Written by Ben Bunting: BA(Hons), PGCert.
Male fertility has been a scorching topic throughout the evolution of research. Globally, almost 48.5 million couples experience the distressing condition of infertility.
Astonishingly, males are approximated to be solely responsible for over 20-30% of infertility cases. 
Male fertility is directly related to several hormones in the body, notably testosterone.
Fertility is directly related to the health of sperms. The more (in number) and better-quality sperms your body produces, the chances are that you'll get your partner pregnant.
Testosterone and other hormones of the male reproductive physiology, like luteinizing hormone (LH), play a role in the normal development and functioning of sperms.
The high prevalence of male infertility and the associated problems have pushed scientists to find various methods to improve this condition.
One of the ways that are continuously being explored is dietary modification.
Several nutritional supplements are thought to increase testosterone and other reproductive hormones in men, enhancing fertility.
One of these supplements claimed to improve testosterone levels and/or male fertility is D-aspartic acid.
This article will highlight what D-aspartic acid is and its role and benefit in the male reproductive system.
We shall cover the following key points:
- What's D-AA?
- Erectile dysfunction
- D-AA and male fertility
- How to use D-AA
- Is it banned?
What is D-aspartate?
D-aspartic acid (DAA) is one of the amino acids among the many in our body, the smallest structural unit of the protein.
Aspartic acid is found in two forms, D and L. They are also known as 'right-handed' and 'left-handed,' respectively.
D-aspartic acid is found primarily in the central nervous system (CNS) and reproductive system.
Its role appears to be modulating various CNS functions and regulating hormones. It is also found in human semen and spermatozoa, implicating its role in male fertility.
Erectile dysfunction (ED) refers to the inability to get or maintain an erection despite sexual stimulus. ED is a fairly common condition affecting around 30 million of the male population in the US alone . It primarily affects males over 50 years of age.
Many factors are known to cause ED. Firstly, some men have decreased testosterone (male sex hormone), leading to decreased libido and problems with erection.
Secondly, if you are experiencing an underlying condition like diabetes or hypertension, it can cause ED.
These conditions tend to decrease blood flow (by narrowing blood vessels) through the penile tissue, which is responsible for normal erection. Thirdly, if you're experiencing
conditions like depression or anxiety (neurological disorders), you can have a psychogenic ED.
D-Aspartic acid and Erections
As mentioned above, D-aspartic acid is found in various areas of the brain as well as in the human seminal fluid and sperms. This idea has led to the theory of dietary D-aspartic acid's potential benefit in improving erection.
Current studies provide a mixed view on D-aspartic acid supplementation's effects on promoting erection.
Some studies support the argument that D-aspartic acid mildly increases testosterone levels, while other studies show no direct connection between consuming d-aspartic and testosterone levels. 
One study concluded that 3 grams of D-aspartic acid per day for two weeks showed no increase in testosterone levels in athletic males.
On the other hand, d-aspartic acid has demonstrated an increase in total testosterone levels in non-athletic males. Moreover, the long-term consequences of DAA are not yet known.
Another study showed a positive relation between DAA and erection. DAA was injected into specific areas of the brain of male rats. 
The study indicated that this injection caused rats to get an erection and yawn. The erection was caused by an increase in nitric oxide in the brain.
To sum up, there is a need to conduct more research on DAA'sDAA's potential for treating erectile dysfunction.
D-aspartate acid and male fertility
Despite the inconclusive data regarding the relation between D-aspartic acid, research shows a positive effect of DAA on semen quality.
One study on 30 sub-fertile patients concludes that DAA improves sperm concentration 2-fold. It also suggests that sperm motility or the ability of sperms to move also increased after DAA supplementation. 
Furthermore, 27% of the patients in the study successfully got their partners pregnant. These results show that D-aspartic acid can be used solely or as an adjunctive supplement for the treatment of male infertility.
How to use D-aspartic acid?
D-aspartic acid is a water-soluble amino acid and can be taken orally with or without food. For adequate effects, a dose of 3 grams once or twice per day. 
You can also take DAA half an hour before your workout. Taking DAA before going to bed is beneficial as a relaxed body is more efficient in absorption.
Summing up, taking D-aspartic anytime around the day won't affect you. You should avoid taking it with large meals (heavy fast-food meals, etc.) as the bulky food might physically lower its absorption.
Is it banned?
The answer is NO! D-aspartic acid mimics one of the natural amino acids present in your body. DAA is considered to be widely safe.
A study assessing the effects of 3 and 6 grams showed no adverse effects of supplementation with DAA. Moreover, there were no safety concerns or contraindications associated with the use of D-aspartic acid. 
Some research subjects taking D-aspartic acids reported mild irritability, headaches, and nervousness. However, these symptoms were very unspecific, providing no definitive risk warning against the use of DAA. 
Most studies consider DAA as a safe-to-use supplement; however, there is still a need for a large-scale study to assess the effects of DAA in different populations and age groups.
D-aspartic acid is an amino acid found in the brain and testes of humans. It is associated with the release of testosterone and luteinizing hormone (LH) along with several other functions in the body.
The oral use of DAA correlates with improving fertility. However, there is no definitive correlation between DAA use and increased testosterone levels.
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- National Institute of Diabetes and Digestive and Kidney Diseases. (n.d.). Definition & Facts for Erectile Dysfunction | NIDDK. [online] Available at: https://www.niddk.nih.gov/health-information/urologic-diseases/erectile-dysfunction/definition-facts.
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- Scirp.org. (2012). D-Aspartate, a Key Element for the Improvement of Sperm Quality - Advances in Sexual Medicine - SCIRP. [online] Available at: https://www.scirp.org/journal/paperinforcitation.aspx?paperid=24016 [Accessed 15 Mar. 2022].
- The effects of d-aspartic acid supplementation in resistance-trained men over a three month training period: A randomised controlled trial Geoffrey W. Melville , Jason C. Siegler, Paul W. M. Marshall Published: August 25, 2017 https://doi.org/10.1371/journal.pone.0182630
- Melville, G.W., Siegler, J.C. and Marshall, P.W. (2015). Three and six grams supplementation of d-aspartic acid in resistance trained men. Journal of the International Society of Sports Nutrition, [online] 12, p.15. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4384294/.
- Willoughby, D.S. and Leutholtz, B. (2013). d-Aspartic acid supplementation combined with 28 days of heavy resistance training has no effect on body composition, muscle strength, and serum hormones associated with the hypothalamo-pituitary-gonadal axis in resistance-trained men. Nutrition Research, 33(10), pp.803–810. Available at: https://pubmed.ncbi.nlm.nih.gov/24074738/