D-Aspartic Acid
Also known as: DAA, D-Asp, D-aspartate
Effective Dosage
3-6 g daily based on study doses
What the Science Says
D-Aspartic Acid (DAA) is a naturally occurring amino acid found in various tissues throughout the body. It is thought to stimulate the release of hormones involved in testosterone production. One clinical trial found that a combination supplement containing 2.66 g of DAA plus zinc and CoQ10 produced a modest but statistically significant increase in testosterone and sperm motility in infertile men after 3 months. However, a separate study using 3 g/day in healthy male athletes found no significant effect on testosterone or related hormones after 2 weeks.
What It Doesn't Do
Won't dramatically boost testosterone in healthy men with normal levels. Short-term use (2 weeks) shows no measurable hormone changes in athletes. Not a proven standalone fertility treatment. No evidence it directly builds muscle or improves athletic performance.
Evidence-Based Benefits
In a small RCT of infertile males, D-aspartic acid combined with ubiquinol and zinc (2660 mg/day for 3 months) significantly improved progressive sperm motility and increased total testosterone levels (PMID: 40248985). Animal and metabolic research suggests D-aspartic acid accumulates in tissues in a dose-dependent manner and may influence lipid metabolism and neurotransmission pathways (PMID: 41086472). However, short-term supplementation at 3 g/day for 2 weeks in trained male climbers showed no significant effect on testosterone, free testosterone, or luteinizing hormone (PMID: 29893592).
Weak EvidenceEffective at: 2660-6000 mg daily based on study doses
Source: auto-research
Absorption & Bioavailability
Unknown — no pharmacokinetic data provided in the available studies. Animal data suggests D-amino acids can accumulate in tissues with repeated dosing.
Red Flags to Watch For
- Most positive results come from combination supplements (with zinc and CoQ10), making it impossible to isolate DAA's specific contribution
- Studies in healthy, trained athletes show no testosterone benefit, suggesting effects may only apply to men with hormonal deficiencies
- Very few high-quality standalone RCTs exist; the evidence base is thin and inconsistent
- Long-term safety data is lacking; one animal study noted dose-dependent tissue accumulation of D-amino acids
Research Sources
- PubMed
- NIH DSLD
This information is for educational purposes only and is not medical advice. Always consult a healthcare professional before starting any supplement regimen. Last updated: 2026-04-06