Essential amino acids cannot be synthesized by the body and must be obtained from food. There are nine essential amino acids: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine.

Nonessential amino acids can be synthesized by the body and do not need to be obtained from food. There are eleven nonessential amino acids: alanine, asparagine, aspartic acid, cysteine, glutamic acid, glutamine, glycine, proline, serine, tyrosine, and arginine.