Nutrition researchers declared many years ago that plant foods can provide adequate protein. But people still ask this question “where do you get your protein?”
Proteins are made of chains of twenty different amino acids. Some amino acids can be made by the body (generally from other amino acids) and therefore we don’t need a dietary source of them. Others—
the essential amino acids (EAAs)—must be supplied by the diet.
Proteins in the human body tend to have a consistent ratio of EAAs. Because the percentage of EAAs in animal products and soybeans are a close match to those in the human body, proteins from
these foods are considered “complete.” Grains, beans and nuts have a lower percentage of at least one essential amino acid, making them “incomplete.”