ingroup concluded that aloe vera did not heal burns, FAST FOODS such as PIZZA, fried FISH sandwiches,recent clinical studies indicate burn healing is fried chicken, or HAMBURGERS. The most commonspeeded up by aloe, possibly by improving collagen sources are ﬁsh and FISH OILS, FLAXSEED OIL, andformation and by improving blood ﬂow to dam- pumpkin seeds; ﬁsh oil and ﬂaxseed oil are sold asaged areas. There is preliminary evidence that aloe supplements. Because oils containing essentialmay help prevent severe conditions such as CAN- fatty acids readily oxidize and become rancid theyCER. Very rarely, aloe vera may cause a rash in sen- need to be protected from oxygen and heat. They
32. 24 alpha tocopherolare usually packaged with ANTIOXIDANTS, such as Whether this is a cause or an effect of the disease isVITAMIN E. Buying small quantities of these oils and not known.refrigerating them in sealed containers after open- Patients with kidney disease and anyone regu-ing reduces the risk of rancidity. These oils should larly consuming antacids that contain aluminumnot be used for cooking. compounds should be aware of the risks. Patients should avoid taking medications containing alu-alpha tocopherol See VITAMIN E. minum with orange juice (CITRIC ACID); this combi- nation can dramatically increase aluminum uptake in the body. Acidic foods like TOMATO sauce, apple-aluminum A metallic ion that is widely distrib- sauce, and SAUERKRAUT should not be placed in alu-uted in water and soil. Drinking water often con- minum foil or in uncoated aluminum cookwaretains aluminum beyond levels leached from soil because these foods dissolve aluminum, which canand clay because aluminum hydroxide is often then be absorbed.added to municipal water supplies to clarify drink-ing water. Aluminum is often added to food. Aluminum Alzheimer’s disease A progressive, degenerativecompounds make PROCESSED FOOD more creamy disease of the brain and the leading cause of SENIL-and pourable. They are quite versatile and are ITY in the United States. About 4 million Americansfound in INFANT FORMULA, pickles, relishes, BEER, have Alzheimer’s disease, roughly 10 percent of theCREAM OF TARTAR, grated CHEESE, canned foods, U.S. population over the age of 65 and nearly halfBAKING POWDER, and self-rising FLOUR. Aluminum is of the population over 85. The disease can alsoalso found in the medicine chest: A major source of strike younger adults (a small percentage of peoplealuminum is ANTACIDS (such as Maalox), which in their 30s and 40s have Alzheimer’s). On average,have a high aluminum hydroxide content. Anti- a person lives between eight and 20 years after theperspirants, over-the-counter analgesics (pain onset of symptoms, which include short-termrelievers, such as buffered ASPIRIN for arthritis), and memory loss, difﬁculty performing simple tasks,other pain medications contain aluminum. The and disorientation to time and place. Alzheimer’saverage daily intake from all sources ranges from disease results from the death of nerve cells in the10 to 100 mg. Most of this is not absorbed; of the forebrain and the hippocampus responsible forfraction of aluminum that is absorbed by the body, memory and learning. Patients also have a deﬁ-most is subsequently excreted. ciency of ACETYLCHOLINE, a NEUROTRANSMITTER Although aluminum is not a heavy metal, accu- made by neurons that helps carry nerve impulsesmulated evidence suggests that this substance may between cells. Currently, diagnosis of Alzheimer’sbe harmful. Aluminum may cause dialysis demen- disease is very difﬁcult, yet a comprehensive diag-tia, SENILITY, and brain damage in young patients nosis is critical in treating the senile patient.undergoing hemodialysis for kidney failure. Their Symptoms occurring before the age of 65 areincreased aluminum intake is due to the use of designated early-onset Alzheimer’s; after 65, it isantacids containing aluminum and to the elevated called late-onset Alzheimer’s.aluminum content of water used for dialysis. More Despite intensive research over the last decade,generally, high levels of aluminum may inhibit it is not known whether Alzheimer’s disease is aphosphate uptake by the intestine and may function of AGING, or whether it is the result of aincrease CALCIUM losses by excretion by the kid- speciﬁc disease process. Alzheimer’s seems to beneys. The imbalance may cause brittle bones and a multifaceted disease, with environmental andmay disturb bone formation. Other evidence sug- genetic factors contributing. There is an associationgests that excessive aluminum impairs the body’s with Down’s syndrome and thyroid disease. Smok-immunity. ing a pack of cigarettes a day increases the odds of Aluminum seems to accumulate in the brain developing Alzheimer’s disease. Diet also plays awith age, and high levels of aluminum are found in part. A healthy diet with low fat intake may reducethe brains of victims of ALZHEIMER’S DISEASE. the risk of developing Alzheimer’s disease; studies
33. Alzheimer’s disease 25also suggest that a high-fat diet during early and dence links immune system activation with the dis-mid-adulthood may be associated with an in- ease process.creased risk of developing Alzheimer’s, especially Research points to the following possible causesin people with a genetic marker called apoE-4. In a of senility: exposure to toxins, oxidative damageretrospective study that examined food eaten by due to FREE RADICALS, abnormal protein metabo-304 men and women (72 with Alzheimer’s disease lism, slow viruses, the narrowing by cholesteroland 232 healthy individuals), researchers found deposits of arteries feeding the brain, ZINC and VIT-that people with the apoE-4 gene who also ate the AMIN B12 deﬁciencies, head trauma, and adversemost fat were seven times more likely to develop drug reactions that decrease blood and oxygen sup-Alzheimer’s than were people with the marker ply to the brain.who ate lower-fat diets. In a separate 2000 study of Clinical trials of an experimental vaccine for theAmericans between the ages of 40 and 50, those disease, called AN-1792, were halted abruptly inwho carried the apoE-4 gene and whose diet con- early 2002 when several participants developedsisted of 40 percent fat calories had 29 times the brain inﬂammation after taking it. The drug was arisk for Alzheimer’s compared to non-apoE-4 carri- form of beta-amyloid, a protein fragment found iners on the same high-fat diet. the amyloid plaques that grow over the brain tissue Some population studies have reported an asso- of Alzheimer’s patients. Researchers had hopedciation between low-fat diets and a lower incidence exposure to the protein would trigger participants’in Alzheimer’s. For example, in China and Nigeria, IMMUNE SYSTEMs to produce antibodies to the amy-where fat intake is low, the risk of developing loid plaques.Alzheimer’s is 1 percent at age 65 compared to 5 Experiments in mice have shown that FOLICpercent in the United States. In the Netherlands ACID—a vitamin found in high amounts in darkresearchers reported an association between de- green, leafy VEGETABLES, CITRUS FRUITS and JUICES,mentia and diets high in total fat, saturated fat, and whole wheat BREAD, and dry BEANS—may helpcholesterol. ward off Alzheimer’s disease. Since 1998 the U.S. Scientists have identified four genes that FDA has required the addition of folic acid toincrease the risk of developing Alzheimer’s. APOE- enriched breads, CEREALS, FLOURS, CORNMEAL,4 is implicated in late-onset cases. This gene can be PASTA, RICE, and other GRAIN products.passed down from one or both parents. Patients There is limited evidence that antioxidants maywho have one copy of the gene have a three times help ﬁght or prevent some of the brain cell damagegreater risk of developing the disease than do in Alzheimer’s disease that may be attributed topatients who do not. Patients who inherit two free radicals, thus slowing the progression of thecopies have an eight times greater risk of develop- disease. In particular, some evidence suggests thating Alzheimer’s. The other three genes—presenilin vitamin C or vitamin E supplements can slow the1, presenilin 2, and amyloid precursor protein—are course of Alzheimer’s over several years. In aassociated with early-onset cases. Nearly everyone National Institute on Aging study, the antioxidantwho carries one or more of these genes will vitamin E delayed by six months the progression ofdevelop early-onset Alzheimer’s. some symptoms of Alzheimer’s disease. Another hypothesis for Alzheimer’s links In another National Institute on Aging study,chronic CALCIUM deﬁciency to increased uptake of people in the middle to late stages of Alzheimer’sALUMINUM and silicon by the brain. Aluminum con- who took vitamin E at levels 70 times higher thancentrates in the brains of patients with the disease; the recommended daily dose noticed some beneﬁ-whether this is a cause or an effect is unknown. In cial effects. At a dose of 2,000 IU daily, vitamin Epostmenopausal women, estrogen (hormone) re- was able to slow the expected rate of decline com-placement therapy may help prevent Alzheimer’s. pared to patients who did not take the vitamin.The importance of estrogen in brain health is grad- Other studies suggest that taking antioxidantsually being recognized. Alternatively, there may be (vitamins C and E) might signiﬁcantly lower thealterations in nerve cell membranes. Other evi- risk of developing Alzheimer’s. In one preliminary
34. 26 amanitaMassachusetts study, none of the 50 subjects who Nutritional approaches to treatment employused either vitamin C or E developed Alzheimer’s CHOLINE and LECITHIN (phosphatidylcholine) sup-at follow-up studies. In a Dutch study of 5,000 peo- plements. The rationale for their use is based onple, a diet high in antioxidants reduced the risk of the fact that the brains of diseased patients do notdeveloping Alzheimer’s. make enough acetylcholine, and supplying this Other antioxidants, such as GINKGO biloba and building block could boost acetylcholine produc-PHOSPHATIDYLSERINE, melatonin, ﬂavonoids (chem- tion. Results of clinical studies have not shownicals found in many plants, including fruits and consistent improvements. Researchers have usedvegetables), and carotenoids (pigments found in drugs that help maintain acetylcholine levels withplants such as carrots) also may help ease symp- mixed results. A growth promoter called nervetoms of Alzheimer’s disease. Small studies of growth factor may enhance brain function in agedginkgo did find slight improvement among patients experimental animals. Preliminary research sug-with Alzheimer’s who took the herb. Although gests that GINKGO biloba, a leaf extract, is known toGerman physicians have approval to use ginkgo to have antioxidant and anti-inﬂammatory propertiestreat Alzheimer’s, and it has been used for thou- and to enhance NEUROTRANSMITTER function, allevi-sands of years in Chinese medicine, North Ameri- ates the symptoms of Alzheimer’s disease.can physicians disagree as to its beneﬁts as a Scientists are currently studying whether a low-memory treatment. fat, high-ﬁber diet may reduce the risk of develop- According to several studies, eating plenty of ing Alzheimer’s disease just as it lowers the risk ofdark-colored fruits and vegetables may slow brain other diseases associated with aging, like cardiovas-aging. Extracts of blueberries and strawberries cular disease and cancer. Finnish researchers whoreversed age-related decline in lab animal brain studied 1,500 patients for 21 years found that sub-function. Blueberries may be the best anti- jects with high CHOLESTEROL and high blood pres-Alzheimer’s antioxidant of all. When Tufts Univer- sure had a corresponding higher risk of developingsity researchers analyzed more than 40 fruits and Alzheimer’s. French researchers noted a linkvegetables, they found that raw blueberries con- between high blood pressure and Alzheimer’s risk.tained the highest level of antioxidants (nearly 60 (See also CARNITINE; SENILITY.)times the recommended daily levels)—more than Rogaeva E., A. Tandon, and P. H. St. George-Hyslop.blackberries, beets, spinach, and garlic. Animals fed “Genetic Markers in the Diagnosis of Alzheimer’s Dis-an antioxidant-rich blueberry extract diet showed ease.” Journal of Alzheimer’s Disease 3, no. 3 (Junefewer age-related motor changes and outper- 2001): 293–304.formed their study counterparts on memory tests. Stramek, J., and N. Cutler. “Recent Developments in the Some studies on wine have reported a lower Drug Treatment of Alzheimer’s Disease,” Drugs andrisk, but they have not been consistent. It might be Aging 14, no. 5 (1999): 359–373.that wine may increase even more risk of develop-ing Alzheimer’s for people who carry the apoE-4 amanita A genus of MUSHROOM that includesgene that has been linked to Alzheimer’s—while many poisonous species, along with a few edibleprotecting people who do not carry the gene. ones. Amanita species can be confused with edible However, supplements containing high doses of mushrooms. The most common cause of mush-antioxidants can cause adverse effects. In addition, room poisoning is the ingestion of A. phalloideshigh doses of vitamin E are potentially harmful if (death cap) and A. virosa (destroying angel). Thesecombined with blood-thinning drugs. No one species produce speciﬁc toxins called amatoxinsshould take these or any supplements without con- and phallotoxins, compounds with cyclic AMINOsulting a doctor. ACID structures. A single mushroom may contain It is safer to consume antioxidants as part of a enough of these poisons to kill an adult. Eating thehealthy diet; antioxidants are found in most dark mushroom can cause LIVER, HEART, and KIDNEYcolored fruits and vegetables, whole grains, damage, as well as symptoms of common shocklegumes, nuts, and wheat germ. and delirium.
35. amino acids 27amaranth (Amaranthus cruentus; grain amaranth) broken down and are used for energy in the body.A nutritious alternative to WHEAT. The tiny spherical Amino acid synthesis is important because approx-seeds are the size of poppy seeds. Originally grown imately half of the different amino acids used asin Mexico as a staple food of the Aztecs, it was eaten PROTEIN building blocks can be made from CARBO-in rituals of Native Americans until the Spanish HYDRATES. Amino acids such as ALANINE, GLUTAMICconquest of Mexico, when its cultivation was out- ACID, and GLUTAMINE made by the brain and MUSCLElawed. Amaranth is now cultivated in the United help transport NITROGEN waste products via theStates, and its excellent nutritional qualities account bloodstream to the LIVER for disposal. When aminofor its present popularity. Amaranth possesses a acids are degraded, the ﬁrst step (transamination)higher PROTEIN content than most CEREAL GRAINS; releases nitrogen with the help of VITAMIN B6. Thethe nutritional value of amaranth protein ﬁnal nitrogen-containing waste product is UREA.approaches that of MILK. Its protein contains a high The second step of amino acid degradationpercentage of the essential AMINO ACID lysine, which requires the oxidation of the carbon atoms ofis low in other grain proteins like wheat. Amaranth amino acids to produce ATP, the energy currency ofdoes not contain typical wheat ALLERGENS, nor does cells. The waste product is CARBON DIOXIDE. Anit contain GLUTEN; therefore, people allergic to alternative route permits the liver to convert mostwheat can often eat amaranth because it belongs to amino acids to blood sugar (GLUCOSE) when thean unrelated plant family. Amaranth is available in diet does not provide adequate carbohydrates thathealth food stores as a whole grain, a FLOUR, and as can be digested to glucose to fuel the brain. ThisCRACKERS and breakfast cereals. Amaranth ﬂour has process is called GLUCONEOGENESIS. HEME (the pig-a nutty ﬂavor and can be used to supplement wheat ment of red blood cells), neurotransmitters (brainﬂour. Popped amaranth seed is mixed with honey chemicals that carry nerve impulses), purinesto make a Mexican confection known as alegria. (building blocks of RNA and DNA), and HORMONESAmaranth species have also been cultivated in Asia represent important amino acid derivatives. (Seeas a source of greens (een choi in China, hiyu in also UREA CYCLE.)Japan, and CHAULAI in India). One hundred gramsof amaranth provides protein, 15 g; carbohydrate, amino acids (alpha amino acids) Small organic66 g; ﬁber, 4.5 g; fat, 5.7 g; and fat, 4.5 g. acids that serve as raw materials of PROTEINS. The 50,000 to 100,000 different proteins in the bodyamine A very large family of basic organic com- are combinations of just 20 different types of aminopounds that contain nitrogen. Amines become pos- acids. During protein synthesis, amino acids areitively charged ions (cations) in the blood. linked together like beads on a string to form longPhysiologically important amines include the hor- chains (polypeptides). Each type of protein pos-mones EPINEPHRINE (adrenaline) and norepineph- sesses a unique amino acid sequence, speciﬁed byrine, and neurotransmitters such as ACETYLCHOLINE the cell’s genes.and SEROTONIN, chemicals released by activated As the name implies, each amino acid possessesnerve cells. CHOLINE serves as a raw material for an amino group and a carboxylic acid functionalboth acetylcholine and LECITHIN, a common LIPID of group, and therefore amino acids behave as bothcell membranes. All AMINO ACIDS used to build PRO- ACIDS and BASES. They also possess side chains withTEINS have properties of amines. Tyramine found in different properties. For example, certain aminofermented foods is an amine that can cause acids, like ASPARTIC ACID and GLUTAMIC ACID, areheadache and food sensitivities. A variety of acidic; others like ARGININE and LYSINE are basic;amines in food can react with the food additive METHIONINE and CYSTEINE contain SULFUR. Anothernitrite to produce cancer-causing substances group repels water and has the branched chains:(nitrosoamines). VALINE, LEUCINE, and ISOLEUCINE. Just as hands and feet are mirror images of eachamino acid metabolism Chemical processes by other, amino acids occur as mirror-image formswhich amino acids are either synthesized or are (optical isomers). The left-hand forms are desig-
36. 28 amino sugarsnated as “L,” and the right-handed opposites are eight amino acids to prevent malnutrition. Thesedesignated as “D.” Only L-amino acids are supplied dietary “essential” amino acids are lysine, valine,by food and synthesized in the body, and only the PHENYLALANINE, TRYPTOPHAN, isoleucine, leucine,“L” forms occur in proteins. Therefore, unless indi- METHIONINE, and THREONINE. Two other amino acidscated otherwise, an amino acid can be assumed to may be conditionally essential. HISTIDINE may notbe the “L-” form when mentioned in nutrition lit- be formed in adequate amounts by infants anderature. The only common amino acid that does growing children, and arginine may be inade-not exist as optical isomers is glycine, the simplest quately synthesized by adults with liver disease andof amino acids. by BREAST-FEEDING mothers. DIGESTION of food proteins releases amino acids, Amino acids like phenylalanine and arginine,which are absorbed in the INTESTINE. Depending on thought to stimulate GROWTH HORMONE release andthe person’s body size and the type of protein that thus promote FAT loss, are neither safe nor effectiveis consumed, 55 g to 65 g of protein a day supplies methods for weight control. Large amounts (sev-adequate amino acids for an adult. Few Americans eral grams per day) of single amino acids used asare likely to be protein-deﬁcient, because the typi- supplements or additives, can drastically affect thecal U.S. diet generally supplies twice as much pro- body and damage the KIDNEYS. The therapeutic usetein as needed. With a varied diet, neither a meat of amino acids is still in experimental stages. Theeater nor a knowledgeable VEGETARIAN needs extra U.S. FDA removed amino acids from the GENERALLYprotein to obtain adequate amino acids. RECOGNIZED AS SAFE list of FOOD ADDITIVES, and it is MEAT, FISH, POULTRY, and DAIRY products like EGGS prudent to consult a health care provider beforeare the best sources of essential amino acids. Pro- supplementing with individual amino acids. (Seeteins that provide ample amounts of essential amino also BIOLOGICAL VALUE; CHEMICAL SCORE; FOOD COM-acids are said to be COMPLETE PROTEINS. Several plant PLEMENTING.)proteins approach the quality of animal protein: soy, Cynober, Luc A., ed. Amino Acid Metabolism and Therapy inAMARANTH and QUINOA are examples. However, most Health and Nutritional Disease. Boca Raton, Fla.: CRCplant proteins are deﬁcient in at least one essential Press, 1995.amino acid. For example, LEGUMES are low inmethionine; CORN is low in lysine. These foods canbe balanced during the day by eating “complemen- amino sugars A family of nitrogen-containingtary” protein foods that provide ample amounts of sugars. Cells attach NITROGEN to the simple sugarsthose amino acids deﬁcient in another food. GLUCOSE and GALACTOSE to produce GLUCOSAMINE Surplus dietary amino acids may be used for and galactosamine, respectively. These and similarenergy, and amino acids from the breakdown of amino sugars are used to produce carbohydrate-cellular protein can be important fuel sources containing proteins (GLYCOPROTEINS) that coat cellwhen food intake is inadequate. After 12 to 24 surfaces, and for structural materials (MUCO-hours without food, MUSCLE protein breaks down POLYSACCHARIDES) that help form the matrix of car-rapidly, releasing amino acids into the bloodstream tilage for ligaments and joints.and processing them in the LIVER. The liverremoves NITROGEN and converts it to UREA, while ammonia (NH3) The nitrogen waste producedconverting the amino acids to GLUCOSE and releas- primarily from AMINO ACID metabolism. Ammoniaing it into the bloodstream to maintain blood sugar is highly toxic to the nervous system and the brain.levels. In this way, most amino acids can contribute It may interfere with metabolic processes requiredto blood glucose; consequently, muscle protein can for energy production in the brain. Normally thehelp fuel the brain during STARVATION when the brain transforms ammonia into GLUTAMINE, a safe,glucose supply becomes critical. neutral amino acid released into the bloodstream. Ten amino acids are designated as dietary “non- Next, glutamine is absorbed by the intestine, whichessential” amino acids because they are synthesized releases the ammonia for disposal by the LIVER.by the body and do not need to be supplied in food. Normally the liver very efﬁciently metabolizesOn the other hand, the diet must provide the other ammonia to UREA, the ultimate nontoxic waste
37. anabolic steroids 29product, via the UREA CYCLE to keep the level of nurture the future embryo, seedling or sprout. It isammonia in the blood at very low levels. Urea is often the major form of starch and it possesses aexcreted safely in urine. Ammonia is also produced highly branched, bushy structure resembling liverin the intestinal tract by bacteria. Ammonia is GLYCOGEN (animal starch). In contrast, AMYLOSE isabsorbed by the intestine and transported directly made up of single straight chains of glucose units.via the portal vein to the liver for disposal. Amylopectin forms a paste in hot water. Starch Liver disease, such as CIRRHOSIS, reduces urea occurs in seeds, tubers, and root vegetables asproduction and leads to elevated blood levels of both amylopectin and amylose, although the ratioammonia (ammonemia), which causes neurologi- of two forms varies with the source. Cooking soft-cal abnormalities. Genetic defects in the ammonia- ens starch granules, making them available todisposal mechanism of the urea cycle generally DIGESTION by AMYLASE. The ultimate product oflead to brain damage. amylopectin digestion is GLUCOSE. Commercial pro- cessing converts starch to glucose, then to HIGH- FRUCTOSE CORN SYRUP, a major sweetener. (Seeammoniated glycyrrhizin See GLYCYRRHIZIN. also COMPLEX CARBOHYDRATE; FRUCTOSE; POLYSAC- CHARIDE.)amphetamines Prescription drugs that stimulatethe central nervous system. Benzedrine sulfate,Amphaplex 10, Bexidrine and Biphetamine are amylose A water-soluble form of STARCH foundexamples of amphetamines that temporarily sup- in seeds, tubers, and root vegetables. It is made uppress APPETITE and were once prescribed for weight of long chains of GLUCOSE units, and often containsloss. Amphetamines are now used to control a thousand or more glucose units. Amylose differshyperactivity in children and to control bouts of from the other prevalent form of starch, AMY- LOPECTIN, which is highly branched. Amylose formsuncontrollable sleepiness (narcolepsy). Ampheta-mine abuse can cause exhaustion, ADDICTION, suici- large spiral conﬁgurations when dissolved in waterdal depression during withdrawal, cardiac and can react with iodide to form a characteristicproblems, insomnia, HYPERTENSION, and MALNUTRI- blue-purple pigment. Amylopectin and amyloseTION. (See also ALCOHOL-DRUG INTERACTIONS; occur together in starch, and the relative amountsAPPETITE SUPPRESSANTS; DIETING.) vary depending on the plant sources. During diges- tion, AMYLASE breaks down amylose to maltose, a disaccharide composed of two glucose units. Anamygdalin See LAETRILE. intestinal enzyme, MALTASE, then hydrolyzes mal- tose to the simple sugar glucose, the ultimate prod-amylase (alpha amylase) The enzyme produced uct of starch digestion.in the body that breaks down STARCH. Starch diges-tion begins in the mouth with amylase secreted in anabolic steroids A family of steroids related toSALIVA, as saliva is mixed with food during chew- the male sex hormone TESTOSTERONE. These areing. Starch digestion is completed in the intestine classiﬁed as prescription drugs used to make up forby amylase secreted by the PANCREAS. hormone imbalance and deﬁciencies. However, Amylase converts starch to a two-sugar frag- synthetic analogs of testosterone have beenment called maltose, which is too large to be obtained illegally by athletes and by teenage malesabsorbed. Therefore the intestinal enzyme MALTASE to build muscles, and the U.S. FDA has describeddegrades maltose to GLUCOSE, which is readily steroid abuse as a drug epidemic. While testos-taken up by the intestine and transported as blood terone stimulates growth during adolescence, theglucose. (See also CARBOHYDRATE; DIGESTIVE TRACT.) synthetic derivatives can cause many side effects. Athletes compound this unsafe practice by “stack-amylopectin The water-insoluble form of ing” anabolic steroids—taking a combination ofSTARCH. Plants synthesize this very long chain of brands at 10 to 100 times the recommended dosesGLUCOSE units as a storage form of energy, often to for weeks at a time.
