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Phenylalanine

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What other names is Phenylalanine known by?

2-amino-3-phenyl-propanoic acid, Acide Alpha-aminohydrocinnamique, Acide Isovalérique de Phénylalanine, Alpha-aminohydrocinnamic Acid, Beta-phenyl-alanine, Bêta-phenyl-alanine, DLPA, D-Phenylalanine, D-Phénylalanine, DL-Phenylalanine, DL-Phénylalanine, D,L-Phenylalanine, D,L-Phénylalanine, Fenilalanina, L-Phenylalanine, L-Phénylalanine, Phenylalanine Ethyl Ester HCl, Phenylalanine Isovaleric Acid, Phenylalanine Methyl Ester HCl.

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

Phenylalanine is used for depression, attention deficit-hyperactivity disorder (ADHD), Parkinson's disease, chronic pain, osteoarthritis, rheumatoid arthritis, alcohol withdrawal symptoms, and a skin disease called vitiligo.

Some people apply it directly to the skin for vitiligo.

Possibly Effective for...

  • A skin condition called vitiligo. Taking L-phenylalanine by mouth in combination with UVA exposure or applying L-phenylalanine to the skin in combination with UVA exposure seems to be effective for treating vitiligo in adults and in children.

Possibly Ineffective for...

  • Attention deficit-hyperactivity disorder (ADHD). Some research suggests that patients with ADHD have lower levels of amino acids such as phenylalanine, so there was hope that providing phenylalanine might treat ADHD. However, taking phenylalanine by mouth does not seem to have any effect on ADHD symptoms.
  • Pain. Taking D-phenylalanine by mouth does not need to reduce pain.

Insufficient Evidence to Rate Effectiveness for...

  • Acupuncture anesthesia. Early research suggests that taking D-phenylalanine by mouth might enhance acupuncture anesthesia while having a tooth pulled. However, it does not seem to improve acupuncture anesthesia for back pain.
  • Alcoholism. Early research suggests that taking a combination of D-phenylalanine, L-glutamine, and L-5-hydroxytryptophan for 40 days can improve some symptoms of alcohol withdrawal.
  • Depression. Limited clinical research performed in the 1980s suggests L-phenylalanine or DL-phenylalanine might be useful for depression. However, this research needs to be confirmed. Taking D-phenylalanine does not appear to improve symptoms of depression.
  • Multiple sclerosis. Early research suggests that using Cari Loder's regiment, which includes L-phenylalanine, lofepramine, and intramuscular vitamin B12 for 24 weeks, does not improve disability in people with multiple sclerosis.
  • Parkinson's disease. Limited research suggests taking one form of phenylalanine (D-phenylalanine) might decrease symptoms of Parkinson's disease. However, taking another form (DL-phenylalanine) does not seem to work.
  • Phenylalanine deficiency. Early research suggests that taking phenylalanine by mouth might improve phenylalanine deficiency in children with tyrosinemia.
  • Arthritis.
  • Other conditions.
More evidence is needed to rate the effectiveness of phenylalanine for these uses.

Natural Medicines Comprehensive Database rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, and Insufficient Evidence to Rate (detailed description of each of the ratings).

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