What Are Amino Acids?

Amino Acid is any of about twenty (20) complex substances that form the building blocks of protein. All amino acids contain nitrogen, carbon, hydrogen, and oxygen. Some of them contain sulfur as well. When food is digested, the protein in it is broken down into amino acids, which are then put together again in various combinations to make the particular kinds of protein that enter into human muscle, red blood cells, and other body tissue. Any amino acids left over are broken down further to supply energy. 

Some amino acids can be manufactured by the body (chiefly in the liver) if they are not supplied in the diet. However, there are eight (8) amino acids that the body needs but cannot manufacture. They must be obtained from protein in the diet. These so-called essential amino acids are isoleucine, leucine, lysine, methionine, phenylalanine, threonine, trypthophan, and valine. Arginine and histidine are included in this list by some authorities. Alanine, cystine, glycine, proline, serine, tyrosine, and other amino acids can be manufactured by the body. 

A given protein food does not necessarily contain all of the essential amino acids. Gelatin, for example, is pure protein but lacks the essential amino acid tryptophan. In order to ensure an adequate intake of all the essential amino acids, the diet should include a variety of animal protein foods such as meat, fish, poultry, eggs, milk, and cheese.