Phenylalanine (DLPA) Information and Facts

Phenylalanine is an essential amino acid that cannot be produced by the body and thus must be obtained through the diet. Dietary sources of the amino acid are principally derived from animal and vegetable proteins. Vegetables and juices contain small amounts of the free amino acid. The free amino acid is also found in fermented foods such as yogurt and miso. The alternative sweetener aspartame is a dipeptide of L-phenylalanine, as is methyl ester and L-aspartic acid. Phenylalanine is used in different biochemical processes to produce neurotransmitters, dopamine, norepinephrine, and epinephrine.

Phenylalanine can be converted in the body to tyrosine, which in turn is used to synthesize two important neurotransmitters, dopamine and norepinephrine. It is available in three different forms: L-, D- and DL-. The L- form is the most common and the type which is incorporated into the body's proteins. The D- form acts as a painkiller and the DL- as a combination of the two.

Some studies indicate that L-phenylalanine may be helpful for some individuals suffering from depression. It may also be useful when used in connection with vitiligo. There is some evidence that L-phenylalanine may exacerbate tardive dyskinesia in some schizophrenic patients and in some who have used neuroleptic drugs.


L-phenylalanine supplements, as well as DL-phenylalanine (see DL-Phenylalanine) supplements, are available in the nutritional supplement marketplace. Those who use L-phenylalanine supplements typically use 500 milligrams to 1.5 grams daily.