38. 30 anabolism In men, the side effects of anabolic steroid use Growth and an anabolic state, seen as aninclude lowered sperm count, enlarged prostate increase in body mass and muscle mass, occur dur-gland, shrinking testicles, balding, and enlarged ing childhood, adolescence, pregnancy, and strenu-breasts. If taken before puberty, anabolic steroids ous physical activity, such as body building. Thecan stunt growth. These effects seem to be weight gained in these situations representsreversible if anabolic steroids have been used for a increased protein, bone, or fat, not ﬂuids. Increasedshort time. Some women body builders also use fat stores and accumulated body fat representsteroids to build muscle. Side effects in women do stored surplus energy in adults and can result fromnot seem to be reversible: masculinization, includ- too little exercise, the over-consumption of FOOD,ing increased muscles, increased size of clitoris, heredity, or a combination of the above factors.growth of facial hair, a deepening voice, shrinkage (See also ADIPOSE TISSUE; ANABOLIC STEROIDS.)of breast size, uterine atrophy, and menstrual irreg-ularities. Severe cases of acne and bouts of rage are anaerobic Cellular processes that do not requiresigns of anabolic steroid use, especially in males. oxygen. Energy can be produced in cells withoutAnabolic steroid use can have more subtle, long- oxygen. Anaerobic GLYCOLYSIS refers to an energyterm detrimental effects; damage may show up yielding process by which ATP, the energy currencyyears later as a HEART ATTACK, high blood pressure, of the cell, is produced from GLUCOSE without theCANCER, and LIVER damage in both men and participation of oxygen. As an example, skeletalwomen. muscle produces LACTIC ACID and ATP from glucose when oxygen supplied to muscle is inadequate toanabolism (biosynthesis) Processes involved in meet energy needs during strenuous physical exer-synthesizing the molecules needed for cellular tion. Accumulated lactic acid is then convertedgrowth and maintenance. Thus the formation of back to glucose during the recovery period follow-PROTEIN, DNA, RNA, LIPID, CARBOHYDRATE, FAT, and ing EXERCISE when the oxygen supply is again ade-GLYCOGEN are anabolic processes. Anabolism con- quate. Anaerobic processes are important forsumes chemical energy in the form of ATP and certain bacteria as well. Anaerobic bacteria in theNADPH (a reducing agent), which are supplied by intestine grow without oxygen and block theCATABOLISM, the energy-yielding oxidative pro- growth of potential disease-producing microorgan-cesses involved in degradation. Optimal function isms. Anaerobic fermentation of SUGAR by yeastand health rely upon a balance of anabolic and yields alcohol-containing products such as WINEcatabolic processes (homeostasis). These two and BEER. (See also AEROBIC; CATABOLISM.)branches of metabolism are controlled by theENDOCRINE SYSTEM, which in turn responds to anaphylaxis An extreme reaction of the immuneexternal inﬂuences such as diet. Anabolic processes system in response to exposure to foreign sub-require small building blocks supplied by breaking stances. Insect bites, drugs, injected serum, and cer-down STARCH, PROTEIN, and FAT in foods to build tain foods can create anaphylaxis. This abnormallarger molecules. GLYCEROL and FATTY ACIDS are the response or immediate hypersensitivity is usuallysubunits of fat; AMINO ACIDS yield proteins; and glu- very rapid in susceptible individuals who may havecose yields glycogen. Fat and carbohydrate degra- been sensitized by previous exposure, and maydation provides an energized form of ACETIC ACID produce shock (“anaphylactic shock”). The massive(acetyl CoA) to synthesize fatty acids and choles- release of histamines and other inflammatoryterol. Other specialized products are also assembled agents leads to spasming of smooth muscles, espe-from several different types of smaller precursors. cially those of the air passageways, and to wide-For example, heme, the iron-containing pigment of spread swelling due to the increased water leakingthe oxygen transport protein HEMOGLOBIN, is syn- out of capillaries. Symptoms range from asthma tothesized from an amino acid (GLYCINE) and SUCCINIC fever, itching, hives, and ﬂushed skin in mild cases,ACID, a common intermediate in energy-producing to chest constriction, irregular pulse, painful,pathways. labored breathing, and convulsions in severe cases.
39. anemia 31Anaphylaxis can be life-threatening and may plements they are not subject to the same rigorousrequire emergency room care. (See also ALLERGIC government testing as are prescription drugs. Ana-RHINITIS; ALLERGY, FOOD; ALLERGY, IMMEDIATE.) bolic steroids do stimulate muscle growth, but use of these drugs solely for that purpose is illegal. Con- sequently, many athletes and bodybuilders see pro-anchovy, European (Engraulis encrasicholus) A hormones as a way to obtain the same ﬁtnesssmall, herringlike marine ﬁsh harvested mainly in beneﬁts that anabolic steroids confer without vio-the eastern Atlantic Ocean and the Mediterranean lating the law.Sea. Anchovies are usually sold ﬁlleted, salted, and Little is known about the potential side effects ofpacked in oil. Their distinctly sea-salty taste is used prohormones like androstenediol, but if they havein appetizers or as a garnish on pizza and in salads. the same testosterone-related body enhancing abil-Anchovies are a key ingredient in Caesar salad ities as anabolic steroids, their side effects are prob-dressing. One anchovy packed in oil and salt pro- ably similar. In men short-term side effects includevides calories, 8.4; protein, 28.8 g; iron 4.6 mg; lowered sperm count, enlarged prostate gland,sodium, 3,668 mg; fat 5 g; cholesterol, 85 mg. shrinking testicles, balding, and enlarged breasts. Women may experience masculinization, increasedandrogen A class of steroid hormones that pro- size of clitoris, growth of facial hair, deepeningmotes secondary male characteristics (masculiniza- voice, shrinking breasts, and menstrual irregulari-tion). Androgens function in the body to stimulate ties. Long-term side effects for both sexes includeanabolic processes, such as deposition of muscle increased risk of HEART ATTACK, high blood pres-protein. Examples include TESTOSTERONE and sure, CANCER, and liver damage.androsterone, produced by gonads. Blue, J. G., and J. A. Lombardo. “Steroids and Steroid- The synthetic ANABOLIC STEROIDS resemble like Compounds,” Clinics in Sports Medicine 18, no. 3testosterone. These drugs have been obtained ille- (1999): 667–689.gally by male and female athletes and by those whowish to speed up or increase muscle mass and anemia A condition characterized by subnormaldecrease body fat beyond the rate obtainable by levels of HEMOGLOBIN, the oxygen-binding PROTEINtraining. The use of anabolic steroids causes physi- in blood. Half a million Americans are at risk forcal and mental changes that may be irreversible anemia, including 40 percent of pregnant women,and increase the risk of disease. (See also pre-menopausal women, vegans (those who eat noANABOLISM.) animal products), adolescents relying on JUNK FOOD diets, infants, and children with inadequate diets.androstenediol (4-androstenediol, 5-androstene- Anemia may result from either an inadequatediol) An androgenic steroid that a certain liver number of RED BLOOD CELLS (erythrocytes) or anenzyme converts to the male hormone testos- abnormally low hemoglobin content of red bloodterone. Androstenediol is one of several popular cells. With deﬁcient functional red blood cells, the“prohormones” sold as DIETARY SUPPLEMENTS and oxygen supply to tissues is inadequate for optimaltaken primarily by athletes and bodybuilders, who RESPIRATION, causing shortness of breath, FATIGUE,believe these substances can increase muscle mass weakness, pallor, headache, and lowered resistanceand strengthen much the same way as ANABOLIC to infection. There are two general types of anemiaSTEROIDS. Other prohormones in the androstene- based on red blood cell size. Megaloblastic anemiadiol family that are sold as dietary supplements is characterized by large red blood cells; their short-include dehydroepiandrosterone (DHEA), andro- ened life span results in a decreased number ofstenedione (“andro”), 19-norandrostenedione, and cells. Microcytic anemia is characterized by small19-norandrostenediol. red blood cells with reduced hemoglobin content. The bodybuilding attributes credited to andro- Many nutritional deﬁciencies lead to anemia.stenediol and related prohormones have not been Inadequate dietary IRON, COPPER, FOLIC ACID, PRO-substantiated by credible research. As dietary sup- TEIN, VITAMIN B6, vitamin B12, VITAMIN C, VITAMIN A,
40. 32 anemia, aplasticVITAMIN E, and RIBOFLAVIN can cause this condition. hemoglobins, and spherocytosis (spherical redEach of these nutrients is required for the produc- blood cells). Hemolytic anemia is the result oftion of red blood cells (ERYTHROPOIESIS). Iron deﬁ- excessive hemolysis (destruction of red blood cells)ciency anemia is the most common diet-related in susceptible people exposed to bacterial toxins,anemia in the United States and it represents the toxic chemicals, or drugs that may produce JAUN-last stage of iron deﬁciency. It is characterized by DICE. Anemia also may result from reduced nutri-small, pale red blood cells (microcytic anemia), due ent uptake due to the presence of parasites andto chronic blood loss or inadequate iron intake. chronic infections, gastrointestinal disease orSymptoms include FATIGUE, pallor, and shortness of bowel resection. (See also HEAVY METALS; HEMAT-breath. Studies of the nutritional status of devel- OCRIT; LEAD; MALNUTRITION.)oped nations have routinely found up to 30 per- Pruthi, R. K., and A. Tefferi. “Pernicious Anemia Revis-cent of a population with iron deﬁciency. Groups ited,” Mayo Clinic Proceedings 69, no. 2 (1994):that are at highest risk are children under the age 144–150.of two years, teenage women, pregnant women, Viteri, Fernando E. “Iron Supplementation for the Con-and the elderly. Pregnancy drastically increases the trol of Iron Deﬁciency in Populations at Risk,” Nutri-requirement of iron. In terms of blood loss the most tion Reviews 55, no. 6 (June 1997): 195–209.common causes of iron deﬁciency are excessivebleeding during menstruation and intestinal bleed- anemia, aplastic A form of ANEMIA in which theing due to parasites, ulcers, or malignancy. Iron numbers of RED BLOOD CELLS as well as white cellsdeﬁciency can be caused by impaired iron uptake are reduced. This type of anemia is caused by expo-by the intestine, due to a lack of stomach acid sure to chemicals (such as solvents), toxic heavy(ACHLORHYDRIA) or from chronic DIARRHEA. With metals, some drugs like chloramphenicol, or ioniz-iron deﬁciency, the resulting anemia can be treated ing radiation (like X rays). Radiation therapy,by iron supplementation. chemotherapy, and lead poisoning can damage Deﬁciencies of either folacin or vitamin B12 can bone marrow, thus reducing red blood cell produc-cause anemia because each is essential for DNA tion. Both the blood platelet count and immunitysynthesis and deﬁciencies impair erythrocyte pro- decline, with a concomitant increased susceptibilityduction. Folic acid deﬁciency is much more com- to infection. Destruction of the bone marrow ismon because folic acid stores in the body are small, potentially life-threatening.yet folic acid participates in many biosyntheticreactions. On the other hand, vitamin B12 is storedin the LIVER, and only trace amounts are required anemia, pernicious A form of ANEMIA causeddaily for a few speciﬁc functions. Anemia due to either by a dietary deﬁciency of VITAMIN B12 or byinadequate folic acid and vitamin B12 produces inadequate B12 absorption. It is characterized bylarge (macrocytic) cells with a short life span. This quite large red blood cells (macrocytic) that areform of anemia can occur when intake of fresh overloaded in the hemoglobin (hyperchromic).vegetables is very limited, or when the need for Low vitamin B12 consumption is a concern forfolic acid outstrips intake, as may occur during strict VEGETARIANS who avoid meat and meat prod-pregnancy or in ALCOHOLISM. Treatment with folic ucts. Pernicious anemia is also caused by inade-acid can ameliorate megaloblastic anemia, yet quate vitamin B12 uptake. Normally, the gastricmask an underlying vitamin B12 deﬁciency. This lining secretes a PROTEIN called INTRINSIC FACTORpoint emphasizes that treatment of anemia that’s needed to speciﬁcally bind vitamin B12.requires expert medical supervision. Because this protein is required for vitamin B12 Anemia can also indicate a serious condition absorption by the intestine, inadequate intrinsicunrelated to diet. Non-nutritional causes of ane- factor production, even with adequate dietary B12,mia include chronic blood loss and congenital can cause pernicious anemia.defects in red blood cell formation, such as tha- Pernicious anemia affects the nervous system aslassemia or sickle cell anemia, due to mutant well as the blood. Symptoms include memory loss,
41. anorexia nervosa 33weakness, personality and mood swings, and anise (Pimpinella anisum) An HERB belonging tonumbness and tingling in the hands and feet. If this the PARSLEY family that originated in India and wasanemia continues unchecked, nerve damage may cultivated in ancient China and Egypt. The fruit,be irreversible. Pernicious anemia is most common aniseed, is dried and used as a seasoning. The dis-in males between the ages of 40 and 65 years who tinctive, licorice-like ﬂavor of anise extract adds tohave a family history of the condition. Treatment the taste of shortbread cakes, such as pizella (Italy)for intrinsic factor defect involves vitamin B12 and pains á l’anis (France). Anise is used in certaininjections. Oral doses of vitamin B12 can remedy candies. Crushed aniseed together with cinnamondietary deﬁciencies when intrinsic factor produc- and coriander is used to make a liqueur, anisette.tion is normal. (See also FOLIC ACID.) Chopped anise leaves have been used in pickled vegetables and soups.angiotensin A protein-like hormone formed inthe blood that raises blood pressure. Angiotensin annatto (Bixa orellara) A yellow-red, natural,contracts the muscles of CAPILLARIES and ARTERIES vegetable food-coloring agent obtained from a(vasopressor), which increases resistance for blood small tropical tree that is native to Central America.ﬂow. Angiotensin is liberated by the action of Annatto is prepared from the pulp of the fruit andRENIN, an ENZYME formed by the kidneys, on a from the waxy layer around the seeds, and is usedserum PROTEIN (angiotensinogen) produced by the to give a yellow or orange color to several cheesesliver. The release of renin by the kidneys is trig- (Cheddar, Cheshire, Edam) and to smoked had-gered when they experience lowered blood ﬂow, dock, butter, and a variety of pastries and sweets.for example, due to dehydration. Angiotensin alsoplays an important role in the regulation of blood anorexia nervosa An EATING DISORDER involvingpressure by stimulating the ADRENAL GLANDS to compulsive STARVATION, resulting in a loss of 25secrete ALDOSTERONE. Aldosterone, in turn, pro- percent or more of the body weight. Anorexia ismotes SODIUM retention and water retention by the characterized by a sudden or severe weight loss, akidneys, to help regulate water balance. (See also continued effort to lose weight, a refusal to main-ANTIDIURETIC HORMONE; HYPERTENSION.) tain normal body weight, a failure to grow during adolescence, missed consecutive menstrual periods (amenorrhea), plus nausea, bloating, or constipa-animal drugs in meat See ANTIBIOTICS; MEAT CON- tion. Starvation symptoms include ACIDOSIS, KETO-TAMINANTS. SIS, and ELECTROLYTE imbalance. Behavioral aspects include food hoarding, food phobia, ritualization ofanion A negatively charged ion. Anions are the food preparation while eating very little, eatingopposite of CATIONS, which carry positive charges. alone, phobia of being obese, and feeling fat whenImportant anions are formed when weak acids ion- actually underweight. Anorexics seem to preferize. Anions, together with their cation counter- PROTEIN over CARBOHYDRATE. A ZINC deﬁciency mayparts, occur in blood and are called electrolytes. be involved in the disease because zinc supple-They are required to maintain the appropriate ments (25 mg/day) have helped some patients gaineffective concentration of ions and PROTEINS in the weight.blood. Key anions in blood are chloride (Cl–), Although boys and men can be anorectic, 90phosphate (H2PO4–), and bicarbonate (HCO3–). percent to 95 percent of patients are girls andChloride (Cl–) is the predominant anion in body women. Anorexia and bulimia together affect 5ﬂuids. Neither chloride nor phosphate can be made percent of young women in developed nations,by the body; they are essential nutrients to be sup- although the disorder is absent from less developedplied by the diet. Phosphate and bicarbonate ions nations. Anorexia usually begins with a desire tohelp buffer blood at nearly a constant pH. These lose weight or to prevent weight gain. Extremeanions are examples of “conjugate bases,” formed social pressure to be trim, an abnormal family envi-when weak acids ionize. (See also ELECTROLYTES.) ronment, an imbalanced ENDOCRINE SYSTEM or ner-
42. 34 anorexigenicvous system can trigger this behavior. The typical anorexigenic Capable of diminishing the APPETITE.patient is a white, female adolescent who is a bright Disease inﬂuences (DIABETES, OBESITY, CANCER) andoverachiever, attempting to meet high parental certain drugs can diminish appetite. Certain sub-expectations and wanting more control over her stances produced by the body also modulatelife. Low self-esteem may be an issue. APPETITE, especially hormones. Somatostatin and Anorexia is a multifaceted disorder and a broad- corticotrophin-releasing factor (produced by thebased treatment approach has been most success- HYPOTHALAMUS to control secretions by the PITUITARYful. Therapeutic programs use nutrition counseling, GLAND) and hormones of the gastrointestinal tractindividual psychotherapy, behavior modiﬁcation, (vasoactive intestinal peptide) decreased feeding infamily counseling and medications when required. experimental animals when trace quantities wereSuch a multidisciplinary approach involves nutri- administered directly to the brain.tionists and dietitians, nurses, physicians, socialworkers and counselors, and self-help groups. Their antacid A substance that neutralizes STOMACHgoals are to establish and maintain a desired body ACID used to relieve ACID INDIGESTION (heartburn),weight while resolving emotional issues and which manifests itself as a pain in the upperimproving the home environment. Fundamental to abdomen. Acid indigestion is very common; itnutritional care is a counseling program to help affects one-third of Americans. Medications topatients change their attitudes about food. Depend- relieve this condition are some of the most widelying on the patient’s nutritional status, a nutritional used over-the-counter drugs. Antacids are also usedprogram might entail nutritionally balanced meals, therapeutically to treat PEPTIC ULCERS. Stomach painadjusted for patient preferences, vitamin and min- can be due to STRESS or emotion, and not simply theeral supplements to remedy deficiencies, slow result of excess stomach acid. However, a severerefeeding with progressive increments in total daily pain could point to a more serious condition, suchCALORIES to reach the desired level of calories; and as a heart attack. Therefore, patients should seekongoing nutritional counseling. Anorexics will be medical attention for any severe chest pain accom-managed by an outpatient treatment program or by panied by short breath, weakness, and sweating.hospitalization when weight loss has been severe, Antacid use poses potential problems, andwhen there are serious metabolic problems, when antacids should be used only occasionally. Theythe family is in crisis, or where the patient is suici- work best when taken one-half to two hours afterdal. Nutritional rehabilitation programs vary a meal. Antacids may block the action of medica-according to the severity of the condition, but less tions, such as tetracycline, digitalis, and anticon-restrictive approaches seem to have better results vulsants. Protracted use of antacids interferes withfor weight gain. Psychotherapy usually focuses on calcium METABOLISM and bone formation. CONSTI-feelings about body image, self-esteem, food, con- PATION or DIARRHEA are the two most commontrol of one’s life and choices, and gaining indepen- adverse reactions to antacid use. In particular,dence from harmful family influences. Long antacids that contain ALUMINUM hydroxide or cal-illnesses, severe weight gain, a dysfunctional family cium carbonate can lead to constipation. Regardingbackground, late age of onset of the illness, and late aluminum-containing antacids, there are indica-occurring treatment make recovery more difﬁcult. tions that aluminum intake should be minimized The mortality rate is about 6 percent to 10 per- because aluminum may cause calcium and phos-cent due to mineral imbalances. The National Asso- phorus depletion. Aluminum hydroxide seems tociation of Anorexia and Associated Disorders and have minimal complications when combined withthe American Anorexia/Bulimia Association are magnesium hydroxide.among the resources available to anorexics. (See Calcium carbonate is a common antacid. Al-also DIET; MALNUTRITION.) though it neutralizes acids effectively, it may causeWoodside, D. B. “A Review of Anorexia and Bulimia Ner- acid overproduction later (rebound effect). Calcium vosa,” Current Problems in Pediatrics, 25, no. 2 (1995): carbonate can also block IRON uptake. Another 67–89. option is sodium bicarbonate, a major ingredient of
43. antibiotics 35several popular antacids. However, it should be MOLDS, and FUNGI. Natural or synthetic compoundsnoted that the typical American diet provides exces- are used extensively as antibiotics to treat infectioussive SODIUM, and sodium bicarbonate antacids could diseases in animals and plants as well as in humans.increase the burden for sodium-sensitive people. A Sulfanilamides, penicillins, and erythromycins arefurther reservation: Bicarbonate-based antacids examples of major families of these drugs. Antibi-may promote alkaline blood (alkalosis) or they may otics impact human health in several ways. The pro-alter KIDNEY or heart function. longed use of broad-spectrum antibiotics in treating Calcium carbonate is the major ingredient of disease drastically alters the intestinal microﬂora byseveral antacids. They have been recommended destroying beneﬁcial bacteria. The loss of beneﬁcialbecause they are inexpensive and calcium carbon- bacteria can permit less desirable, opportunisticate has a high content of calcium (40 percent of the microorganisms like yeast to ﬂourish, cause intesti-weight). However, taking antacids as a calcium nal inﬂammation, and decrease production of nutri-supplement can seriously lower stomach acidity ents important in maintaining health of the COLON.and decrease the efﬁciency of digestion. Under nor- Antibiotics can affect speciﬁc vitamin require-mal conditions, most forms of calcium supplements ments; chloramphenicol blocks RIBOFLAVIN and VIT-(calcium aspartate, calcium carbonate, calcium AMIN B6 and B12, for example. Penicillin increasesgluconate, and calcium orotate) are absorbed about POTASSIUM requirements. Antibiotics can decreaseas well as the calcium in whole MILK. Remember nutrient absorption in general by altering thethat calcium uptake requires an adequate intake of intestinal lining. Neomycin interferes with the up-VITAMIN D, MAGNESIUM, COPPER, and ZINC, while take of FAT, AMINO ACIDS, CARBOHYDRATE, water-adequate physical EXERCISE promotes calcium soluble and fat-soluble VITAMINS, CALCIUM, IRON,deposition in bones. (See also ALUMINUM; BONE; and VITAMIN K. Tetracycline decreases absorption ofOSTEOPOROSIS.) fat, amino acids, calcium, iron, MAGNESIUM, and ZINC, while increasing the rate of urinary excretionanthocyanins A family of plant pigments respon- of RIBOFLAVIN, FOLIC ACID, and VITAMIN C.sible for red to blue-red colors in fruits such as Antibiotics can have a direct impact on the foodBLACKBERRIES, RASPBERRIES, BLUEBERRIES, and CHER- supply. Half the antibiotics produced in the UnitedRIES. They belong to the family of FLAVONOIDS, plant States are applied to livestock. The beneﬁts aresubstances that are nonnutrients but have beneﬁ- more rapid growth and healthier animals. On thecial effects. When eaten, these materials bind to other hand the potential exists for generating drug-connective TISSUE, where they crosslink and resistant pathogenic bacteria and persistent antibi-strengthen COLLAGEN, the primary structural PRO- otic residues in meat and dairy products. TheTEIN of the body. Liberal consumption of ﬂavonoid- application of antibiotics in animal husbandry andrich foods may be appropriate for individuals the permissible levels of antibiotic residues in ani-subjected to oxidative STRESS and chronic inﬂam- mal products are regulated by the U.S. FDA. The fol-mation. Flavonoids generally function as antioxi- lowing examples illustrate the dimensions of thisdants to prevent tissue damage by FREE RADICALS, food safety issue.highly reactive molecules that can attack cells. Chloramphenicol This drug can cause ANEMIAThey help counter inﬂammation and associated in humans due to damage to bone marrow. Thoughpain by blocking the production of proinﬂamma- banned from use with food-producing animals,tory agents including prostaglandins and leuko- periodic spot inspections showed it was widelytrienes. (See also PHYTOCHEMICALS.) used in cattle and hogs in the 1980s. The degree to which chloramphenicol continues to contaminate meat through illegal application, and the degree toanti-aging nutrients See AGING. which such a contamination affects health, are unknown.antibiotics Chemicals that destroy or prevent Penicillin This common antibiotic is used togrowth of microorganisms including BACTERIA, treat dairy herds, among others. The allowable peni-
44. 36 antibodiescillin level in MILK is 0.01 units per milliliter (about IgG (gamma globulin) is the major class of anti-20 drops) of milk, but spot checks have found 10 bodies found in the blood. Elevated IgG is impli-times this level in commercial milk. Such high levels cated in slow-developing food allergies (delayedcan cause allergic reactions in susceptible individuals. hypersensitivity). After avoiding foods that cause Sulfamethazine This sulfa drug is a widespread such allergies, the immune system can return tocontaminant in MEAT, POULTRY, and milk. One- normal as allergen-speciﬁc IgG gradually disap-fourth of milk sampled in the late 1980s was con- pears from the blood. It may then be possible to tol-taminated, despite the U.S. FDA ban on this drug in erate allergenic foods if eaten infrequently.milk. Sulfamethazine is suspected of being a CAR- Secretory IgA is the major antibody released byCINOGEN. (See also ACIDOPHILUS; MEAT CONTAMI- mucosal surfaces such as the mouth and theNANTS; PESTICIDES.) intestinal tract, where it binds potentially danger- ous microorganisms and prevents their sticking toantibodies A class of PROTEINS produced by the tissue and initiating infections. Secreted IgA isIMMUNE SYSTEM to combat viruses, bacteria, and also an important antibody in COLOSTRUM andFUNGI and to neutralize foreign substances. Anti- BREAST MILK that helps protect the nursing infantbodies are made in response to foreign substances from infection until its own immune system isby B cells, a type of lymphocyte or white cell found able to mount a vigorous defense. (See also ALLER-in bone marrow or the lymphatic system. The GEN; ALLERGY, FOOD; ALLERGY, IMMEDIATE; BREAST-progeny of B cells are called plasma cells and are FEEDING; IMMUNE SYSTEM; ROTATION DIET.)responsible for antibodies appearing in body ﬂuidsin COLOSTRUM and on mucosal surfaces. anticaking agents A class of FOOD ADDITIVES used The body produces millions of different antibod- to maintain free-ﬂowing powdered and granularies and each type of antibody attacks a different materials. These useful additives are added to tableforeign material (ANTIGEN). The basis of this diver- salt, powdered sugar, malted milk powders, garlicsity lies in antibody structure, which allows a close and onion powders, powdered coffee whiteners,ﬁt with the antigen, much like a lock ﬁtting in a vanilla powder, BAKING POWDER, dried egg yolk, andkeyhole. Antigen-antibody binding then enables seasoning salts. Examples include DEXTROSE and sil-scavenger cells to engulf and degrade antigens. icates (aluminum silicate, magnesium silicate,Long after exposure to the antigen, information for sodium calcium aluminosilicate, calcium silicate,synthesizing it remains embedded in special lym- and silicon dioxide). These agents are judged to bephocytes called memory cells that enable the body safe food additives. (See also ALUMINUM; SODIUM.)to produce antibodies rapidly when again threat-ened by the foreign invaders. anticancer diet See CANCER. Antibodies reacting to normally harmless mate-rials may trigger overreactions of the immune sys-tem and may cause AUTOIMMUNE DISEASE, in which anticancer nutrients See CANCER.the body attacks its own tissues. Insulin-dependentDIABETES MELLITUS and rheumatoid ARTHRITIS are antidiuretic hormone (ADH, vasopressin) Aexamples. Allergic reactions are another example pituitary HORMONE that decreases urine output andof an overreaction of the immune system. conserves water in the KIDNEYS. ADH represents In nutrition, the most important classes of anti- the body’s primary water-conserving mechanism.bodies are IgE, IgG, and IgA. IgE antibodies are The anterior PITUITARY GLAND releases ADH into theresponsible for rapid allergic symptoms (immediate bloodstream in response to physiologic STRESS,hypersensitivity) related to HISTAMINE release: red, DEHYDRATION, diminished blood volume, or highrunny nose; hives; asthma; swelling; itching; or, in SODIUM concentration in the blood. The mechanismextreme situations, shock (ANAPHYLAXIS). This class involves these steps: First, receptors located in theof antibody is important in TISSUES and is less HYPOTHALAMUS detect increased osmolarity (ionprominent in the blood. concentration) of blood, then the hypothalamus
