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2 the only diet you will ever need tp_2013

  1. 1. 1Asst. Prof. Theeraporn PuntheeranurakDepartment of Biology, Faculty of ScienceMahidol UniversityEmail: theeraporn.pun@mahidol.ac.thSCBI 109 Integrated Biology2The Only Diet You Will Ever Need2.1 Nutrients- Macronutrients- Micronutrients2.2 Enzymes and Metabolism- Enzymes- Calories and Metabolic Rate2.3 Body Fat and Health- Evaluating How Much Body Fat is Healthful- Obesity- Anorexia and BulimiaSCBI 109 Integrated Biology3• Organisms are composed of matter.• Matter is anything that takes up space and has mass.• Matter consists of chemical elements in pure formand in combinations called compounds.4Essential elements
  2. 2. 5What are nutrients?• Essential substances that your bodyneeds in order to grow and stayhealthy• Some provide energy.• All help build cells and tissues,regulate bodily processes suchas breathing.• No single food supplies all thenutrients the body needs tofunction. Body needs certain essential ‘nutrients’for its well-being.FUNCTIONS OF FOOD1. Energy-yielding,2. Body-building, and3. Protective foodstuffsaccording to predominant role they play in sustaining life.Nutrients in the Human Diet• Macronutrients– Water– Amino Acids andProteins– Lipids– Carbohydrates• Micronutrients– Vitamins– MineralsSix categories of nutrients:
  3. 3. MacronutrientsFunction and sources of carbohydrateCarbohydrate provides the main source of energy for thebody.Some forms of complex carbohydrates may reducecholesterol which is beneficial for health.Further classification of carbohydrateThere are different ways to classify carbohydrate.One method is into:1) sugar;2) starch.Classification of carbohydrateSugarMonosaccharides are the simplest form of carbohydratemolecules, e.g. glucose, fructose and galactose.Disaccharides are formed when two sugar molecules jointogether, e.g. sucrose (glucose and fructose), lactose(glucose and galactose) and maltose (2 molecules ofglucose).StarchPolysaccharides are made up of many monosaccharidesmolecules joined together, e.g. starch, glycogen, celluloseand pectin.
  4. 4. 13- Monosaccharide (CH2O)n, n > 3 : simple sugarsGlucose, Fructose, Galactose, RiboseClassification of carbohydrate14- Oligosaccharide (with glycosidic linkage)Maltose, Lactose, SucroseClassification of carbohydrate15- Polysaccharide : starch, glycogen, cellulose, chitinStorage polysaccharidesStructural polysaccharides- Polysaccharide :• complex carbohydrate• compose of hundreds or thousands of monomer• link by glycosidic linkage• same monomer or different• form of linkage can lead to different properties evenmade from the same monomerClassification of carbohydrate16
  5. 5. Another classification systems for sugarsIntrinsic can be described as sugars incorporated into thecellular structure of food,e.g. sugars in whole fruits and vegetables.Extrinsic sugars can be described as not bound into cellularstructure, e.g. lactose in dairy products.Non-milk extrinsic sugars (NMES) are sugars not bound intocellular structure and also not found in milk,e.g. honey, fruit juices, table sugar and confectioneryare all examples of foods containing NMES.Excessive consumption of carbohydrateIncreased body weightWhen too much carbohydrate is consumed and not used forenergy over an extended period of time, it is stored as fat.Building up too much fat will increase body weight.Increase dental cariesIt is important that teeth are brushed twice a day and foodshigh in sugar should be eaten with main meals, rather thanin between snacks to prevent dental caries.Lack of carbohydrateThe short term effects of a lack of carbohydrates are weightloss and lethargy (drowsiness).Kwashiorkor (lack of protein) and Marasmus (total lack of nutrient) aretwo forms of deficiency disease which can develop inextreme conditions. These occur where energy and proteinare lacking in the diet over an extended period of time.ProteinProtein is needed for growth, development and repair of thebody.Excess protein can be broken down and used as a sourceof energy.Protein is made up of different combinations of amino acids.These are the building blocks of protein.Amino acids are compounds containingcarbon, hydrogen, oxygen, nitrogen
  6. 6. 2120 amino acids of proteins (essential and non-essential)The amino acids are grouped here according to the properties of theirside chains (R groups).ProteinIndispensable or dispensable?The human body is able to make most amino acids itselfand these are known as non-essential or dispensable aminoacids.There are some amino acids that cannot be made by thebody. They are called indispensable amino acids (IAA) orsometimes essential amino acids. (phenylalanine, valine,threonine, tryptophan, isoleucine, methionine, leucine, lysine, histidine*and arginine*, *essential for infant)It is essential that these are provided in the diet as the bodycannot make them.Body needsAdults only need 8 indispensable amino acids for growthand repair.Children need to obtain 10 indispensable amino acids.(phenylalanine, valine, threonine, tryptophan,isoleucine, methionine, leucine, lysine, histidine* andarginine*, *essential for infant)Biological value and complementationIt is not just the amount of protein, but the quality orbiological value of the protein that needs to be considered.If a protein contains all the indispensable amino acids it issaid to have a high biological value.If a protein does not contain all the indispensable aminoacids it is said to have a low biological value.
