Phenylalanine

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:

 

 

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.