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4 peer-reviewed studies
What the evidence says
Most D-Aspartic Acid studies are mechanism or observational rather than RCTs that measure a clinical effect — keep findings provisional.
Most evidence is from medium-quality randomised trials published 2013–2025 with a typical study size of 22 participants.
Based on 4 studies · 4 RCTs · 22 total participants
Confidence
ModerateBy outcome
1 study in the last 5 years
A randomized trial (n=22 resistance-trained men) found D-aspartic acid produced NO change in total or free testosterone.
Melville GW et al. · PLoS One (2017)
A randomized trial found D-aspartic acid combined with heavy resistance training did NOT raise testosterone or improve performance.
Willoughby DS et al. · Nutr Res (2013)
A trial of 3g and 6g D-aspartic acid in resistance-trained men found no benefit — and the higher dose tended to LOWER testosterone.
Melville GW et al. · J Int Soc Sports Nutr (2015)
A 2025 randomized trial of a D-aspartic acid + ubiquinol + zinc combination in infertile men found increased total testosterone and sperm motility — but the effect cannot be isolated to DAA.
GamalEl Din SF et al. · Arch Ital Urol Androl (2025)