AI’s D-Aspartic Acid is a single-ingredient test-booster which may be moderately effective in the short-term.
D-Aspartic Acid is an amino acid that acts as a precursor to N-Methyl-D-aspartic acid (NMDA), which takes on a similar role to the excitatory neurotransmitter glutamic acid. In rats, D-Aspartic acid supplementation was found to increase testosterone significantly. For this reason, it has become a popular additive in workout supplements. Out of the three human studies done specifically to test the effect of D-Aspartic Acid on testosterone, two have shown a significant increase in testosterone levels.
One study, the subjects of which were infertile men (low testosterone) showed a significant increase in tesosterone after 90 days of supplementation. Another study, this time on men with normal test levels, found a significant increase in testosterone after just 12 days. However, a 2013 study found that athletes who supplemented with D-Aspartic Acid for 28 days showed no difference in testosterone levels. It is possible that D-Aspartic Acid did not increase testosterone in athletes because their testosterone levels were already maximized.
Since the 12 day study showed significant increase but the 28 day study showed no such results. This study did however show elevated levels of D-aspartate oxidase, the enzyme that breaks down D-Aspartic Acid, indicating that prolonged use causes ‘negative feedback’ which eventually returns testosterone to normal.
Ultimately, D-Aspartic Acid appears effective for increasing testosterone in individuals with low testosterone levels, and may be effective in the short term for individuals with normal testosterone levels as well. Recommended doses range from 2.5-3g of DAA. A full serving of AI’s DAA contains the upper end of this range, 3 grams.
THE BOTTOM LINE:
D-Aspartic Acid can increase testosterone in the short-term, but the effects are likely to fade within a few weeks. That being said, it is a much safer alternative to increasing testosterone than pro-hormones (although much less potent as well). At about 24 cents per serving AI Sports Nutrition’s DAA is the least expensive DAA supplement we’ve reviewed.
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- D’Aniello, Autimo, Anna Di Cosmo, Carlo Di Cristo, Lucio Annunziato, Leonard Petrucelli, and George Fisher. “Involvement of D-Aspartic Acid in the Synthesis of Testosterone in Rat Testes.” Life Sciences 59.2 (1996): 97-104.
- Willoughby, Darryn S., and Brian Leutholtz. “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 (2013): 803-810.
- Topo, Enza, et al. “The role and molecular mechanism of D-aspartic acid in the release and synthesis of LH and testosterone in humans and rats.” Reprod Biol Endocrinol 7 (2009): 120.