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Other name(s):

a-amino-b-phenyl-propionic acid

Unsubstantiated claims

Please note that this section reports on claims that have not yet been substantiated through studies.

Phenylalanine may improve memory and learning ability. It may also enhance mood and alertness. It’s also said to help treat some types of depression. It’s also been used to help treat schizophrenia and Parkinson's disease.

Phenylalanine tends to decrease appetite. It’s been used to treat obesity.

It’s also claimed to boost pain tolerance in premenstrual syndrome (PMS) and migraine headaches.

Recommended intake

Phenylalanine has been taken off of the market in the U.S. The U.S. Food and Drug Administration (FDA) says that the supplement may be harmful.

Side effects, toxicity, and interactions

High levels of phenylalanine are linked with the genetic issue phenylketonuria. In infants with this issue, high levels of phenylalanine cause intellectual problems. It can also lead to seizures and delays in development.

Pregnant women with the condition who don’t stay on a phenylalanine-free diet during pregnancy may give birth to a baby with signs of phenylketonuria.

Women who are pregnant or breastfeeding shouldn’t use phenylalanine supplements.

People who have phenylketonuria, melanoma (pigmented type), or tyrosinemia (type I and II) shouldn’t take phenylalanine.

You also shouldn’t take it if you take monoamine oxidase inhibitors (MAOIs).

Online Medical Reviewer: Poulson, Brittany, RD, CDE
Online Medical Reviewer: Wilkins, Joanna, R.D., C.D.
Date Last Reviewed: 8/1/2016