PROTEINS IN THE DIET Humans have about 10kg protein and need to replace about 300g daily: recycle ~230g need to eat ~30g meat/fish/egg protein ~40g grain.

PROTEINS IN THE DIET

Humans have about 10kg protein and need to replace about 300g daily: recycle ~230g

need to eat ~30g meat/fish/egg protein ~40g grain protein per day

Most of us >100g/day

FOOD WATER PROT FAT CARB kcal /100gMeatBeef 62 32 5 0 180Chicken 71 24 4 0 140Salmon 64 27 7 0 180GrainBread 36 10 3 50 250Rice, cooked 70 3 0 26 120DairyMilk, whole 87 3 3 5 65Cheese 37 25 32 2 400Eggs 74 13 11 1 160FruitsApples 84 0.2 0 15 60Bananas 76 1 0.2 22 85Nuts – Almonds 5 19 54 20 600VegetablesPotato 75 2 0.1 21 90Corn 74 3 1 21 90Tomato 94 1 0.2 5 22

Some grains lack some amino acids

CORN lacks lysine and tryptophanRICE lacks lysine and threonineWHEAT lacks lysineSOY lacks methionine (need 2g/day of this one)

KWASHIORKOR is common in Africa where corn is almost the exclusive food consumed: characterized by bloated and swollen belly, scaly skin, retarded growth and mental apathy

Not generally a problem with a balanced vegan diet in North America as a variety of seeds and nuts provide all necessary amino acids

From an efficiency standpoint, consuming animal proteins is not necessarily the best option:

To produce 1kg of animal protein requires the following kg of feed:

Beef 20 Pork 8Chicken 5 Eggs 4Catfish/Carp 2.5

Animal protein sources have changed a lot over the last few decades (chicken was ~ equal to mutton in 1950):

1990 (M tons) 2003 Growth/y WorldBeef 53 59 0.8Pork 70 96 2.5Mutton 10 12 1.6Chicken 41 76 4.9Ocean Fish 85 93 0.8Farm Fish 13 40 9.7

High protein – low carb diets (Atkins, Zone, Protein Power…)

Result in quick weight loss because eliminating carbohydratesresults in loss of body fluids – but, according to the AmericanHeart Association, are not effective long term: impedefat metabolism, generally substitute carbohydrates with fats,restricts mineral intake, causes ketosis (and nausea)

Some people can’t metabolize excess protein resulting in liver andkidney disorders

2002: Acrylamide, a potent carcinogen, identified in many popular foods such as fries, potato chips, cakes, bread, coffee, cookies

Comes from carb rich foods that are fried or baked

Source identified from amino acid asparagine + dicarbonyl compound from browned sugars

H2N-CO-CH2CH<COOH

NH2

+ R-CO-CHO

H2N-CO-CH=CH2

heat

Is this a risk? Maybe not: NOAEL (no observed adverse affect limit) is 500x higher at 0.5 mg/kg body weight than the amount

in a normal portion of the worst offender, french fries (ca. 50 g/serving)

FOOD - MINERALS AND VITAMINS

RDA/DRI=800/1000-1300*mg

RDA is old recommended daily allowance, DRI is new joint Canada/US intake values

2mg

*generally higher values are for 15-18 yr olds, and 50+

3(F)-4(M)mg

100-150/150mg

10-18/10(M)-15(F)mg

300-400/320(F)-420(M)

800-1200/700-1250 (15-18y)

/55(F)-70(M)g

15/12(F)-15(M)

I

HO

I

O

I

I

COOHNH2

IODINEIodine required for Thyroxine which controls the thyroid gland: regulates rate at which cells use O2 and the base metabolic rate

GOITER = swollen neck (size of head) caused by too much or too little iodine. All salt in NA has 0.1% KI added to avoid this problem

thyroxineL-form is active amino acid

VITAMINS

OIL (FAT) SOLUBLE = A, D, E, F, KWATER SOLUBLE = B, C.

