Phenylalanine Unit Converter

Phenylalanine is an essential amino acid, meaning your body cannot make it and it must come from the foods you eat. It is one of the building blocks of protein and plays a key role in producing important brain chemicals.

In the body, phenylalanine is converted into another amino acid called tyrosine by an enzyme in the liver (phenylalanine hydroxylase). Tyrosine is then used to produce the neurotransmitters dopamine, norepinephrine, and epinephrine, as well as thyroid hormones and the pigment melanin.

A plasma phenylalanine test measures how much of this amino acid is circulating in your blood. Abnormal levels can signal problems with protein metabolism or specific genetic conditions.

Phenylalanine comes entirely from the diet because the body cannot produce it. It is found in high-protein foods such as meat, fish, eggs, dairy products, nuts, soybeans, and legumes, as well as in foods and drinks containing the artificial sweetener aspartame.