L-Phenylalanine is an amino acid, which are the building blocks of proteins in your body.

L-Phenylalanine exists in two forms or arrangements; L-phenylalanine and D-phenylalanine. They’re nearly identical but have a slightly different molecular structure. The L-form is found in foods and used to produce proteins in your body, while the D-form can be synthesized for use in certain medical applications.

Your body is unable to produce enough L-phenylalanine on its own, so it’s considered an essential amino acid that must be obtained through your diet and can be found in a wide variety of foods — both plant and animal sources.

In addition to its role in protein production, phenylalanine is used to make other important molecules in your body, several of which send signals between different parts of your body.

L-Phenylalanine has been studied as a treatment for several medical conditions, including skin disorders, depression, and pain.

Your body needs phenylalanine and other amino acids to make proteins, many of which are found in your brain, blood, muscles, internal organs, and virtually everywhere else in your body.

What’s more, L-phenylalanine is crucial for the production of other molecules, including;

  • Tyrosine: This amino acid is produced directly from phenylalanine. It can be used to make new proteins or converted into other molecules on this list.
  • Epinephrine and norepinephrine: When you encounter stress, these molecules are vital for your body’s 'fight or flight' response.
  • Dopamine: This molecule is involved in feelings of pleasure in your brain, as well as forming memories and learning skills.