Maca contains substantial quantities of protein, fat, fiber, and minerals including iron, which also contribute to its nutritional value. It also contains glucosinolates,³ the strong-smelling compounds that are responsible for the pungent smell and taste of mustard family plants. Neither these nor any other constituents in maca have definitively been shown to contribute to its actions.

Preliminary studies have shown that maca can increase libido in healthy men.⁴ It does this without influencing levels of testosterone or any other sex hormones.⁵ Healthy men who take maca have also been shown to have increased semen volume, increased sperm counts, and enhanced sperm motility.⁶

Numerous animal studies show that maca extracts can increase sex drive and improve fertility.^{7, 8, 9} Other studies support that it can relieve the negative effects of stress reactions.¹⁰ The red cultivar, though not the black or cream, also reduced enlarged prostates in rats.¹¹