  7. 7. High and low biological valueHigh biological value (HBV) proteins include:meat, fish, eggs, cheese, and milk.Low biological value (LBV) proteins include:cereals, pulses, some nuts and vegetables.In general, animal protein sources have a higherbiological value, than vegetable sources.Vegetarians and vegans need to eat wisely to ensurethey are getting all the indispensable amino acids.The body’s needs for proteinBabies and children have a high need for proteinbecause they are growing.Adolescents need protein for their rapid growth spurt.Pregnant women need more protein than otheradults because of the growing baby.Nursing mothers also need more protein for lactation.Protein deficiencyProtein deficiency is rare, but there is a condition calledPEM – protein energy malnutrition. This can be seen ininfants with stunted growth or thin arms and legs, and largedistended abdomens.Marasmus (total lack of nutrient) - this condition mainly affectsinfants causing them to become thin and weak. The bodyadapts to the shortage of energy and nutrients. All energystores are depleted as it is used to supply vital organs.Kwashiorkor (lack of protein) - this condition is known to be thebody’s adaption to shortage of energy and nutrients.FatFat performs many functions in the body including:• providing essential fatty acids;• providing a concentrated source of energy;• carrying fat soluble vitamins and is important for theirabsorption;• surrounding and protecting body organs;• forming an insulating layer keeping the body warm.Fat is made up offatty acids and glycerol.GlycerolFatty Acid 1Fatty Acid 2Fatty Acid 3
  8. 8. Essential fatty acidsThe body can make most fatty acids.Essential fatty acids (EFA) are required for importantfunctions in the body. These must be provided by the dietbecause our bodies cannot make them.Two EFAs are known for humans: alpha-linolenic acid (an omega-3fatty acid) and linoleic acid (an omega-6 fatty acid).Sources of saturated and unsaturated fats• Saturated fatMeat, coconut oil, palm oil, cakes and biscuits, lard.• Unsaturated fat* Mono unsaturated fatRapeseed oil, avocado and olive oil.* Polyunsaturated fatOily fish, sunflower oil and pine nuts.Over consumption of fatEating too much saturated fat has become a problem in oursociety.There are many health problems linked with too muchsaturated fat in the diet, e.g. coronary heart disease, andstrokes.Micronutrients
  9. 9. MicronutrientsMicronutrients are needed in much smaller amounts thanthe macronutrients.In general vitamins are needed to regulate the maintenanceand growth of the body, and to control metabolic reactions incells.Most vitamins are provided to the body through the diet,however, the body can make vitamin D, vitamin K andniacin.Vitamin A (retinol, carotene)Vitamin A is fat-soluble vitamin needed for the normalstructure and functioning of the cells in the skin and bodylinings, e.g. in the lungs.This vitamin also helps with vision in dim light, as well akeeping the immune system healthy.It is found in two forms; retinol in foods from animalsources and carotenoids (the most abundant of whichis the beta-carotene) from plant sources.Vitamin A – retinol is found in liver and whole milk,Vitamin A – carotenoids are found in dark green leafyvegetables, carrots and orange coloured fruits.Too much or too little?Deficiency leads to poor vision in dim light or nightblindness. Severe deficiency can lead to total blindness.Vitamin A is stored in the liver and too much vitamin A canbe toxic.Consuming too much vitamin A whilst being pregnant hasbeen linked to birth defects.Vitamin D (Cholecalciferol)Vitamin D is needed for the absorption of calcium andphosphorous from foods, to keep bones healthy.Recent research also suggests that vitamin D enhancesimmune function and improves muscle strength.Vitamin D is found in the diet, but most of our vitamin D ismade in the body the action of ultra violet rays on the skin.Vitamin D occurs naturally in some animalproducts, including fish liver oils, oily fish,egg yolk, and butter.Cereals, margarine and low fat spreads arealso fortified with vitamin D.
