Amino acids are the building blocks of proteins.
A total of 20 different kinds of amino acids form proteins. The kinds of amino acids determine the shape of the proteins formed. Commonly recognized amino acids include glutamine, glycine, phenylalanine, tryptophan, and valine. Three of those — phenylalanine, tryptophan, and valine — are essential amino acids for humans; the others are isoleucine, leucine, lysine, methionine, and threonine. The essential amino acids cannot be synthesized by the body; instead, they must be ingested through food.
They are essential to nearly every bodily function. Every chemical reaction that takes place in your body depends on amino acids and the proteins that they build.