Aspartic acid is one of the 20 common amino acids that are used by the body to construct proteins and is considered to be non-essential since it can be made from oxaloactetate, an intermediate of the tricarboxylic acid cycle. There are two isomers of aspartic acid, the L-isomer and the D-isomer. Only the L-isomer is used in proteins while the d-isomer is used as a neurotransmitter as d-aspartic acid and n-methyl-d-aspartic acid. D-aspartic acid is known to stimulate the NMDA receptor but to a lesser extent than glutamine. Activation of the NMDA receptor also requires the binding of glycine (a stimulatory amino acid) but recent evidence has shown that D-serine is even more potent in this regard.
More recently, D-aspartic acid has been shown to have some intriguing effects in several animal species and humans. D-aspartic acid has been shown to enhance gonadotropin releasing hormone release from the hypothalamus as well as growth hormone and luteinizing hormone release from the pituitary (1,2). Sodium D-aspartic acid has also been shown to directly increase testosterone production by the testes (3,4,5). So, not only does d-aspartic acid cause the release of more testosterone but also the production of more testosterone. D-aspartic acid does this by increasing the levels of steroidogenic acute regulatory (StAR) protein (6).
StAR plays a critical role in the production of steroid hormones in the testes and adrenals. In fact, StAR mediates the rate-limiting step in steroid hormone production, the importation of cholesterol into the mitochondria (6,7). All steroid hormones are manufactured from cholesterol in the mitochondria and if cholesterol doesn’t get into the mitochondria, then steroid hormones, and more specifically, testosterone does not get produced. D-aspartic acid increases StAR which increases cholesterol entry into the mitochondria which results in increased testosterone production.
A study dosed 3.12 grams of sodium-d-aspartate to adult males (27 to 37 yrs old) for 12 days resulting in a 42% increase in average testosterone levels (1). These may not seem like huge increases in testosterone but these are controlled, scientific results in normal healthy men. Evidence exists in the literature that shows D-aspartic acid to be more effective at increasing LH levels in animals that have been castrated suggesting that D-aspartic acid may be even more effective in hypogonadal males or those whose natural production may be suppressed following a steroid cycle.
Of the mind and muscle sponsors, one product seems to meet the criteria of a great D-aspartic acid supplement. Testosterone Conversion Factor-1 (TCF-1), a product from Primordial Performance, delivers the exact ingredient, in the exact dosage used in the human study mentioned above. As a grape flavored oral liquid, this product should be worthy choice for anyone wanting to explore the benefits of d-aspartic acid.
- D’Aniello A. D-Aspartic acid: an endogenous amino acid with an important neuroendocrine role. Brain Res Rev. 2007 Feb;53(2):215-34.
- Pinilla L, Tena-Sempere M, Aguilar E. Role of excitatory amino acid pathways in control of gonadotrophin secretion in adult female rats sterilized by neonatal administration of oestradiol or testosterone. J Reprod Fertil. 1998 May;113(1):53-9.
- Topo E, Soricelli A, D’Aniello A, Ronsini S, D’Aniello G. The role and molecular mechanism of D-aspartic acid in the release and synthesis of LH and testosterone in humans and rats. Reprod Biol Endocrinol. 2009 Oct 27;7:120.
- D’Aniello A, Di Fiore MM, D’Aniello G, Colin FE, Lewis G, Setchell BP. Secretion of D-aspartic acid by the rat testis and its role in endocrinology of the testis and spermatogenesis. FEBS Lett. 1998 Sep 25;436(1):23-7.
- D’Aniello A, Di Cosmo A, Di Cristo C, Annunziato L, Petrucelli L, Fisher G. Involvement of D-aspartic acid in the synthesis of testosterone in rat testes. Life Sci. 1996;59(2):97-104.
- Nagata Y, Homma H, Matsumoto M, Imai K. Stimulation of steroidogenic acute regulatory protein (StAR) gene expression by D-aspartate in rat Leydig cells. FEBS Lett. 1999 Jul 9;454(3):317-20.
- Arakane F, King SR, Du Y, Kallen CB, Walsh LP, Watari H, Stocco DM, Strauss JF 3rd. Phosphorylation of steroidogenic acute regulatory protein (StAR) modulates its steroidogenic activity. J Biol Chem. 1997 Dec 19;272(51):32656-62.