D-aspartic acid was the substance believed to be totally groundbreaking when it comes to its impact on secretion of hormones such as testosterone. When D-aspartic acid dietary supplements for athletes appeared on the market, it has introduced some confusion, for suddenly we all gained access to a safe and effective way to increase secretion of androgens, which - as underlined and emphasized by manufacturers - had its confirmation in scientific studies. Unfortunately, recent experiments with this substance do not inspire great optimism.
What is D-aspartic acid?
D-aspartic acid (known as DAA) is an amino acid naturally occurring in the body and present in certain amounts in food. This compound is the enantiomer (or mirror reflection) of L-aspartic acid - an endogenous amino acid which builds protein. Thanks to its different configuration, DAA also has a different biological properties than the L-aspartic acid.
What do we know about DAA's influence on the organism?
D-aspartic acid is synthesised and metabolised in your body and has quite an important and broad role. Although, it is not a building block of protein itself (although it is found in articular cartilage, and in cell membranes of red blood cells, and may be accumulated in the brain, which is not necessarily a good thing), it takes an active part in many biochemical processes acting for example as a neurotransmitter. In this article I will mainly describe its effects on secretion of sex hormones, gonadotropins and activity of selected enzymes involved in metabolism of these hormones.
Its influence on hypophysis
It has been confirmed in studies that DAA affects all the pituitary, hypothalamus and directly the gonads. Within the areas of the brain involved in the production of gonadotropins, d-aspartic acid increases the release of LH; one study showed an increase in the production of this hormone by 30 - 60%. It is worth noting that LH is a factor stimulating testicles to synthesize testosterone resulting in its increased level. This effect was also observed in the study, but I will elaborate on it in a moment. You should, however, remember that some research was also observed that the DAA increases secretion of growth hormone (beneficial effects) and prolactin (this has adverse effects).
Its influence on gonads
The impact of DAA on the Leydig cells in the testes is extremely interesting. It appears that the amino acid may affect the activity of StAR protein involved in the transport of cholesterol at the cellular level. Availability of cholesterol can be a limiting factor in the production of testosterone. D-aspartic acid, owing to the above mentioned mechanism, may thereby increase the rate of synthesis of this hormone. And there is evidence that this is what happens. One study conducted on healthy volunteers was observed that after 12 days of supplementation with DAA at a dose of 3 g per day there was increase in testosterone level by an average of 42%! This is spectacular considering that we are talking about a dietary supplement and not a pharmaceutical composition.
Limitation of the study
The said study has just one limitation: it has been conducted on people with an average activity (while previous studies related to either animals or men with infertility). Supplements containing DAA, however, are usually recommended for physically active people, who have higher levels of testosterone than non-training individuals. So, an experiment with athletes ought to be conducted. Until recently we lacked data on which we could base, but some time ago two interesting attempts tried to verify the effect of supplementation of d-aspartic acid on hormone levels among people burdened with physical effort.
DAA in sports
The first interesting study, which is worth noting is the study conducted by researchers at the Baylor University with the participation of young, physically active men. Participants were given 3g of D-aspartic acid per day for 4 weeks. The authors of the project evaluated the effect of supplementation on testosterone, gonadotropin hormone and estradiol, as well as the impact on body composition and exercise capacity (for strength training). What happened? Well, DAA supplementation did not bring any benefits in relation to these aspects. Volunteers receiving d-aspartic acid observed the same "benefit" as the participants receiving placebo.