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Proteins and Vegetarianism Lecture 5 Units 15, 16 Chemistry Composition: C H O N (S) Amino Acids “building blocks” – Amine group (NH2) – Acid group (COOH) – Differ by side group (“R”) 9 : from food 11 Nonessential AA: can be made from other AA Amino Acid, Peptide & Protein Amino acid NH2 R C Peptide and protein COOH AA1-AA2-AA3-AA4--- AAn Digestion & Absorption HCl Enzymes split long chain of AA for absorption Blood transports AA to liver & muscle Functions of Protein Growth, build & maintenance of tissues Regulate body processes: Water (fluid) balance--prevent edema Acid-Base (pH) balance--buffers Immune system - antibodies Energy source--4 calories / gram Protein Synthesis DNA code controls : Which AA needed What order AA go on new chain AA3 AA1 + AA2 AA1AA2 AA1AA2AA3 Requires: Calories Essential AA from AA pool Non-essential AA from synthesis or diet Process of Protein Synthesis DNA ------RNA ---- Protein Transcription Translation DNA=deoxyribonucleic acid RNA=ribonucleic acid Catabolism of Protein Breakdown of protein to AA AA converted to fat when excess AA N from AA is reused for AA synthesis; excess is excreted in urine – May cause loss of Ca in urine – Kidney disease problem Protein Quality Complete Protein High quality All essential AA in needed amounts Animal sources Incomplete Protein Plant sources 70% of protein from animal sources in US Complementary Protein Plant protein (legume) with limiting AA combined with different plant protein (grain) different limiting AA eaten together give complete protein Plants provide Incomplete Protein Low in one or more ess. AA Eat in combo to “complete” the AA balance Protein Requirements .8 gm/kg body weight Protein RDA 46 gm for women 58 gm for men 10-12% kcal from protein Actual US Intake >80 gm >110 gm ~17% kcal from protein Food Sources of Proteins Meat Fish Poultry Eggs Beef & pork rich in iron but high in fat More Good Protein Sources Dairy products select low fat (butter not protein) Legumes Cereal grains Seeds Nuts Plant sources of protein are low in fat What about protein for athletes? Athlete needs 1.26 gm / Kg (~90 gm) (but typical US male eats >110 gm and female eats >80 gm) Thus… supplements not needed What does the body do with the added amino acid? What builds muscle: exercise and a good diet Amino Acid Supplement High intake of a single AA leads to AA imbalance and is harmful Many AA supplements on market, Surplus of AA causes diarrhea, loss of appetite, GI upsets Tryptophan supplements were banned in 1990 Athletes Vegetarian Diets Semi-vegetarian: – lacto vegetarian – ovo vegetarian Strict vegetarian: – “Vegan” – healthy diets use complementary proteins Macrobiotic diet: locally grown and whole foods; Yin(“cold”)&yang(“warm”) foods Vegetarian Diets & Health Associated with low risk of chronic diseases May lead to Vegans: vitamins B12 and D, Ca, Zn are at risk Adequately planned vegetarian diets can The key to achieve healthy diet: variety Protein deficiency--Marasmus Chronic food deprivation,diseases Protein & calories Impairs brain development & learning Severe weight loss Infection, diarrhea Protein deficiency -Kwashiorkor Deficiency in protein but not calories Children 1-3 years Some weight loss Edema Hair: dry, brittle, changes color (lack of AA to make melanin)