Nutrition encyclopedia


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Nutrition encyclopedia

  1. 1. THE ENCYCLOPEDIA OF NUTRITION AND GOOD HEALTH Second EditionRobert Ronzio, Ph.D., C.N.S., F.A.I.C. Kennedy Associates
  2. 2. The Encyclopedia of Nutrition and Good Health reports information and opinions of medical literature that may be of general interest to the reader. Although the author has made every effort to assure that all the information in this book is cor- rect at the time of printing, the reader is advised that medical knowledge is con- stantly changing, and this book should not be relied upon without the consultation and advice of a physician. In addition, in any book of this scope, some errors may occur. The author and Facts On File, Inc., disclaim any responsibility for any con- sequences that may result from any use or reliance thereon by the reader. The Encyclopedia of Nutrition and Good Health, Second Edition Copyright © 2003 by Robert RonzioAll rights reserved. No part of this book may be reproduced or utilized in any form or by any means, elec- tronic or mechanical, including photocopying, recording, or by any information storage or retrieval sys- tems, without permission in writing from the publisher. For information contact: Facts On File, Inc. 132 West 31st Street New York NY 10001 Library of Congress Cataloging-in-Publication Data Ronzio, Robert A. [Encyclopedia of nutrition & good health] The encyclopedia of nutrition and good health / Robert Ronzio.—2nd ed. p. cm. Includes bibliographical references and index. ISBN 0-8160-4966-1 (HC) 1. Nutrition—Encyclopedias. I. Title. RA784 .R646 2003 613.203—dc21 2002035221 Facts On File books are available at special discounts when purchased in bulk quantities for businesses, associations, institutions, or sales promotions. Please call our Special Sales Department in New York at (212) 967-8800 or (800) 322-8755. You can find Facts On File on the World Wide Web at Text and cover design by Cathy Rincon Printed in the United States of America VB FOF 10 9 8 7 6 5 4 3 2 1 This book is printed on acid-free paper.
  3. 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.
  4. 4. CONTENTSAcknowledgments viiIntroduction viiiEntries A–Z 1Glossary 680Index 682
  5. 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. 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. 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- 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. 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. 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. 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. 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. 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. 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. 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. 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 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. 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. 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 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,, 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. 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. 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. 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. 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. 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. 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. 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 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