D-Aspartic acid is one of two forms of the amino acid Aspartic Acid. Unlike its naturally occurring counterpart, no food offers pure D-Aspartic acid, but rather a blend of both forms (D- and L-).

D-Aspartic acid is able to increase testosterone levels in healthy men according to a recent study, and seems to do so by both neurological and testicular methods which are synergistic.

It also has other notable hormonal effects, as a metabolic by-product of D-Aspartic Acid is a regulator of growth hormone secretion and is intimately involved in Melatonin secretion rates.