D-Aspartic Acid is taking the supplement world by storm because this testosterone boosting amino acid has been shown to be very safe and effective at raising the body’s natural testosterone levels. It has been shown in studies to boost testosterone by up to 42% in normal healthy males which is astounding considering that it is a totally natural supplement, and very inexpensive.
BUT WHAT IS IT?
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 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).
THE HEAVY SCIENCE
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.