45. antioxidant 37stimulates the pituitary gland to release ADH. (See benzoate, which occurs naturally in FRUIT and VEG-also ENDOCRINE SYSTEM; HOMEOSTASIS.) ETABLES, prevents the growth of most microorgan- isms but requires acidic conditions for itsantigen A foreign material recognized by the antimicrobial action. Calcium propionate preventsIMMUNE SYSTEM. Antigens stimulate the formation the growth of mold and several bacteria and is aof speciﬁc antibodies, which bind the provoking common additive in BREAD to be stored at roomantigens to neutralize them. Generally, a single temperature. These too are safe food additives.type of antibody recognizes one type of antigen.Antigens may be PROTEINS, glycolipids, POLYSACCHA- antineuritic An agent that is capable of reliev-RIDES, microorganisms, or cells. The body has the ing damaged nerve inflammations (neuritis). Theability to neutralize a huge number of antigens inflammation of peripheral nerves of the wholebecause it can synthesize an immense variety of body may be due to nutritional deficiency, toxicantibodies. Because some antigens may share com- exposure, or metabolic imbalance. Neuropathy ormon structural features, antibodies may cross- nerve damage may result from long-term defi-react. Thus, antibodies against cow’s MILK may ciencies of the B vitamins THIAMIN, NIACIN, VITAMINcross-react with goat’s milk, and antibodies against B6, VITAMIN B12, or PANTOTHENIC ACID due to diet-WHEAT protein (GLUTEN) can cross-react with simi- ary deficiencies or to chronically poor absorptionlar proteins in other grains. (See also ALLERGEN; by the INTESTINE. As an example, thiamin counter-ALLERGY, FOOD.) acts neuritis, a typical symptom of severe thiamin deficiency. Alcoholics are prone to thiamin defi-antihistamine See HISTAMINE. ciency and neuritis because alcohol rapidly depletes the body’s thiamin stores. (See also MAL- NUTRITION.)antimetabolite A drug that interferes with celldivision. By mimicking an enzyme’s usual nutrient antioxidant A compound that prevents or retardsreactant, an antimetabolite tricks the cell’s machin- the oxidation of sensitive molecules found in theery and prevents normal growth. Sulfa drugs are body or in foods. Antioxidants occur in many foodsbacterial antimetabolites that block the bacterial naturally as nutrients or non-nutrients, or as syn-synthesis of the B vitamin FOLIC ACID, required for thetic additives. Antioxidants typically block oxida-bacterial growth. Because animal cells depend on tion by preventing damage caused by FREEfolic acid in the diet and cannot synthesize it, they RADICALS, extremely reactive forms of oxygen andare immune to sulfa drugs. A somewhat different other molecules that lack an electron and tear elec-strategy underlies the use of the anticancer drug trons from molecules they meet. In the body, likelymethotrexate. Methotrexate attacks cancer cells targets are DNA, PROTEINS, and LIPIDS (unsaturatedthat have a high rate of growth, by blocking the FATTY ACIDS).activation of folic acid to its biologically active form Free radicals form in the body by normal cellu-(coenzyme). Without a ready supply of the coen- lar processes. These include phagocytosis (engulf-zyme form, cancer cells stop growing rapidly. ing viruses and bacteria) by immune cells; incomplete reduction of oxygen as mitochondriaantimycotic agents FOOD ADDITIVES used to pre- burn fuels; production of hydrogen peroxide by thevent SPOILAGE. These PRESERVATIVES retard growth breakdown of fatty acids and the generation ofof YEASTS and MOLDS. Examples are sorbates, NITRIC OXIDE, a free radical that functions as a local-SODIUM BENZOATE, and CALCIUM PROPIONATE. Sorbic ized vasodilator, a defensive chemical and as neu-acid and POTASSIUM and sodium sorbates retard rotransmitter. Free radicals and reactive forms ofspoilage in CHEESE, syrup, JELLY, cake, MAYONNAISE, oxygen occur by chemical modiﬁcation of pol-SOFT DRINKS, WINE, dried fruit, MARGARINE, and soft lutants and toxic substances within the LIVER. FreeCANDY. Sorbates are readily broken down in the radical damage may contribute to CANCER, CAR-body and are considered safe additives. Sodium DIOVASCULAR DISEASE, and AGING; consequently,
46. 38 antioxidantantioxidants are a current focus of extensive med- of coronary heart disease is weak. Ongoing clinicalical research. It is intriguing that certain antioxi- trials may help decide whether vitamin C supple-dants are both anticancer nutrients and antiaging mentation is beneﬁcial for preventing heart dis-nutrients. Because there is such a large variety of ease. There is some evidence that high dietaryreactive molecules and free radicals, the body vitamin C may lower the risk of several cancers,requires a wide range of antioxidant defenses. A such as breast cancer and stomach cancer. Evidence“pecking order” exists among antioxidants; some does not indicate that high doses of vitamin Care more readily oxidized than others and will be decrease cancer risk, however.consumed rapidly unless replenished or recycled in Vitamin E acts as a fat-soluble, free radical trapthe body. Certain antioxidants are “preventive that seems to protect the brain from free radicalinhibitors,” that is, they block the initiation of free damage and to partially reverse age-related declineradical attack. Preventive inhibitors include defen- of the immune system in experimental animals. Insive ENZYMES like CATALASE and GLUTATHIONE PEROX- addition, vitamin E promotes the normal functionIDASE (destroy hydrogen peroxide and lipid of smooth muscle cells and reduces platelet adhe-peroxides) and SUPEROXIDE DISMUTASE (destroys sion to arterial cells, factors which could reduce thesuperoxide), chelating agents like CITRIC ACID that risk of atherosclerosis. Many population studieslock up metal ions, proteins that bind metal ions, have found a reduced risk of coronary heart diseaseincluding ALBUMIN, TRANSFERRIN, and FERRITIN. with increased intake of vitamin E. However, mostOther antioxidants, “chain breakers,” convert free clinical studies of vitamin E supplementation forradicals to stable (safe) products. VITAMIN E and VIT- several years found no beneﬁt in reducing heartAMIN C are essential chain-breaking antioxidants. It disease risk.is worth remembering that under certain condi- Selenium works together with vitamin E bytions, an antioxidant may become an oxidant. If helping an enzyme system (glutathione peroxi-the antioxidant becomes a free radical, then it, too, dase) block free radical attack and to disarm reac-must be disarmed and regenerated. tive lipids. Selenium is also required for a healthy immune system. Selenium deficiency increases Antioxidants as Nutrients the risk of cancer of the esophagus, stomach, andVITAMIN A, BETA-CAROTENE, vitamin C, vitamin E, rectum.and SELENIUM are key antioxidant nutrients. CAROTENOIDS, including beta-carotene, trap free Antioxidants as Nonnutrients in Foodradicals, while vitamin A helps guide normal tissue In addition to vitamins, trace minerals, ﬁber, anddevelopment. Inadequate carotenoid intake carotenoids, vegetables and fruits provide manyincreases the risk of cancers of the lung, bladder, other ingredients important for long-term health.esophagus, stomach, colon, rectum, prostate, and Vegetables and fruits contain orange-red and yel-skin. Studies indicate that when used alone, beta- low pigments called carotenoids. They include ca-carotene does not prevent cancer or heart disease. rotenes such as beta-carotene and LYCOPENE (fromIndeed, there are hints that unless beta-carotene is tomatoes) and xanthophylls, oxygen-containingprotected by another antioxidant, such as vitamin derivatives such as zeazanthin and lutein. Xantho-E, it may actually increase damage. A multitude of phylls occur at high levels in dark green leafy veg-studies indicates that the consumption of foods rich etables. Though relatively few carotenoids serve asin carotenoids protects against cancer, cataracts, sources of vitamin A, they help protect the bodyand cardiovascular diseases. as versatile antioxidants, and they enhance the Vitamin C destroys water-soluble free radicals immune system, complementing the actions ofand protects against cancer. It is needed for a beta-carotene. Fruits, vegetables, seasoning, spices,healthy IMMUNE SYSTEM and it also speeds wound and herbs (tea) possess a wide range of complex-healing. Vitamin C also protects LOW-DENSITY molecules called polyphenols (FLAVONOIDS) andLIPOPROTEIN (LDL) cholesterol from oxidation. Evi- phenolic acids that are complex ring structures.dence for the role of vitamin C in reducing the risk Flavonoids include ISOFLAVONES (soybean), fla-
47. antioxidant 39vones (such as QUERCETIN from tea, berries, fruits) with vitamin E, which it protects. Coenzyme Qand ﬂavonones (such as naringenin and HESPERIDIN production declines with age and the heart mayfrom citrus), ﬂavanonols (such as catechins, con- become deﬁcient in this nutrient.densed and hydrolyzable TANNINS), anthocyanins URIC ACID is found in the blood. It is a nitrogen-(purple, red, and blue pigments of fruits and containing waste product from the breakdownberries), coumarins (from citrus), ellagic acid (from of DNA and RNA.GRAPES), and others. In general, ﬂavonoids possess CITRIC ACID, succinic acid, and other complex or-multiple properties; thus they can quench free rad- ganic acids generated by metabolism can bindicals, inhibit inﬂammation, strengthen capillary iron and copper, preventing them from catalyz-walls, and reduce oxidative damage to serum cho- ing of free radical-generating reactions.lesterol. The optimal intake of ﬂavonoids and MELATONIN, a hormone produced by the pinealcarotenoids is not known and the long-term effects gland, possesses strong antioxidant properties.of supplementation with large amounts of phyto- BILIRUBIN, a breakdown product of HEMOGLOBIN,chemicals has not been studied. It should be acts as an antioxidant in blood.pointed out that beta-carotene, vitamin C, andeven vitamin E under the appropriate conditions Antioxidants as Food Additivescan become oxidants (prooxidants). Certain Antioxidants are extensively utilized to prevent orflavonoids also exhibit prooxidant properties. retard deterioration that produces off-ﬂavors orChelated (complexed) iron in the presence of vita- color changes in foods, making them less appetizingmin C can generate free radicals spontaneously in or less nutritious. Oxidation can also be promotedthe test tube and this could be a potential problem by enzymes in foods when exposed to air. Thisin the body with iron overload diseases. Finally, explains why apples, bananas, pears, peaches, andcertain ﬂavonoids can speciﬁcally block the thyroid potatoes darken after being sliced. The food industryhormone-generating enzyme in thyroid cells. As often employs synthetic antioxidants, particularlywith many dietary constituents, a little may be butylated hydroxyanisole (BHA), butylated hydrox-beneﬁcial, while a lot could be harmful. ytoluene (BHT), ethylene diaminetetracetic acid Foods rich in vitamin A and beta-carotene and (EDTA), and PROPYL GALLATE, as well as vitamin C, asrelated carotenoids include orange-colored vegeta- preservatives to extend the shelf life of processedbles like CARROTS and SQUASH plus dark green leafy foods by preventing free radical damage.vegetables like CHARD, KALE, and SPINACH. Fresh Spontaneous oxidation of fats and oils in thefruit, frozen juice concentrate, and vegetables like presence of oxygen, sunlight, and metal ions causesgreen PEPPER and BROCCOLI supply vitamin C. Veg- rancidity unless blocked by antioxidants. (BHA)etable oil, wheat germ, and nuts provide vitamin E. and BHT are used to prevent rancidity in fats andSelenium occurs in whole grains, SEAFOOD, CAB- oils, particularly in baked goods like crackers andBAGE, ONIONS, and GARLIC. Fruits and vegetables cookies. Their safety has been questioned. EDTA isalso provide ﬂavonoids. a common additive in salad dressings, MARGARINE, MAYONNAISE, sandwich spreads, pureed fruits, and Antioxidants Made by the Body vegetables, as well as cured shellﬁsh, BEER, and softGlutathione is a sulfur-containing antioxidant pre- drinks. EDTA is judged to be a safe food additive. sent in very large amounts in the cytoplasm. Propyl gallate retards spoilage of fats and oils and is Besides helping to keep proteins reduced, it often used with BHA and BHT to maximize their assists amino acid transport, helps regulate the antioxidant effects. Several studies with experi- internal oxidation state of the cell, maintains mental animals suggest that propyl gallate may vitamin E in a reduced state, and detoxiﬁes cause tumors. A close relative of vitamin C, ery- potentially harmful substances. throboric acid, is a common antioxidant used in theCOENZYME Q assists mitochondria to burn fat and preservation of processed meats such as bologna, carbohydrate for energy and it functions as a frankfurters, and BACON. SULFITES are used as lipid soluble membrane antioxidant together antioxidants to prevent discoloration of fruit and
48. 40 antipastovegetables. Spices and herbs, including thyme, in developing nations, scurvy in developed coun-rosemary, and sage, are sometimes used as food tries is usually associated with ALCOHOLISM andadditives to retard spoilage. (See also ATHEROSCLE- poverty. Sodium erythroborate, an antioxidantROSIS.) used with vitamin C in processed meats, has no antiscorbutic effects.Fairﬁeld, K. M., and R. H. Fletcher. “Vitamins for Chronic Disease Prevention in Adults.” Journal of the American Medical Association 23, no. 287 (June 19, 2002): antivitamin (vitamin antagonist) A compound 3,116–3,126. that diminishes the effect of a vitamin by speciﬁcSingh, Ram B. et al. “Effect of Antioxidant Rich Foods on mechanisms rather than by a general effect. Drugs Plasma Ascorbic Acid, Cardiac Enzyme and Lipid Per- can act as antivitamins, thus the anticancer drug oxide Levels in Patients Hospitalized with Acute methotrexate is a FOLIC ACID antivitamin. The drug Myocardial Infarction,” Journal of the American Dietetic prevents tumor cells from making tetrahydrofolate, Association 95, no. 7 (July 1995): 775–780. the coenzyme or activated form of folic acid required for DNA synthesis. Another case is isoni-antipasto Cold hors d’oeuvres (from the Italian azid, a drug employed to treat tuberculosis, whichante, meaning before, and pasto, for main course of is an antagonist of VITAMIN B6. This drug blocks thethe meal). A wide variety of foods is suitable for utilization of vitamin B6 by the bacteria causing theantipasto: marinated VEGETABLES and FISH; OLIVES; disease. Dicumarol, a drug that prevents blood clotshard SAUSAGES like salami; ANCHOVIES; SARDINES; (anticoagulant), is an antagonist of VITAMIN K.pickled onion, BEETS, PEPPERS, ARTICHOKE hearts, Antivitamins occur in foods. For example, AVIDIN, aCHICKPEAS; and hard and soft cheeses. heat-sensitive PROTEIN in raw egg white, binds biotin, and prevents its uptake in the intestine. Theantirachitic Refers to compounds related to VITA- viscera of raw FISH contain a THIAMIN antagonist,MIN D that are capable of preventing RICKETS, the thiaminase, which breaks down this vitamin in thedisease that results from a severe vitamin D deﬁ- intestine. The ackee plum of Jamaica contains a RIBOFLAVIN antagonist and has caused an illnessciency. Vitamin D is a family of 11 closely relatedsterols with similar activity; however, only two related to riboﬂavin deﬁciency. A vitamin or nutri-account for most of the vitamin D activity in foods. ent can become an antivitamin of another. ForErgocalciferol (vitamin D2) is the commercial, sup- example, very high levels of VITAMIN A block theplemental form, and cholecalciferol (vitamin D3) effects of vitamin K. (See also ANTIMETABOLITE.)occurs in animal tissues and ﬁsh oils. The precursorof vitamin D3, dehydrocholesterol, occurs in the apoenzyme An inactive form of an ENZYME, lack-skin where it is activated by sunlight. The body ing the appropriate small helper molecule (cofactorconverts vitamin D to the active form, calcitriol, or coenzyme) required for activity. Apoenzymewhich is a hormone. thus refers to only the PROTEIN (polypeptide) por- tion of an enzyme. Enzymes that require coen- zymes or metal ions to assist them in catalyzingantiscorbutic Capable of preventing SCURVY, the reactions are entirely inactive unless they are com-disease caused by chronic VITAMIN C deﬁciency. bined with their non-protein helpers. CellularSources of vitamin C (ascorbic acid), usually fresh protein-synthesizing machinery produces apoen-fruit and vegetables, relieve the symptoms of zymes, and coenzymes and metal ion cofactors arescurvy. Although scurvy has been known since the added later to create a holoenzyme, which is activetime of the ancient Egyptians, the antiscorbutic because it contains the required helper group.effect of limes and other fruit was not discovered inEurope until late in the 18th century, after experi-ments involving diets of British seamen. It was not apoferritin The iron-free PROTEIN required foruntil 1907 that scurvy was discovered to be caused IRON storage in TISSUES. Apoferritin must be ﬁrstby a nutritional deﬁciency. Though still prevalent synthesized in cells before their iron atoms com-
49. appetite 41bine with apoferritin to form FERRITIN, the iron- to balance the body’s energy requirements. Possi-storage protein. Ferritin, a large rust-red protein, bly one mechanism stimulates feeding and a sec-contains a mixture of iron hydroxide and iron ond suppresses intake. Current research focuses onphosphate and accounts for most stored iron, espe- a complex array of factors that stimulate or inhibitcially in the intestinal lining, LIVER, spleen, and appetite and feeding. Substances that decreasebone marrow. Apoferritin can be contrasted with appetite include neurotransmitters, such as sero-another apoprotein of iron metabolism, TRANSFER- tonin and norepinephrine; the peptide hormones,RIN. Transferrin transports iron in the bloodstream including cholecystokinin and peptide YY3-36,to sites in the body that require iron, especially the produced by the small intestine; and corticotrophinbone marrow. Generally, transferrin is about 30 releasing factor from the hypothalamus. Leptin ispercent bound up with iron. Because 70 percent of released into the bloodstream by fat cells that sig-its binding capacity is available for more iron, this nal the hypothalamus to stop sending signals thatapoprotein offers a reserve of iron transport capac- trigger eating fat and CARBOHYDRATE while increas-ity in the blood. ing the metabolic rate of fat tissue. Factors stimu- lating appetite include the hormone ghrelin,apolipoprotein A family of PROTEINS that are produced by the gastrointestinal tract; galanin, aingredients of serum LIPOPROTEINS, the lipid-protein brain peptide; and neuropeptide Y, which acts as acomplexes that transport FAT and CHOLESTEROL in transmitter in the brain.the lymphatic system and bloodstream. There areat least nine different apoproteins associated with appetite The learned desire to eat, often a spe-different lipoproteins, including Apo A, Apo B, Apo ciﬁc food, for taste and enjoyment. Appetite is aC, Apo D, and Apo E. Apo A is located on HDL pleasant feeling based on previous experiences(high-density lipoprotein), the desirable form of with foods. Appetite can be triggered by associationblood cholesterol, and serves as an analytical with aromas, meal time, memories, and certainmarker for this lipoprotein. Apo B and Apo E occur food advertisements. In contrast, HUNGER relates toas LOW-DENSITY LIPOPROTEIN (LDL), the undesirable the innate need to eat and is associated with anform of blood cholesterol. They guide LDL binding unpleasant sensation coupled with a physiologicalto TISSUES like MUSCLE so that cholesterol can be need. A variety of foods may satisfy hunger.taken up. Apo C is a constituent of both VERY LOW- Appetite is determined by many factors, includ-DENSITY LIPOPROTEIN (VLDL) and CHYLOMICRONS, ing social inﬂuences (religion, philosophy, culturalwhich transport fat in the blood. Apo C activates an taboos); taste and palatability; state of health; effectenzyme (LIPASE) in blood vessels that liberates of medications; preferences and aversions learnedFATTY ACIDS from these carriers to be absorbed by by experience; environmental factors, such as cli-tissues. Apo D helps transfer cholesterol between mate; and metabolic factors (HORMONE levels,lipoproteins in the blood. Genetic researchers have caloric requirements).discovered that one allele of the Apo E gene (Apoe- The physiologic basis of appetite and hunger isE4) is a risk factor for ALZHEIMER’S DISEASE. not completely understood. The HYPOTHALAMUS ofAlthough the gene’s role is still unclear, scientists the brain seems to be the interpretative center andsuspect that the E4 allele promotes the growth of clearinghouse for hunger signals. Anxiety, STRESSthe amyloid protein plaques that grow on the and psychological disturbances may cause thebrains of Alzheimer’s patients. release of appetite-stimulating chemical signals from different regions of the brain.appestat The hypothetical center in the brain Multiple chemical messengers including asthat may regulate APPETITE and food intake. While many as 25 neuropeptides affect food intake.the exact site of regulation of appetite is not yet Appetite is regulated by a balance of signals thatdeﬁned, it probably involves the HYPOTHALAMUS, a either stimulate or inhibit food intake. Several fac-part of the brain that regulates HUNGER and THIRST. tors that stimulate appetite include neuropeptide Y,Hunger may be regulated much like a thermostat a brain protein that induces lab animals to con-
50. 42 appetite suppressantssume more FAT and CARBOHYDRATE and acts as a possibly men). Consequently, the FDA recom-neurotransmitter. It is produced by the hypothala- mended that consumers not use any products thatmus and other regions of the brain. The levels of contain PPA and ruled that PPA is not consideredneuropeptide Y are modulated by hormones and safe for nonprescription use. As a result the FDA isby blood glucose levels. Another brain protein in the process of removing PPA from all drugcalled GALANIN stimulates an appetite for fat. The products and has requested that all drug compa-hormone ghrelin, produced by the small intestine nies discontinue marketing products containingand stomach, acts as a powerful appetite stimulant. PPA. In addition, the FDA has issued a publicBlood levels of ghrelin increase in dieters and also health advisory concerning PPA. In response togenerally increase just before meals. In contrast, the request made by the FDA in November 2000,another peptide hormone called leptin, produced many companies have voluntarily reformulatedby fat cells, regulates the hypothalamus to inhibit and are continuing to reformulate their productsfood consumption while increasing fat metabolism. to exclude PPA.In addition, when peptide YY3-36 (PYY) is released Amphetamines (Dexedrine, Benadrine) are pre-from the small intestine and travels to the hypo- scription drugs used to temporarily curb appetite,thalamus, it turns off neurons that stimulate although appetite generally returns within twohunger. These various hormones, their receptors, weeks. Bulking agents are forms of plant ﬁber thatand molecular mimics are the focus of intense cur- swell in water, ﬁlling the stomach and creating sati-rent research on controlling obesity. ety. PSYLLIUM, GUAR GUM, and GLUCOMANNAN fall into this category. These bulking agents are often Appetite and Exercise included in PROTEIN powders used in weight lossAfter beginning an EXERCISE program, appetite may protocols to help satisfy hunger. Two appetite sup-increase during the ﬁrst few weeks, then return to pressants, fenﬂuramine and dexfenﬂuramine, werenormal, while moderate exercise (15 miles per taken off the market by the FDA in 1997, when itweek of jogging or walking) may suppress appetite. was discovered that thousands of patients whoResearch suggests that exercise increases the intake took these drugs developed potentially deadly pri-of CALORIES by normal-weight men by an average mary pulmonary hypertension and heart valveof 200 calories, even when they burn an additional abnormalities. Dexfenfluramine was shown to600 calories. On the other hand, exercise does not cause these injuries when taken alone, and fenﬂu-seem to increase normal-weight women’s caloric ramine was linked to valve problems in patientsintake above the levels needed to make up for who combined it with the drug phentermine in athose burned by exercising. Regular exercise may mixture popularly known as “fen-phen.” Both fen-not increase appetite or excessive eating in over- ﬂuramine and dexfenﬂuramine helped patientsweight women. (See also CRAVING.) lose weight by increasing serotonin levels in theBray, G. A. “Reciprocal Relation of Food Intake and Sym- blood stream, which provided a sense of well-being pathetic Activity: Experimental Observations and and satiety. The problem researchers discovered Clinical Implications,” International Journal of Obesity after the drugs were removed from the market was and Metabolic Disorders 24, supp. 2 (June 2000): that the drugs destroyed the body’s ability to con- S8–S17. trol the amount of serotonin circulating in the blood. Excessive amounts of serotonin can causeappetite suppressants A variety of drugs and cell damage to cardiopulmonary structures. (Seeplant products are used to curb appetite. In the also DIETING; DIET PILLS; FIBER.)past PHENYLPROPANOLAMINE (PPA) was used as aningredient in many over-the-counter weight loss apple (Malus pumila) The rounded FRUIT of theproducts, but following adverse reports of links to apple tree; originated in Asia Minor. It has beenhemorrhagic stroke with these products, Yale Uni- grown for thousands of years and today is the mostversity scientists discovered that PPA does increase widely cultivated fruit tree in the world. Apples arethe risk of hemorrhagic stroke in women (and one of the most popular fruits in North America
51. arachidonic acid 43and in Europe. Although there are an estimated apricot (Prunus armeniaca) The oval FRUIT of a7,000 varieties, only 20 are available in the United tree belonging to a member of the PEACH family.States and just eight account for 80 percent of The ripened, fragrant fruit is golden yellow and hasapple sales: Red Delicious, McIntosh, Golden Deli- little JUICE, unlike the PLUM to which it is alsocious, York, Rome Beauty, Stayman, Granny related. Apricots originated in China, where wildSmith, and Jonathan. Apples are typically 2.5 to apricots were harvested 7,000 years ago. Apricots3.5 inches in diameter and range in color from rus- were later cultivated in India and were introducedset red to yellow. The ﬂesh can be white (Cortland) into the Mediterranean after the Greek conquestor yellow (Golden Delicious); the ﬂavor may be tart under Alexander the Great. The name is derived(Winesap) or sweet (Grimes). from the Latin term for early ripening. Apricots are Apples are available year-round because they best picked when ripe. They do not store well andstore well when refrigerated, although this can become grainy and soft. Canned apricots main-decreases the content of VITAMIN C. Certain vari- tain their texture and are frequently used ineties like Red Delicious, McIntosh, and Rome desserts and fruit salads. Apricots are also usedBeauty store better than others. On the other hand, in JAMS, pastries, and cakes. Dried apricots areapples stored at room temperature become mealy exported by California, Iran, Australia, and Turkey.and will turn mushy. Apples are used in a wide Apricots are a rich source of POTASSIUM, BETA-variety of desserts (turnovers, fritters, tarts, pud- CAROTENE, and FIBER. Three apricots (106 g) pro-dings, compotes, pies, strudels) and in JAMS, JEL- vide calories, 51; protein, 1.15 g; carbohydrate,LIES, and apple butter. A signiﬁcant percentage of 11.2 g; ﬁber, 2.23 g; potassium, 361 mg; vitamin A,the European and U.S. apple crop is used to pro- 317 retinol equivalents; vitamin C, 8 mg; and smallduce apple JUICE and CIDER. amounts of other vitamins. Goals of North American apple breeding pro-grams include developing apples that will ripen arachidonic acid A long chain POLYUNSATURATEDbefore early August, when the ﬁrst traditional red FATTY ACID that is the parent of important hormone-apples, the Jonathans, ripen. Another has been to like agents called PROSTAGLANDINS and LEUKO-develop apples that ripen in November. Eventually TRIENES. It is a complex fatty acid, with 20 carbonsapples should be available that will extend the and four double bonds. Arachidonic acid belongs toapple season (fresh picked apples) from early the omega-6 family of unsaturated fatty acids,August to late October. which are derived from the ESSENTIAL FATTY ACID, A typical unpeeled apple with only 80 to 125 LINOLEIC ACID. Because arachidonic acid can becalories can be served as a low-calorie, low-fat made in the body, it is not classiﬁed as one of thedessert or snack and can provide one of the recom- essential nutrients. MEAT and DAIRY products are richmended two to four servings of fruit per day. sources, and they contribute to the body’s supply.Unpeeled apples are an important source of FIBER; Arachidonic acid is processed by the “cyclooxy-an apple can supply about 20 percent of the mini- genase pathway,” a series of ENZYMES that yieldmum of ﬁber recommended for daily consumption. prostaglandins and related compounds. Pros-Most of the ﬁber is soluble ﬁber (PECTIN). The taglandin PGE2 and its relatives can increase BLOODsweeter the apple, the greater the sugar (FRUCTOSE) PRESSURE, induce BLOOD CLOTTING, and cause paincontent. Commercial applesauce may contain and inﬂammation. ASPIRIN and non-steroidal anti-added sugar. For comparison, a half-cup of apple inﬂammatory drugs are effective pain relieversbutter provides 186 calories; a half-cup of sweet- because they speciﬁcally block the cyclooxygenaseened applesauce, provides 92 calories; a half-cup of enzyme. Another prostaglandin from arachidonicunsweetened applesauce, 50 calories. A typical acid, PGI2, helps to counterbalance blood clotting,3.25-inch-diameter apple (212 g) provides calories, while still another derivative of arachidonic acid,125; protein, 0.4 g; carbohydrate, 32 g; ﬁber, 6.6 g; prostacyclin, blocks blood clotting. Therefore,potassium, 244 mg; vitamin C, 12 mg; and traces of aspirin use carries the added risk of increasedother vitamins. (See also ALAR.) bleeding.
