Source: D-Aspartic Acid RCT (Topo 2009) — The original positive trial used ~3.12 g/day for 12 days; later trials (e.g. Melville 2015) at 3–6 g found no benefit in trained men — evidence is unsettled.
The positive testosterone data is one 12-day study (~3.1 g/day); several later trials found no benefit or a decrease — treat as unsettled.
An amino acid marketed as a testosterone booster and a staple of T-booster stacks.
May act on the hypothalamus and testes to nudge LH and testosterone release.
Generally safe short-term. The evidence is genuinely mixed — the famous positive study was small and short, and follow-ups in trained men found no benefit or even a drop. Don't expect much.
| Per serving | |
|---|---|
| Typical branded single-ingredient product | $0.50 |
| Bulk powder at the clinical dose (250g, $21.97) | $0.26 |
Buying bulk powder instead of a branded bottle saves about 47% per serving.
Bulk price: $21.97/250g →Educational only — not medical advice. Grades and clinical doses are computed from public labels against sourced research (citations on the main site); prices last verified 2026-07-21. Expensive Powder has no sponsors; bulk links may earn an affiliate commission, which never affects a grade. Talk to a clinician before starting any supplement.