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 scientific studies.

Phenylalanine may help improve memory and learning ability, enhance mood and alertness, and help treat some types of depression.

It has been used to help treat schizophrenia and Parkinson's disease.

Phenylalanine tends to decrease appetite and has been used in treating obesity.

It is claimed to improve pain tolerance associated with pre-menstrual syndrome and migraine headaches.

Recommended Intake:

Phenylalanine has been withdrawn from the U.S. marketplace. The FDA has determined that supplemental phenylalanine may be harmful.

Side Effects, Toxicity and Interactions:

Elevated serum levels of phenylalanine are associated with the genetic condition phenylketonuria. In infants with phenylketonuria, high levels of phenylalanine cause mental retardation and wide systemic damage.

Pregnant women with phenylketonuria who do not remain on a phenylalanine-free diet during pregnancy may deliver an infant with all the signs of phenylketonuria.

Women who are pregnant or breast-feeding should not use phenylalanine supplements.

People who have phenylketonuria, melanoma (pigmented type) or tyrosinemia (type I and II) should not take phenylalanine.

Phenylalanine should not be taken in conjunction with antidepressants belonging to the class of monoamine oxidase (MAO) inhibitors.

Additional Information:

Click here for a list of reputable Web sites with general information on nutrition.


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  2. Lide DR, Frederikse HPR, eds. Handbook of Chemistry and Physics. 75th ed. Boca Raton, FL: CRC Press, Inc.; 1994.

  3. Murray RK, Granner DK, Mayes PA, Rodwell VW. Harper's Biochemistry. 25th ed. Stamford, CT: Appleton & Lange; 2000.

  4. Meisenberg G, Simmons WH. Principles of Medical Biochemistry. Mosby Pub. Co.; 1998.

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  7. Nelson WE, Behrman RE, Kliegman RM, Arvin AM, eds. Nelson Textbook of Pediatrics. 15th ed. Philadelphia: W.B. Saunders Company; 1996:329-334.

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