VITAMIN A = RETINOL: derived in body from -carotene (orange pigment in carrots)

CH2OH

2

liver

oxn

-carotene retinol (vitamin A alcohol)

CHO

citral

Commercially, citral from lemon grass can be converted to Vitamin A or carotene

-carotene retinol citral

US uses RDA (recommended dietary allowance), CAN uses RNI (recommended nutrient intakes)

RDA = 5000 IU (International units) (~1500 RE)= 1.5 mg retinol = 1.72 mg of Vit A acetate ≡ 3 mg carotene

NOW 1000 RE (retinol equivalents) = 1 mg (1000g) of retinolThese differ by country, eg. UK = 800RE = 0.8 mg; Canada = 870 RE = 0.87mg and by gender: F = 80% of male

Function: Vitamin A protects against invading bacteria - makes mucus secreting cells produce sticky stuff which trap

bacteria; - prevents night blindness - (regeneration of retinal pigments); - keeps skin and tear ducts healthy

DEFICIENCY: Light sensitivity, night blindness, infections~ 1 million people in India suffer night blindness

EXCESS: probably most toxic vitamin in excess irritability, dry peeling skin, pressure in head

severe liver injury if >25,000 IU. only 5x normal dose

also TERATOGENIC: birth defects of eyes, ears, heartavoid liver if pregnant (limit 8,000 IU)

SOURCES: fish liver oils, egg yolks, apricots, peaches CAROTENE: not poisonous, present in carrots, green vegetables

VIT A is fat soluble so passes up food chain: highest in polar bear liver (~20,000 IU/g!!)

Adults store a year’s supply in fat India: diet is deficient; GM modified rice to produce carotene

trans-RETINOIC ACID; RETIN-A; TRETINOIN

Causes the skin to peel: used in cosmetics as an anti-acne agent, anti-skin damage, anti-wrinkle...OK in limited doses topically Some questions as to its efficacy: see the FDA site on RENOVA:http://www.fda.gov/cder/foi/label/2000/21108lbl.pdf

cis-RETINOIC ACID; ISOTRETINOIN; ACCUTANE

Orally for severe acne, BUT it has severe side effects and is powerful TERATOGEN: requires two pregnancy tests to startsee: http://www.aocd.org/skin/dermatologic_diseases/accutane.html

Tretinoin Isotretinoin

VITAMIN D (calciferol) 400 IU = 10 g of Vit D3

US = 5-10 g; UK 5-7 g; CAN 3-5 g

HO 7

sunlight

HO

7-dehydrocholesterol Vit D3 cholecalciferol

Sources: Pre-vitamin in cereals, bread, milk sunlight converts it to active vitamin

Function: Vitamin D controls Ca and P absorption from foods, metabolism, transport of Ca in bloodstream and formation of bones

DEFICIENCY: soft, deformed bones (RICKETS) not enoughCa3(PO4)2 to stiffen them; poor teeth

Stored in fat

Excess is toxic: 250 g/d for 4 weeks or 5 mg/d for 2 weeks causes nausea, vomiting, diarrhea, headache

Too much Ca/P:

stiffens joints

VITAMIN E -TOCOPHEROL

USRDA = 30 IU (30 mg) old racemic RH/LH mixture

now use d-(RH) -tocopherol = 16.7 mg

OH

O

Function: prevents oxidation of fatsmaintains red blood cell membranesnecessary for proper functioning of:

genitals, lungs, liver, kidneys

Not destroyed by heat but sensitive to O2

Not as fat soluble as A or D so storage in body is shorter

DEFICIENCY: edema (water under skin), anaemia in kids, muscular dystrophy

EXCESS Vitamin E: recently recognized as a potential health hazardincreases LDL, depresses platelet formation by causing Vit K deficiency (slows blood clotting), shows immunosuppresant properties

(see for eg. http://emedicine.medscape.com/article/126268-overview)

Sources: plenty in grains, meats, eggs, nuts, salmon (oily fish)

VITAMIN F = (-6)-linoleic acid (see fats section)

9,12-octadecadienoic acid

Function: Important for structural cell membranes

Sources: present in all fats, some vegetable oils and many expensive supplements

DEFICIENCY coarse sparse hair, eczema (RDA = 1.3 g)

OH

O

VITAMIN KO

O

H

n

n = 5-13

Function: Synthesis of prothrombins (blood coagulants)

DEFICIENCY: haemorrhages, slow blood clotting (RDA ~ 80 g/d)

EXCESS: clotting

Sources: Found in leafy veg like cauliflower, broccoliMust watch intake if on blood thinners

ANTI-VITAMIN K: dicoumarol is found in clover, alfalfa

substitute is warfarin (blood thinner, rat poison)

O OO O

HO OHO O

OHO

Dicoumarol [Dicumarol] Warfarin

Inhibits Vit K dependent synthesis of blood clotting factors

WATER SOLUBLE VITAMINS: washed out so need more frequently

B-GROUP co-enzymes in growth and energy production

B1 THIAMINERDA = 1.5mg N

N

N

SNH2

OH

+

Cl-

Function: carbohydrate metabolism (decarboxylation of pyruvate and ketoglutarate), energy production, ATP levels, heart and circulatory system functioning

