D-aspartic acid
One 12-day trial in sedentary men reported testosterone 42% above baseline. In resistance-trained men, 3 g a day did not change testosterone, and 6 g a day lowered it in one 2-week trial and left it unchanged over 12 weeks. Strength and muscle gains with training did not differ from placebo. A 2017 systematic review called human results inconsistent.
Add to Bio HackChecked 2026-11-09
- Status
- Dietary supplement in the US.
- Also called
- DAA, D-Asp, D-aspartate, sodium D-aspartate, DADAVIT, testosterone booster
- Taken for
- testosterone, muscle growth, strength, libido, male fertility, sperm quality
Strong several reviews agree · Moderate one review or consistent trials · Limited one or a few small studies · Untested no study in people, listed with what it rests on
Shown to help1
Reported risks2
- LimitedOne small trial found 6 g a day for 14 days lowered total and free testosterone in 24 trained men. A 12-week trial found no change.How often is not known
- LimitedOne small trial found estradiol fell 16% from baseline over 12 weeks at 6 g a day in men.How often is not known
What people take it for, and what was found
Shown to help1
Sperm quality in men with infertility
One trial found a product combining D-aspartic acid, ubiquinol and zinc raised sperm motility in infertile men. D-aspartic acid's own share is unknown.
The numbers and sources
- Effect
- In infertile men given 2,660 mg of D-aspartic acid with 200 mg of ubiquinol and 10 mg of zinc daily for 3 months, progressive sperm motility rose from 10.63 to 15.21 (p = 0.047) and total testosterone from 5.06 to 5.89 (p = 0.009). A placebo group took starch granules [7].
- Population
- 24 men per group with idiopathic infertility in Egypt [7].
- Sources
- [7]
- Caveats
- A three-ingredient product, so the effect of D-aspartic acid alone cannot be separated. The abstract reports the active group's change and does not give the between-group comparison [7].
Mixed results1
Testosterone
Mixed results: one 12-day trial found testosterone up 42% from baseline in untrained men, while trials in trained men found no rise or a fall at 6 g.
The numbers and sources
- Effect
- In 23 men aged 27 to 37 given 3.12 g of sodium D-aspartate a day for 12 days, testosterone rose from 4.5 to 6.4 ng/mL, a 42% increase over baseline, and LH rose 33%. Twenty men on placebo did not change [1]. In resistance-trained men, 3 g a day for 28 days did not change total or free testosterone, LH or estradiol [2]. In 24 trained men over 14 days, 3 g a day had no effect, and 6 g a day lowered total and free testosterone [3]. In 22 trained men over 12 weeks, 6 g a day did not change total or free testosterone [4]. In 16 boxers at simulated altitude, 6 g a day for 14 days did not change resting testosterone or LH [5]. A systematic review of 4 human studies found the results inconsistent and the studies few and of poor quality [6].
- Population
- Healthy men in Italy [1]; resistance-trained men [2][3][4]; male boxers [5].
- Sources
- [1], [2], [3], [4], [5], [6]
- Caveats
- The rise in [1] was reported against the same men's baseline, and the product was a commercial preparation also containing vitamins B6, B12 and folic acid. All trials were small and lasted 2 to 12 weeks.
Not shown to help1
Strength and muscle with training
Not shown to add to strength or muscle gains from resistance training in trained men over 28 days to 12 weeks.
The numbers and sources
- Effect
- Over 28 days of heavy resistance training, body composition and strength rose in both groups and did not differ between 3 g of D-aspartic acid and placebo [2]. Over 12 weeks of supervised training, isometric strength rose 17% and quadriceps and calf muscle size increased similarly in both groups on 6 g a day or placebo [4].
- Population
- Resistance-trained men [2][4].
- Sources
- [2], [4]
- Caveats
- Small samples, 22 randomized in [4].
Claimed, not studied in people1
Libido
Not studied in people. The claim rests on raising testosterone, which rose in one 12-day trial and in rats but not in later trials in trained men.
No study in people. This rests on how it acts in the body, animal studies.
The numbers and sources
- Effect
- In 23 men given sodium D-aspartate for 12 days and in rats, LH and testosterone release rose [1]. Later trials in resistance-trained men found no rise in testosterone at 3 g a day for 28 days, and a fall at 6 g a day for 14 days [2][3]. Where testosterone is low, raising it does change desire: in 790 men aged 65 or older with low testosterone, a year of testosterone gel raised sexual desire, activity and erectile function against placebo [8]. No study measured libido in people taking D-aspartic acid.