52. 44 arame A second chain of reactions, the lipooxygenase vidual amino acids is considered experimental andpathway, converts arachidonic acid to leukotrienes, long-term effects on health are being worked out;extremely powerful inﬂammatory agents linked to therefore, their use therapeutically should bethe allergic response including swelling and pain. under the guidance of a physician.FISH OILS are rich in the omega-3 family of unsatu- Brittenden, J. M. B. et al. “L-arginine Stimulates Hostrated fatty acids, rather than the omega-6 fatty Defenses in Patients with Breast Cancer,” Surgery 115,acids. Because they block leukotriene production no. 2 (1994): 205–212.from arachidonic acid, ﬁsh oils can reduce exces-sive chronic inﬂammation. ariboﬂavinosis A disease arising from a chronic deﬁciency of the B vitamin RIBOFLAVIN. Symptomsarame See SEAWEED. characterizing this condition include sores on the TONGUE (bald tongue), sores at the corners of thearginine (Arg, L-arginine) A basic AMINO ACID. mouth, skin irritation, and blood-vessel formationArginine helps form the nitrogenous waste prod- in the cornea. Oral doses of riboﬂavin rectify thisuct UREA, as part of the chain of reactions called deﬁciency. Typically, malnutrition produces a gen-the UREA CYCLE, which disposes of the toxic waste eral deﬁciency of most B COMPLEX vitamins, ratherAMMONIA in the LIVER. More generally arginine than of a single vitamin like riboﬂavin because theyhelps build PROTEINS. Arginine and LYSINE are occur together in foods. Furthermore, riboﬂavin isclassiﬁed as basic rather than acidic amino acids. one of the enrichments of BREAD and BREAKFASTArginine is often considered a non-essential CEREALS in the United States and deﬁciency isamino acid because of the capacity of the body to uncommon. However, the dietary requirement forsynthesize it. However, endogenous arginine riboﬂavin increases under certain conditions. Forformation may be inadequate in newborn infants example, riboﬂavin in MILK is destroyed by sun-and in adults with liver disease. Arginine is light, thyroxine (thyroid medication) decreasesalso converted to NITRIC OXIDE to regulate BLOOD riboﬂavin absorption in the INTESTINE, and boricPRESSURE. acid increase urinary loss of this vitamin. There Good dietary sources of arginine are nuts, may be populations in America for whomCEREAL GRAINS, MEAT, FISH, and POULTRY. Arginine riboﬂavin intake is a problem. A nutritional surveysupplements have been used by athletes to increase of the U.S. population (NHANES I) revealed thatGROWTH HORMONE production and increase MUSCLE nearly 22 percent of African Americans could bemass. Whether growth hormone levels can be riboﬂavin deﬁcient.manipulated by diet is controversial. Oral doses ofarginine can stimulate the production of anabolic aromatic compounds A family of organic com-hormones such as INSULIN and prolactin. pounds related to benzene. Typically, their ring or Animal studies of arginine supplementation cyclic structures are composed of alternating singlehave produced intriguing results. Arginine speeds and double bonds. Benzene (one ring, an industrialup wound healing in lab animals and in patients. solvent), naphthalene (two rings, an ingredient ofArginine-rich diets also increase T-cell function in mothballs), and BENZOPYRENE (four rings) are allpatients with traumatic injury or surgery. In exper- carcinogens. Benzopyrene is a product of charcoalimental animals arginine activates the thymus grilled or BARBECUED MEAT.gland and lymphocytes. It may enhance the release Aromatic rings are constituents of a wide rangeof growth hormone and prolactin, which indirectly of physiologically important compounds. Forstimulate the immune system. The estimated doses instance, the amino acids PHENYLALANINE, TYROSINE,of arginine required to bolster immunity (up to 30 HISTIDINE, and TRYPTOPHAN contain aromatic ringg daily) may cause bone disorders in children and structures. Important body regulators like EPI-adolescents. High doses of arginine may cause nau- NEPHRINE, norepinephrine, and SEROTONIN (nervesea and DIARRHEA. The use of large doses of indi- chemical neurotransmitters) and HISTAMINE (an
53. arthritis 45inﬂammatory agent) are aromatic compounds, as organs, including the brain, where it can causeare ESTROGENS (female hormones). major pathological changes. ATHEROSCLEROSIS is a Aromatic compounds are made more water- type of arteriosclerosis in which arteries accumu-soluble, hence excretable by the KIDNEYS, through late waxy deposits called PLAQUE.ring oxidations carried out by LIVER detoxifying en- The cause of arteriosclerosis is unknown,zymes (oxidases). Unfortunately, these enzymes although AGING, altered FAT METABOLISM, and fam-can transform the aromatic compounds into highly ily history have been implicated. DIABETES MELLI-reactive ones during oxidation, and they can TUS, HYPERTENSION, increased blood FAT and bloodbecome CARCINOGENS. (See also CYTOCHROME P450.) CHOLESTEROL levels, cigarette smoking, OBESITY, being male, an inability to cope with STRESS, andarrowroot (Maranta arundinacea) The STARCH or physical inactivity increase the risk of this disease.FLOUR from the underground stems or rhizomes of A typical treatment program entails regular EXER-several Central American tropical plants. The name CISE; stress management; abstinence from smoking;refers to its former use by Indians to treat wounds control of diabetes, high blood pressure, andinﬂicted by poisoned arrows. As a food, pulped weight; and lowering dietary cholesterol and satu-tubers produce a white ﬂuid that is dried, pow- rated fat. (See also CARDIOVASCULAR DISEASE.)dered, and milled. Arrowroot ﬂour can be used inwheat-free dishes. This thickening agent can artery A vessel transporting oxygenated bloodreplace CORNSTARCH in recipes for soups, cream away from the heart. Most arteries carry oxy-sauces, pie ﬁllings, puddings, and glazes that need genated blood and nutrients to peripheral tissuesto remain clear after cooking. Arrowroot thickens like MUSCLE. Arteries lead to arterioles (minuteat a lower temperature than wheat ﬂour and corn- arteries), which in turn lead to capillaries, the small-starch. Sauces prepared with arrowroot should be est vessels. In the capillaries, OXYGEN, GLUCOSE, andserved soon after thickening, because the consis- other nutrients are delivered to cells. In exchange,tency will not hold. Arrowroot has a neutral ﬂavor blood acquires waste products like AMMONIA andand does not need to be cooked to remove residual CARBON DIOXIDE. Because the vascular or blood cir-taste. It is ideal for sauces that should not boil. culatory system is a closed system (that is, blood returns to its starting point, the heart), blood ﬂowsarsenic A toxic heavy metal. Arsenic as a pollu- out of capillaries to veins (vessels that lead bloodtant occurs in smog and cigarette smoke. High back to the heart). Blood is pumped to the lungs todoses are thought to interfere with neurological release carbon dioxide in exchange for oxygen. Thedevelopment in children and to increase the risk of pulmonary artery, carrying blood from the heart tosome types of CANCER. As an ingredient in some the lungs, is the only artery that does not carry oxy-pesticides, it can contaminate produce. genated blood. Several arteries are prone to PLAQUE Arsenic may be an essential trace nutrient. In accumulation. The arteries feeding the heart (coro-very low amounts it is a growth promoter in POUL- nary arteries) are prime candidates for disease inTRY and pigs. It plays an as yet unknown function men. (See also CARDIOVASCULAR DISEASE.)in METABOLISM in animals and perhaps in humansas well. Traces of arsenic occur in common foods: arthritis A family of inﬂammatory diseases of theFISH, SHELLFISH, POULTRY, and CEREAL GRAINS. (See joints, including chronic degenerative joint diseasesalso HEAVY METALS.) such as osteoarthritis and rheumatoid arthritis. Thirty-seven million Americans suffer from variousarteriosclerosis A group of pathological condi- forms of arthritis; two-thirds of them are women.tions characterized by thickened, stiffened arteries. Many conditions are predisposing factors for jointAlterations in the innermost or outermost vessel inﬂammation, including viral infection (Lyme dis-layers can cause arteries to lose their elasticity. ease), some types of FOOD POISONING, disruption ofArteriosclerosis alters the function of TISSUES and the body’s chemistry (GOUT), disruption of the
54. 46 artichokeIMMUNE SYSTEM (AUTOIMMUNE DISEASE), certain bac- NIGHTSHADE FAMILY may be implicated. Individualsterial infections (pneumococcus, staphylococcus, who are sensitive to tomatoes, pepper, or eggplantand streptococcus), certain parasitic infections (gia- may experience less joint pain when abstainingrdia), physical injury, OBESITY, and physical and from these foods. VEGETARIAN diets may be beneﬁcialemotional STRESS. Arthritis is associated with in rheumatoid arthritis perhaps due to the decreasedAGING, and heredity also plays a role. consumption of ARACHIDONIC ACID. This polyunsatu- Osteoarthritis is the most common form of joint rated fatty acid, found primarily in MEAT and dairydegeneration. It affects weight-bearing joints, espe- products, contributes to inﬂammation through itscially the hips and the knees. In this type of degen- conversion to certain prostaglandins and LEUKO-eration the affected joint may exhibit worn TRIENES, hormone-like compounds that stimulatecartilage, with bone overgrowth and bone spurs. the inﬂammatory process. FISH and FISH OIL beneﬁtOsteoarthritis is related to abnormal CALCIUM some patients. Fish oil also reduces the formation ofmetabolism and stress or injury to the joint. Symp- these inﬂammatory substances, hence the overalltoms include morning stiffness, pain that worsens effect of eating cold-water ocean ﬁsh is to reducewith joint function, localized tenderness, creaking, inﬂammation. (See also ALLERGY, FOOD; DEGENERA-cracking of joints during movement, and restricted TIVE DISEASES.)mobility. In primary osteoarthritis, degenerativewear and tear often occurs after the age of 50, artichoke (Cynara scolymus) The leafy, ediblewithout trauma or previous inﬂammatory disease, buds of a perennial plant resembling the thistle; thebecause with aging there is a decreased ability to ﬂeshy base is surrounded by scale-like leaves. Therestore normal collagen and cartilage. Secondary artichoke originated in Sicily and is now widelyosteoarthritis refers to a disease caused by a factor grown in other warm climates. In the Unitedin the patient’s medical history, such as a prior States, globe artichokes are cultivated in mid-injury. coastal regions of California. The artichoke has VITAMIN E and VITAMIN C seem to enhance the diuretic properties and has a long folk history instability of cartilage constituents (chondroitin sul- treatment of LIVER complaints. Research supportsfate). The essential amino acid METHIONINE and its therapeutic effects. Artichokes contain cynarin,MANGANESE are also needed to produce chondroitin a substance that has signiﬁcant regenerating effectssulfate. VITAMIN A and VITAMIN B6, as well as ZINC and stimulates BILE ﬂow from the liver.and COPPER are needed for COLLAGEN, the structural The heart of the artichoke and the top layers ofprotein that helps form cartilage. A deﬁciency of the inside scaly leaves are edible after cooking.these nutrients can accelerate joint deterioration. Artichokes are used as a ﬁlling in omelettes and as Rheumatoid arthritis refers to inﬂamed joints fritters. Artichoke hearts can be stuffed, used as awith overgrowth of joint tissue and swollen and stiff garnish, or served cold with sauce. Canned arti-joints that often cripple the patient. Symptoms chokes are prepared from the hearts and leaves ofinclude FATIGUE, low-grade fever, joint stiffness, and young buds. When packed in oil, canned arti-pain, in addition to painful, swollen joints. Gener- chokes should be drained and rinsed to lower theally, small joints are ﬁrst affected. Unlike osteo- CALORIE content. A medium-sized artichoke (120 g)arthritis, rheumatoid arthritis is an autoimmune contains 53 calories; protein, 2.8 g; carbohydrate,condition, in which the body attacks itself. Speciﬁ- 12.4 g; ﬁber, 4.0 g; fat, 0.2 g; calcium, 47 mg; iron,cally, antibodies are launched against joint tissue. 1.6 mg; potassium, 316 mg; niacin, 0.71 mg; andAlthough some medical opinion disclaims the effects small amounts of other vitamins.of food on arthritis, accumulated clinical evidenceindicates that certain foods can aggravate arthritis in artiﬁcial ﬂavors (ﬂavoring agents) These ﬂavorssusceptible individuals and that food allergies can represent the largest group of FOOD ADDITIVES andincrease joint pain. Common foods in this category are used to replace more expensive natural ﬂavorsare nuts, DAIRY products like MILK and CHEESE, grains and to improve the taste of manufactured or syn-like CORN and WHEAT, and BEEF. Vegetables of the thetic foods. Although approximately two-thirds of
55. artiﬁcial food colors 47all food additives are ﬂavorings and ﬂavoring risk than any other class of food additive. Becauseagents, they are used in very small amounts. Com- manufactured and processed foods often lack themon examples include FUMARIC ACID, HYDROLYZED fresh colors of whole foods, synthetic dyes haveVEGETABLE PROTEIN, vanillin, and cinnamaldehyde. been used for years to make such foods look moreMONOSODIUM GLUTAMATE (MSG) is classiﬁed as a appetizing or more wholesome. They provide noFLAVOR ENHANCER rather than a ﬂavor. nutritional beneﬁts. The U.S. FDA does not require speciﬁc ﬂavoring Certiﬁcation of artiﬁcial food colors (indicatedagents to be listed on the food label because they by the FD&C designation) implies the dyes meetare consumed in small amounts. Consumption standards of purity, but does not assure safety. Theaverages no more than several ounces a year per D&C designation stands for dyes permitted only inperson. Substituting an artiﬁcial ﬂavor for the nat- drugs and cosmetics, not foods. Most dyes need notural food or ﬂavor lowers the price; however, the be speciﬁed on food labels, and instead they can beconsumer needs to be made aware that artiﬁcial grouped under the heading “artiﬁcial coloring.”ingredients have been used. The U.S. FDA permits Consequently the consumer may not be able tothe general term “artiﬁcial ﬂavoring” to be used. identify the dyes used in a processed food or bev-Although nonspeciﬁc, this designation is still help- erage. Six dyes can be used in any food: FD&C Blueful to consumers because foods that list artiﬁcial No. 1 and No. 2, Green No. 3, Red No. 40, and Yel-ﬂavorings on their food labels will probably contain low No. 5 and No. 6. They are common additives inlittle of the natural food that would normally pro- CANDY, SOFT DRINKS, desserts like ICE CREAM, bakedvide that ﬂavor. goods, and SAUSAGES. Citrus Red 2 is used only to The long-term safety of many synthetic or nat- color ORANGE skins.ural flavors has not been rigorously studied, How safe are artiﬁcial food colors? Many studiesalthough the review process has weeded out sev- with experimental animals suggest that artiﬁcialeral natural and synthetic ﬂavorings. Natural root food dyes cause CANCER. Few safety studies werebeer ﬂavoring (safrole) was shown to cause CANCER carried out before the DELANEY CLAUSE, forbiddingin animals and was withdrawn in 1960. The safety the addition of cancer-causing agents to any food,of cinnamon ﬂavor, natural or synthetic, has been became law in 1962. Examination of the safety ofquestioned. It is similar to cinnamyl anthranilate, synthetic dyes in use before 1960 has been gradual.which was used in grape and cherry ﬂavors in ice Debate centers on the issue of whether additivescream and beverages until the FDA proposed in that slightly increase the risk of cancer represent a1982 that it be banned because it causes cancer in tolerable risk and can be used in food.lab animals. Benzylacetate, an artiﬁcial ﬂavoring Safety concerns about approved synthetic dyesused in CHEWING GUM, puddings and CANDY, was can be summarized as follows. FD&C Red No. 40 isfound to cause cancer in rats and mice by the a suspected cause of LYMPH tumors in experimentalNational Toxicology Program. On the other hand, animals. It is widely used in soft drinks, sausage,many ﬂavors, for example caramel, are safe. A GELATIN desserts, other desserts, and candy. A longmajor stumbling block in moving forward with controversy surrounds FD&C Red No. 3. It causesassessing the safety of artiﬁcial ﬂavors is that the THYROID and lymph tumors in experimental ani-most prevalent artiﬁcial ﬂavors, which might pose mals. FD&C Yellow No. 5 (TARTRAZINE) is the onlya health threat, have not been prioritized for toxi- dye that must be speciﬁcally listed on food labels.cological studies. (See also CONVENIENCE FOOD; FEIN- Some asthmatics and individuals allergic to ASPIRINGOLD DIET; FOOD LABELING; PROCESSED FOOD.) are also allergic to this dye, which is used in soft drinks, sausage, baked goods, candy, and gelatinartiﬁcial food colors (food dyes, certiﬁed food col- desserts. FD&C Blue No. 1 causes chromosomalors, synthetic food dyes, FD&C colors, coal tar dyes) damage, and FD&C Blue No. 2 may cause brainSynthetic colors account for 80 percent of food col- tumors in experimental animals. Both are used inoring agents used in the food industry, and these candy and soft drinks. FD&C Yellow No. 6 has beensynthetic additives pose a greater potential health placed on permanent approval by the U.S. FDA,
56. 48 artiﬁcial sweetenersalthough it may cause adrenal KIDNEY tumors in calorie desserts. (See also CONVENIENCE FOOD; DIET;rats. FD&C Green No. 3 causes bladder tumors in NATURAL SWEETENERS.)experimental animals. (See also ALLERGY, FOOD; Henkel, John. “Sugar Substitutes: Americans Opt forCARCINOGEN; CONVENIENCE FOOD; FEINGOLD DIET; Sweetness and Lite,” FDA Consumer 33, no. 6 (Novem-FOOD LABELING.) ber–December 1999): 14–16.artiﬁcial sweeteners Very common FOOD ADDI- ascorbic acid See VITAMIN C.TIVES used in PROCESSED FOODS and low-CALORIEbeverages. To satisfy consumers’ desire for sweetswithout the surplus calories of sugary, fat-laden ascorbyl palmitate A fat-soluble antioxidantfoods, food and beverage producers rely on artiﬁ- FOOD ADDITIVE, derived from VITAMIN C (ascorbiccial sweeteners. Only four artiﬁcial sweeteners acid). Ascorbyl palmitate helps retard rancidity inare currently approved in the United States: VEGETABLE SHORTENING by preventing the oxidationASPARTAME, SACCHARIN, ACESULFAME-K, and SUCRA- of unsaturated fatty acids. It is used to add vitaminLOSE. These additives contribute few or no calories. C to fortiﬁed foods and to vitamin supplements asCYCLAMATE, the ﬁrst artiﬁcial sweetener, has been well. Palmitic acid, a common fatty acid, is linkedbanned. Nutrasweet (aspartame) accounts for to ascorbic acid to make it fat-soluble. (See alsonearly 75 percent of the $1 billion artificial ANTIOXIDANTS.)sweetener market. However, its instability to heathas restricted its use to powdered mixes, SOFT ashwagandha (Withenia somnifera, Indian gin-DRINKS, CHEWING GUM, and a sweetener for COFFEE. seng) A plant in the pepper family that is nativeSaccharin is heat stable and contains no calories, to India. The plant’s roots have been used medici-but when used alone some users ﬁnd a metallic nally in India and Africa for thousands of years toaftertaste. Acesulfame-K (Sunett) and sucralose treat a variety of ailments including inﬂammation,(Splenda) are the newest of the approved arti- fever, infertility, and impotence. The roots are be-ﬁcial sweeteners. They are both heat stable and lieved to contain withanoloids, naturally occurringmay be used in baked goods. Sucralose, which is oxygenated ergostane-type steroids that are similar600 times sweeter than sugar, cannot be digested to ginsenosides, the active components of ginseng.and therefore adds no calories to the foods it Ashwagandha is marketed in the United States pri-sweetens. marily as a herbal remedy, an anti-inﬂammatory, a Several lines of evidence suggest that artiﬁcial memory and energy enhancer, and an aphrodisiac.sweeteners probably do not assist with weight loss. None of these beneﬁts have been conﬁrmed inde-A 1998 survey by the Calorie Control Council pendently in the United States.revealed that 144 million Americans consume low-calorie products that have been sweetened artiﬁ-cially. Nevertheless, the average American still eats asparagine (Asn, L-asparagine) One of the 20 AMINO ACIDS employed as a building block for PRO-about 20 teaspoons of sugar a day, of which about TEINS. It was the ﬁrst amino acid to be isolated60 percent is in the form of corn sweeteners. Theuse of artiﬁcial sweeteners has not lowered the (from asparagus juice in 1806). Asparagine isincidence of OBESITY in the United States; just formed in the body from the amino acid ASPARTIC ACID and thus is classiﬁed as a nonessential aminothe opposite may be true. Obesity is a major healthproblem for many Americans. Women saccharin acid. Cells convert aspartic acid to aspargine by theusers were found to be more likely to gain, not enzymatic addition of AMMONIA. This process cre-lose, weight than non-users. No study suggests that ates a neutral (uncharged) amino acid from anartiﬁcial sweeteners diminish APPETITE. Artiﬁcial acidic one.sweeteners may actually trigger a CRAVING for CAR-BOHYDRATES and increase appetite, especially after asparagus (Asparagus officinalis) A vegetableeating, and thus contribute to a craving for high- with succulent shoots and scale-like leaves, belong-
57. aspergillus 49ing to the lily-of-the-valley family. Asparagus was they must avoid aspartame because its digestionknown to the ancient civilizations of Egypt and produces phenylalanine. Food labels must warnRome. Although it still grows wild in Europe, it is that the product contains phenylalanine, althoughwidely cultivated. Asparagus is a perennial, and its products do not list the amounts of aspartame theyunderground stem produces white, purple, or contain.green shoots or spears. Asparagus root has been Certain individuals may be sensitive to aspar-used as a mild diuretic in folk medicine. Martha tame. There have been occasional reports ofWashington and Mary Washington are the princi- migraines, disorientation, ringing ears, and confu-pal varieties grown in the United States. sion after eating foods containing aspartame. Reac- Asparagus deteriorates quickly, unless refriger- tions occur in women three times more frequentlyated after harvesting. When kept at room tempera- than in men. Although an adult may tolerate theture for two days, spears lose half their VITAMIN C aspartame in six cans of diet soda, this might be toocontent and they become tougher. Asparagus much for a child, because of the child’s lower bodyshould be steamed or cooked before use in weight. Aspartame is not recommended for preg-omelettes and scrambled eggs, in salads, served AU nant and nursing women or for infants less than sixGRATIN or plain, hot or cold, with a sauce or pureed. months.Asparagus shoots supply vitamins and minerals Wein, Debra. “Are artiﬁcial sweeteners safe? EN updatesand are quite low in CALORIES. Four medium-sized a sticky issue,” Environmental Nutrition 18, no. 2 (Feb-spears (cooked, 60 g) contain protein, 1.6 g; carbo- ruary 1995): 1, 4.hydrate, 2.6 g; ﬁber, 1.1 g; iron, 0.4 mg; potassium,186 mg; vitamin A, 50 retinol equivalents; niacin,0.63 mg; vitamin C, 16 mg; and small amounts of aspartic acid (Asp, L-aspartic acid) An acidicother vitamins. AMINO ACID and one of the 20 amino acids incorpo- rated into PROTEINS. Aspartic acid possesses an extra acidic functional group. Aspartic acid is readilyaspartame By far the most popular ARTIFICIAL formed from OXALOACETIC ACID, a KREB’S CYCLESWEETENER in America, aspartame is nearly 200 intermediate that is produced during the conver-times sweeter than SUCROSE. The patent for this sion of CARBOHYDRATE to energy. Hence it is asweetener expired in 1992 and several versions of nonessential amino acid.aspartame are now marketed. Aspartame contains In addition to serving as a protein buildingtwo amino acids, ASPARTIC ACID, and PHENYLALA- block, aspartic acid is the precursor of the aminoNINE, plus methanol (wood alcohol). Though a acid ASPARAGINE. It also donates nitrogen atoms tocaloric sweetener, fewer aspartame calories are create UREA, the main nitrogenous waste product ofneeded to obtain a degree of sweetness comparable the body, and to synthesize PURINES, the raw mate-to that of table sugar. Aspartame does not have a rials of ATP, DNA, and RNA. During STARVATION,bitter aftertaste, nor does it contribute to tooth oxaloacetic acid can be converted to blood sugardecay. It has been approved by the U.S. FDA for use (GLUCOSE) by the LIVER, and therefore aspartic acidin fruit juice-based drinks, MALT beverages with less is classiﬁed as a glycogenic amino acid.than 3 percent ALCOHOL, baking mixes, and ﬂa-vored beverages. Aspartame was approved by the U.S. FDA as a aspergillus (Aspergillus ﬂavus) A common MOLDsafe substitute for table sugar for healthy people known to produce AFLATOXIN B, the most potent,consuming up to 23 mg per pound of body weight. naturally-occurring CARCINOGEN for liver cancer.For reference, a can of diet SOFT DRINK typically Aﬂatoxin was discovered in the early 1960s in En-contains 180 to 200 mg of aspartame. Aspartame is gland when thousands of turkeys consumed moldynot safe for everyone. It can be unsafe for genetic groundnut meal and developed severe liver lesions.reasons; people with the inherited disease of This mold is widespread and occurs in soil, air, andphenylalanine metabolism, PHENYLKETONURIA, can- foliage throughout the world. Different strains pro-not metabolize high levels of phenylalanine, and duce varying amounts of mycotoxins (mold tox-