  10. 10. Too much or too little?Deficiency of vitamin D leads to rickets (โรคกระดูกอ่อน) and theformation of soft bones. This causes the bones in the legs tobend. Deficiency in adults causes Osteomalacia resulting inpain and muscular weakness.Vitamin D can be stored by the body. Too much vitamin D canlead to excess levels of calcium in the blood.Young children, housebound older adults, and people whopractice religions where their skin must be covered, may be atrisk of deficiency through lack of exposure of their skin tosunlight.Vitamin E (Tocopherol)Vitamin E is a group of similar molecules with commonproperties and functions.Vitamin E acts as an antioxidant and protects cells in thebody against damage.Vitamin E is mainly found in vegetable oils, nuts,seeds and wheat germ.Deficiency and excess of vitamin EA deficiency in this vitamin is rare because it is so widelyavailable in the diet.In very rare cases neurological disabilities such as lostreflexes have developed.Vitamin E has a low toxicity, but in very large doses mayinterfere with absorption of vitamin A.Vitamin KVitamin K is needed for normal clotting of blood and isalso required for normal bone structure.Infants are given vitamin K at birth.Vitamin K is also produced by the bacteria in the gut.Vitamin K is found in green leafy vegetables e.g.broccoli, lettuce, cabbage, spinach and meat anddairy products.
  11. 11. Too much or too little?Deficiency of vitamin K is rare inadults, but is sometimes seen innew born babies.Thiamin (B1)Thiamin is needed for the release of energy fromcarbohydrate. It is also involved in the normal functioning ofthe nervous system and the heart.Thiamin is mainly found in whole grains, nuts, meat(especially pork), fruit and vegetables and fortifiedcereals.Too much or too little?Thiamin deficiency can lead to the development of thedisease beri-beri. Symptoms include fatigue, weakness ofthe legs (ชาปลายเท้า) and anorexia (ไม่อยากอาหาร).As the body excretes any excess thiamin, there is noevidence of any toxic effects of high doses.Riboflavin (B2)Riboflavin is needed for the release of energy fromcarbohydrate, protein and fat.It is also involved in the transport and metabolism of iron inthe body and is needed for the normal structure and functionof skin and body linings.Riboflavin is found in milk, eggs, rice, fortifiedbreakfast cereals, liver, legumes, mushrooms and greenvegetables.
  12. 12. Too much or too little?There is no deficiency related disease, however, thetongue, lips and skin become affected when the body is lowin riboflavin (ปากนกกระจอก).As the body excretes any excess riboflavin, there is noevidence of any toxic effects of high doses.Niacin (B3)Niacin is important for releasing energy from food, and isimportant for the normal structure of the skin and bodylinings.Niacin is also needed for the normal functioning of thenervous system.Niacin can be found in meat, wheat and maize flour,eggs, dairy products and yeast.Too much or too little?Deficiency of niacin can result in the disease pellagra.Symptoms can include:• dermatitis (คันตามผิวหนัง, ภูมิแพ้);• dementia (โรคสมองเสื่อม);• diarrhoea.Problems associated with excessive intakes are rare.Vitamin B12Vitamin B12 is needed for the formation of red bloodcells and the normal functioning of the nervous system.Vitamin B12 also helps to release energy from food.Vitamin B12 is found exclusively in animal products,plant products do not provide any vitamin B12.It is found in meat, fish, cheese, eggs, yeastsextract and fortified breakfast cereals.