- Population
- Men and rats [1]. Resistance-trained men [2][3]. 790 older men with low testosterone, given testosterone itself [8].
- Sources
- [1], [2], [3], [8]
- Caveats
- The testosterone trial tested the hormone, not D-aspartic acid, in men with low levels [8]. D-aspartic acid's effect on testosterone is itself inconsistent [1][2][3].
Doses studied
Trials used 3.12 g a day of sodium D-aspartate for 12 days [1], 3 g a day for 28 days [2], 3 or 6 g a day for 14 days [3], 6 g a day for 12 weeks [4] and 6 g a day for 14 days [5]. The infertility trial used 2,660 mg a day with ubiquinol and zinc for 3 months [7].
Risks
Reported risks1
Lower estradiol over 12 weeks
One small trial found estradiol fell 16% from baseline over 12 weeks at 6 g a day in men.
The numbers and sources
- How common
- How often is not known: the sources give no rate.
- Effect
- Over 12 weeks at 6 g a day, estradiol fell 16% (95% CI -27% to -5%) from baseline. The placebo group showed improved spinal responsiveness at the gastrocnemius that the supplement group did not [4].
- Population
- 10 men analyzed in the supplement group and 9 on placebo [4].
- Sources
- [4]
- Caveats
- One small trial. The authors received no specific funding [4].
Mixed results1
Lower testosterone at 6 g a day
One small trial found 6 g a day for 14 days lowered total and free testosterone in 24 trained men. A 12-week trial found no change.
The numbers and sources
- How common
- How often is not known: the sources give no rate.
- Effect
- In trained men, 6 g a day for 14 days lowered total testosterone (p = 0.03), and free testosterone was lower than with the flour placebo (p = 0.005). Estradiol, SHBG and albumin did not change [3].
- Population
- 24 resistance-trained men [3].
- Sources
- [3]
- Caveats
- The 12-week trial at the same dose found no change in testosterone [4].
Claims tested and not found
- That D-aspartic acid raises testosterone in trained men. Testosterone did not rise at 3 g for 28 days [2], fell at 6 g for 14 days [3], and did not change at 6 g for 12 weeks [4].
- That D-aspartic acid adds to strength or muscle gains from training. Strength and muscle size rose equally with placebo [2][4].
Sources
- Topo E, Soricelli A, D'Aniello A, et al. The role and molecular mechanism of D-aspartic acid in the release and synthesis of LH and testosterone in humans and rats. Reproductive Biology and Endocrinology. 2009. https://doi.org/10.1186/1477-7827-7-120
- Willoughby DS, Leutholtz B. D-Aspartic acid supplementation combined with 28 days of heavy resistance training has no effect on body composition, muscle strength, and serum hormones associated with the hypothalamo-pituitary-gonadal axis in resistance-trained men. Nutrition Research. 2013. https://doi.org/10.1016/j.nutres.2013.07.010
- Melville GW, Siegler JC, Marshall PW. Three and six grams supplementation of d-aspartic acid in resistance trained men. Journal of the International Society of Sports Nutrition. 2015. https://doi.org/10.1186/s12970-015-0078-7
- Melville GW, Siegler JC, Marshall PWM. The effects of d-aspartic acid supplementation in resistance-trained men over a three month training period: A randomised controlled trial. PLOS ONE. 2017. https://doi.org/10.1371/journal.pone.0182630
- Płoszczyca K, Czuba M, Zakrzeska A, et al. The Effects of Six-Gram D-Aspartic Acid Supplementation on the Testosterone, Cortisol, and Hematological Responses of Male Boxers Subjected to 11 Days of Nocturnal Exposure to Normobaric Hypoxia. Nutrients. 2023. https://doi.org/10.3390/nu16010076
- Roshanzamir F, Safavi SM. The putative effects of D-Aspartic acid on blood testosterone levels: A systematic review. International Journal of Reproductive BioMedicine. 2017. https://doi.org/10.29252/ijrm.15.1.1
- GamalEl Din SF, et al. Evaluation of in vivo supplementation of 2660 mg D-aspartic acid and 200 mg ubiquinol and 10 mg zinc on different semen parameters in idiopathic male infertility: a randomized double blind placebo controlled study. Archivio Italiano di Urologia e Andrologia. 2025. https://doi.org/10.4081/aiua.2025.13554
- Snyder PJ, Bhasin S, Cunningham GR, et al. Effects of testosterone treatment in older men. New England Journal of Medicine. 2016. https://doi.org/10.1056/NEJMoa1506119