Deficiency: Beriberi*, muscular atrophy, nervous disorders

Sources: grain skin, soybeans, bran, peanuts, meat, liver, eggs

(bread and cerials are enriched: 2.1 mg/100g)

*Beriberi: laboured breathing, enlarged heart, mental confusion, paralysis of arms/legs – common with exclusive white rice diet

B2 RIBOFLAVINRDA = 1.2-1.8 mg

N

N

NH

N

O

O

HO OHOH OH

Function: used as part of co-enzyme FAD (flavin adenine dinucleotide); metabolism of fats and proteins

DEFICIENCY: cracks around mouth, sore eyelids, oily skin around

nose, DERMATITIS, fatigue, stops tissue growth

Sources: liver, milk, eggs, leafy veg

Added to enriched bread, cereals: 3.6 mg/100g

B3 NIACINRDA 13-20mg N

COOH (orCONH2)

Function: part of co-enzyme NAD (nicotinamide adenine dinucleotide) metabolism and synthesis of carbs, fats, proteins, (alcohol)

Deficiency – the three D’s: Diarrhea, dermatitis and dementia (Pellagra)

High levels of Niacin have been shown to raise HDL and lower LDL but high levels of niacin can also cause liver damage:http://www.nlm.nih.gov/medlineplus/ency/article/002409.htm

Sources: yeasts, liver, peanuts, whole grains, potatoesCorn is deficient in niacin so people in SE USA used to get pellagra

Added to enriched bread, cereals: 21 mg/100g

B5 PANTOTHENIC ACID

Incorporated into Co-enzyme A

Function: transfers C2 units in metabolism of fats and carbsDeficiency: retarded growthSources: liver, salmon, eggs, nuts, yeasts, broccoli, cauliflower

OHNH

OH

OH

O O

Function: metabolism/synthesis of proteinsDeficiency: oily dermatitis, nausea, vomiting, weakness, dizzinessSources: yeasts, bran, carrots, bananas, liver, eggs, meats

Morning sickness during pregnancy is reduced with extra B6

EXCESS: (100 mg/d): loss of balance, numbness (sold 100-500 mg)

B6 PYRIDOXINE1.7-2.0 mg/d N

HOOH

OH

B7 BIOTIN 0.3-1 mg/d NHHN

S

O

COOH

Function: carboxylase coenz (transfer CO2 in food metabolism)Deficiency: sleepiness, muscle pains, aversion to food,

increase in blood cholesterol, dry scaly skinSources: most vegetables, liver, milk, nuts

Function: coenzymes of growth, especially red blood cells Deficiency: anaemia, fatigue, poor appetite, forgetfulnessSources: liver, whole grains, yeast, green veg

B9 FOLIC ACID

0.15-0.4 mg/d

(2x pregnant F)

CONHN

N

N

N

NH

H2N

OHCHCH2CH2COOH

COOH

Folic Acid Controversies

Pregnant women: protects baby from spina bifida BUT

Swedish study suggests increased chance of twins and cerebral palsy

Is this risk > spina bifida risk?

US has made folic acid a compulsory additive in cereals:

reduces blood homocysteine, reduces heart disease

http://www.hc-sc.gc.ca/iyh-vsv/med/folic-folique_e.html

http://www.marchofdimes.com/professionals/690_1403.asp

B12 COBALAMINRDA = 6 g/d

Function: catalyzes synthesis of nucleic acids, red and white blood cells, RNA to DNA conversion

Deficiency: pernicious anaemia inability to absorb vitamin from food (need to have them injected)

Sources: Meat and dairy, seafood No significant plant sources

Needs to be formed by bacteria or consumed in meat

C ASCORBIC ACID

RDA = 50-60 mg/d

Deficiency – Scurvy: bleeding hair follicles, edges of nails, bleeding stinking gums, weight loss, blacklungs, damaged liver, swollen legs...

Only need ~ 10 mg/d to prevent scurvy

Sources: all citrus fruit, potatoes, tomatoes, cabbage

English sailors corrected the deficiency with limes: ‘limeys’

Need 300mg of Vit C in body, of which need to replenish ~60 mg/dCannot be stored for long: excrete excessive doses (>200 mg/d)Pauling advocated (and took) > 2 g/d

Function: ANTI-OXIDANT that scavenges free radicalsslows or prevents invading viruses (VIT C – Common Cold connection)regenerates Vit E in the body

heat and oxygen sensitive (old bottles are not good)

O

OH OH

O

OH

OHO

O O

O

OH

OH

O2 + 2 H+ + 2 e- H2O2

+ 2 e- + 2 H+