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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
D-Aspartic Acid doesn't have enough studies with structured effect-size data yet to pool a verdict. Browse the studies below for individual findings.
Most evidence is from high-quality meta-analyses and randomised trials published 2013–2026.
Based on 9 studies · 1 meta-analysis · 6 RCTs
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.
26 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momentum for D-Aspartic Acid, not proof of effect — a registration is a plan, and posted results are sponsor-reported, not peer-reviewed.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 Oct 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 9 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.
Dosing for D-Aspartic Acid: Commonly 3g daily — but trials show no benefit (and 6g may lower testosterone). Individual needs vary, so check the right dose for you with a healthcare provider.
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 has a safety rating of "moderate". That is a category, not a measure of individual risk, and there are precautions worth knowing. Reported side effects include irritability/headache, possible testosterone decrease (high dose). How often they occur is not established for all of them. Use caution if any of these apply to you: Pregnancy/breastfeeding (not studied).
L-Citrulline
Likely helpsAmino acid that boosts nitric oxide production, improving blood flow, exercise performance, and recovery.
Creatine
Likely helpsIncreases phosphocreatine stores for faster ATP regeneration, boosting strength, power output, and cognitive function under stress.
Whey Protein
Likely helpsComplete protein with high leucine content that maximizes muscle protein synthesis.
Beta-Alanine
Likely helpsIncreases muscle carnosine to buffer acid during high-intensity exercise, extending endurance for 1-4 minute efforts.
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Reviewed by Dr. Baher Al Hakim · Last reviewed June 2026 · evidence from 9 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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