D-Aspartic acid

Tier 3 — weak evidence · Testosterone · Fertility · Athletic

An amino acid that temporarily stimulates LH and testosterone production. The 2009 study showed a significant boost after 12 days, but larger trials in trained men found no benefit. May modestly help men with clinically low testosterone. Ineffective in healthy, trained adults. No serious side effects in published trials.

Dose: 2–3 g/day for 2–3 months; only potentially useful in men with low testosterone; no benefit in trained athletes