Phenylalanine (abbreviated as Phe or F)is an a-amino acid. It is an essential amino acid and cannot be made by the body.

The genetic disorder phenylketonuria (PKU) is the inability to metabolize phenylalanine. Individuals with this disorder are known as "phenylketonurics" and must abstain from consumption of phenylalanine.

A non food source of phenylalanine is the artificial sweetener aspartame. It is metabolized by the body into several chemical byproducts including phenylalanine.  Accordingly, all products in Australia, the U.S. and Canada that contain aspartame must be labeled: "Phenylketonurics: Contains phenylalanine."

References

IUPAC-IUBMB Joint Commission on Biochemical Nomenclature. Nomenclature and Symbolism for Amino Acids and Peptides. Recommendations on Organic & Biochemical Nomenclature, Symbols & Terminology etc. Retrieved on 2007-05-17.