proteins and vegetarianism lecture 5 units 15, 16
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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 COOH
Peptide and protein
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 qualityAll 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)
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