Phenylalanine is an aromatic amino acid that is classified as essential. From a nutritional standpoint, phenylalanine must be obtained (exclusively) from either dietary or supplementary sources. Adequate intake is critical, as it is responsible for tasks related to the central nervous system. This amino acid may impact the neurotransmitters responsible for mood, pain, appetite, and memory. [1]

Phenylalanine acts as a precursor to the amino acid tyrosine. The conversion of phenylalanine to tyrosine takes place by means of the enzyme L-phenylalanine hydroxylase. Upon this conversion, the body uses tyrosine to synthesize two critical neurotransmitters/catecholamines - dopamine and norepinephrine. Studies have shown that these two agents assist the body by improving organ perfustion, as well as oxygen delivery and consumption. [2] The release of both dopamine and norepinephrine by the adrenal glands is considerably increased in times of elevated stress; a subsequent process requiring adequate amounts of usable phenylalanine.

Phenylalanine exists in three different chemical forms; the L-, D-, and DL- forms. The L- (LPA) form is the most common form of phenylalanine. being the natural amino acid found in bodily proteins. The D- (DPA) form is the L- form’s mirror image and is synthesized in a laboratory. DL-phenylalanine (DLPA) is a 50:50 combination of the two previous forms. This is the most common form of phenylalanine used in dietary supplements because both forms wield specific physiological processes.