58. 50 aspicins). As “storage fungus,” it develops when foods Task Force (USPSTF) strongly recommends thatare stored. Aspergillus has long been studied by doctors discuss with their patients who are at anfood technologists. Foods often contaminated with increased risk of coronary heart disease the beneﬁtsaspergillus after storage include PEANUTS, CORN, and harms of aspirin therapy. Studies have shownBARLEY, CASSAVA, cottonseed meal, peanut meal, that regular use of aspirin reduced the risk of coro-RICE, SOYBEANS, and WHEAT. In addition, aspergilli nary heart disease by 28 percent in patients whocan contaminate FRUITS, several MEATS, spices, had never had a heart attack or stroke but whocheddar CHEESE, and various prepared foods. were at increased risk. These patients included menImproper drying and storage, high humidity, and over the age of 40, postmenopausal women, and allmechanical damage to grains or nuts favor mold who smoked or suffered from diabetes or highgrowth and widespread contamination. Food con- blood pressure (HYPERTENSION).taminated by mold should be discarded. Its toxins Other potential beneﬁts of aspirin include pre-cannot be washed off. (See also FUNGUS.) venting dangerous high blood pressure during pregnancy; helping victims suffering from demen-aspic A gelatin-based salad with a clear body. tia due to minor STROKES; and reducing the risk ofAspic jelly is prepared from the clariﬁed broth of cancers of the ESOPHAGUS, STOMACH, and COLON,boiled MEAT, FISH, or POULTRY. SHELLFISH, VEGETA- according to studies by the American Cancer Soci-BLES, or FRUIT can also be set in a molded jelly. Pow- ety. Most of these beneﬁts are evident with lowdered GELATIN can be dissolved to prepare gels for dosage—the equivalent of one tablet daily or everyDESSERTS and entrees. Aspics can be colored and other day. Aspirin’s long history of use has deﬁnedﬂavored with WINE or sherry. Fresh PINEAPPLE juice potential risks. Aspirin can cause water retention,contains a very powerful degradative enzyme that decrease KIDNEY function, and promote allergic-likewill break down gelatin. Therefore, cooked rather reactions in susceptible people. Asthmatics arethan fresh pineapple should be used. more likely to react to aspirin. For the person with food allergies, aspirin can accentuate allergy symp-aspirin (acetylsalicylic acid) One of the most toms. Some effects of aspirin can be observed afterwidely used analgesics (pain relievers). More than short-term usage. For example, aspirin use20 million pounds of this over-the-counter medica- increases VITAMIN C loss after only four to ﬁve days.tion are sold in the United States each year. In addi- Because aspirin thins the blood, it may causetion to reducing pain, aspirin reduces fever and bleeding in individuals who are prone to stomachswelling associated with inﬂammation. Several irritation or ULCERS; who have a history of hemo-grams daily are often prescribed to treat the symp- philia, hemorrhagic stroke, uncontrollable hightoms of ARTHRITIS. At the cellular level, aspirin blood pressure, eye problems due to diabetes, liverblocks the formation of PROSTAGLANDINS and or kidney disease; who are facing surgery; or whothromboxanes, HORMONE-like compounds that pro- are in the last trimester of pregnancy. Aspirinmote pain, fever, swelling, and tissue reddening, increases gastric bleeding, especially in the elderlyfrom ARACHIDONIC ACID, their immediate FATTY ACID who drink alcoholic beverages. Aspirin should notprecursor. be used by people taking other nonsteroidal anti- Moderate aspirin use may combat a variety of inﬂammatory drugs or drugs to thin the blood.diseases. Studies indicate that aspirin can reduce Children and teenagers up to the age of 18 shoulddeaths from heart attack when given soon after the not be given aspirin for viral infections because itattack and that daily aspirin use lowers the risk increases the risk of Reye’s syndrome (a seriousof HEART ATTACKS in men and women. These ob- condition affecting the central nervous system,servations are explained by aspirin’s blocking liver, and heart). (See also ALCOHOL-DRUG INTERAC- TIONS; ALLERGY, FOOD.)prostaglandins that promote the clumping of smallblood cell fragments called platelets. This is a criti- Hayden, M. “Aspirin for the Primary Prevention of Car-cal step in the formation of blood clots that could diovascular Events: A Summary of the Evidence forbe life threatening. The U.S. Preventive Services the U.S. Preventive Services Task Force,” Annals of
59. assessment, nutritional status 51 Internal Medicine 136, no. 2 (January 15, 2002): atinine excretion decreases with age. Health of the 161–172. immune system is compromised by nutrient deﬁ- ciencies, and total lymphocytes (white cell) countas purchased (A.P.) Refers to untrimmed foods is often used to assess the status of the immune sys-with inedible portions (bone, husk, rind) intact. tem. Infections and steroid therapy can invalidateThis term describes food available from retail out- this as a nutrition parameter.lets. The term as purchased appears in tables describ- Physical Exam and Clinical Evaluationing the nutrient composition of foods, where it is Although clinicians can usually identify patientsimportant to indicate the form of a speciﬁc food with moderate to severe malnutrition, they may bethat was analyzed. less experienced at identifying patients with mild nutritional depletion. A medical history evaluatesassessment, nutritional status The use of objec- health status and uncovers underlying healthtive data to determine an individual’s nutritional issues and factors that can affect nutrition, such asstatus. Dietitians and nutritionists collect data from alcohol and drug use, chronic disease, disabilities,clients in order to develop appropriate individual- or use of medications. While some signs relateized plans that assure that nutritional goals will be directly to nutritional deﬁciencies as noted above,met. Typically an in-depth nutrition assessment further investigation may be needed to deﬁne theincludes four components: anthropometric mea- underlying cause. For example, a fatty stool maysurements, laboratory tests, physical exam, and indicate pancreatic insufﬁciency or inadequate bileclinical evaluation and diet analysis. Anthropomet- production, or impaired absorption as in celiac dis-ric measurements provide basic data like height ease. Conditions such as shortness of breath, diar-and weight. Commonly these measurements are rhea, constipation, nausea, gingivitis, physical pain,used to calculate a BODY MASS INDEX (BMI), which poor-ﬁtting dentures, and medications may inter-is the weight in kg divided by height in meters. fere with food intake and digestion. EmotionalBody fat is often estimated from measurement of stress can lead to anorexia or depression and dra-tricep skinfold thickness or midarm circumference. matically affect nutrient consumption. ManyThe major problem with interpreting anthropo- lifestyle factors inﬂuence food intake, includingmetric values is that there are no universally income, family structures, eating habits, physicalagreed upon standards for comparison. Addition- activity, accessibility to food, use of alcohol andally, human error can result in inconsistent mea- drugs, and philosophical or religious beliefs.surements. Other means of assessing body fat and Dietary history is an essential part of nutritionlean body mass such as measuring electrical con- assessment. The simplest form is the 24-hourductivity of a region of the body (BIOELECTRIC IMPE- recall. An interview or a questionnaire is used toDENCE ANALYSIS) are common in clinics. determine all foods eaten in the preceding 24 hours Chemical laboratory tests can aid in detecting and to estimate the quantities by using plastic foodmarginal nutritional deﬁciencies. However, inter- models of typical serving sizes. Alternatively, foodpretation depends upon the clinician’s understand- consumption frequency can be estimated using aing of the many factors that may affect a given food checklist (food frequency questionnaire), forparameter. Typical markers include serum albumin, weekly or monthly intake of 40 to 80 of the mostthe most prevalent non-cellular protein in blood, frequently used foods. This is a descriptive, qualita-which has been used to assess the adequacy of tive approach. In contrast, food records and dietdietary protein. Serum transferrin, a blood protein diaries describe the individual’s current foodthat transports IRON, is affected by iron deﬁciency intake, recorded daily in terms of common house-anemia, pregnancy, and by serum iron overload. hold measures. To involve the client in behaviorUrinary creatinine, a waste product from MUSCLE, modiﬁcation, she or he may also be required tocan help determine muscle protein stores, since the record eating patterns, including locations, times,amount of creatinine excreted in the urine is pro- events, and feelings associated with a given meal.portional to a person’s muscle mass. However, cre- For evaluation, intake data are translated into
60. 52 assimilationnutrient intake. Food composition tables form the rier. Because astaxanthin has been shown to pro-basis of detailed nutrient intake calculations, and vide potential health beneﬁts in numerous testsextensive computer software is available to aid in using laboratory animals, it is the subject of exten-dietary analysis. Food scoring systems can be based sive research to determine whether these resultson identifying foods that are the main contributors can be duplicated in humans. Scientists are cur-to the elevation of blood cholesterol, that con- rently investigating its ability to enhance IMMUNEtribute saturated fat or that compose a major food SYSTEM function, prevent cancer, promote orgroup. restore vision, and prevent or treat neuronal dam- In the ﬁnal analysis, dietary nutrient intake is age associated with ALZHEIMER’S DISEASE, PARKIN-compared to a standard for evaluation. Typically SON’S DISEASE, and spinal cord injuries.this is the RECOMMENDED DIETARY ALLOWANCE Jyonouchi, H. et al. “Astaxanthin, a Carotenoid Without(RDA). Since the RDAs are derived for large popu- Vitamin A Activity, Augments Antibody Responses inlations, an individual’s calculated nutrient intake Cultures Including T-Helper Cell Clones and Subopti-that is somewhat lower than the RDA need not mal Doses of Antigen,” Journal of Nutrition 125, no. 10indicate a deﬁciency. Nutrient intake values less (1995): 2,483–2,492.than two-thirds of the RDA are best interpreted asplacing the individual at risk for undernutrition. asthma An inflammatory respiratory disorder with labored breathing, chest constriction, wheez-assimilation The process by which nutrients are ing, and coughing. Asthma affects an estimated 10incorporated into cells and TISSUES of the body. million Americans of all ages, and the incidence isAssimilation is the culmination of DIGESTION and rising yearly. This respiratory condition occursABSORPTION . Food entering the body can be when muscles surrounding small air passagewaysthought of as raw materials that first must be bro- spasm, thus restricting air ﬂow in and out of theken down to individual nutrients by digestion. lungs. The inﬂammation of MUCOUS MEMBRANESThe nutrients must then be taken up into the and overproduction of mucus further obstruct airbloodstream by absorption, and then used by cells ﬂow. It is the resistance to air ﬂow that producesfor growth and maintenance through a complex the wheezing sound so characteristic of asthma.array of chemical reactions controlled by ENZYMES Asthma is an aspect of an allergy attack calledand categorized as METABOLISM. Therefore, inter- immediate hypersensitivity because the effectsference at any stage—digestion, absorption, assim- appear within hours of an allergic reaction. A wideilation—can lead to malnutrition regardless of range of external factors can cause asthma, includ-whether the individual is consuming a balanced ing inhaled ALLERGENS (pollen, mold spores, animaldiet. dander, dust); foods (EGGS, nuts, CHOCOLATE, SHELL- FISH); and some drugs. Alternatively, internalastaxanthin A CAROTENOID found in algae in causes like upper respiratory tract infections canoceans around the world, astaxanthin is what gives cause persistent asthma.the pinkish hue to the ﬂesh of salmonids (SALMON There are five classes of medications usedand rainbow TROUT) and the shells of lobster, crab, for chronic inﬂammation. For treatment of acuteand shrimp. Astaxanthin is added to the feed of asthma attacks, EPINEPHRINE and bronchodilat-farm-raised ﬁsh and crustaceans to compensate for ors, cromolyn sodium or glucocorticoids (anti-the lack of it in their diet. Researchers have inﬂammatory steroids), can be used. However,demonstrated that astaxanthin is a powerful steroids have been linked to bone loss and otherANTIOXIDANT, more effective than BETA-CAROTENE or problems. Antihistamines are often prescribed forVITAMIN E in slowing oxidative damage by FREE the wheezing, sneezing, and itching associatedRADICALS to LOW-DENSITY LIPOPROTEIN (LDL) choles- with allergy attacks. Eliminating the offendingterol (the good form of cholesterol), cell mem- allergens is a direct way of avoiding further distressbranes, cells, and tissues. Unlike beta-carotene, when the allergens occur in the home or work-astaxanthine is able to cross the blood–brain bar- place.
61. atherosclerosis 53 Many asthmatic patients respond to nutritional spoonful of the root is boiled in a cup of water forapproaches. Food allergies are related to an esti- 10 to 15 minutes and drunk three times a day. As amated 75 percent of childhood cases and to tincture 2 to 4 ml is taken three times a day.)approximately 40 percent of adult asthmatics.ELIMINATION DIETS, in which allergenic foods are atherosclerosis (hardening of the arteries) Aavoided for one to four weeks, may alleviate symp- progressive, chronic CARDIOVASCULAR DISEASE char-toms. CORN, WHEAT, CITRUS FRUITS, DAIRY products, acterized by thickening of arterial walls andFISH, and CHOCOLATE are often implicated. Certain deposits called atherosclerotic PLAQUE. Atheroscle-additives can cause symptoms. FD&C Yellow No. 5 rosis is the major cause of heart disease, a wide-(TARTRAZINE) can trigger asthma. SULFITES, which spread condition in the United States where anare common preservatives, trigger asthmatic estimated 65 million people have a form of heart orattacks in susceptible people. Sulﬁtes appear in blood vessel disease. Atherosclerosis occurring inWINE and certain salad-bar vegetables that have arteries supplying oxygen to the heart causes coro-been pickled or canned and in other processed nary heart disease and contributes to HEARTfoods. Eating apples and the mineral selenium may ATTACKS. Medical progress and changes in diet andlower the risk of asthma, which suggests that cer- lifestyle have signiﬁcantly reduced the number oftain antioxidants may protect the lungs from dis- deaths from atherosclerosis in the last decade.ease. Researchers have found that people who ate There are multiple causes for clogged arteries;at least two apples a week faced a 22 percent to 32 some, like heredity, age, and gender, are risk factorspercent lower asthma risk than did those who ate that cannot be controlled. In an estimated 5 per-fewer apples. cent of cases, a genetic defect in the transportation Certain nutrient deﬁciencies are also associated and utilization of CHOLESTEROL is implicated. On thewith asthma, such as VITAMIN B6 and MAGNESIUM. other hand, many factors can be controlled toVITAMIN C serves as an anti-inﬂammatory agent reduce an individual’s probability of developingand may be helpful. Sulﬁte sensitive people may atherosclerosis. HYPERTENSION (high blood pressure)beneﬁt from VITAMIN B12 and MOLYBDENUM. In and OBESITY contribute to atherosclerosis. Familysome asthmatics with low STOMACH ACID, supple- history often accompanies these conditions, yetmented hydrochloric acid may help reduce symp- lifestyle choices can limit their impact. For exam-toms. (See also ALLERGIC RHINITIS; ALLERGY, ple, the failure to cope adequately with STRESS canIMMEDIATE; HISTAMINE.) affect the course of hypertension and obesity, while excessive consumption of ALCOHOL or CALORIESastragalus A Chinese herb derived from the root contributes to obesity. A sedentary lifestyle con-of the perennial Astragalus membranaceus used in tributes to obesity and elevated blood cholesterol.traditional Chinese medicine for more than 4,000 As other examples of personal choice and diseaseyears to strengthen the immune system. Regarded risk, cigarette smoking can cause hypertension andas a potent tonic for increasing energy levels and high dietary saturated fat often leads to high bloodstimulating the immune system, astragalus has also cholesterol.been used as a diuretic, as a vasodilator, and as a The roots of atherosclerosis generally go back totreatment for respiratory infections. childhood, when the inner surfaces of arteries ﬁrst Astragalus, also known as milk vetch root and become rough; then “fatty streaks” develop ashuang-qi, is taken in China by cancer patients to deposits of LIPIDS, ﬁbrous TISSUE, CALCIUM, andboost immunity after drug or radiation treatment blood components accumulate. During adolescenceand is one of the most frequently used food sup- and early adulthood, further deterioration of theplements and remedies in China. It is available as a wall can lead to further accumulation of calciumdry or powdered root, as an extract, or as the cen- and cholesterol in arterial walls. The body cantral ingredient in herbal tea. While some patients respond to fatty streaks by forming tough anduse only the root, others also use the leaves and ﬁbrous deposits called plaque. One form of plaqueﬂowers. It may be used as a decoction. (One tea- consists of proliferated cells and a second type con-
62. 54 atherosclerosissists primarily of accumulated lipids, especially of plays an important role in the formation, progres-cholesterol and cholesterol linked to fatty acids. sion, and disruption of atherosclerotic plaque.Thickening and hardening of plaque with calcium Laboratory blood tests to measure an individ-can progress throughout a lifetime and can ulti- ual’s risk of developing atherosclerosis havemately narrow arteries sufﬁciently to restrict blood become increasingly sophisticated. Elevated bloodﬂow and cause clot formation. Often the blood clot lipids have often been regarded as a risk factor forblocks the already obstructed artery, preventing atherosclerosis. However, elevated serum TRIGLYC-oxygen and nutrients from reaching tissues it ERIDES (FAT) and elevated serum cholesterol levelswould normally feed. are at best only crude indicators of risk of The initial events in plaque formation are not cardiovascular disease. A ratio of total serum cho-completely understood. However, a growing body lesterol to HDL cholesterol is more useful. HDLof clinical evidence implicates an oxidized form of (HIGH-DENSITY LIPOPROTEIN) helps remove choles-cholesterol called LOW-DENSITY LIPOPROTEIN (LDL). terol from tissues and returns it to the liver for dis-LDL transports cholesterol from the LIVER to all posal or redistribution, thus HDL serves a quiteother tissues, and LDL is the most prevalent cho- different role from LDL.lesterol carrier in blood. LDL cholesterol can be a An even more accurate assessment of risk oftarget of FREE RADICALS, highly reactive and damag- atherosclerosis can be obtained from a determina-ing forms of oxygen; in the process, LDL choles- tion of the ratio of specific marker proteins,terol becomes oxidized. Possibly an early event in apoprotein B, a marker for LDL cholesterol, to apo-atherosclerosis, phagocytic cells that patrol artery protein A, a marker for HDL cholesterol. Anotherwalls (macrophages and neutrophils, among oth- cholesterol carrier called lipoprotein (a), a closeers) ingest oxidized LDL at damaged arterial sites cousin of LDL, may be useful as a predictor of heartand in the process become transformed into “foam” disease for children, especially for those whose par-cells that accumulate lipids. Muscle cells may ents or parent had suffered a heart attack beforemigrate into the developing mass as it develops into the age of 42. Elevated homocysteine is considereda fatty streak. an independent risk factor. Vascular inﬂammation Atherosclerosis has also been proposed to be the in coronary heart disease may be assessed by mea-result of the tumor-like growth of arterial cells suring a blood marker for inﬂammation called C-injured by oxidized cholesterol, CARCINOGENS, or reactive protein.other agents such as HOMOCYSTEINE, a degradation Recent evidence suggests that atherosclerosisproduct of the amino acid METHIONINE. It is not may be reversed. One protocol prescribes a near-known whether reducing blood levels of homocys- VEGETARIAN diet supplying only 10 percent of totalteine will lower the risk of cardiovascular disease. calories from fat and 5 mg of cholesterol a day;Alternatively, mechanical injury to the arterial wall abstinence from smoking and alcohol; 30 minutesmay induce clumping of platelets, cell fragments of EXERCISE daily at least six times per week; at leastrequired in blood clot formation. Still others an hour daily of stress-reduction exercises, includ-propose that localized overproduction of growth ing yoga and meditation, with twice weekly meet-factors (platelet-derived growth factor) could stim- ings in a support group. The mental as well as theulate underlying smooth muscle to proliferate. The physical aspects of this program seem essential fordetailed involvement of platelets, oxidized blood its success in opening arteries partially blockedlipids, nitric oxides, circulating carcinogens, antiox- through disease. (See also HYPERCHOLESTEROLEMIA;idants, macrophages, and white blood cells in VEGETARIAN.)plaque formation and abnormal lipid metabolism is Brown, A. J., and W. Jessup. “Oxysterols and Atheroscle-still being actively investigated. Sudden death, rosis,” Atherosclerosis 142, no. 1 (January 1999): 1–28.heart attacks and unstable angina are often caused Futterman, L. G., and L. Lemberg. “The Use of Antioxi-by coronary blood clots (thrombosis), due to dis- dants in Retarding Atherosclerosis: Fact or Fiction?”lodged atherosclerotic plaque. Unstable sites are American Journal of Critical Care 8, no. 2 (March 1999):generally inﬂamed. Indeed, chronic inﬂammation 130–133.
