HEA 201 Chapter 4, Fall 2007

Nutrition 1. Nutrients  Carbohydrates - Categories Simple: also called sugars e.g. glucose, fructose, sucrose, lactose Complex: digestible: starch: hundreds of glucose units indigestible: fibers: e.g. pectin, cellulose - Major functions Energy: provide 4 kcal/g glucose: basic fuel for all cells, only fuel for NS cells  spare protein for tissue building Fibers: do not provide energy important for normal functioning of digestive system - Daily need: starch & sugars: 55-60% of total energy intake fibers: about 30g - Food sources Glucose & fructose: fruits & honey Sucrose: table sugar (sugar canes & beets), honey, maple syrup Lactose: milk, some dairy products Starch: cereals (wheat, rice... & products), legumes (beans, peas, lentils), potatoes, bananas Fibers: fruits, vegetables, grain covers  Lipids - Categories Fats (fatty acids) .SFA (solid at room t, unhealthy): saturated in H .UFA (generally liquid at room t, healthy fats): MUFA PUFA: include 2 essential FA: -3 & -6 .Trans FA (very unhealthy fats): UFA but abnormal distribution of H: worse than SFA obtained during hydrogenation of vegetable oils (margarine) Cholesterol - Major functions Fats (stored in adipose tissue as triglycerides) provide energy (9 kcal/g) insulate body & protect internal organs Cholesterol does not provide energy used to form vitamin D used to form steroid hormones (e.g. sex hormones) - Daily need Fats: less than 30% of total energy intake (SFA: less than 10% of total energy intake) Cholesterol: made by liver from SFA (= major source of body chl) upper limit: 300 mg - Food sources SFA: animal fats (except fish fat) meat, poultry (esp. skin), egg yolks, milk & products plant fats rich in SFA: palm oil & coconut oil MUFA: oleic acid: olive oil, peanuts, almonds, avocados PUFA: vegetable seeds & their oils (soybean, sunflower, corn) fish Chl: only animal products best: organ meat (e.g. liver) & egg yolk  Proteins - Categories .Complete (high-quality protein) contain all essential AA all animal protein (except gelatin) .Incomplete (low-quality proteins) lack at least 1 essential AA plant protein (except soy proteins) - Major functions: Tissue synthesis Can also provide energy (4 kcal/g) - Daily need: 0.9g / kg of body weight for adults (~ 15% of total energy intake) - Food sources: Animal: meat, poultry, fish, milk & products, eggs (yolk & white) Plant: richest are legumes, also in cereals & potatoes  Vitamins - Categories: .Fat-soluble: A, D, E, K Generally stored in the body (except K), not excreted in urine =>  symptoms of deficiency develop relatively late (months) Θ can accumulate & become toxic (hypervitaminosis A & D) .Water-soluble: B, C Generally not stored in body (except B12), excreted in urine => Θ symptoms of deficiency develop within days  lower risk of toxicity - Major functions Do not provide energy Necessary for various body functions - Daily need: very small amounts (µg to mg) Vitamin Major Sources Major Functions Deficiency A .Vit A: liver, milk fat .Provit A (carotene): dark green leafy vegetables orange fruits & vegetables .Vision .Antioxidant (carotene) Night blindness D .Fortified foods (milk, cereals) .Body synthesis (sunlight) Blood Ca maintenance => bone & teeth mineralization Bone problems: .Children: rickets .Adults:osteoporosis E Vegetable seed oils, nuts Antioxidant Anemia K .Green leafy vegetables .Intestinal bacteria Blood clotting Hemorrhage Vitamin Major Sources Major Functions Deficiency B family .Meat, poultry, eggs, yeast .Bran & germ of cereals (except B12: only animal foods) Many biochemical reactions (e.g. energy-production reactions) .Impaired growth .Anemia C Fresh fruits & vegetables (esp. if acidic, e.g. citrus fruits) .Immune response .Antioxidant .Iron absorption Scurvy  Minerals - Categories (based on amounts needed for adults) Macrominerals: e.g. Ca, Mg, Na, K Microminerals (trace minerals): e.g. Fe, I, F - Daily need for adults Macrominerals:  100 mg Microminerals: less than 1 to a few mg - Major functions Do not provide energy Necessary for various body functions Mineral Major Sources Major Functions Deficiency Calcium .Milk & products .Green leafy vegetables .Legumes .Bone & teeth formation .Nerve & muscle function .Bone problems (rickets & osteoporosis) .Muscle cramps Magnesium .Green leafy vegetables .Unrefined grains .Bone structure .Muscle contraction Muscle cramps Sodium .Table salt .Processed foods .Body water distribution .Nerve & muscle function Muscle problems Potassium .Wide distribution Iron .Meat, poultry, fish, eggs .Legumes, green leafy vegetables .O2 transport (hemoglobin) .Normal brain functioning .Anemia .Fatigue Iodine .Seafood & iodized salt Part of thyroid hormones Goiter Fluoride .Seafood .Tea .Fluoridated water & foods Teeth resistance to caries Frequent caries Water - Represents about 70 % of body weight - Major functions Medium for chemical reactions Transport (blood) Temperature regulation (sweat) Lubrication (mucus, tears…) Waste removal (urine) - Daily need About 2.5 liters (1 to 1.5 l from drinks, preferably mineral water) Need increased by illness exercise high temperatures high altitude, airplane high coffee & alcohol intake ( urination) - Food sources Beverages (water, juices, sodas…) Foods (variable amounts) 2. Healthy Nutrition  Dietary Guidelines - Eating a variety of foods for adequate intake of all nutrients - Maintenance of a healthy body weight - Eating plenty of plant products (starch, fibers, vitamins, minerals) - Keeping fat, SFA and cholesterol intake low - Moderate consumption of Sodium (salt): increases risk of hypertension Sugars: “empty calories” + dental caries Alcohol: dependence & health (e.g. liver) problems  Food Guide Pyramid - Includes 5 food categories that cannot substitute for each other Grains Vegetables Fruits Milk Meats and beans - Daily consumption of foods from all 5 groups, in different amounts - Limited fat (preferably from fish or plant sources), sugars & salt intake - Balance between food and physical activity New Pyramid Old Pyramid  Ways to decrease fat intake - Remembering relative fat content of animals: fish < poultry < meat - Choosing fish & legumes as an alternative protein-source to meat - Grilling, boiling, steaming instead of frying - Replacing butter & mayo with mustard & ketchup - Adding flavor to foods by using herbs, spices, lemon, marinades - Reducing high-fat snacks & appetizers (chips, salamis, hod dogs…) - Removing visible fat before cooking & excess fat during or after - Mixing 1 egg + egg whites to make omelets - Choosing low-fat/fat-free products (milk, cream, mayo, butter,dressing) - Choosing water-packed canned fish & meat (instead of oil-packed) - Choosing low-fat frozen yogurts & sherbets instead of ice cream  Vegetarian Diets - Types .strict vegetarians (“vegans”): only plant products .lacto: plant products + milk & products .lacto-ovo: plant products + milk & products + eggs .lacto-ovo-pesco: plant products + milk & products + eggs + seafood .lacto-ovo-pesco-pollo: plant products + milk & products + eggs + seafood + poultry - Benefits .high in fibers, starch, vitamins, minerals and phytochemicals .low in fat, SFA, no cholesterol - Health status of vegetarians: lower incidence of .cardiovascular diseases (lower cholesterol levels) .overweight .cancer .hypertension .osteoporosis - Cautions for strict vegetarians .iron: adequate vitamin C intake increases plant Fe absorption .vitamin B12: supplements or B12-fortified foods are necessary .complementary proteins for adequate intake of all essential AA (e.g. cereals & legumes) 3. Reading Food Labels  Labels focus on following nutrients Total fat & saturated fat Cholesterol Sodium Carbohydrates: fibers & sugars (starch = the rest) Proteins  Amounts given per serving  Daily Values (DV) - Total amount of a nutrient an average adult should get/not exceed - Sodium, cholesterol, vitamins and minerals: same amounts for all - Fats, proteins & carbohydrates: amounts based on a 2000 kcal diet  Labels in expanded version, bottom includes general nutrition info Criteria for choosing  Calories: the lower the better if one is watching weight  Total fat: no more than 3g / 100 kcal  Saturated fat: no more than 1g / 100 kcal  Cholesterol: - Avoiding very high amounts - Careful about plant products w/o chl but cooked with SFA/trans FA (e.g. chips)  Sugars: trying to keep low  Sodium: keep low  Fibers, Ca & other vitamin & minerals - Good = 10%DV - High = 20%DV 4. Antioxidants and Phytochemicals  Antioxidants - Prevent damage by O-containing free radicals that can damage membrane  cell dies damage DNA  risk of cancer oxidize LDL  stick better to artery walls - Include -carotene (provitamin A) vitamin E vitamin C selenium  Phytochemicals - Chemicals naturally occurring in plants - Prevent cancers - Examples of phytochemical-rich foods Hot peppers Citrus fruits, tomatoes Broccoli, cabbage, cauliflower 5. Supplements  Mostly vitamins & minerals, individually or combined  People consume them to -Protect themselves from diseases (cancer, heart…) - Have more energy - Lengthen their life - Make sure they have adequate amounts if diet supply not enough  Safety concerns - A and D: risk of hypervitaminosis (D: overcalcification) - Water-soluble vitamins & minerals some toxic in large doses (Ca: overcalcification, Na: hypertension) others excreted anyway  useless => Best is to get vitamins & minerals from diversified diet  Situations where supplements might be recommended/needed - Pregnant & breastfeeding women Iron for RBC Folate for normal nervous system development & RBC Calcium for bones - Post-menopausal women: calcium for osteoporosis - Strict vegetarians: vitamin B12 - Elderly - People with illnesses/medications that interfere with appetite/digestion 6. Food Safety I. Biological Hazards: bacteria, viruses & parasites  Do not generally alter smell, taste or appearance of food  Symptoms of disease classically include vomiting, abdominal pain, diarrhea nausea, fever, dehydration  Severity of disease depends on agent (type and amount ingested) general condition of individual (health, age…) immune system status 1. Bacteria - Are destroyed by proper heating, survive when frozen - Some can turn into spores to survive harsh conditions (heat, acid…) - Can multiply on food (PHFs: potentially hazardous foods) that are moist / rich in protein /  neutral pH / at 5 - 60°C - E.g.1 Salmonella: food sources: mostly poultry & eggs - E.g.2 Staphylococcus causes disease through production of heat-stable toxin food sources: ready-to-eat foods prepared with human contact found in/on nose, hair & skin (load  by antiseptic lotions & soaps) - E.g.3 Bacterium that causes botulism causes disease through production of heat-sensitive neurotoxin can be fatal food sources: improperly canned foods, esp. if low acid 2.Viruses - Generally transferred to food from infected persons, - Do not multiply in food - Are destroyed by proper heating, survive when frozen - E.g. Hepatitis A virus disease duration: weeks (if mild) to months (if severe) symptoms: classical then swelling of liver & jaundice 3. Parasites - Are generally present in flesh of infected animals - Do not multiply in food - Are killed by heat and appropriate freezing - E.g. Taenia segmented flat worm, few m long causes classical symptoms and weight loss food sources: raw or undercooked pork & beef  Protecting oneself from biological hazards includes - Not eating raw/undercooked animal products (flesh, eggs, milk) - Not leaving PHFs between 5 & 60°C for more than 2 consecutive h - Avoiding cross contamination (from raw meat to ready-to-eat foods) can occur through hands, utensils, food contact surfaces… II. Chemical Hazards 1. Naturally Occurring - E.g. Mycotoxins produced by molds (food spoilage organisms) ingestion of small doses over time can cause cancer, liver damage, death 2. Man-Added  Food additives: majority are safe, some are not - Coloring agents - Taste enhancers: e.g. MSG can cause Chinese Restaurant Syndrome - Preservatives e.g.1 sulfites (prevents discoloration of foods): can cause allergies e.g.2 nitrites (used in meat curing): can cause digestive tract cancers  Pesticides (chemicals to control insects, weeds, fungi) - Leave residues on fruits & vegetables - Ways to decrease exposure to pesticides buying organically grown products whenever possible washing carefully removing outer leaves from leafy vegetables (e.g. lettuce) peeling removes surface pesticides, but not pesticides inside  Cleaning or sanitizing chemicals  Chemicals from containers - E.g.1 metals from cans & containers (tin, copper, iron, lead, zinc) - E.g.2 chemicals from plastic that migrate into food when waving (headaches & chest tightness) III. Food Allergies  When IS reacts to a food component as if it was a potential threat  Exaggerated immune reaction is what causes the symptoms  Symptoms include headache vomiting, diarrhea itching, puffy, teary eyes runny nose rash  Commonly allergenic foods eggs nuts wheat seafood cow's milk