  13. 13. Deficiency of vitamin B12Deficiency of vitamin B12 can lead to pernicious anaemia(โลหิตจาง).It can also lead to some neurological problems.Deficiency is rare, but may be a problem for peoplefollowing strict vegan or vegetarian diets.Folate (Folic acid)Folate is important for the formation of healthy red bloodcells.It is also needed for the nervous system and specifically forthe development of the nervous system in unborn babies.It can reduce the risk of neural tube defects in a fetus, e.g.spina bifida.Good sources of folate include green leafyvegetables brown rice, peas, oranges, bananas andfortified cereals.Deficiency of folateDeficiency of folate can lead to megaloblastic anaemia.Symptoms can include insomnia (โรคหลับยาก), depression andforgetfulness.It is recommended that all women who are planning apregnancy take a daily supplement of folic acid. Oncepregnant, supplementation should continue for the first 12weeks to reduce the risk of neural tube defects.Vitamin C (Ascorbic acid)Ascorbic acid is needed to make collagen which is requiredfor the normal structure and function of body tissues, suchas skin, cartilage and bones.It also acts as an antioxidant that protects the body fromdamage by free radicals.Sources of ascorbic acid include fresh fruits, especiallycitrus fruits and berries, green vegetables, peppersand tomatoes. Ascorbic acid is also found in potatoes(especially in new potatoes).
  14. 14. Too much or too little?Scurvy (ลักปิดลักเปิด) can result from lack of ascorbic acid. Ittends to occur in infants and the older adults.Scurvy leads to spots on the skin, bleeding gums and looseor loss of teeth.Over nutrition of ascorbic acid is rare.MineralsMinerals are inorganic substances needed by the body formany different functions.Some minerals are needed in very tiny amounts, these areknown as trace elements, such as fluoride.Calcium (Ca)Calcium is important for the formation and maintenance ofstrong bones and teeth, as well as the normal functioning ofnervous system and muscles.It is also involved in blood clotting.Milk and dairy products are the most important sourcesof calcium. Other sources include bread, calciumenriched soya products, green leafy vegetables and fishwith soft edible bones.Too much or too little?Poor intakes of calcium can result in poor bone health whichcan increase the risk of diseases such as osteoporosis laterin life.Taking high doses of calcium supplements can causestomach pains and diarrhoea.
  15. 15. Iron (Fe)Iron is needed for needed for the formation of haemoglobinin red blood cells which transport oxygen around the body.It is also required for energy metabolism and has animportant role in the immune system.Haem iron is present in animal sources in the formof haemoglobin.Non haem iron is present in plant sources such asbeans, nuts, dried fruits, wholegrains, soya beanflour and dark green leafy vegetables.Too much or too little?A lack of iron will lead to anaemia. Symptoms include:• feeling of tiredness;• lacking in energy;• general weakness;• poor concentration.Too much iron in the diet can result in constipation,nausea and vomiting.Phosphorus (P)Phosphorus is essential for the structure bones and teeth,for the structure of cell membranes and for energymetabolism.Phosphorus is found in red meat, dairy products, fish,poultry, bread, rice and oats.Potassium (K)Potassium is essential for water and electrolyte balance andnormal functioning of cells, including nerves.Potassium is present in all foods, but found richly in fruit(dried fruits, bananas, berry fruits), leafy greenvegetables (e.g. broccoli and spinach) meat, nuts,seeds and pulses.
