D-Aspartic acid (DAA) is an amino acid which is produced naturally by the body. It is an alternate form of L-Aspartic Acid, which is one of the 22 amino acids used by the body for protein synthesis. While D-Aspartic Acid is not usually incorporated into protein within the body, it has a number of other functions, and is well known for its role in neurotransmission.
DAA is used as a supplement by men looking to increase testosterone levels and build muscle.
Providing the body with extra DAA may stimulate testosterone production in a number of ways. DAA is the precursor to a molecule called N-methyl-D-aspartate (NMDA). This is a neurotransmitter that stimulates the release of gonadotropin releasing hormone (GnRH) from the hypothalamus, which then stimulates the release of Luteinising Hormone (LH) from the anterior pituitary gland (1). LH then stimulates the production of testosterone by the Leydig cells in the testes. In addition, DAA can be taken up directly by the testes, where it plays a role in upregulating the transport of testosterone precursors into Leydig cells, which is the rate limiting step in testosterone production (2).
Studies have shown this increase in testosterone to cause a significant increase in male fertility and sperm quality. DAA has been shown to have a more significant effect on men with low testosterone levels than those in the normal or high range, for whom, increases in testosterone have been shown to be transient (3). As many people know, a boost in testosterone levels can increase muscle mass and strength whilst decreasing fat mass, boost libido, lift mood and improve focus. Many athletes and bodybuilders use DAA for these reasons.
D-Aspartic Acid Side Effects
While DAA is quite successful in increasing testosterone levels, There has been research in animals that has shown that it can also upregulate the production of an enzyme called aromatase, which is responsible for converting testosterone to oestrogen (4). The effects of oestrogen can counteract those of testosterone and cause side effects like gyno and fat accumulation. The concurrent use of an aromatase/oestrogen inhibitor can prevent these effects and ensure the maximum gains are achieved from the boost in testosterone.
Through boosting the GnRH levels, DAA may also boost the levels of prolactin, which can have a variable effect, but in some men this may cause a decline in testosterone. This is more pronounced at higher doses.
Like any supplement that boosts testosterone, DAA has the potential to cause side effects like acne, increased hair growth, increase in aggresssion and enhanced libido. Some men have also reported increased hunger when using DAA.
DAA has been reported to cause mood swings and depression in some people. This may be due to the conversion of DAA into neurotransmitter NMDA, which can in turn increase levels of an amino acid called homocysteine. This is though to then interact with the NMDA receptor, causing abnormal neurotransmitter release and psychological side effects (5). The levels of homocysteine can be reduced by folic acid or betaine supplementation, and this may reduce these type of side effects in DAA users.
Like many amino acid supplements, people with sensitive stomachs may experience mild discomfort after higher doses of. Taking DAA alongside food can help reduce this symptom.
How Much D-Aspartic Acid Should I Take?
A dose of 2-3g per day is used in most trials. Studies of people using this amount on a long term basis showed no biochemical abnormalities.
Best Time to take D-Aspartic Acid
DAA may be taken at any time of the day, but many people believe that this supplement is best cycled to achieve the best results from the transient testosterone boosts that DAA can provide. A standard dosage regime for DAA is 12 days on, 7 days off.
(1) Pampillo M, Scimonelli T, Bottino MC, Duvilanski BH, Rettori V, Seilicovich A, Lasaga M. The effect of D-aspartate on luteinizing hormone-releasing hormone, alpha-melanocyte-stimulating hormone, GABA and dopamine release. Neuroreport. 2002 Dec 3;13(17):2341-4.
(2) 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.
(3) Gemma D'Aniello, Salvatore Ronsini, Tiziana Notari, Natascia Grieco, Vincenzo Infante, Nicola D'Angel, Fara Mascia, Maria Maddalena Di Fiore, George Fisher, Antimo D'Aniello. D-Aspartate, a Key Element for the Improvement of Sperm Quality. ASM. Vol.2 No.4, October 2012
(4) Lamanna C, Assisi L, Botte V, Di Fiore MM. Department of Zoology, University of Naples 'Federico II', Naples, Italy. Endogenous testicular D-aspartic acid regulates gonadal aromatase activity in boar. J Endocrinol Invest. 2006 Feb;29(2):141-6.
(5) Poddar, R, and S Paul. "Homocysteine-NMDA receptor-mediated activation of extracellular signal-regulated kinase leads to neuronal cell death." Journal of Neurochemistry. 110.3 (2009): 1095-106.