63. ATP 55Ridker, P. M. “Inﬂammation, Atherosclerosis, and Car- say it increases the risk of developing cancer. The diovascular Risk: An Epidemiologic View,” Blood National Cancer Institute recommends patients con- Coagul Fibrinolysis 10, suppl 1 (February 1999): S9–12. sume no fewer than ﬁve daily servings of fruits and vegetables, many of which contain cancer-ﬁghtingAtkins diet A high-protein, low-carbohydrate ANTIOXIDANTS, to minimize the risk of cancer. Recentweight loss program based on the book Dr. Atkins research shows that patients who are most success-Diet Revolution, ﬁrst published in 1972 by the late ful at losing weight and keeping it off do so by exer-Dr. Robert Atkins, who described a theory that cising regularly and lowering their daily caloricmost people are overweight because they eat too intake by eating foods low in sugar and fat and highmany CARBOHYDRATES. Patients who follow the in ﬁber. (See also WEIGHT MANAGEMENT.)Atkins plan eat a diet of almost all protein and fat. “The Truth About Dieting,” Consumer Reports, June 2002.Red meat, butter, cheese, eggs, mayonnaise, and Miller, B. V. et al. “Effects of a Low Carbohydrate, Highsimilar high-fat, high-protein foods that are usually Protein Diet on Renal Function,” Obesity Research 8,restricted on other weight-loss programs form the suppl. 1 (2000): 82S.basis of the Atkins diet. During the first two weeks of the plan— atopic dermatitis See DERMATITIS.the “induction period”—patients are restricted toconsuming no more than 20 g of carbohydrates aday. This induces the body to go into a state of fat- ATP (adenosine triphosphate) A compound con-burning fasting called ketosis. During ketosis the taining “high energy” phosphate bonds that func-body burns ketones, which is fuel created by the tion as the energy currency of cells. ATP containsbreakdown of fat cells. The theory is that instead of chemical ENERGY and must be constantly replen-burning carbohydrates for fuel the body feeds on its ished and recycled within cells. It is used for allstores of fat. energy-requiring processes including synthesis of Use of this diet continues to be controversial. all cellular constituents (PROTEINS, FAT, LIPIDS, POLY-Ever since Dr. Atkins published his theory, nutri- SACCHARIDES, DNA) and cell division, movementtion and health experts have criticized it as and MUSCLE contraction, nerve impulses, and evenunhealthy, and it has been denounced by the the maintenance of ELECTROLYTE balance in cells.American Heart Association. The Atkins plan con- ATP is not stored and it cannot be eaten to increasetradicts numerous studies that have demonstrated its level in the body.the signiﬁcant correlation between diets high in ATP is produced by CATABOLISM, the summationsaturated fat and increased heart disease risk, and it of all chemical processes in the cell that convertcontradicts dietary recommendations set forth in energy stored in fat and CARBOHYDRATE to ATP.the U.S. Department of Agriculture’s (USDA) FOOD MITOCHONDRIA, subcellular structures that functionGUIDE PYRAMID, which recommends six to 15 daily as the cell’s powerhouses, produce most of the ATPservings of high-carbohydrate foods such as fruit, in many types of cells, except red blood cells, by therice, bread, cereal, and whole grain products. There oxidation of fat and carbohydrate. The cellularis little evidence that carbohydrates alone affect mechanism coupling this oxidation with the trap-body weight. Being overweight reﬂects consuming ping of about 40 percent of the released energy astoo many calories. ATP is called OXIDATIVE PHOSPHORYLATION. In this Critics of the diet say the high levels of saturated process, electrons obtained from fuel oxidationfat in the food it recommends can elevate choles- pass through a sequence of electron carrier pro-terol levels and lead to cardiovascular disease and teins (CYTOCHROMES), which operate like a bucketHEART ATTACK. Atkins supporters say blood choles- brigade. Simultaneously, inorganic phosphate ionsterol levels may rise initially but quickly return to attach to ADP (adenosine diphosphate) to formprediet levels or drop to even lower levels with time. ATP, while oxygen is reduced to WATER.Because the diet recommends that patients restrict VITAMINS of the B COMPLEX assist the enzymictheir intake of fruits and vegetables, some experts machinery of the mitochondrial engine in its
64. 56 atrophyenergy conversions. Without B vitamins, fuel is not Following the FEINGOLD DIET, which limits con-burned efﬁciently, curtailing ATP output. They do sumption of artiﬁcial colors and preservatives andnot create ATP nor are they burned as fuel, how- eliminates sensitive food from the child’s diet, canever. (See also CARBOHYDRATE METABOLISM; FAT sometimes be beneﬁcial. However, experience hasMETABOLISM; KREB’S CYCLE.) shown that effective treatment involves the entire family in order to create a supportive environment.atrophy A reduction in size and function of a tis- A high-protein, low-carbohydrate diet with limitedsue, organ, or structural element of the body. MAL- reﬁned sugar may be beneﬁcial, but the role ofNUTRITION, decreased physical activity, a change in sugar in behavior is controversial. The DIETARYHORMONE balance, reduced cell proliferation, and GUIDELINES FOR AMERICANS state that sugar does notdiminished oxygen supply can cause atrophy of tis- cause hyperactivity. Indeed, several clinical trialssues. Emaciation characterizes extreme STARVATION, have not detected an association. On the otherANOREXIA, or disease processes preventing nutrient hand, excessive dietary sugar leads to nutrient deﬁ-assimilation. ciencies that contribute to hormonal imbalances affecting behavior. Conventional treatment to regulate ADHD reliesattention deﬁcit-hyperactivity disorder (ADHD) on psychological counseling, behavior modiﬁcationBehavior disturbances characterized by overactiv- and drugs (stimulants, tranquilizers, and tricylicity and restlessness, aggressive behavior, poor self ANTIDEPRESSANTS). (See also ADDICTION AND SUGAR;control, and short attention span. As many as 4 ALLERGY, FOOD.)percent of children suffer from hyperactivity,which affects more boys than girls through adoles-cence. As many as 30 percent to 50 percent of indi- au gratin From the French term for a goldenviduals who had ADHD as children continue to crust on the surface of a prepared dish. In thehave it as adults. Multiple factors have been impli- United States, this term usually refers to a foodcated in hyperactivity and inattentiveness: coated with grated, strongly ﬂavored CHEESES or BREAD crumbs and melted BUTTER, therefore higher• Artiﬁcial FOOD ADDITIVES: Some experts believe in CALORIES than baked or steamed foods. A scal- that synthetic chemicals like ARTIFICIAL FOOD COL- loped or sauce dish can be lightly coated with bread ORS, PRESERVATIVES, and salicylates (compounds crumbs, crushed corn flakes, ground nuts, or related to aspirin) affect the nervous system. cracker crumbs and heated to form a golden brown• Food allergies and FOOD SENSITIVITIES: Clinical crust. More generally, VEGETABLES, FISH, and PASTA studies indicate that elimination of offending dishes can be cooked so that a layer forms on the foods from an allergic child’s diet can sometimes surface, thus protecting underlying food from dry- improve scholastic performance dramatically. ing out.• Abnormal CARBOHYDRATE METABOLISM: Some people with ADHD may be unable to metabolize autoimmune diseases Disorders of the IMMUNE SUGAR normally. Behavioral problems have been SYSTEM in which the body attacks itself. Normally, reported to be linked with excessive consump- the body employs the immune system to discrimi- tion in these individuals. nate very carefully between foreign invaders,• Toxic exposure: Excessive aluminum, lead, and which are attacked, and its own TISSUES. In autoim- copper may be associated with hyperactivity. mune diseases, the immune system mistakenly• Nutritional deﬁciencies: Deﬁciencies of iron, cal- produces ANTIBODIES against speciﬁc tissues. Such cium, magnesium, zinc, and essential fatty acids an attack can lead to crippling damage. Studies to have been linked to ﬁdgeting, restlessness, and deﬁne underlying causes suggest there is a major learning difficulties. Occasionally, children breakdown in the way the body discriminates respond to niacin, vitamin B6, and thiamin sup- between foreign cells and its own tissues. Monitor- plementation. ing self-recognition is a complex process involving
65. avitaminosis 57many components of the immune system that are much less common than rheumatoid arthritiscurrently being studied: and occurs most frequently in women between the ages of 20 and 40. The rate of occurrence has• Normal controls (T-helper cells) that regulate B steadily increased in the last 30 years, although cells responsible for forming “self-directed” anti- its cause is unknown. bodies may be bypassed. T-cells and B cells are Multiple Sclerosis (MS) Characterized by blurred the two major types of lymphocytes (white vision and a gradual loss of control of move- blood cells). ment as nerve tissue is damaged. There is also• “Rheumatoid factor,” antibodies present in 50 spotty damage to the motor and sensory nerves. percent to 95 percent of patients. This disease apparently begins early in life.• Defects in the production of cells regulating Early stages are characterized by feeling clumsy antibody production (T-helper cells or T-sup- and heavy, with “pins and needles” sensations pressor cells) due to genetic defects or defects and feeling light-headed. Living in northern caused by viruses. states increases the risk of getting MS. One or• Speciﬁc antibody-binding sites. HLA antigens on two people per thousand Americans have the cell surfaces are linked to a susceptibility to sev- disease. The cause of MS is unknown, and there eral autoimmune diseases, like insulin-indepen- is no proven cure. Abnormalities in the dent diabetes and LUPUS ERYTHEMATOSUS. immune response have been detected in• FOOD SENSITIVITY and ALLERGY are implicated in patients with MS, possibly triggered by a prior some cases. viral infection. Most nutrition research has focused on decreased dietary FAT and increased Examples of different autoimmune diseases ESSENTIAL FATTY ACIDS. (See also NIGHTSHADEinclude the following: FAMILY.)Rheumatoid Arthritis A disease progressing from Harbige, L. S. “Nutrition and Immunity with Emphasis on Infection and Autoimmune Disease,” Nutrition and inﬂammation of the joint to a deterioration of Health 10, no. 4 (1996): 285–312. cartilage. It is characterized by special antibod- ies, “rheumatoid factors” in the blood that can be measured clinically. Patients with rheuma- avidin A protein in EGG white that binds to toid arthritis have increased amounts of a spe- BIOTIN, making this B vitamin unavailable for ciﬁc type of “histocompatibility” (HLA) antigen. intestinal absorption. Avidin in one of several These antigens control transplantation reac- nutrient binding proteins in egg white that help tions. In some cases food allergies are impli- prevent bacterial growth, which could threaten the cated. fertilized egg. Avidin binds biotin so tightly andInsulin-dependent Diabetes Glucose accumulation selectively that it has been used to experimentally in the blood due to the destruction of insulin- induce biotin deﬁciency in animals, which other- producing cells of the PANCREAS. With the loss of wise is difﬁcult to study. There is no risk of biotin the ability to make INSULIN, there is an absolute deﬁciency due to avidin when consuming cooked requirement for the hormone. This disease is eggs because avidin is inactivated by heat. (See also also characterized by the presence of a ANTIVITAMIN.) speciﬁc kind of antibody recognition site (histo- compatibility or HLA antigen). The best early avitaminosis A vitamin deﬁciency disease. Such marker of this disease appears to be an antibody diseases can be caused by a dietary deﬁciency, by against the insulin-producing tissue of the pan- maldigestion or by the MALABSORPTION of a vitamin. creas. Though rare in industrialized nations, acute vita-Lupus Erythematosus (Systemic) A chronic in- min deficiency diseases are all too common ﬂammatory disease that can attack many or- throughout developing nations, especially among gans, especially their connective tissues. It is children and elderly populations. Preclinical signs
66. 58 avocadoand symptoms usually precede the appearance of a CHOLESTEROL while maintaining HDL cholesterolfull-blown deﬁciency disease such as SCURVY (VITA- levels with typical high fat consumption.MIN C); PELLAGRA (NIACIN); BERIBERI (THIAMIN); RICK- The ﬂesh has a buttery consistency and a mild ﬂa-ETS (VITAMIN D); and ANEMIA (various vitamins such vor. Fresh avocados may be used as hors d’oeuvresas FOLIC ACID and VITAMIN B12, among others). The or in salads, mousses, and soufﬂes. Sliced avocadosMINIMAL DAILY REQUIREMENT was a standard opera- darken rapidly when exposed to air and room tem-tionally deﬁned by the minimal amount of a nutri- perature. The enzyme-catalyzed darkening can beent that must be supplied to prevent deﬁciency reduced by refrigeration or by adding LEMON juicedisease. (See also MALNUTRITION.) or VINEGAR. One half of an avocado, four inches long (100 g) provides calories, 160; protein, 2.0;avocado (Persea Americana) A fruit native to fat, 15 g; carbohydrate, 7 g; potassium, 600 mg;Central and South America, and cultivated in the iron, 1.0 mg; vitamin A, 60 retinol equivalent; vit-United States in California and Florida. Depending amin C, 8 mg; niacin, 1.9 mg; thiamin, 0.1 mg;on the variety, avocados vary from bell-shaped and riboﬂavin, 0.1 mg.green to pear-shaped with a coarse, shell-like skin.This fruit is unusually high in FAT, ranging from azodicarbonamide A FOOD ADDITIVE used to age5 percent to 20 percent, although most of it is (condition) WHEAT ﬂour. Aging is an OXIDATIONmonounsaturated. A MONOUNSATURATED OIL de- process. During aging, FLOUR constituents, includ-rived from the avocado is rather expensive and ing PROTEIN, are chemically altered to yield an elas-resembles OLIVE OIL in FATTY ACID composition. tic dough that is lighter and easier to manage.Avocado oil contains 69 percent monounsaturated Elastic doughs can rise more readily with the CAR-fatty acids and 14 percent POLYUNSATURATED FATTY BON DIOXIDE released by LEAVENING AGENTS. BeforeACIDS. The corresponding values for olive oil are 72 the use of food additives, wheat ﬂour was storedpercent and 9 percent respectively. These monoun- for several months in order to alter the propertiessaturated oils are more healthful than saturated of GLUTEN. Flour conditioning agents now accom-oils and polyunsaturates because they lower LDL plish the same result in a matter of days.
67. Bbaby food Foods other than MILK and INFANT food poisoning: In the diarrheal form, infection isFORMULA fed to babies during their ﬁrst year. Com- associated with VEGETABLES, SAUCES, puddings, PAS-mercially prepared baby foods in jars (cooked or TRY, and MEAT dishes that have been improperlypureed food) and in packets (as dehydrated food) refrigerated after cooking, permitting bacterialoffer a large variety of wholesome and nutritious spores to begin growing. The bacteria produce tox-food, including MEATS, CEREALS, VEGETABLES, FRUITS, ins (ENTEROTOXIN) in the intestine that cause symp-DESSERTS, and combination foods. Food consistency toms including severe DIARRHEA and abdominalvaries from strained to chunky according to the pain, and, occasionally, associated nausea. Symp-developmental age of the child. toms generally appear 10 to 12 hours after con- No ARTIFICIAL FOOD COLORS or ARTIFICIAL FLAVORS suming contaminated food and usually diminishare added. However, FOOD ADDITIVES may be in- within 24 hours.cluded to inhibit MOLDS, increase texture, or soften A second food poisoning syndrome (EMETIC syn-foods. Until the 1980s, most bottled baby foods drome) is due to the production of a differentcontained MODIFIED CORNSTARCH as a thickener. toxin, which is produced in the food itself. FriedThis questionable food additive is now seldom used RICE is often a culprit in Asian restaurants. In thein baby foods. typical scenario, boiled rice is allowed to dry; then Salt and SUGAR were once common additives to it may be stored overnight or longer before it ismanufactured baby foods. Ironically, these were fried. Heat resistant bacterial spores may form.often added to satisfy the parent’s taste. Baby foods Symptoms generally appear within one to ﬁveare now either unsweetened or contain low hours and include nausea, vomiting, and malaise.amounts of sugar, and manufacturers have elimi- To minimize this source of food poisoning,nated salt. There is no health reason for adding freshly cooked food is best eaten hot. FoodSODIUM, SUCROSE, MONOSODIUM GLUTAMATE (MSG), allowed to cool slightly and kept warm for ex-or PRESERVATIVES to baby foods. Furthermore, tastes tended periods may promote bacterial growth.for salty and sugary foods can be acquired, which Cooked food should be kept hot or cooled rapidlysuggests a potential risk of establishing a child’s and refrigerated.preference for PROCESSED FOOD at an early age.Although all ingredients are listed on baby food bacon Smoked and cured cuts from the back andlabels, the labels can be misleading. For example, rib area of the hog. Bacon is a high-fat food that is“high meat” dinners need be only 26 percent meat usually thinly sliced and fried or grilled. Baconin baby food, and “chicken and rice” for babies burns easily, and old bacon burns twice as fast asneed be only 5 percent chicken according to regu- fresh. Bacon, 100 g or about three ounces, cookedlations. (See also BREAST-FEEDING; FOOD LABELING.) and drained of FAT, represents 573 CALORIES, andKurtzweil, Paula. “Labelling Rules for Young Children’s most of this is due to SATURATED FAT. Canadian-style Food,” FDA Consumer 29, no. 2 (March 1995): 14–18. bacon resembles HAM and comes from a muscle in the eye of a pork loin; it should be cooked moreBacillus cereus A bacterium capable of causing like ham. It is a leaner meat than U.S. bacon; 100 gFOOD POISONING. There are two forms of B. cereus equals 183 calories. 59
68. 60 bacteria, intestinal NITRITES are added to bacon and other cured metabolized by bacteria to short-chain fatty acidsmeats to retard bacterial growth and to maintain a (ACETIC ACID, PROPIONIC ACID, and BUTYRIC ACID) andbrighter color. The legal limit of nitrite in bacon was methane and hydrogen. The short-chain fatty acidsset at 100 ppm (parts per million) in 1985. Cancer may supply more than 10 percent of the body’sresearchers are concerned that nitrite can react with energy needs, and butyric acid speciﬁcally pro-nitrogen-containing compounds (AMINES) in foods motes the health of the colon. Other useful bacter-to form a potent carcinogen (cancer-causing agent) ial products include VITAMIN K and BIOTIN incalled nitrosoamine. Among cured MEATS, levels of quantities usually adequate to meet most dailynitrosoamines were found to be highest in bacon requirements.because it is fried at high temperatures, which pro- A state of imbalanced intestinal bacteria is calledmotes nitrosoamine formation. The U.S. Depart- dysbiosis, which is characterized by low levels ofment of Agriculture requires that VITAMIN C desirable bacteria and the appearance of harmful,(ascorbic acid) or another ANTIOXIDANT be added to opportunistic organisms. Many factors can causeminimize the formation of nitrosoamine when the dysbiosis. The most common cause is the chronicmeat is cooked. (See also MEAT.) use of broad-spectrum antibiotics that destroy many types of bacteria, including the beneﬁcial ones. A Western-style diet, characterized by highbacteria, intestinal Microorganisms that nor- meat, high fat, and low ﬁber consumption, favorsmally grow in the human INTESTINE. In adults the dysbiosis. STRESS, inadequate stomach acid to ster-intestine contains more bacteria than there are cells ilize food in the stomach, and aging can imbalancein the body. The colon contains most of the intesti- gut bacteria.nal bacteria, weighing typically 4 to 6 pounds and Pancreatic insufﬁciency can lead to carbohy-including nonspore-forming anaerobic bacteria, drate maldigestion and inflammation or otheranaerobic streptococci, and acid-forming bacteria. alteration of the intestine, which can limit carbo-In this regard, lactobacillus species and biﬁdobacter hydrate digestion and uptake. Excessive undigestedspecies are most important. In a healthy person, carbohydrate resulting from maldigestion and MAL-the bacterial ﬂora are relatively constant. This is ABSORPTION can promote bacterial proliferationremarkable, considering the many pounds of food leading to DIARRHEA, FLATULENCE, and bloating. LAC-ingested daily and the huge number of microor- TOSE INTOLERANCE, which is due to the inability toganisms in the environment. digest milk sugar, leads to intestinal discomfort “Friendly” gut bacteria are important in main- when bacteria are able to ferment undigested lac-taining a healthy intestinal ﬂora that beneﬁt the tose. Unusually rapid movement of food throughbody. Lactobacillus species occupy the lower por- the digestive tract (shortened transit time) andtions of the small intestine, where they adhere to diarrhea change the amounts and the relative com-the intestinal wall and prevent potential pathogens position of intestinal bacteria. Lactic acid bacteria(disease-producing microorganisms) from growing supplements are available to help repopulate theon the intestinal wall. The exclusion of potential intestine and help relieve symptoms of diarrhea.pathogens from attachment sites on the intestinal (See also ACIDOPHILUS; ESCHERICHIA COLI.)wall where they might colonize in the presence ofnormal bacteria is referred to as microbial interfer- Gibson, Glenn R., and Marcel B. Roberfroid. “Dietaryence. Lactobacillus and biﬁdobacteria break down Modulation of the Human Colonic Microbiota: Intro- ducing the Concept of Prebiotics,” Journal of Nutritioncarbohydrate to produce LACTIC ACID, which helps 125, no. 6 (1995): 1,401–1,412.create an acidic environment that is unfavorable formany potential pathogenic microorganisms. Thesebacteria also produce substances that limit the bacterial toxins Complex substances producedgrowth of undesirable organisms, including yeasts. by disease-causing bacteria. Toxins cause disease, Intestinal bacteria ferment much of the FIBER an especially FOOD POISONING. Enterotoxins representundigested carbohydrates, which are further one class of bacterial toxins. These substances irri-
69. baking powder 61tate the lining of the intestines, causing diarrhea bagel A doughnut-shaped, dense roll made withand intestinal muscle spasms. high-protein ﬂour. The basic ingredients are typical The two most common toxin-producing bacte- of most BREADS; FLOUR, water, YEAST, and salt.ria that contaminate food and cause food poison- Recent trends are to add sweeteners like sugar oring are staphylococcus and clostridium. They honey. Most of the CALORIES come from CARBOHY-produce protein enterotoxins and are a common DRATE, not FAT. Egg bagels contain additional fatcause of food poisoning in the United States and and CHOLESTEROL derived from eggs. Bagels are tra-other countries. Other pathogenic bacteria, like ditionally eaten with cream cheese and lox. A typ-SALMONELLA, cause illness by infecting the intesti- ical plain bagel weighing 68 grams (2.4 oz) suppliesnal tract. Foods most likely to be involved in out- 200 calories; carbohydrate, 38.2 g; protein, 7.5 g;breaks of enterotoxin poisoning are contaminated, and fat, 1.75 g. Larger bagels may weigh threecooked foods such as HAM, POULTRY, BEEF, cream- times as much and supply an additional 75 to 80ﬁlled pastry, FISH, SHELLFISH, potato salad, maca- calories, and 1 to 2 grams of fat per ounce.roni salad, and egg and milk products. Followingcontamination of a food, the staphylococcal bacte- baker’s yeast Strains of the yeast Sacchromycesria require several hours of incubation at warm cervisia used to leaven bread and other bakery items.temperatures to form toxins. Sometimes large The purpose of yeast is to metabolize carbohydratesamounts of warm food placed in refrigeration cool and generate CARBON DIOXIDE, which when trappedso slowly that staphylococcal growth and toxin as bubbles makes the dough rise. Yeast enzymesproduction occur. Brief reheating does not destroy break down glucose released from the starch inenterotoxins. dough. To maximize this leavening effect, strains of Neurotoxins represent a second class of bacterial S. cervisia have been selected for their ability to fer-toxins. The most notorious neurotoxin causes BOT- ment sugar with maximum carbon dioxide forma-ULISM, in a rare, potentially deadly form of food tion and minimal ALCOHOL production. Thus baker’spoisoning that occurs throughout the world. This yeast differs from BREWER’S YEAST, which maximizesdisease is caused by the anaerobic, spore-forming ALCOHOL production from sugar. Dried, easy-blendbacillus Clostridium botulinum, which can produce a baker’s yeast is available in packets. It must beneurotoxin in inadequately canned or contami- reconstituted in warm water before it is added tonated food. Botulinum toxins are heat-stable pro- dough in order to activate yeast ENZYMES to gener-teins that persist in cooked food. They are among ate carbon dioxide; the dehydrated yeast them-the most poisonous natural toxins; only two micro- selves cannot reproduce. Sugar fermentation is bestgrams can be lethal to an adult. Spores of clostrid-ium botulinum are not killed at the temperature of carried out at 80° F to 95° F, the temperature rec-boiling water, thus canning procedures must ommended to permit dough to rise.employ higher temperatures (230° F–250° F) forseveral minutes to assure destruction of this spore- baking powder A mixture of chemicals that gen-forming bacteria. erates CARBON DIOXIDE in dough, both in the mixing Endotoxins are a third class of bacterial toxins. bowl and in the oven and without the interventionThey represent a heterogenous group of products of yeast. Bubbles of carbon dioxide create pockets inreleased from bacterial cell walls and protoplasm the dough that make leavened bread and bakedwhen bacteria die and disintegrate. They are nor- goods lighter. Baking powders typically containmally excluded by the intestinal mucosal barrier three types of ingredients to maximize their effec-and intestinal antibodies. However, with gut tiveness: sodium bicarbonate, an acidic chemical,inﬂammation the intestinal lining becomes leaky and an anticaking agent like CORNSTARCH or calciumand endotoxins may be absorbed to a limited silicate to prevent caking in high humidity. In theextent. CYTOTOXINS are then capable of attacking presence of water, the acidic ingredient reacts withcells of speciﬁc organs and causing disease. (See the basic salt, sodium bicarbonate, to generate car-also FOOD TOXINS; LEAKY GUT.) bon dioxide bubbles. Sodium bicarbonate is consid-
70. 62 baking sodaered a safe food additive. Baking powder (and bak- balanced diet A diet that supplies all essentialing soda) contribute approximately 25 percent of nutrients in the appropriate amounts for optionalthe typical American’s SODIUM consumption, and health throughout the life span. Food should pro-typical dietary guidelines recommend cutting back vide VITAMINS, MINERALS, PROTEIN, CARBOHYDRATE,on sodium to minimize the risk of high blood pres- FAT, OILS, and FIBER to meet individual needs. Thesure in susceptible people. CALORIES consumed should match the amount used Three types of baking powders are available that in order to stabilize body weight.are classed according to their acidic ingredients. Tar- Variety characterizes a balanced diet, whichtrate baking powders contain sodium or calcium tar- emphasizes fresh, minimally processed, or wholetrate. These acidic salts reach quickly, and doughs foods. Exchange lists, which can be found in somecontaining them cannot be stored. Phosphate bak- nutrition books, simplify making healthful fooding powders contain calcium acid phosphate, which choices by supplying a variety of options; for exam-can react in cold dough as well as releasing carbon ple, among different protein sources. While notdioxide during baking. Sodium pyrophosphate is speciﬁcally a low-fat, low-CHOLESTEROL diet, a bal-sometimes added as an acidic ingredient. Studies anced diet tends to have less saturated fat, reﬁnedsuggest that pyrophosphate may harm fetal animals. carbohydrate and cholesterol. Diseases like CANCER,Pregnant women may wish to avoid this particular HYPERTENSION, OSTEOPOROSIS, diabetes, and CARDIO-food additive. Double-acting baking powders, desig- VASCULAR DISEASE have reached epidemic propor-nated (SAS), incorporate sodium ALUMINUM phos- tions and are linked to unbalanced diets. Aphate (or sulfate) and calcium acid phosphate. They balanced diet deﬁnitely plays a role in preventinggenerate carbon dioxide in cold dough, but they are these and other chronic diseases.most active when they contact the heated oven. A Those who rely on PROCESSED FOOD, high in fat,serving of cake prepared with these baking powders sugar, salt, and other FOOD ADDITIVES, run the riskcan contain 5 to 15 mg of aluminum. Aluminum of an unbalanced diet. Consumption of such foodswas once thought to be a safe food additive, but its increases the need for other foods in the diet thatsafety has been questioned because it has been are nutrient dense. However, the temptation is toshown to accumulate in the brains of senile patients. eat more of the same processed foods, which may(See also ALZHEIMER’S DISEASE.) also be less nutritious because of the way they were grown, stored, or processed. People who skip mealsbaking soda (bicarbonate of soda, sodium bicar- without replacing them with nutritious snacks, andbonate) A common leavening agent used in who choose a weight loss diet, consuming less thanbaked goods. Baking soda can be used in place of 1,500 calories per day, are likely to have inade-baking powder when an acidic ingredient is also quate diets. Individuals at an increased risk includeadded. Sour milk, molasses, or CREAM OF TARTAR are low-income, pregnant, or lactating women; low-sufﬁciently acidic to make dough and batter rise. income children and teenagers; elderly persons eat-The chemical reaction is the same as that occurring ing alone; and strict VEGETARIANS, who may notwhen baking powders are used, although baking consume enough needed nutrients. Pollution andsoda produces more tender, lighter baked goods. job-related chemical hazards may increase nutrientBecause bread and baked goods are a large part of needs beyond those supplied by the usual diet.the American diet, baking powder and baking soda Limiting food choices because of income or strictare major dietary sources of SODIUM: They con- religious or philosophical preference requires plan-tribute one-quarter of the average person’s sodium ning to assure adequate consumption of all essen-intake. Excessive sodium intake increases the risk tial nutrients.of high blood pressure in susceptible people. To test Replacing EMPTY CALORIES and sugary foods withthe effectiveness of any baking powder, mix a tea- more nutritious options represents a major chal-spoon of baking powder with a half teaspoon of hot lenge in achieving a balanced diet. Variety simpliﬁeswater. A fully active powder will bubble vigorously. the task. Vegetables supply low-fat energy in theBaking soda is classiﬁed as a safe food additive. (See form of starch, vitamins, beta-carotene, minerals,also BAKER’S YEAST.) and ﬁber. Dark green leafy vegetables include