  16. 16. Sodium (Na)Sodium is needed to regulate body water content andelectrolyte balance.Sodium is also needed for the absorption of some nutrientsand water from the gut.Sodium is present in very small amounts in rawfoods. It is often added as salt during processing,preparation, preservation and serving.High salt processed foods include bacon,cheese, yeast extract and smoked fish.Too much or too little?Consuming too much sodium increases the risk of highblood pressure. High blood pressure is linked with anincreased risk of heart disease and stroke.Sodium deficiency is unlikely, but can be caused byexcessive sweating or vomiting and diarrhoea.It is recommended that adults and children over the age of11 years cut down on salt and consume no more than 6gper day.Fluoride (F)Fluoride is needed for the formation of strong teeth andprotects against dental decay (caries).Fluoride is a trace element, therefore only a small amount isrequired for good health.Fluoride can be found in drinking water and in smallamounts in tea and saltwater fish.Some areas add fluoride to the drinking water.Fluoride toothpastes are another important source.Too much or too little?An excessive intake of fluoride can lead to mottling ordiscolouration of teeth.
  17. 17. Nutrient interactionsSome nutrients work together in the body completingdifferent functions.For example:• the vitamins A,C and E;• calcium phosphorus and fluoride;• calcium and vitamin D;• iron and vitamin C;• carbohydrates and B vitamins.Anti-oxidantsVitamins A, C and E are anti-oxidants and work together inthe body to protect cells against oxidative damage from freeradicals.This damage to cells can increase the risk of developingdiseases such as heart disease and cancer.Calcium, phosphorus and fluorideThese nutrients are involved in the mineralisation of teethand bones which keep them hard and strong.Vitamin D and calciumVitamin D controls the amount of calcium available.A lack of vitamin D in the body results in reducedabsorption of calcium.Iron and ascorbic acidAscorbic acid aids the absorption of non haem iron (nonmeat sources of iron) when eaten at the same time.This is particularly important for people following strict veganor vegetarian diets.
  18. 18. Carbohydrates and Vitamins BRiboflavin and thiamin are involvedin the release of energy fromcarbohydrate.70• A fundamental task of proteins is to act as enzymes—catalyststhat increase the rate of all the chemical reactions within cells(over a millionfold).• Enzymes increase the rate of chemical reactions withoutthemselves being consumed or permanently altered by thereaction.– A substrate is a molecule that is acted upon by an enzyme.– A product is a result of the reaction between the enzyme and thesubstrate.Energy diagrams for catalyzed and uncatalyzed reactions • An enzyme converts a substrate to a higher energy state, ortransition state.• Activation energy is the energy required to reach the transitionstate, which constitutes a barrier to the progress of thereaction.
  19. 19. • The substrate binds to a specific region of the enzyme called theactive site.• The binding of a substrate to the active site of an enzyme is a veryspecific interaction.• Most biochemical reactions involve interactions between two ormore different substrates.• The simplest model of enzyme-substrate interaction is the lock-and-key model in which the substrate fits precisely into the active site.7475• mostly adds –ase at the end of substrate name eg.maltase, lipase, protease, sucrase, cellulase, amylase• or at the end of reaction name eg. hydrolase, isomerase,dehydrogenase, kinase, ligase• effects of enzyme activity• temperature• pH (acid-base)• inhibitor• etc.76
  20. 20. • Coenzymes are low-molecular-weight organic molecules that participatein specific types of enzymatic reactions by working together withenzymes to enhance reaction rates.• Nicotinamide adenine dinucleotide (NAD+) is a coenzyme that functionsas a carrier of electrons in oxidation-reduction reactions.Role of NAD+ in oxidation–reduction reactions• Several other coenzymes also act as electron carriers, and stillothers are involved in the transfer of a variety of additional chemicalgroups.• Many tasks that a cell must perform, such as movement and thesynthesis of macromolecules, require energy.• The totality of an organism’s chemical reactions is calledmetabolism (from the Greek metabole, change).• Energy is the capacity to cause change. In everyday life, energy isimportant because some forms of energy can be used to do work-that is, to move matter against opposing forces, such as gravity andfriction.• Calorie: a unit of energy. The calorie approximates the energy needed toincrease the temperature of 1 gram of water by 1 °C.80Metabolic Rates and Weight• Basal Metabolic Rate (BMR) – the amount of energyyour body uses at complete rest• About 60–70% of calories consumed per day supportBMR
