The Protein Myth (Source: Physicians Committee for Responsible Medicine)

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The Protein Myth

 

This table should dispense once and for all the claim that plant proteins are inferior to animal proteins because they are missing or lacking some essential amino acids. All plant proteins contain all essential amino acids in varying amounts.

 

 

 

 

 

 

TRY

THR

ISO

LEU

LYS

MET+CYS

PHE+TYR

VAL

 

Ideal

11

35

42

70

51

26

73

48

 

Food

 

 

 

 

 

 

 

 

 

Soy Bean

13

49

44

74

61

27

83

46

 

Azuki Bean

10

34

49

84

75

20

83

51

 

Potato

16

36

49

59

60

29

81

56

 

Eggs

16

49

82

87

67

56

97

72

 

Rice

11

44

39

72

39

44

94

61

 

Wheat

12

29

53

78

25

30

101

49

 

Oats

13

35

42

83

45

57

84

61

Anyone who says that we have to eat an amino acid in particular ratios at each meal doesn't really understand how the body deals with protein. What we need to do is to replenish our amino acid pool, and the amino acids do not, repeat, do not have to come from the same protein. Not even from the same meal. Soy protein can supply the lysine at lunch, wheat protein can supply the methionine at dinner. Although we do not have a store of amino acids per se, we do have an amino acid pool (circulating amino acids in the blood). The half-life of amino acids in this pool vary, but the life of the essential amino acids is at least 4 to 6 hours after digestion.

Protein synthesis goes on constantly and the source of amino acids is the amino acid pool, and not necessarily the proteins you absorb immediately following a meal. Eating replenishes the amino acid pool, and there is enough of a supply that you don't have worry about eating enough of a particular amino acid at each meal. It all works out over the day.

In any developed society it is almost impossible to be protein deficient. Even strict vegetarians (vegans) can easily get all their protein requirements from complex carbohydrates. It is possible if a person consumes only sugar (simple carbohydrates) for extended period of time a protein deficiency may develop. Under normal circumstances a low protein diet is not a health concern. In Third World countries, where there are food shortages, protein deficiency coupled with insufficient calories does occur with some frequency. Digestibility

Humans are very good at digesting protein. We can digest and absorb 70% - 90% of plant protein and 85% - 100% of animal (or human) protein. Remember, we digest human protein all the time -- our own tissues. We're very efficient at reclaiming and recycling our own protein.

Protein Requirements

The World Health Organization (WHO) established a daily protein requirement less than the UK Department of Health and Social Security and US RDA. Using the high and low recommendations together provides an acceptable range for daily protein requirement.Men and women have ideal protein intake ranges based on their ideal body weight: Woman's ideal body weight is 100 pounds for 60 inches in height + 5 pounds for each additional inch over 60 inches. Men's ideal body weight is 106 pounds for 60 inches in height + 6 pounds for each additional inch over 60 inches. Most experts say the daily requirements for protein do not increase for people over their ideal body weight. This is because amino acids are not needed to support fat cells.

Minimum Daily Protein Requirement: WHO recommends 0.45 grams of protein per kilogram of ideal body weight per day. One kilogram equals 2.2046 pounds.

Maximum Daily Protein Requirement: US RDA recommends 0.8 grams of protein per kilogram of ideal body weight per day. The UK Department of Health and Social Security is approximately the same. One kilogram equals 2.2046 pounds.

The average woman in the U.S. is 5'4". Ideal body weight is 120 pounds, or 54.5 kilograms. Ideal protein intake requirement is 24.5 grams to 43.6 grams or 25.5 to 43.7 grams if working endurance training.The average man in the U.S. is 5'8". Ideal body weight is 140 pounds or 63.6 kilograms. Ideal protein intake requirement is 28.6 grams to 50.9 grams or 29.6 to 51 grams if working endurance training.

The protein requirement of the body is at its highest during growth periods in children and adolescents, and in pregnancy. The amount or extra protein required for an athlete or those doing hard physical labor is so minimal as to make this statement almost mythical. Protein ExcessThere is far more risk to your health from a high protein diet than from low protein diet.

 

Proteins have a high amount of nitrogen. When nitrogen is broken down in the liver it creates ammonia. Ammonia is poisonous. The increased level of ammonia in the body is harmful to cells and may decrease athletic performance. High levels of protein intake require increased amount of vitamin B6. It is possible to become deficient in vitamin B6 while using a high protein diet. Calcium loss, which leads to osteoporosis, occurs with high levels of protein intake. Diets high in the sulphur containing amino acids put people at greater risk for cardiovascular disease.

Diets high in protein stress the kidneys, because the kidneys have to get rid of the protein breakdown by-products, which can be very toxic when left to accumulate. Stress on kidneys occurs when more than 2 grams per kilogram of ideal body weight per day is consumed. Diets high in protein are often also high in purines -- this can lead to gouty arthritis.

Source: John McDougall, MD; Harvard School of Public Health; Physicians Committee for Responsible Medicine.