Protein combining

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Protein combining (also protein complementing) is the theory that vegetarians must eat foods such as beans and rice together, or at least on the same day, so the different amino acids in the foods combine to form a complete protein, containing all nine essential amino acids necessary for human growth and maintenance.

Contents 1 Source of the theory 2 The contemporary view 3 Protein quality 4 References

[edit] Source of the theory

The protein combining theory was based on interpretation of studies performed in the early 1900s on the growth of rats. The theory entered popular consciousness with the publication of Frances Moore Lappé's 1971 bestseller Diet for a Small Planet. In later editions of Diet for a Small Planet, beginning in 1981, Lappé changed her position on protein combining. In the tenth anniversary edition of Diet for a Small Planet, Lappé wrote:

"In 1971 I stressed protein complementarity because I assumed that the only way to get enough protein ... was to create a protein as usable by the body as animal protein. In combating the myth that meat is the only way to get high-quality protein, I reinforced another myth. I gave the impression that in order to get enough protein without meat, considerable care was needed in choosing foods. Actually, it is much easier than I thought.

"With three important exceptions, there is little danger of protein deficiency in a plant food diet. The exceptions are diets very heavily dependent on [1] fruit or on [2] some tubers, such as sweet potatoes or cassava, or on [3] junk food (refined flours, sugars, and fat). Fortunately, relatively few people in the world try to survive on diets in which these foods are virtually the sole source of calories. In all other diets, if people are getting enough calories, they are virtually certain of getting enough protein."^[1]

[edit] The contemporary view

Some of the earliest research to refute the idea that proteins must be combined was performed in the 1950s by William Rose, but the results of that research did not enter the popular press until 1983 with the debut book of John McDougall, M.D., The McDougall Plan (ISBN 0-8329-0392-2). In that volume, McDougall shows the requirements for each individual amino acid as determined by Rose and then shows how each is easily met by a single unrefined plant food by itself, such as corn, brown rice, oatmeal, wheat flour, potatoes, broccoli, and pumpkin. McDougall writes:

"Many people believe that animal foods contain protein that is superior in quality to the protein found in plants. This is a misconception dating back to 1914, when Osborn and Mendel studied the protein requirements of laboratory rats. (11) .... Based on these early rat experiments the amino acid pattern found in animal products was declared to be the standard by which to compare the amino acid pattern of vegetable foods.... It has since been shown that the initial premise that animal products supplied the most ideal protein pattern for humans, as it did for rats, was incorrect. Therefore, the idea that vegetable foods were deficient in certain amino acids for our needs was inappropriately based on a standard diet ideal for rats. At that early time no one knew the actual protein or amino acid requirements for humans."^[2]

More recently, McDougall has challenged the American Heart Association for perpetuating the idea that protein combining is necessary without providing any evidence that that is the case.^[3]

[edit] Protein quality

Different protein sources have different biological values, compared against the nutritional standard of the egg.^[4]

[edit] References