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Proteins and Vegetarianism Lecture 5 Units 15, 16
21

Lecture5 proteins

Jul 05, 2015

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Vedpal Yadav
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Page 1: Lecture5 proteins

Proteins and

Vegetarianism

Lecture 5 Units 15, 16

Page 2: Lecture5 proteins

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

Page 3: Lecture5 proteins

Amino Acid, Peptide & Protein

Amino acid

NH2

R C COOH

Peptide and protein

AA1-AA2-AA3-AA4--- AAn

Page 4: Lecture5 proteins

Digestion & Absorption

HCl

Enzymes split long chain of AA for

absorption

Blood transports AA to liver & muscle

Page 5: Lecture5 proteins

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

Page 6: Lecture5 proteins

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

Page 7: Lecture5 proteins

Process of Protein Synthesis

DNA ------RNA ---- Protein

Transcription Translation

DNA=deoxyribonucleic acid

RNA=ribonucleic acid

Page 8: Lecture5 proteins

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

Page 9: Lecture5 proteins

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

Page 10: Lecture5 proteins

Complementary Protein

Plant protein

(legume) with

limiting AA

combined with

different plant

protein (grain)

different limiting AA

eaten together give

complete protein

Page 11: Lecture5 proteins

Plants provide Incomplete

Protein

Low in one or

more ess. AA

Eat in combo

to “complete”

the AA

balance

Page 12: Lecture5 proteins

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

Page 13: Lecture5 proteins

Food Sources of Proteins

Meat

Fish

Poultry

Eggs

Beef & pork rich in

iron but high in

fat

Page 14: Lecture5 proteins

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

Page 15: Lecture5 proteins
Page 16: Lecture5 proteins

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

Page 17: Lecture5 proteins

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

Page 18: Lecture5 proteins

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

Page 19: Lecture5 proteins

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

Page 20: Lecture5 proteins

Protein deficiency--Marasmus

Chronic food

deprivation,diseases

Protein & calories

Impairs brain

development &

learning

Severe weight loss

Infection, diarrhea

Page 21: Lecture5 proteins

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)