Phenylalanine is an essential amino acid – meaning that the body cannot synthesize it on its own and we must get it from the diet. The primary dietary sources of phenylalanine are high protein foods such as meat, fish, eggs and dairy products. Another significant dietary source for some people may be through consumption of sugar-free products containing the artificial sweetener aspartame (Nutrasweet), which is formed by a combination of phenylalanine with another amino acid – aspartic acid

Amino acids come in two forms, designated as "L-" and "D-" forms. The "L-" form is the naturally occurring form in foods, whereas the D- form is the synthetic variety. When an amino acid is synthesized commercially, there is usually a mixture of the L- and D- forms. Sometimes the D- form is removed, but in the case of phenylalanine, the combination of the two forms is used to take advantage of the unique characteristics of both forms. The combined form of the supplement is known as D, L-phenylalanine or DLPA.

 

DLPA has two distinct fates in the body. The L-form of phenylalanine can be converted in the body to another amino acid – tyrosine. Tyrosine, in turn, can be converted into one of several neurotransmitter molecules (L-dopa, norepinephrine, and epinephrine), each of which have important functions in brain metabolism. The D-form of phenylalanine cannot be converted to tyrosine, but it can be converted to another compound called phenylethylamine (as can the L-form), which may have effects in elevating mood, treating depression and altering pain sensation.

 

Mega-dose intakes of any amino acid are discouraged and phenylalanine is no exception – where nerve damage may result with intakes approaching 2 grams per day. A condition known as phenylketonuria (PKU), in which phenylalanine cannot be broken down, requires individuals to follow a diet low in this amino acid. Do not take DLPA in conjunction with prescription antidepressants. 

 

Like 5-HTP, DLPA may have some benefits for people who may be concerned with possible drug/herb interactions reported for St. John’s wort. Rarely used as a stand-alone supplement, DLPA may be better suited as an ingredient in a larger blend of nutrients/herbs targeting pain/depression and appetite/weight loss.  

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