Essential Amino Acids
Amino acids are organic compounds which contain both an amino group and a carboxyl group. According to Tillery, et al., the human body can synthesize all of the amino acids necessary to build proteins except for the ten called the "essential amino acids", indicated by asterisks in the amino acid illustrations. An adequate diet must contain these essential amino acids. Typically, they are supplied by meat and dairy products, but if those are not consumed, some care must be applied to ensuring an adequate supply. They can be supplied by a combination of cereal grains (wheat, corn, rice, etc.) and legumes (beans,peanuts, etc.). Tillery points out that a number of popular ethnic foods involve such a combination, so that in a single dish, one might hope to get the ten essential amino acids. Mexican corn and beans, Japanese rice and soybeans, and Cajun red beans and rice are examples of such fortuitous combinations.
The University of Arizona's Biology Project gives the following summary:"The 10 amino acids that we can produce are alanine, asparagine, aspartic acid, cysteine, glutamic acid, glutamine, glycine, proline, serine and tyrosine. Tyrosine is produced from phenylalanine, so if the diet is deficient in phenylalanine, tyrosine will be required as well. The essential amino acids (that we cannot produce internally) are arginine (required for the young, but not for adults), histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. These amino acids are required in the diet. Plants, of course, must be able to make all the amino acids. Humans, on the other hand, do not have all the the enzymes required for the biosynthesis of all of the amino acids."
The failure to obtain enough of even 1 of the 10 essential amino acids has serious health implications and can result in degradation of the body's proteins. Muscle and other protein structures may be dismantled to obtain the one amino acid that is needed. "Unlike fat and starch, the human body does not store excess amino acids for later use—the amino acids must be in the food every day."(Biology Project)
Shipman, Wilson and Todd
Tillery, Enger and Ross
University of Arizona