Evidence Level
D-Aspartic Acid (DAA) has been studied for its potential effects on hormonal profiles and reproductive health. A 2009 study by Topo et al. demonstrated that DAA supplementation led to a significant increase in testosterone levels, though subsequent research has yielded inconsistent results. For instance, Willoughby and Leutholtz (2013) reported no notable changes in testosterone levels among resistance-trained men after DAA supplementation, while Melville et al. (2015) also observed no significant effects on hormonal markers in a group of young, active males.
Recent studies have explored the potential benefits of DAA for specific populations. GamalEl Din et al. (2025) conducted a randomized double-blind placebo-controlled trial with 75 participants and found that DAA, when combined with ubiquinol and zinc, significantly improved sperm motility and testosterone levels in men with idiopathic male infertility. This suggests that DAA may be more effective for individuals with suboptimal hormonal status due to age or lifestyle factors.
In contrast, other studies have reported no significant effects of DAA supplementation on hormonal responses. For example, Płoszczyca et al. (2023) examined the impact of 6g/day DAA on male boxers exposed to hypoxic conditions and found no changes in testosterone or cortisol levels. Similarly, Crewther et al. (2019) observed no significant effects on serum biomarkers associated with the hypothalamic-pituitary-gonadal axis in a group of male climbers.
Overall, while DAA may offer benefits for individuals with subfertile conditions or low testosterone levels, its efficacy appears limited in young, active men with already-optimal hormonal profiles.