Peruvian root (Lepidium meyenii) used traditionally as an adaptogen.
Human trials have used 1.5 to 3.5 g/day of powdered or gelatinized maca, or 2,400 mg/day of a dry extract, for 6 to 12 weeks.
Across those trials maca supplementation is associated with higher self-reported sexual desire and sexual function scores, while serum testosterone and estradiol do not differ from placebo.
The clearest signals sit at or near 3 g/day.
Colour-specific uses (red for prostate, black for fertility and cognition, yellow for general energy) are traditional and preclinical only, and are not established in human trials.
See the evidence gaps note below.