What is it?
For starters, aspartic acid is one of the 20 common amino acids falling into the grouping of one of two acidic amino acids. This basically means that in a neutral pH the carboxyl group (-COOH) side chain possesses acidic properties, allowing it to release and receive hydrogen ions to bind to the open oxygen molecule. As a hydrophilic molecule, it can dissolve easily in water. In regards to essentialness, Aspartic acid is a non-essential amino acid because aspartic acid can actually be synthesized by the human body during the citric acid cycle from a transamination of oxaloacetate3.
Aspartic acid exists in two configurations, L- and D-, which differ by the orientation of the amino group (NH2) with respect to the –COOH. D-Aspartic Acid (D-Asp) is an endogenous amino acid that is utilized during embryonic and early postnatal stages for development of the nervous system as well as in the neuroendocrine system1,5. It is linked to neurotransmission based on its location during development in the axon terminals and synaptic vesicles5. Now, from a research standpoint, D-Asp human research is still up and coming but is a topic of interest because of its links to luteinizing hormone (LH) and testosterone production. For this reason, the supplement company has become very intrigued by the ingredient and has marketed it as a testosterone boosting product. While the research may be emerging, there have been a few studies which outline how D-Asp works in the body and how it may yield testosterone boosting effects.
Mode of action
D-Asp is located in the pituitary gland and in the testis, where it is synthesized by D-Aspartate racemase5. Its production is mediated by secondary molecules: cGMP in the pituitary gland and cAMP in the testis5. Research for this process has mostly taken place in rats where it was discovered that at birth the testes, more specifically the Leydig cells, have high concentrations of D-Asp5. For this reason, D-Asp has been linked to spermatogenesis because of its eliciting release of LH and, consequently, testosterone5,2. This neuromodulation and biosynthesis of sex hormones by D-Asp has different effects in men and women. In men, the higher concentrations of D-Asp lead to increased motility of semen, while in women, D-Asp reduces in the follicular fluid, diminishes oocyte quality, and lowers the level of fertilization as women age5,2.
Moving on into supplementation, there is one major study that has found positive results in males taking D-Asp which will increase release of LH, thus having positive on testosterone release5. In order for D-Asp to be effectively used, it should be in the form of sodium-D-Aspartate (Na-D-Asp)5. When taken at a dose of about 3g for 12 consecutive days, a 33% increase in LH and a 42% increase of testosterone were reported5. Also, after three days of stopping treatment, both LH and testosterone continued to be at higher levels, showing that an accumulation effect takes place5.
In contrast, there is one study that shows that resistance trained men who have normal testosterone ranges actually seem to decrease the amounts of free and total testosterone when using 6g/d of D-Asp for 14 days4. Please note that this study also did not use the Na-D-Asp form, however it can still be deduced that the accumulation effect noted in the previous study will alter how D-Asp is handled in the body. Remember, the body always tries its best to maintain homeostasis, and something highly regulated in the body is hormone release. If D-Asp is causing an increase in LH, then the negative feedback mechanisms of the body are going to produce an anti-effect to start to lower those levels immediately.
To combat this issue of an accumulation of D-Asp and consequential decrease in testosterone, cycling D-Asp is a must. There are many ways to cycle testosterone boosting supplements, but something to consider is that after 14 consecutive days using D-Asp, a drop in LH and testosterone can occur. Some researchers recommend doing a two day on, one day off since even 3 days off of D-Asp will still stimulate LH5. Keep in mind though that since there is an accumulation effect, one cannot simply run D-Asp supplementation year-round, there needs to be a time when it is cycled off and reintroduced or there will be little to no effect, or could even decrease levels already present.
Food for thought
D-Asp has been shown to elicit positive increases in LH and testosterone in men who have low to normal testosterone levels5. While there are not many studies currently showing the effects D-Asp has on humans in general, there is a lot of optimism in this amino acid and how it can positively affect testosterone levels. Many products are on the market today raving effects D-Asp has on testosterone, but use these with caution as they do affect hormone levels, make sure to follow dosing protocols, and remember to cycle.
Article By: Rachel Shmagranoff
Disclaimer
All programs and articles provided are intellectual property of James Shmagranoff. No copies or redistribution of these is allowed without express permission from James Shmagranoff. James Shmagranoff is not a doctor and nothing contained within this article is to be taken as medical advice. Always follow the directions of your medical practitioner.
Sources
1D’aniello, A., 2006. D-aspartic acid: An endogenous amino acid with an important neuroendocrine role. Brain research Reviews, 215-234.
2D’Aniello, G. Ronsini, S., Notari, T., Grieco, N., Infante, V., D’Angelo, N., Mascia, F., Maddalena Di Fiore, M., Fisher, G. & D’Aniello, A. (2012). D-Aspartate, a key element for the improvement of sperm quality. Advances in Sexual Medicine, 2, 47-53. http://file.scirp.org/pdf/ASM20120400001_62630923.pdf
3Garrett, C.M. (2013). Biochemistry (Fifth Ed.) Belmont, California:Brooks/Cole. pp78-84, 863
4Melville, G., Siegler, J., & Marshall, P. (2015). Three and six grams supplementation of d-aspartic acid in resistance trained men. Journal of the International Society of Sports Medicine, 12 (15).
5Topo, E., Soricelli, A., D’Aniello, A., Ronsini, S., & D’Aniello, G. (2009). The role and molecular mechanism of D-aspartic acid in the release and synthesis of LH and testosterone in humans and rats. Reproductive Biology and Endocrinology, 7 (120).
Comments