Protein isn't just found in meat, eggs and milk. There's also protein in vegetables, beans, legumes, and grains. However, the protein in these foods is not considered "complete" because it lacks one or more of the essential amino acids. Generally speaking, proteins from vegetable sources are lower in quality and that's the reason bodybuilders eat so many proteins from animal sources. The complete proteins are those that come from animal sources such as eggs, milk and meat.
Many grains and legumes contain substantial amounts of protein, but none provide the full array of essential amino acids. Beans, for example, are very high in protein with about 15 grams per cup. However, they are missing the essential amino acid Methionine. Grains are lacking the essential amino acid Lysine. It's been frequently pointed out that combining two incomplete sources of vegetable protein such as rice and beans provides you with the full complement of essential amino acids. This may be true, but there's a decided difference between simply meeting your minimum amino acid requirements for health and consuming the optimal quality of protein for building muscle. Combining complementary vegetable sources of protein will help you maintain your health, but it probably doesn't cut it for the serious trainee or bodybuilder.
There are many different methods of determining protein quality, including biological value, protein efficiency ratio, chemical score, and protein digestibility corrected amino acid score. If you've ever seen advertisements for protein powders and supplements, you've no doubt heard of one or more of these measures of protein quality. In fact, protein quality terminology is frequently bandied about to persuade you to buy certain types of protein powders.
Was this article helpful?