Phenylalanine

Phenylalanine is an amino acid, a “building block” of protein. There are three forms of phenylalanine: D-phenylalanine, L-phenylalanine, and the mix made in the laboratory called DL-phenylalanine.

D-phenylalanine is not an essential amino acid. Its role in the body is not currently understood. L-phenylalanine is an essential amino acid. It is the only form of phenylalanine found in proteins. Major dietary sources of L-phenylalanine include meat, fish, eggs, cheese, and milk.

Phenylalanine is most commonly used for a skin disorder that causes white patches to develop on the skin (vitiligo). It is also used for aging skin, pain, obesity, and many other conditions.