Maca's ability to help restore libido is probably what it is best known for. It is often described as an aphrodisiac for both sexes and is clinically proven to improve sexual function in humans.

The first known published human study on Maca's effect on libido and fertility in men was conducted in Peru and published in the Asian Journal of Andrology. Study data showed that Maca increased sexual desire (libido) by 180% and increased sperm count by 200%. Other benefits included increased sperm mobility, increased DHEA levels, decreased anxiety and stress, lower blood pressure and a general sense of well-being.

In the prestigious medical journal Urology (April 2000), scientists studied the effects of Maca on rats with erectile disorders and low testosterone levels. The Maca-fed group had an amazing 400% more copulation than the non Maca-fed group. Rodents with low testosterone levels demonstrated a significant increase in sexual activity, indicating a possibility that men with low testosterone or erectile dysfunction may experience improvement. In the studies, the more Maca extract fed to the animals, the greater their strength, libido and sexual function.

In studies with rats, females given Maca showed significantly increased Graaf follicles and other favorable endometrium characteristics, which indicate a higher fertility level. Male rats had significantly higher sperm production and motility rates than in control groups. The effects were measurable within 72 hours of dosing the animals.