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D-Aspartic Acid (DAA)
An amino acid marketed as a testosterone booster. The honest verdict: randomized trials in resistance-trained men show NO testosterone or performance benefit — and higher doses may even LOWER testosterone. An early signal in untrained men did not replicate.
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 high-quality meta-analyses and randomised trials published 2013–2026 with a typical study size of 92 participants.
Based on 24 studies · 1 meta-analysis · 8 RCTs · 183 total participants
Confidence
Moderate confidenceBy outcome
Multiple RCTs in resistance-trained men show no testosterone or performance benefit — with higher doses tending to lower testosterone — so this low Emerging score reflects evidence of ineffectiveness rather than uncertainty.
25 trials ongoing or recruiting · 70 completed on ClinicalTrials.gov
23 of the completed trials have posted results
Registered trials show research momentum for D-Aspartic Acid, not proof of effect — a registration is a plan, and posted results are sponsor-reported, not peer-reviewed. They are never counted toward the evidence rating above.
Browse these trials on ClinicalTrials.govClinicalTrials.gov · as of Sep 2026
D-aspartic acid (DAA) is an amino acid involved in testosterone synthesis signaling, marketed as a natural testosterone booster. An early 2009 study in untrained men reported a short-lived testosterone rise, which fueled the supplement's popularity.
The honest picture from subsequent randomized trials: in resistance-trained men, DAA produces NO increase in total or free testosterone and NO performance/muscle benefit — and at least one trial found the higher 6g dose tended to DECREASE testosterone. The early untrained-men signal has not reliably replicated.
It is not an effective testosterone booster for the people who typically take it.
DAA participates in LH/testosterone release signaling — but this doesn't raise testosterone in trained men.
Acts on NMDA receptors in the hypothalamus/pituitary axis.
How D-Aspartic Acid works — from molecular targets to health outcomes. Click an edge to see supporting research.This visualization is in beta — pathways are being refined and expanded.
Not effective in trained men; higher doses may be counterproductive.
Avoid — not studied.
Few documented drug interactions. This possible interaction has not been individually evaluated for this supplement; its likelihood and severity are unknown. If you take an anticoagulant or antiplatelet medicine, ask a pharmacist or prescriber before using this product. Do not stop or change prescribed medicines based on this notice.
Tip: Reduce dose
Tip: Avoid 6g/day
D-Aspartic Acid has an evidence score of 3/10 — emerging evidence based on 20 indexed studies. An amino acid marketed as a testosterone booster. The honest verdict: randomized trials in resistance-trained men show NO testosterone or performance benefit — and higher doses may even LOWER testosterone. An early signal in untrained men did not replicate. Representative study: PMID 37697053.
The commonly studied dose of D-Aspartic Acid is Commonly 3g daily — but trials show no benefit (and 6g may lower testosterone). Individual needs vary — start at the lower end of the range and adjust based on how you respond.
Timing is flexible for D-Aspartic Acid — consistent daily use matters more than the time of day. Marketed at ~3g/day; note trials show no testosterone benefit and higher doses may be counterproductive.
D-Aspartic Acid is generally safe at recommended doses, with a few precautions worth noting. Reported side effects are uncommon and include irritability/headache, possible testosterone decrease (high dose). Use caution if any of these apply to you: Pregnancy/breastfeeding (not studied).
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Reviewed by Dr. Baher Al Hakim · Last reviewed June 2026 · evidence from 24 studies · how we score · editorial policy
This information is for educational purposes only. It is not a substitute for professional medical advice. Always consult a qualified healthcare provider before starting, stopping, or changing any supplement or medication.
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