71. barbecued meat/charcoal broiled meat 63CHARD, KALE, and COLLARD, in addition to spinach. bananas have a pleasant taste, are inexpensive, areThe cabbage family encompasses BROCCOLI, BRUSSELS easily chewed and are available year-round. TheSPROUTS, CAULIFLOWER, and Chinese cabbage. Winter banana originated in India and is now cultivated inSQUASH, summer squash, and YAMS represent yel- many tropical regions. The banana tree resembles alow-colored vegetables. Whole grains are also palm. Although there are many varieties ofimportant: WHEAT, CORN, MILLET, RICE, TRITICALE, RYE, bananas, they fall into two major groups: Fruitand BUCKWHEAT for starch and minerals, vitamins, bananas are eaten raw and occasionally cooked;and ﬁber. LEGUMES supply ﬁber and protein: beans plantains are cooked as vegetables. Yellow bananasand peas, CHICKPEAS, lima beans, and LENTILS. A bal- are the most common variety sold in the Unitedanced diet includes low-fat dairy products: low-fat States. These bananas are harvested green to avoidCHEESE, low-fat or skim MILK, YOGURT, KEFIR, and damaged, overripe fruit at the market. GreenEGGS for protein and CALCIUM. Nuts and seeds pro- bananas will ripen at room temperature in a fewvide plant oils: ALMONDS and SUNFLOWER and PUMP- days, and ripened fruit (solid yellow ﬂecked withKIN seeds. Lean MEATS, POULTRY, FISH, and SHELLFISH brown spots) can be refrigerated to prevent furtherprovide trace minerals, vitamins, and AMINO ACIDS. A ripening. Refrigeration darkens the skin but doesvariety of fruits supply VITAMIN C, POTASSIUM, and not affect the ﬂavor. Overripe bananas are used inﬁber. (See also DIETARY GUIDELINES FOR AMERICANS.) breads, mufﬁns, and other baked goods. Bananas are a rich source of potassium. A single eight-inchbalm (Melissa officinalis; lemon balm, garden banana (114 g) provides 105 calories; protein, 1.2balm, balm mint) A lemon-scented herb native to g; carbohydrate, 26.7 g; ﬁber, 3.3 g; iron 0.35 mg;Europe. Lemon balm is a perennial growing up to potassium, 451 mg; thiamin, 0.05 mg; riboﬂavin,two feet in height with broad, dark green leaves. Its 0.11 mg; niacin, 0.81 mg.pale yellow ﬂowers grow in clusters. Leaves andsprigs contribute a subtle lemon ﬂavor to beverages barbecued meat/charcoal broiled meat MEAT(teas and lemonade), as well as to stufﬁngs, sauces, that is cooked over a gas, electric, or charcoal grill.ﬁsh, white meat dishes, soups, and salad dressing. Cooking over charcoal is an ancient form of cook- ing, and most foods, including meat, FISH, and POULTRY, can be cooked on a grill. Foods acquire abamboo shoot (Arundinaria, Bambusa, Dendro- distinctive ﬂavor when grilled. Some meats are bet-calamus) The young, tender, sprouting stems of ter ﬂavored if they have been marinated before-several types of bamboo that are used in Asian hand. Vegetables like corn, potatoes, peppers, andcooking. This plant grows in tropical Asia. Edible mushrooms can be wrapped in aluminum foil andshoots are white and conical in shape, averaging 25 cooked on a grill. Barbecued food can be BASTED orinches in diameter and 4 inches in length. They are served with any of a variety of traditional sauces.peeled and sliced into strips before cooking. Boiling To prevent food poisoning, meat and poultrybamboo shoots removes a toxin (hydrocyanic should be defrosted in the refrigerator. Leftoveracid). Canned bamboo shoots are precooked. Pre- marinade should be discarded. Cooked food shouldcooked bamboo shoots are used in soups, stir fries, never be put back on a plate that held raw food.and hors d’oeuvres and can accompany MEAT and Likewise, all surfaces and utensils touched by rawFISH. Salted, dried shoots are used as a seasoning. In foods should be washed thoroughly with soap andJapan, bamboo shoots are a spring vegetable. The hot water.shoots have a high water content. Canned bamboo Barbecuing meat allows fat to drip on hot coalsshoots (1 cup, 131 g) provide 25 calories; protein, or hot metal, which forms CANCER-causing agents2.3 g; carbohydrate, 4.2 g; ﬁber, 3.3 g; iron, 0.42 (BENZOPYRENES). These vaporize, adhere to soot,mg; with traces of vitamins, minerals, and fat. and deposit on the surface of the meat. To lessen the production of carcinogens, meat should bebanana (Musa paradisiaca) A seedless fruit of the trimmed of all visible fat before cooking. Otherbanana tree, the most popular fruit in the United methods to reduce fat drippings include wrappingStates. Their popularity is based on the fact that meat in foil, placing foil under meat as it cooks,
72. 64 barbituratesprecooking meat to shorten grilling time, marinat- basal energy expenditure (BEE) The increaseding meats before grilling, and cooking meat slowly energy requirements of patients recovering fromat low temperatures. disease or injury. In practice, BEE represents an estimate of the CALORIES needed to sustain physio-barbiturates See ALCOHOL-DRUG INTERACTIONS. logic functions while a patient is at rest. BEE is measured without intervening emotional stress or physical exertion, at least an hour preceding thebarley (Hordeum) A CEREAL GRAIN, related to measurement, and at a comfortable temperatureWHEAT and other grasses. Archaeological evidence several hours after a meal. The goal of recoveringsuggests that barley was the earliest cultivatedgrain. Several varieties of barley are grown; the from illness, injury or surgery is to provide enoughinedible husk must be removed from all of them. calories to meet energy needs and to maintain bodyWhole kernels are available as scotch barley. Pearl weight and optimal metabolic function. In additionbarley is polished; that is, it is milled until it resem- to BEE, a set of factors is used to predict the caloricbles small pearls. Pearl barley contains fewer nutri- needs required for healing various degrees ofents; its COMPLEX CARBOHYDRATE content is high, its injury. An activity factor of 1.2 (for bedriddenPROTEIN content moderate, and it is used primarily patients) or 1.3 (for ambulatory patients) is multi-in soups, stews, and broths. Because it contains lit- plied by injury factors: 1.2 for minor surgery, 1.35tle gluten, the sticky protein prevalent in wheat for trauma, 1.6 for severe infection (sepsis), 2.1 forﬂour, barley is not a chief ingredient of bread. Its burns. Patients with burns have the longest periodmajor commercial use is as a malting agent in BEER, of increased energy needs.ale, and whiskey manufacture. Barley is a good source of beta glucan, a water- basal metabolic rate (BMR) The energy ex-soluble form of ﬁber. Several studies suggest that pended to maintain the body at rest. The BMR isbarley can lower cholesterol levels as much as 15 measured in the morning for an awake, restingpercent in individuals who have very high choles- individual 12 to 18 hours after the last meal. Oxy-terol levels; the viscous ﬁber seems to retard fat and gen consumption (in liters of oxygen) for a deﬁnedcholesterol absorption by the intestine. The ﬁber interval is multiplied by 4.8 calories per liter of oxy-tends to bind bile salts, thus increasing cholesterol gen to yield the BMR, the heat produced during theremoval from the body, and fat soluble substances, timed interval. In practice, it is easier to measure thetocotrienols, appear to suppress cholesterol synthe- resting metabolic rate (RMR), measured either sit-sis by the liver. Pearl barley (raw) supplies 349 ting or lying down, in a comfortable environmentcalories per half cup (100 g); protein, 8.2 g; carbo- several hours after a meal or signiﬁcant physicalhydrate, 79 g; ﬁber, 8.2 g; fat, 1 g; iron, 4.2 mg; activity. RMR does not require an overnight fast andpotassium, 160 mg; zinc, 2.23 mg; thiamin, 0.14 is nearly equal to BMR. Normally this ranges frommg; riboﬂavin, 0.05 mg; niacin, 4.0 mg. 1,200 to 1,800 CALORIES per day. The BMR repre- sents a considerable energy expenditure, account-barley malt A natural sweetener derived from ing for 60 percent to 75 percent of the calories. Thisgerminated barley. Barley malt tastes like black- energy is used for normal functions of the body,strap MOLASSES, which it can replace in a recipe. In such as glandular secretions and maintenance ofthe process of preparing barley malt, the grain is cellular metabolism, as well as activation of thefirst sprouted. The sprouted barley supplies autonomic nervous system, which maintains heart-ENZYMES that then break down barley starch to the beat, breathing and other involuntary activity.sugar, maltose. Although this sweetener contains a Many factors inﬂuence an individual’s metaboliclittle THIAMIN (9 percent of the RECOMMENDED rate: diet history; degree of activity of the sympa-DIETARY ALLOWANCE per tablespoon) and lesser thetic nervous system; physical and emotionalamounts of other B COMPLEX, it represents a reﬁned stress; body temperature; menstrual cycle; sleep;CARBOHYDRATE, classified as EMPTY CALORIES adaptation to altitude; occupation; race; and evenbecause it contains little else. the season of the year. Differences in metabolic
73. basil 65rates due to differences in body size, sex, or age ate occur in the blood and body ﬂuids and in otherlargely disappear if the data are related to fat-free nitrogen-containing compounds. A very importantbody mass. The decrease in basal metabolic rate weak base is BICARBONATE, which, in the blood andobserved with aging is primarily due to decreased digestive juices, neutralizes acids, thereby increas-lean body mass. A genetic component also con- ing the pH. Bicarbonate plays an important role intributes to the differences in BMR among individu- buffering the blood. (See also BUFFER.)als. BMR is partially controlled by the THYROIDGLAND; thus low thyroid activity may promote basic food groups A simple guide for makingweight gain. BMR decreases with illness, FASTING, food selections designed to help consumers plan aand even stringent DIETING. This decrease is a tem- BALANCED DIET which has now been superseded byporary adaptation of the body to semi-STARVATION the FOOD GUIDE PYRAMID. This guideline emphasizesand accounts for the frequently observed decrease MEAT and dairy products to avoid undernutrition. Itin the rate of weight loss a week into a dieting pro- advises eating two servings of meat selections daily,gram. Recent studies indicate that after dieting, two of MILK and dairy products, four of VEGETABLESBMR rises to a new level that it is appropriate for and FRUITS, and four of GRAINS. There are severalthe new body weight. disadvantages. The Basic Four Food Group guide- Physical conditioning is another factor. Calories lines lack serving sizes and provide only the mini-are burned more rapidly after exercising than not. mum numbers of servings. Overnutrition andThe duration and intensity of aerobic exercise nutritional imbalances are possible because theyneeded to secure this beneﬁt is an important ques- emphasize a diet high in animal FAT and lacking intion still being studied. If the individual is seden- FIBER. On the other hand, a diet with moderatetary, moderate exercise seems to cause a 10 percent quantities of low-fat dairy products, lean meat,increase in basal metabolism for several hours. A poultry, and ﬁsh can easily meet the needs formoderately active individual needs to do aerobic CALORIES, and minerals like IRON and CALCIUM. (Seeexercise such as swimming, aerobic dancing, or also DIETARY GUIDELINES FOR AMERICANS.)jogging a total of six hours per week to increase themetabolic rate for several days afterward. In addi- SUMMARY OF THE BASIC FOUR FOOD GROUPStion, exercise increases muscle mass, which burnsmore calories than fat does. Food Group Main Nutrient Contributions Nicotine seems to boost metabolic rates in pro- Meat and Protein, iron, riboﬂavin, zinc, vitaminportion to the level of physical activity. This may be meat alternatives B12, thiamina reason why smokers often tend to weigh less Milk and Calcium, protein, riboﬂavin, zinc, milk products vitamin B12, thiaminthan non-smokers, and why smokers tend to gain Fruits and Vitamin A, vitamin C, thiamin,weight when they stop smoking. (See also DIET- vegetables additional iron and riboﬂavin,INDUCED THERMOGENESIS.) ﬁber, folic acid Grains (bread Additional amounts of niacin,Felber, J. P., and A. Golay. “Regulation of Nutrient and cereal iron, thiamin, zinc in whole Metabolism and Energy Expenditure,” Metabolism 44, products) grains; ﬁber no. 2, supp. 2 (February 1995): 4–9. basil (Ocimum basilicum) A pungent herb; abase A substance that can accept hydrogen ions member of the mint family. Its name is derived from(protons) and thus neutralize ACIDS. When added the Greek basilikos, meaning “royal,” because onceto water, bases raise the pH (the degree of a mea- the king alone was allowed to harvest it.sure of acidity; a pH greater than 7.0 is considered Each variety of basil differs in height, color of foliage,to be basic). Typical mineral bases, such as sodium and taste. Of the six common varieties of basil, sweethydroxide (lye) and potassium hydroxide are caus- basil and dwarf basil are most popular in the Unitedtic; they can cause severe burns and are classiﬁed as States. Basil can be used fresh or dried as a season-strong bases. Weak bases are much more common ing in seafoods, salads, potatoes, soups, and espe-in foods and in the body. Ammonia and bicarbon- cially tomato-based dishes, and it is used extensively
74. 66 bassin Italian and Provençal cooking. In folk medicine, convert FAT, PROTEIN and CARBOHYDRATE to ENERGY.basil has been used to remedy ﬂatulence. The B complex is not stored in the body, unlike fat- soluble vitamins, and adequate amounts must be supplied daily.bass (Micropterus) Refers to a number of differ- The name originated from early nutritionalent saltwater and freshwater species of spiny-rayed research, when growth factors for organisms wereFISH. Bass is shaped like SALMON, but the ﬂesh is designated as B1, B2, etc. As they were isolated andwhite. Both freshwater and saltwater varieties characterized chemically, each was found to serveoccur in North America. Freshwater game ﬁsh vari- as a parent of a speciﬁc enzyme helper (coenzyme):eties include white or silver bass and yellow bass. THIAMIN (vitamin B1) forms thiamin pyrophos-Saltwater varieties, like sea bass and striped bass, phate; NIACIN (vitamin B3) forms NAD; RIBOFLAVINare among the best known. Striped bass caught in (vitamin B2) forms FAD; PANTOTHENIC ACID (vita-polluted offshore waters can be contaminated with min B5) forms COENZYME A; VITAMIN B6 formsindustrial pollutants. Fish farms are a major source pyridoxal phosphate; VITAMIN B12 forms methyl-of bass. The ﬂesh has a delicate ﬂavor and is served cobalamin; FOLIC ACID forms tetrahydrofolate; andpoached, braised, or grilled. In order to keep the biotin yields biocytin.ﬂesh intact during poaching, the scales are not The amounts of vitamins required daily areremoved. quite low. Consider the REFERENCE DAILY INTAKE (RDI): folic acid, 400 mcg; niacin, 20 mg;basting Spooning or brushing sauces, cooking riboﬂavin, 1.7 mg; thiamin, 1.4 mg; vitamin B6, 2juices, or melted BUTTER over meat several times mg; vitamin B12, 6 mcg; biotin, 300 mcg; pan-during cooking. This procedure keeps meat, partic- tothenic acid, 10 mg. These amounts are so smallularly leaner cuts, moist during roasting or broiling. that together they would weigh no more than aBasting brushes or a bulb-type baster simplify the metal staple. Vitamins of the B complex work mostoperation. Roast turkey and meat cooked on a effectively when all are present in the appropriaterotisserie are usually basted with fatty drippings or ratios. Common multivitamin supplements maywith butter to prevent them from drying out. If not balance B complex vitamins when they providebasting is performed with stocks or water, the small amounts of some B vitamins and largeresulting excess steam helps keep the meat moist. amounts of others.Prime cuts of meat contain so much fat that basting On average, men require more of the B complexisn’t necessary. than women because their larger bodies need more nutrients. The daily requirement of thiamin increases as more food is eaten; drinking alcoholicbay (Laurus nobilis) An evergreen shrub widely beverages and eating SUGAR tend to deplete thecultivated for its broad, aromatic leaves. The shrub LIVER’s B vitamin supply. Populations with theis a species of laurel (bay laurel, true laurel). The greatest risk for B vitamin deﬁciency include thoseedible bay should not be confused with the garden on weight-loss programs and who skip meals,cherry laurel, Prunus laurocerasus, which is poiso- infants and children, the elderly, and pregnantnous. Bay leaves are one of the most popular culi- teenage girls. The daily intake of nutrients such asnary herbs in North America. They can be obtained folic acid is frequently inadequate in diets relyingas dried leaves or in powdered form. Stews, soup on highly processed convenience foods. Junk foodsstocks, marinades, and ragouts incorporate this with an excess of calories or fat and with reﬁnedversatile seasoning. Because it is so pungent, small carbohydrates (white ﬂour and sugar) displaceamounts are recommended. Bay leaf, together whole, minimally processed foods that are morewith parsley, thyme, cloves, and celery are bound nutritious and contain fewer calories.together as bouquet garni to ﬂavor soups or stocks. As many as 30 percent of people over the age of 65 may not consume vitamin B6, vitamin B12, andB complex (B vitamins) A group of eight water- folic acid in amounts adequate to prevent strokessoluble VITAMINS, required in very small amounts to and heart attacks, due to a buildup of a potentially
75. beans 67harmful amino acid by-product called HOMOCYS- beans (Phaseolus) Seeds of trailing vines, as wellTEINE. When homocysteine accumulates in the as bushy plants belonging to the legume family.blood, there is an increased risk of damage to arter- Beans can be divided into two groups: One yieldsies. Only by consuming 400 micrograms of folic edible pods, picked at an immature stage; anotheracid a day, twice the level speciﬁed by the RECOM- yields only edible seeds. In the former group areMENDED DIETARY ALLOWANCES (RDA), do levels of snap beans, yellow wax, and green beans. Bushhomocysteine decline. varieties grow as short plants and pods at the same The richest sources of the B complex are organ time. Pole beans grow like vines. Each stem grows ameats such as liver and kidney. Low-fat options for single pod, and pods mature at different times. Theyfolic acid include cooked lentils, chickpeas, kidney supply BETA-CAROTENE, FIBER, and some minerals,beans, and spinach; for thiamin, BREWER’S YEAST, including IRON. Canned green beans contain a highextra-lean meat, wheat germ, enriched BREAKFAST level of SODIUM—340 mg per cup of drained beansCEREALS; for riboﬂavin, low-fat milk and other low- as compared to 3 mg from raw beans. Green beansfat dairy products and enriched cereals; for niacin (one cup cooked, 125 g) provide 44 calories; pro-and vitamin B12, ﬁsh, lean meat, poultry, and tein, 2.4 mg; fat 0.4 mg; carbohydrate, 9.9 g; ﬁber,enriched cereals. 3.1 g; calcium, 58 mg; iron, 1.6 mg; vitamin A, 583 A diet that supplies adequate amounts of vita- retinol equivalents; thiamin, 0.09 mg; riboﬂavin,mins and minerals alone does not guarantee that a 0.12 mg; niacin, 0.77 mg; vitamin C, 12 mg.vitamin deﬁciency will not occur. There are several Dried beans include navy, pinto, lima, kidneyreasons for this. Foods must ﬁrst be digested (bro- (red), and fava (or broad) bean. Dried beans areken down to amino acids, vitamins, sugars, fatty excellent PROTEIN sources; one cup of cooked beansacids, and so on) in order to release individual supplies between 12 and 25 g of protein (25 per-nutrients, and DIGESTION may be incomplete if the cent to 50 percent of the RECOMMENDED DIETARYproduction of STOMACH ACID or of DIGESTIVE ALLOWANCE [RDA]). Shell beans are harvestedENZYMES is low. Second, the products of digestion halfway in their maturation to dried beans. Theymust be absorbed by the small intestine to be of include SOYBEANS, BROAD (fava) BEANS, and limaany beneﬁt. An unhealthy intestine will be able to beans.absorb individual nutrients effectively. (See also Shell beans can be used interchangeably withCARBOHYDRATE METABOLISM; CATABOLISM; MALAB- dried beans in recipes. Bean protein, like most plantSORPTION; MALNUTRITION.) protein, is deﬁcient in at least one essential amino“B Makes the Grade,” Consumer Reports on Health 7, no. 6 acid. However, this “incomplete” protein is readily (June 1995): 61–63. balanced by eating beans with whole grains, nuts, or small amounts of ﬁsh, poultry, meat, or dairy products. Dried beans contain STARCH, MINERALSbeach plum (Prunus maritama) A member of the (POTASSIUM, MAGNESIUM, iron, and calcium), and lit-prune family that grows wild in North America. tle fat. Dried beans are also excellent sources ofWhen ripe, the small fruit is dark purple with a ﬁber. For example, a cup of cooked pinto beans sup-tough skin. The ﬂavor combines plum with cherry plies 18.9 g ﬁber. One cup of cooked lima beansand grape ﬂavors; its sour ﬂavor usually limits its (190 g) provides 260 calories; protein, 16.1 g; car-use to jams and jellies. bohydrate, 49 g; ﬁber, 9.7 g; calcium, 55 mg; iron, 5.9 mg; potassium, 116.3 mg; thiamin, 0.25 mg;bean curd A highly nutritious source of plant riboﬂavin, 0.11 mg; niacin, 1.34 mg. Navy beansPROTEIN, prepared from SOYBEANS. To prepare bean (one cup cooked, 190 g) contain 225 calories; pro-curd, soybeans are homogenized and the soy pro- tein 15 g; carbohydrate 40.1 g; ﬁber, 16.5 g; and cal-tein is coagulated by treatment with calcium sulfate cium 95 mg.or nigari, a mineral-rich liquid remaining after salt FLATULENCE after eating cooked dried beans is aextraction of sea water. The precipitated protein is common experience. The culprits in gas-producingpressed into blocks for a low-fat, low-calorie alter- foods are a family of carbohydrate (rafﬁnose,native to meat. (See also TOFU.) stachyose, and verbascose) that cannot be digested
76. 68 beefbut are broken down by gut bacteria that release nation that does not need to meet USDA standards.excessive gas. This problem is reduced by soaking Therefore, the fat content can range from 20 per-beans in water for several hours and discarding the cent to 30 percent. The average fat in “lean groundwater after soaking. Beans are then boiled in water, beef” is 21 percent. In contrast, meat labeled by thewhich is again discarded, rather than incorporated U.S. Department of Agriculture (USDA) as “leaninto soup or chili. Over-the-counter preparations of meat” contains no more than 17 percent fat byan enzyme (alpha galactosidase) that can degrade weight, while “extra lean ground beef” contains 10these sugars are now available. (See also COMPLETE percent fat by weight. Supermarket brands of low-PROTEIN; FOOD COMPLEMENTING.) fat beef are designated as “light select” or “select” grades of beef and range from 5 percent to 15 per-Guste, Roy F. The Bean Book. New York: Norton, 2000. cent fat. Beef often contains chemical residues, such asbeef The ﬂesh of steers, cows, and heifers repre- growth promoters, ANTIBIOTICS like sulfa drugs, ani-senting the ruminant family, Bovidae. The Aber- mal drugs, and pesticides. The health effects of low-deen, Angus, Brahma, Hereford, Santa Gertrudis, level exposure to such compounds are unknown.and Shorthorn represent typical breeds raised in Some of these residues are potential cancer-causingNorth America for MEAT. Although beef consump- agents. In 1989 the European Community bannedtion has declined signiﬁcantly during the last two beef raised with growth hormones. Hormone-freedecades, beef is still America’s most popular meat. beef is now commercially available in many areasThe indirect costs of this preference are high, of the United States. (See also FOOD LABELING;because the production of one pound of beef GRADED FOODS; MEAT CONTAMINANTS; BOVINE SPONGI-requires an estimated ﬁve pounds of GRAIN, and the FORM ENCEPHALOPATHY.)energy equivalent of a gallon of gasoline. Beef is an excellent source of PROTEIN, VITAMINS,and MINERALS (except calcium). On the other hand, beef tallow A hard FAT, high in saturated fatty acids and CHOLESTEROL, which is rendered frombeef is rather high in saturated fat. The high con- trimmed meat (usually beef). Rendering is thesumption of animal fat correlates with increased process of melting fat out of fatty tissue, then ﬁl-blood cholesterol and increased risk of heart dis- tering and purifying the melted fat. Tallow is moreease and cancer. Traditionally, cattle were bred for saturated than pork fat (lard) and chicken fat.a high degree of “marbled” meat, heavily laden Tallow is often used in fast-food restaurants towith fat, and the animals were fattened in feed lots cook FRENCH FRIES because consumers seem to pre-before slaughter. Due to the recent consumer fer the ﬂavor of potatoes fried in animal fat. Thedemand for leaner meat, there is a trend toward practical advantages of beef tallow are that it is rel-producing leaner animals. A three-ounce (85 g) atively inexpensive and it does not break down atserving of round roast, which is about the size of a the high temperatures needed for frying. However,deck of cards, contains: calories, 205; protein, 23 g; the cholesterol becomes oxidized with prolongedfat, 12 g; cholesterol, 62 mg; calcium, 5 mg; iron, heating at high temperatures, and oxidized choles-1.6 mg; zinc, 4.7 mg; thiamin, 0.07 mg; riboﬂavin, terol is known to be a factor in the buildup of0.14 mg; niacin, 3 mg. Choice grades of several cuts plaque in arteries. Beef tallow ﬁnds other commer-of beef (cooked) provide the following calories per cial uses, including the manufacture of candles andthree-ounce serving: chuck roast (18 percent fat) = soap.257; rib roast (36 percent fat) = 400; sirloin steak(27 percent fat) = 240; canned corned beef (10gfat) = 185; trimmed round roast (8 g fat) = 175. bee pollen The fertilizing element from ﬂower- Beef as HAMBURGER is the most commonly eaten ing plants that is collected by bees and available asmeat in the United States and is a major contribu- a food supplement. The composition of nutrients intor of saturated fat to the standard American diet. bee pollen resembles that of legumes with varyingA three-ounce serving of hamburger contains 18 g amounts of B COMPLEX, such as thiamin, riboﬂavin,fat (21 percent fat). “Lean ground beef” is a desig- niacin, folic acid and pantothenic acid, PROTEIN, and
77. behavior modiﬁcation 69MINERALS. By weight it contains 50 percent CARBO- low levels of other B complex vitamins, indicativeHYDRATE and 25 percent protein. Bee pollen con- of its low nutrient density.tains FLAVONOIDS, a type of plant pigment that helps “Nonalcoholic” beers are not strictly alcohol-freenormalize inﬂammation. because they may contain 0.5 percent alcohol. Bee pollen is widely marketed in health food With less alcohol, non-alcoholic beverages containstores as an aid in weight management and as an fewer calories than their alcoholic counterparts.“energizer.” There are no clinical studies that indi- However, beer with 2.5 percent alcohol can still becate bee pollen energizes the body, regulates called “low alcohol” beer because it contains lessweight, tones the skin, or protects against heart dis- alcohol than the usual 3.2 percent alcohol. (Seeease. The ofﬁcial position of the American Dietetic also ALCOHOLISM; BREWER’S YEAST; WINE.)Association is that such claimed ENERGY-boostingsupplements (“ergoneic”) are ineffective. Those beet (Beta vulgaris, garden beet) A red root veg-who are sensitive to pollen may have an allergic etable related to CHARD. Beets may be cultivated forreaction to bee pollen. (See also ROYAL JELLY.) their tops in addition to their roots. Common vari- eties include Crosby’s Egyptian, Ruby Queen, andbeer An alcoholic carbonated beverage that is a Detroit Dark Red. Red beetroot is a food coloringproduct of FERMENTATION of grains such as WHEAT, agent. Beets in general have the highest sugar con-MILLET, and BARLEY. U.S. breweries ferment barley, tent of all other vegetables. White-rooted sugarCORN, or RYE together with hops, with cultured beets are a major source of domestic sugar (SU-yeast strains to provide the alcoholic content, car- CROSE). Cooked, fresh red beets are a source of abonation, and characteristic ﬂavor of this beverage. red pigment, betalaine, a type of FLAVONOID, whichLager beer, the most popular American beer, is is a class of plant products that have beneﬁcialaged to mellow its ﬂavor. The ALCOHOL (ethanol) effects on the immune system, connective tissue,content is typically 3.2 percent. and cellular metabolism. One half cup (cooked, 85 Beer is the oldest known alcoholic beverage and g) provides 26 calories; protein, 0.9 g; carbohy-has the highest consumption of any alcoholic bev- drate, 5.7 g; ﬁber, 1.96 g; iron, 0.53 g; potassium,erage worldwide. Hops were cultivated in the 266 mg; niacin, 0.23 mg; and low levels of VITAMIN1200s by monasteries in Germany for use in brew- C and B COMPLEX vitamins. Beet greens are an ex-ing. Brewing beer follows well-deﬁned steps. In cellent source of ﬁber, beta-carotene, calcium, andorder for the starch in cereal grains to ferment, the iron. Cooked beet greens (one cup, 144 g) providegrains are ﬁrst processed. In malting, grain is 40 calories; protein, 3.7 g; carbohydrate, 7.9 g; ﬁber,soaked long enough to initiate germination, then is 3.0 g; calcium, 165 mg; iron, 2.74 mg; potassium,kiln-dried. The color of beer is related to the extent 1,308 mg; zinc, 0.72 mg; vitamin A, 734 retinolto which malt is heated. The malt is next ground equivalents; vitamin C, 36 mg; thiamin, 0.17 mg;and the pigment, betalaine, mixed in hot water. riboﬂavin, 0.42 mg; niacin, 0.72 mg.Enzymatic degradation produces fermentable sug-ars from the starch. The insoluble material is sepa-rated and the resulting fermentable extract is called behavior See FOOD AND THE NERVOUS SYSTEM.wort. Flowers of hops are added to the headedwort, then yeast is added after cooling. Most lager behavior modiﬁcation Considered a key to thebeer production far exceeds that of ale. Lager fer- successful treatment of EATING DISORDERS, OBESITY,mentation usually lasts seven days, to give a beer and ADDICTIONS, this form of therapeutic interven-ﬂavored by hops and malt. Ale fermentation is typ- tion relies on the premise that eating behavior isically carried out for three days at a higher temper- learned and that undesirable eating practices canature. Directly fermenting roasted grains yields be unlearned. Strategies to change behavior per-more strongly ﬂavored (stout) ale. manently include specifying a written commitment One serving of regular beer (12 oz.) provides to achieving a goal, rewards for accomplishments,116 calories (primarily alcohol), protein, 0.9 g; cal- exercises to assist building self-esteem, supportcium, 18 mg; iron, 0.11 mg; niacin, 1.6 mg; and groups, changes in the availability of certain foods,
78. 70 benomylchanges in the location in which meals are eaten, mains in flour. This additive is classified as a FOODchanges in the social environment, and increased ADDITIVE.physical activity. A major concern with manyweight management programs is that fat can be lost beriberi A condition, caused by chronic THIAMINwithout adequate commitment and training that (vitamin B1) deﬁciency, that affects peripheralare necessary to assure eating patterns are changed nerves, the brain, and the cardiovascular system.permanently. (See also DIETING.) Early symptoms of thiamin deficiency include FATIGUE, irritability, poor memory, anorexia, andbenomyl A post-harvest FUNGICIDE that reduces sleep disturbances; with severe deﬁciencies, paraly-fruit spoilage by killing MOLDS and fungi. BANANAS, sis of limbs, cardiovascular abnormalities, andAPRICOTS, PEACHES, CHERRIES, PEARS, PLUMS, and edema appear. Beriberi rarely occurs in NorthPINEAPPLES are among the commonly treated fruits. America because wheat products and ﬂour areBenomyl has been linked to cancer and birth enriched with thiamin. It is more common in de-defects in experimental animals. veloping nations among populations subsisting on polished rice from which much of the vitamins andbenzopyrene (benzo(a)pyrene) A multiringed minerals have been removed. (See also CARBOHY- DRATE METABOLISM; ENRICHMENT; MALNUTRITION.)organic compound related to benzene. Benzopy-rene is classiﬁed as a polycyclic aromatic hydrocar-bon, a member of a family of compounds that are beta blockers Drugs used to control high bloodpotential mutagens (mutation-producing agents) pressure in salt-sensitive individuals, that may pre-and CARCINOGENS (CANCER-causing agents). The vent fatal HEART ATTACKS. Beta blockers limit highliver converts ingested benzopyrene to highly reac- blood pressure by preventing the kidneys fromtive intermediates (epoxides) that can attack the releasing angiotensin, a hormone that increasesDNA in cells. blood pressure. The drugs are also used to control Traces of benzopyrenes occur in soil as the result migraine headaches and to reduce angina.of microbial activity. Plants can synthesize this There are several precautions to be observedhydrocarbon and may contain up to 10 mcg per kg when using beta blockers. After years of use, theyof dry weight. However, far greater exposure comes may promote heart repair, but they also may dam-from the incomplete burning (pyrolysis) of oil, fat, age the kidneys. Beta blockers increase the risk ofand organic material from cooking, cigarettes, ex- severe allergy reactions in patients taking allergyhaust from industrial combustion and automobiles, shots. Possible side effects include depression (inand home heating. BARBECUED MEAT contains ben- patients with a history of depression or mood disor-zopyrenes due to the FAT dripping on charcoal or ders). FATIGUE, fuzzy thinking, impotence, moodheating elements. MEAT cooked in frying pans, grid- swings, increased blood CHOLESTEROL, and diabetes-dles, or over open ﬂames generates benzopyrenes. like symptoms. Use of alcoholic beverages whileBenzopyrenes contaminate soot, which is deposited taking this medication can be fatal because the com-on meats on overlying grills. bination can cause a drastic drop in blood pressure. (See also ALCOHOL-DRUG INTERACTION; ALLERGY;benzoyl peroxide A bleach that is used to IMMEDIATE; DIABETES MELLITUS; HYPERTENSION.)whiten FLOUR without necessarily aging it. Used ata level of 50 ppm (parts per million) with a mix- beta-carotene (provitamin A) A yellow-orangeture of aging agents, benzoyl peroxide bleaches pigment that is converted to VITAMIN A in the body.most flours within 24 hours. However, along The yellow-orange coloring in fruit and vegetableswith destroying pigments, the peroxide destroys is mainly due to the presence of beta-carotene.the vitamins in flour. The trade-off in producing Commercially, beta-carotene is used as a safe FOODwhite flour that makes excellent dough is de- COLORING. Beta-carotene is the most plentiful of thecreased nutritional value. The breakdown product orange-yellow plant pigments (CAROTENOIDS) inof benzoyl peroxide is benzoic acid, which re- foods, and it has the highest vitamin A activity.
