What the evidence says. Graded mixed: a single 12-day study in untrained men reported a ~42% testosterone rise, but better-controlled RCTs in resistance-trained men found no change — and 6 g/day actually lowered testosterone. No trial shows added muscle or strength. (Mixed evidence: Conflicting results across studies; benefit uncertain.)
What is D-Aspartic Acid?
D-Aspartic Acid is a performance supplement used for marketed to raise testosterone. NutriDex grades the human evidence as Mixed. D-aspartic acid (DAA) is an amino acid sold as a natural testosterone booster. The hype traces to a 2009 study where 23 untrained men taking ~2.7 g/day for 12 days raised testosterone about 42%. That result has not held up: a 2015 RCT found 3 g/day did nothing and 6 g/day reduced total and free testosterone, and a 2017 RCT in resistance-trained men found no change in testosterone (only a ~16% drop in estradiol) and no extra muscle or strength versus placebo. A 2017 systematic review of four human trials called the evidence inconsistent and low-quality. Separate work links low seminal D-aspartate to poor sperm quality, and a small 2025 RCT combining DAA with ubiquinol and zinc improved sperm motility — but DAA's solo fertility benefit is unproven. For its main marketed claim, boosting testosterone and gains, the human data are mixed to negative.
Purported Benefits
✓Marketed to raise testosterone
✓Marketed muscle & strength support
✓Possible male fertility support
Evidence by outcome
The same supplement can be well-proven for one use and unproven for another — here is the human evidence graded outcome by outcome.
Outcome
Evidence
Effect
Studies
Raise testosteroneInitial 42% spike not replicated; later RCTs show no rise and 6 g/day can lower testosterone; review rates evidence inconsistent.
Moderate
— no effect · negligible
4
Muscle & strength gains12-week RCT in trained men with 6 g/day plus training showed no extra strength or muscle vs placebo.
Moderate
— no effect · negligible
1
Male fertility / sperm qualityLow seminal D-aspartate links to poor sperm; one small RCT improved motility but only as a combination with ubiquinol+zinc, so solo effect is unproven.
Preliminary
↔ mixed
2
Dosing & Compounds
Typical Dose
Common label dose is 3 g/day; testosterone-boosting trials used 2–6 g/day for 12 days to 12 weeks, with no consistent benefit.
Active Compounds
D-aspartic acid (D-aspartate)Sodium D-aspartate
Safety & Cautions
⚠
DAA is generally well tolerated at 3 g/day, with occasional headache, irritability, nervousness or mild GI upset reported. Higher doses (6 g/day) lowered testosterone in trials, so 'more' is counterproductive. Because it acts on the hypothalamic-pituitary-gonadal axis, avoid it if you take hormonal therapies (testosterone, aromatase inhibitors, fertility drugs) without medical advice, and it is not appropriate in pregnancy, breastfeeding, or for adolescents. Formal drug-interaction data are lacking. Educational only — always check with your doctor or pharmacist before combining D-Aspartic Acid with any medicine.
D-Aspartic Acid is most often taken for Marketed to raise testosterone, Marketed muscle & strength support, Possible male fertility support. Marketed testosterone booster that fails in trained men.
Does D-Aspartic Acid work — what does the evidence say?
Mixed evidence. Conflicting results across studies; benefit uncertain. D-aspartic acid (DAA) is an amino acid sold as a natural testosterone booster. The hype traces to a 2009 study where 23 untrained men taking ~2.7 g/day for 12 days raised testosterone about 42%. That result has not held up: a 2015 RCT found 3 g/day did nothing and 6 g/day reduced total and free testosterone, and a 2017 RCT in resistance-trained men found no change in testosterone (only a ~16% drop in estradiol) and no extra muscle or strength versus placebo. A 2017 systematic review of four human trials called the evidence inconsistent and low-quality. Separate work links low seminal D-aspartate to poor sperm quality, and a small 2025 RCT combining DAA with ubiquinol and zinc improved sperm motility — but DAA's solo fertility benefit is unproven. For its main marketed claim, boosting testosterone and gains, the human data are mixed to negative.
What is the typical dose of D-Aspartic Acid?
Common label dose is 3 g/day; testosterone-boosting trials used 2–6 g/day for 12 days to 12 weeks, with no consistent benefit.
Is D-Aspartic Acid safe? Any cautions or side effects?
DAA is generally well tolerated at 3 g/day, with occasional headache, irritability, nervousness or mild GI upset reported. Higher doses (6 g/day) lowered testosterone in trials, so 'more' is counterproductive. Because it acts on the hypothalamic-pituitary-gonadal axis, avoid it if you take hormonal therapies (testosterone, aromatase inhibitors, fertility drugs) without medical advice, and it is not appropriate in pregnancy, breastfeeding, or for adolescents. Formal drug-interaction data are lacking.
How many studies support D-Aspartic Acid?
NutriDex cites 8 sources for D-Aspartic Acid, graded "Mixed".
Cite this page
APA
Peh, D. (2026). D-Aspartic Acid: Benefits, Dosage, Side Effects & Evidence. NutriDex — The Supplement Research Compendium. Retrieved 16 Sept 2026, from https://nutridex.info/s/d-aspartic-acid
BibTeX
@misc{nutridex_d_aspartic_acid,
author = {Peh, Daryl},
title = {D-Aspartic Acid: Benefits, Dosage, Side Effects \& Evidence},
year = {2026},
howpublished = {NutriDex --- The Supplement Research Compendium},
url = {https://nutridex.info/s/d-aspartic-acid},
note = {Reviewed by Dr Daryl Peh, MBBS Singapore, MMed FM. Accessed 2026-09-16}
}
For medical claims, citing the underlying primary studies linked above is preferred. NutriDex is an educational reference, not medical advice.