Phenylalanine

Phenylalanine is an amino acid that is important for building proteins. While it is a "natural" substance, the body does not make its own and it must be obtained from dietary sources or supplements. Phenylalanine supplements are claimed to be useful for treating conditions such as depression and ADHD. It may also be effective in the treatment of vitiligo.

 

What Is Phenylalanine?

Phenylalanine is an essential amino acid, which means that we must obtain it from dietary sources, since the body cannot produce it. Even though it is found in many foods, dietary supplements are also available. These supplements are claimed to be useful for a variety of conditions, such as:
 
(Click Phenylalanine Benefits for more information, including additional uses of the supplement.)
 

How Does It Work?

Phenylalanine is an amino acid that is important for building proteins. It is also used by the body to produce tyrosine, another important amino acid. There are two forms of phenylalanine: L-phenylalanine (the naturally occurring form) and D-phenylalanine (a different form that is not important for human nutrition). Most of the time, the word "phenylalanine" is used to mean just the L-phenylalanine form. Products may contain either or both forms (often, the term "DL-phenylalanine" is used to denote the combination of the two forms).
 

Is It Toxic?

Despite what you may read on the Internet, the amino acid is important for human nutrition (especially for building proteins) and is not usually dangerous for most people, other than those with a rare genetic condition known as phenylketonuria (PKU).
 Because phenylalanine is a component of aspartame (an artificial sweetener), it has been the object of much criticism and is often claimed to be a toxic substance. However, it is necessary for human nutrition and is found in a wide variety of natural foods.
 
(Click Dangers of Phenylalanine for more information.)
 

Is It Effective?

The supplement may be effective for treating vitiligo (a skin condition). It is not known if it is effective for other uses.
 
(Click Does Phenylalanine Work? for more information.)
 

Dosing Information

Although recommendations are available for an adequate dietary intake of phenylalanine, as well as all other essential amino acids, less information is available about a safe and effective dose of the supplements for medicinal purposes. Be sure to follow the specific instructions on the label of your particular product.
 
(Click Phenylalanine Dosage for more information.)
 

Side Effects

Although it is a "natural" product, it can still cause side effects, especially in people with certain medical conditions. In particular, it may cause certain side effects in people with schizophrenia or Parkinson's disease.
 
(Click Phenylalanine Side Effects to learn more, including potentially serious side effects that you should report immediately to your healthcare provider.)
 

Drug Interactions With Phenylalanine

Phenylalanine can interact with a few medications (see Phenylalanine Drug Interactions).
 

Is It Safe?

Some people may be more likely to experience problems with this supplement than others. Therefore, you should talk with your healthcare provider before taking it if you have:
 
  • Phenylketonuria (PKU)
  • Any allergies, including allergies to food, dyes, or preservatives.
     
Also, let your healthcare provider know if you are:
 
Make sure to tell your healthcare provider about all medicines you take, including prescription and non-prescription medicines, vitamins, and herbal supplements.
 
(Click Safety of Phenylalanine for more information, including any available warnings and precautions.)
 

What If I Take an Overdose?

It is not known what exactly to expect from an overdose. If you think you may have taken too much, seek immediate medical attention.
 
(Click Phenylalanine Overdose for more information.)
 

How Should Phenylalanine Be Stored?

Refer to the label of your individual product for information on how best to store it. Keep phenylalanine and all other medications or supplements out of the reach of children.
 
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Written by/reviewed by: Kristi Monson, PharmD; Arthur Schoenstadt, MD
Last reviewed by: Kristi Monson, PharmD;