  21. 21. 81 8283The nutrition facts label(also known as the nutritioninformation panel) is a labelrequired on most packaged foodin many countries.84Nathan’s Famous Hot Dog Eating Contest YieldsFrightening Nutrition Facts
  22. 22. 85 8687The glycemic load(GL) of food is anumber that estimateshow much the foodwill raise a personsblood glucose levelafter eating it.88
  23. 23. 89BMI• Body Mass Index• The term BMI is often used when discussingthe obesity epidemic• BMI is a tool for indicatingweight status.• It is a number that showsbody weight adjusted forheight.90• Body Mass Index (BMI) formula:o Weight (kg) / height squared (m2) oro Weight (lbs) x 704.5 / height (in.) / height (in.)• 60 kg / (1.60 m x 1.60 m)• 60 / 2.56 = 23.4 BMI91Body Mass Index: Are You at a Healthy Weight?92
  24. 24. 93 94Above a Healthy Weight• If your BMI lies above the normal area,then you may be at greater risk forhealth problems such as high bloodpressure, heart disease, diabetes, andcertain cancers.95Below a Healthy Weight• If your BMI lies below the normal area, thenyou may be at risk for health problems suchas irregular heart rhythms, depression,anemia, and osteoporosis.• Some people have a low BMI, but are eatingwell and have lots of energy. The best advicefor people below a healthy weight is to beaware of their health risks and maintain astable weight by eating well and keepingactive.96These men have the same height, weight,and BMI, but may have different percentbody fat.63" Height 63"220 lbs Weight 220 lbs27.5 BMI 27.5• BMI is only one of many factors used to predict riskfor disease.• It is important to remember that weight is only onefactor related to disease.
  25. 25. 97BMI is the not the only indicatorfor health riskOther Factors That Are ImportantWhen Calculating Health RiskInclude:• Diet• Physical Activity• Waist Circumference• Blood Pressure• Blood Sugar Level• Cholesterol Level• Family History of disease98ObesityOverweight and obesity are defined as abnormal or excessive fataccumulation that presents a risk to health. A person with a BMI of 30 ormore is generally considered obese. A person with a BMI equal to or morethan 25 is considered overweight.• Waist circumference:– Men <40 inches (102 cm)– Women <35 inches (88 cm)• Waist-to-hip ratio:– Men <1.0– Women <0.8Obesity99 100Selected Health Consequences of Overweight and Obesity
  26. 26. Portion Distortion:Do You Know How Food Portions HaveChanged in 20 Years?French Fries20 Years Ago Today210 Calories2.4 ouncesHow many calories arein these fries?610 calories6.9 ouncesCalorie Difference: 400 calories*Based on 160 pound personHow long will you have towalk to burn* 400 calories?How to burn* 400 calories:Walk leisurely for 1 hr 10MinutesSoda20 Years Ago Today85 Calories6 ½ ouncesCalorie Difference: 165 caloriesHow many calories are in thissoda?250 calories20 ounces*Based on 160 pound personHow long would you haveto garden to burn 165 calories?.How to burn* 165 calories:Garden for 35 MinutesTurkey Sandwich20 Years Ago Today320 caloriesCalorie Difference: 500 caloriesHow many calories are inthis turkey sandwich?820 calories*Based on 130 pound personHow long would you have to biketo burn up 500 calories?How to burn 500 calories:Bike for 1 hour and 25 minutes
  27. 27. 105Anorexia and Bulimia106Anorexia nervosa is a type of eating disorder. People whohave anorexia have an intense fear of gaining weight.They severely limit the amount of food they eat and canbecome dangerously thin.107Bulimia nervosa is an eating disorder characterized by bingeeating and purging, or consuming a large amount of food in ashort amount of time followed by an attempt to rid oneself of thefood consumed (purging), typically by vomiting, taking alaxative or diuretic and/or excessive exercise. Bulimia nervosais considered to be less life threatening than anorexia; however,the occurrence of bulimia nervosa is higher.108