79. beta-carotene 71Because of differences in uptake, storage, and prostate, colon, and lung cancers. While manychemical processing, only about one-sixth of the studies indicate that dietary beta-carotene frombeta-carotene in a plant food ends up as vitamin A fruits and vegetables decreases the risk of lung can-(retinol) in the body. For this reason the vitamin A cer, two large studies—the Nurses Health Studycontent in plant foods is usually given as “retinol and the Health Professionals Follow Up Study—equivalents,” that is, the amount of vitamin A that reported lower lung cancer risk with increased con-could be derived from the carotene content. One sumption of foods rich in lycopene, alpha-carotene,RE (retinol equivalent) is deﬁned as 1 mcg of and a variety of carotenoids, but not speciﬁcally(trans) retinol (vitamin A), 6 mcg of (trans) beta- beta-carotene. Clinical trials have examined thecarotene, or 12 mcg of other carotenoids that can effects of beta-carotene supplementation on lungbe converted to vitamin A. The other way of cancer. Smokers who take beta-carotene can in-expressing the activity of carotenoids is in terms of crease their risk of lung cancer but nonsmokers dointernational units, or IU. One IU of vitamin A is not appear to be at higher risk. The three studiesequivalent to 0.3 mcg and one IU of beta-carotene include the Alpha Tocopherol, Beta-Carotene Can-is equivalent to 0.6 mcg of beta-carotene. Thus 1 cer Prevention Trial (ATBC Trial), the Beta-mg of beta-carotene represents 1,667 IU. Beta- Carotene and Retinol Efﬁcacy Trial (CARET), andcarotene does not carry the risk of vitamin A poi- the Physicians’ Health Study.soning because the body converts it to vitamin A The ATBC Trial was conducted by the Nationalonly as needed. Some manufacturers of multiple Cancer Institute (NCI) in collaboration with thevitamin supplements substitute beta-carotene for National Public Health Institute of Finland. Thevitamin A in their formulations to reduce the dan- purpose of the study was to see if certain vitaminger of vitamin A toxicity. supplements would prevent lung and other cancers Beta-carotene has a number of other functions in a group of 29,133 male smokers in Finland. Inthat make it the most extensively investigated the study 50- to 69-year-old participants took a pillcarotenoid. It is a very important ANTIOXIDANT as it containing either 50 mg of alpha tocopherol (acan help prevent damage to tissues by FREE RADI- form of vitamin E), 20 mg of beta-carotene, both,CALS—extremely reactive, damaging forms of oxy- or a placebo daily for ﬁve to eight years.gen and other chemicals. Beta-carotene helps boost The CARET study is a large NCI-funded chemo-the IMMUNE SYSTEM, and it affects lipid metabolism prevention trial being conducted in six areas in thein important ways. It lowers LOW-DENSITY LIPOPRO- United States to see if a combination of beta-TEIN (LDL), the undesirable form of cholesterol, carotene and vitamin A supplements will preventand raises HIGH-DENSITY LIPOPROTEIN (HDL), the lung and other cancers in men and women aged 50desirable form. The U.S. FDA has approved the use to 69 who are smokers or former smokers, andof beta-carotene to treat a particular form of light men aged 45 to 69 who have been exposed tosensitivity in patients who have a metabolic defect asbestos. The 18,314 participants stopped takingand overproduce pigments called porphyrins (ery- the supplements before the completion of the trial.thropoietic porphyrias). The Physicians’ Health Study was a study of In exploring the role of carotenes in preventive 22,071 U.S. male physicians, of whom 11 percenthealth, attention has focused on the possibility of smoked. The purpose of the study was to testusing beta-carotene and vitamin A to reduce the whether a beta-carotene supplement reduced therisk of HEART ATTACKS in men with coronary heart risk of cancer and heart disease as well as whetherdisease and CANCER. Regarding heart disease, the low-dose aspirin reduced the risk of heart disease.results of population studies have generally not The aspirin component was stopped in early 1988shown a reduction in the risk of coronary heart dis- because of a 44 percent reduction in risk of ﬁrstease with increased consumption of beta-carotene. heart attack among those taking aspirin. The beta-Two studies found increased mortality in smokers carotene component ended December 31, 1995,who took beta-carotene supplements. Populations after more than 12 years of study.studies suggest that increased beta-carotene intake In the ATBC study, 18 percent more lung cancersreduces the risk of cancer, especially breast, were diagnosed and 8 percent more overall deaths
80. 72 beta-caroteneoccurred in study participants taking beta-carotene. in epidemiological studies. Because these are stud-In CARET, after an average of four years of receiv- ies of pills, not food intake, the NCI stresses that theing supplements, 28 percent more lung cancers study results do not change the results of studieswere diagnosed and 17 percent more deaths that show that eating a variety of fruits and veg-occurred in participants who took a combination of etables each day remains a good way to reduce thebeta-carotene and vitamin A than in those who risk of some cancers and other chronic conditions.took placebos. Neither of these studies showed a The overall impression from these studies is thatbenefit from taking supplements. Because the beta-carotene needs to be part of a balanced anti-interim results of CARET were similar to the ATBC oxidant picture, including carotenoids, in order tostudy, the intervention was stopped 21 months protect the body against oxidation and chronic dis-early. Both of these studies involved people who ease. Diets high in fruits and vegetables supply awere speciﬁcally invited to participate because of rich mixture of PHYTOCHEMICALS in addition totheir high risk for developing lung cancer. beta-carotene that can be beneﬁcial to long-term The Physician’s Health Study was completed at health. Natural, mixed carotenoids as found inthe end of 1995 and showed no beneﬁt or harm in whole, minimally processed foods appear to be bet-people taking beta-carotene supplements for more ter antioxidants than synthetic beta-carotene.than 12 years. The optimal intake of beta-carotene and natural CARET participants were told to stop taking the carotenoids to afford maximum protection is notbeta-carotene and vitamin A or placebos because known. According to guidelines to food choicesthe CARET and NCI safety committees saw that the published by the National Cancer Institute and theinterim results clearly showed no beneﬁt from the U.S. FDA, the beta-carotene intake should equalsupplements—and also showed there was a possi- about 6 mg daily. Actual consumption is about 1.5bility they were harming participants. mg per day. This means most Americans should The NCI has never made recommendations as increase their daily intake of foods containing beta-to whether Americans should take supplements to carotene. One sweet potato contains 5 to 10 mg ofprevent or treat cancer. For those who wish to beta-carotene, representing 2,500 retinol equiva-reduce their risk of cancer, the NCI advises that it is lents. About 15 milligrams daily may be recom-prudent to adopt a low-fat diet containing plenty of mended if the patient eats a lot of PROCESSED FOODfruits, vegetables, and grains. The best advice for or has an infection or diabetes.smokers who want to reduce their risk of lung can- Many good sources of beta-carotene andcer is still the most direct: stop smoking. The results carotenoids are eaten rarely in the typical U.S.from CARET and the ATBC Trial suggest that smok- diet although they are readily available. Gooders should avoid taking beta-carotene supplements. sources of beta-carotene include SQUASH, CANTA- The results of the Physicians’ Health Study LOUPE, sweet potatoes, YAMS, CARROTS, yellow-showed no beneﬁt or harm to nonsmokers who colored fruit like NECTARINES, and dark green, leafytook beta-carotene every other day for 12 years. vegetables like KALE, CHARD, greens (BEETS, COL-The results from CARET and the ATBC study do LARD), spinach, and BROCCOLI. Although tomatoes,not provide information about the effects of beta- lettuce and sweet corn are relatively poor sourcescarotene supplements on nonsmokers. of beta-carotene, they contribute signiﬁcantly to In both the ATBC Study and CARET, partici- the nation’s total intake of beta-carotene andpants with the highest levels of beta-carotene in carotenoids, because Americans eat so much oftheir blood, measured before the study began, them. (See also DIETARY GUIDELINES FOR AMERICANS;went on to have fewer lung cancers. These results HYPERVITAMINOSIS.)are consistent with the possibility that a different Dietary Guidelines Advisory Committee, Agriculturalcompound or compounds in foods that have high Research Service, U.S. Department of Agriculturelevels of beta-carotene may be responsible for (USDA), “Report of the Dietary Guidelines Advisorythe protective effect of dietary beta-carotene seen Committee on the Dietary Guidelines for Americans,
81. BHT 73 2000.” Available online. URL: http://www.ars.usda. Betaine helps to replenish the amino acid METHION- gov/dgac. INEin the synthesis of compounds like the hormoneJohnson, E. J. “The Role of Carotenoids in Human epinephrine (adrenaline). (See also GASTRIC JUICE.) Health,” Nutrition and Clinical Care 5, no. 2 (March– April 2002): 56–65.Kritharides, L., and R. Stocker. “The Use of Antioxidant betaline A system for the cold pasteurization of supplements in Coronary Heart Disease,” Atherosclero- food products that uses electron-beam treatment, sis 164, no. 2 (October 2002): 211. which reduces the risk of exposure to foodLee, I-Min et al. “Beta-Carotene Supplementation and pathogens such as SALMONELLA, ESCHERICHIA COLI, Incidence of Cancer and Cardiovascular Disease: The and CAMPYLOBACTER. Cold pasteurization of food Women’s Health Study,” Journal of the National Cancer using electron beams was approved by the U.S. FDA Institute 91 (1999): 2,102–2,106. in 1997. Irradiation of food by electron-beam treat-Lee, K. W., and C. Y. Lee. “Vitamins, Diet, and Cancer Prevention,” American Journal of Clinical Nutrition 75, ment does not affect the nutrient value of food. no. 6 (June 2002): 1,122–1,223. (See also FOOD IRRADIATION.)Pavia, S. A., and R. M. Russell. “Beta-Carotene and Other Carotenoids as Antioxidants,” Journal of the American beta-lipoprotein See LOW-DENSITY LIPOPROTEIN. College of Nutrition 18 (1999): 426–433.Sato, R., K. J. Helzlsouer et al. “Prospective Study of Carotenoids, Tocopherols, and Retinoid Concentra- BHA (butylated hydroxyanisole) A common syn- tions and the Risk of Breast Cancer,” Cancer Epidemiol- thetic ANTIOXIDANT used in the United States since ogy and Biomarkers Prevention 11, no. 5 (May 2002): 1947 to retard RANCIDITY in vegetable oils and foods 451–457. containing them. BHA destroys FREE RADICALS (highly reactive chemical species), before they canbeta-hydroxybutyric acid A simple acid pro- break down the fat. Therefore this antioxidant isduced by the liver’s metabolism of fatty acids. Beta- extensively employed to extend the shelf life ofhydroxybutyric acid belongs to the family of many processed foods containing fat or oil, such asKETONE BODIES, which are derived from fatty acid baked goods, CHIPS, BREAKFAST CEREALS, porkdegradation and accumulate in the blood during SAUSAGES, as well as active dry YEAST and someconditions that promote extensive breakdown of CHEWING GUMS. The average American consumesbody fat, including STARVATION, crash dieting, several milligrams of BHA daily from these sources.uncontrolled diabetes, and ALCOHOLISM. Ketone BHA is relatively nontoxic. Most animal studiesbody accumulation in the blood promotes KETOSIS indicate it is safe, although a 1982 study suggested(acid accumulation in body ﬂuids.) (See also ACI- it may cause CANCER in experimental animalsDOSIS: ELECTROLYTES; FAT.) at very high dosages. A review committee con- cluded that the cancer risk is slight and recom-betaine hydrochloride A common supplemental mended that BHA not be banned, pending furtherform of hydrochloric acid used to increase stomach investigation. Huge amounts of BHA (0.25 percentacidity. Betaine hydrochloride contains 23 percent to 0.5 percent of diet) cause abnormal develop-hydrochloric acid, by weight. As a supplement to ment behavior in the offspring of treated animals.be taken with meals, betaine hydrochloride bol- Rarely does it cause allergic reactions. (See alsosters STOMACH ACID to help improve digestion in BHT; FOOD ADDITIVES.)patients with HYPOCHLORHYDRIA and ACHLORHYDRIA(inadequate stomach acid production). Excessive BHT (butylated hydroxytoluene) A syntheticuse of betaine hydrochloride can irritate the stom- ANTIOXIDANT in use in the United States since 1954.ach wall. Like BHA, BHT helps prevent RANCIDITY in FATS, Betaine is a nitrogen-containing compound VEGETABLE OILS, and PROCESSED FOODS that containrelated to CHOLINE. Its name comes from the fact them. Both BHA and BHT block the oxidation ofthat it occurs in Beta vulgaris, the common beet. POLYUNSATURATED FATTY ACIDS by reacting with FREE
82. 74 bicarbonateRADICALS. These highly reactive forms of oxygen buffer system to maintain the blood at a very nar-attack the double bonds of unsaturated fatty acids row range, pH 7.3 to 7.4. Thus bicarbonate canfound in oils. They create off-ﬂavor odors and neutralize modest amounts of acid that might occurbreak down products that are potentially damaging through ingestion or metabolism.to cells. When included in the packaging material Bicarbonate also occurs in BAKING SODA asitself, BHT (and BHA) can migrate into the con- sodium bicarbonate. In the presence of acidictents such as breakfast cereal, powdered milk, and ingredients like CREAM OF TARTAR, bicarbonatemixes, in addition to baked goods and chips. The forms carbonic acid, which spontaneously decom-U.S. FDA allows BHT and BHA to be added to raw poses into water and carbon dioxide. It is thisand cooked meat toppings for pizzas and meatballs. action that produces the gas bubbles that cause A mixture of synthetic antioxidants is often dough to rise.more effective than single preservatives. Thereforemany products contain BHA, BHT, and PROPYL GAL- bifidobacteria A type of nonspore-formingLATE, a third, less safe antioxidant. BHT is less anaerobic (oxygen-sensitive) bacteria that fermentsexpensive than BHA but is unstable when heated sugars to acids. Biﬁdobacteria ferment GLUCOSE,during PASTEURIZATION and baking. galactose, and FRUCTOSE to produce lactic and acetic The average American consumes 5 to 10 mg of acids. Biﬁdobacteria are often used in Japan duringBHT daily. BHT accumulates in human tissues, food preparation requiring the production of mildalthough the long-term significance of this is acids. In the United States, lactobaccilli are moreunknown. The safety of BHT has been questioned, widely used.and some individuals are allergic to it. It is known Biﬁdobacteria are normal, beneﬁcial residents ofthat BHT induces production of certain liver the human colon. They acidify feces and producedetoxifying enzymes (mixed function oxidases). antibacterial factors that limit the growth of unde-This is viewed as a mixed blessing because an sirable bacteria and contribute to weight gain. Biﬁ-increased level of these enzymes can destroy some dobacteria get their start in the intestine, mosttoxic materials, but they also can transform others readily through breast-feeding. Biﬁdobacteria areinto carcinogens (cancer-causing agents). The rela- the predominant organisms in the large intestine oftionship of BHT to cancer is murky. Several reports breast-fed infants; they can account for up to 99suggest that BHT prevents cancer in experimental percent of the microﬂora.animals. Other studies suggest it has no effect; still In adults, biﬁdobacteria populates primarily theothers conclude BHT can cause cancer. Rats fed 0.1 lower regions of the intestine. In healthy individu-percent to 0.25 percent BHT diets (about 10 to 20 als, the relative proportion of these bacteria re-times the typical American diet) developed behav- mains rather constant. However, reduced gastricioral changes. The U.S. FDA proposed removing acidity, oral antibiotic therapy, and other condi-BHT from the GENERALLY RECOGNIZED AS SAFE tions can disrupt the gut microﬂora. Furthermore,(GRAS) list of FOOD ADDITIVES; however, it has not the levels of biﬁdobacteria can decline with age.been classiﬁed as a regulated food additive. In Biﬁdobacteria are available as supplements. Theview of the concern about safety, some companies major beneﬁcial functions of biﬁdobacteria are:omit BHT from processed foods. (See alsoCYTOCHROME P450.) • prevention of colonization of the intestine by potential disease-producing microorganismsbicarbonate A common substance in the blood with which they compete for nutrients andused to help regulate acid-base balance. Bicarbon- attachment sites;ate forms in the body when carbon dioxide dis- • production of short-chain fatty acids, whichsolves in water or blood to form the weak acid nurture the colon, from ﬁber fermentation;CARBONIC ACID (H2CO3). Carbonic acid sponta- • production of vitamins like biotin.neously yields bicarbonate. Together, bicarbonateand carbonic acid form an effective physiologic (See also ACIDOPHILUS.)
83. bile acids 75biﬁdus factor A heat-stable factor in breast milk contains the phospholipid LECITHIN to help dissolvethat promotes the growth of the bacterium Biﬁdobac- fat and a small amount of free cholesterol, which ister infantis in the intestinal tract of infants. None of a emulsiﬁed by bile salts and lecithin. If the ratio ofvariety of nonhuman milks favor the growth of these water to lecithin to bile salt is altered, cholesterolstrains. Successful implantation of this acid-produc- can become insoluble in the gallbladder and forming bacterium helps to establish normal intestine GALLSTONES in susceptible individuals. Bile also con-ﬂora and limit the growth of less desirable microor- tains bilirubin, or BILE PIGMENT. Bilirubin is a wasteganisms. BIFIDOBACTERIA play an important role in product of hemoglobin metabolism from red bloodbalancing intestinal ﬂora. (See also ACIDOPHILUS.) cells and plays no signiﬁcant role in digestion. Once fat has been digested, bile salts are mainlybilberry (Vaccinium myrtillus) Variously known reabsorbed by the intestine and recycled in theas whortleberry, blueberry, whinberry, or huckle- liver. A small amount is excreted in the feces. It isberry, this wild berry is a rich source of vitamin C believed that some forms of ﬁber can lower bloodand a source of copper. Rarely cultivated, this cholesterol levels indirectly by binding bile salts sospecies is the heather family, which also includes they cannot be reabsorbed. To compensate for thisthe CRANBERRY and the blueberry. The bilberry loss, the liver withdraws cholesterol from the bloodgrows on the heaths and moors of Europe and to manufacture more bile salts, thus loweringnorthern Asia and is known for its round, juicy, blood cholesterol levels.bluish-black fruits. The raw fruit is too acid to be Bile salts may be decomposed by gut bacteria topalatable without adding sugar. Quinic acid and potentially harmful products. A high FIBER diettannin is found in the leaves. helps to maintain a normal transit time to move The astringent fruit is especially valuable in diar- waste out of the body. This action decreases bothrhea and dysentery. A decoction of the leaves or bile salt decomposition and exposure of the COLONbark of the root may be used as a local application to toxic materials. Such observations may explainto ulcers and in ulceration of the mouth and throat. why dietary ﬁber lowers the risk of colon CANCER.Positive results have been noted in studies that (See also ENTEROHEPATIC CIRCULATION.)examined the effect of bilberry in a variety of eyeproblems, including pigmentary retinitis, diabetic bile acids The primary FAT emulsifying agents ofand hypertensive retinopathy, retinal inﬂamma- BILE. Bile acids and their derivatives, the bile salts,tion, macular degeneration, retinitis pigmentosa, are powerful detergents. They are released fromglaucoma, and cataracts. The anthocyanidins in bil- the gallbladder in order to dissolve fat prior to itsberry are the primary agents responsible for its abil- digestion by the INTESTINE. They emulsify fat-solubleity to heal the eyes. VITAMINS and promote their uptake as well. The One serving provides 7.7 g of dietary ﬁber and liver synthesizes bile acids from cholesterol. In thissupplies 60 kcal. process, the liver ﬁrst oxidizes cholesterol to pri- mary bile acids like cholic acid. The sterol ringbile (gall) The juice secreted by the LIVER and structure that typiﬁes cholesterol remains intact.temporarily stored in the GALLBLADDER to aid fat Subsequent steps couple cholic aci