Does Phenylalanine Work?

People considering supplementation with phenylalanine may wonder if it works. While early studies suggest that phenylalanine is effective at treating vitiligo, there is not enough evidence proving that it works to treat other conditions. In addition, phenylalanine is classified as a dietary supplement, not a drug, which means it is not as strictly regulated.

 

Does Phenylalanine Work?

Phenylalanine is an amino acid found in many foods and is also used in dietary supplements. As with most supplements, people use phenylalanine for several different uses. Phenylalanine supplements are sometimes claimed to help with the following conditions:
 

Studies on Phenylalanine

There are three different kinds of phenylalanine:
 
  • L-phenylalanine (the naturally occurring form)
  • D-phenylalanine (which has no nutritional value)
  • DL-phenylalanine (a mixture of both D and L types).
     
Studies suggest that L-phenylalanine may work to treat vitiligo. It is either taken by mouth or applied to the skin in combination with UVA light exposure.
 
Early studies suggest that phenylalanine probably does not work for ADHD or for pain.
 
There is not enough evidence proving one way or another that phenylalanine is effective for other uses.
 

Final Thoughts on the Effectiveness of Phenylalanine

Phenylalanine may work for vitiligo, although more research is necessary to confirm early findings.
 There is not enough evidence suggesting that it is effective for other uses. It is important to remember than phenylalanine is classified as a dietary supplement, not a drug, and is, therefore, less strictly regulated than drugs.
 
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Written by/reviewed by: Kristi Monson, PharmD; Arthur Schoenstadt, MD
Last reviewed by: Kristi Monson, PharmD;