Verified by 
Maca (Lepidium meyenii) is a perennial ground cover that grows high in the Andes under very harsh conditions where few plants can survive. Ancient Andean shepherds ate the fleshy root (similar to ginger) as a vegetable and fed it to their livestock. They noticed that the herb improved their herds' health and appeared to increase their fertility, an observation confirmed centuries later by studies showing that maca boosts livestock sperm counts.
Many plants thought to enhance fertility also gained reputations as sex stimulants, and that's what happened to maca. That belief was confined to South America until about 10 years ago, when the herb began appearing in sexual enhancement supplements in the U.S. Does it work? The jury is still out, but recent studies have come up with tantalizing findings:
Peruvian researchers gave adult men either a placebo or maca (3 g/day). After eight weeks, maca had no effect on male sex hormones, but it "improved sexual desire."
Italian researchers gave either a placebo or maca (2400 mg/day) to 50 men complaining of mild erectile dysfunction. After 12 weeks, both groups reported significant benefits, but the maca group experienced greater improvement.
British scientists surveyed eight bicycle racers regarding their sexual desire, and then timed them on a 40 km course. The racers were then given either a placebo or maca daily. After two weeks, the racers rode the course again and completed another sexual desire survey. Compared with the placebo group, the racers taking the herb clocked faster times and reported greater libido.
Australian researchers took blood from 14 postmenopausal women and surveyed their menopausal symptoms and sexual functioning. Then the women were given either a placebo or maca (3500 mg/day) for six weeks, after which the groups were switched for another six weeks (a crossover study). After taking the herb, new blood samples were drawn. The women's before-and-after blood tests showed that maca had no impact on hormones involved in menopause or sexuality. But while taking the herb, the women reported fewer menopausal problems (anxiety and depression) and improved sexual function.
At Massachusetts General Hospital in Boston, scientists gave one of three treatments to 20 people suffering sexual impairment caused by antidepressant medication (SSRIs): a placebo, low-dose maca (1500 mg/day), or high-dose maca (3,000 mg/day). Compared with the placebo-takers, both maca groups reported enhanced sexual desire. The high-dose group also experienced improved sexual function.
Finally, South Korean researchers reviewed these and other trials and concluded that maca shows some evidence of improving sexual function.
Maca is not a magical aphrodisiac, but these studies all suggest that it modestly tweaks sexual desire and function. No doubt, herb marketers will blow these findings out of proportion, and scientists will react by pooh-poohing maca. But it appears that as far as sex is concerned, maca stimulates more than just the imagination.
Have you tried maca? If so, have you noticed any sexual effects?
The studies:
Books, N.A. et al. "Beneficial Effects of Lepidium Meyenii on Psychological Symptoms and Measure of Sexual Dysfunction in Postmenopausal Women Are Not Related to Estrogen or Androgen Content," Menopause (2008) 15:1157.
Dording, C.M. et al. "A Double-Blind, Randomized, Pilot Dose-Finding Study of Maca Root (L. Meyenii) for Management of SSRI-Induced Sexual Dysfunction," CNS Neuroscience and Therapy (2008) 14:182.
Shin BC et al. "Maca (L. Meyenii) for Improving Sexual Function: A Systematic Review," BMC Complementary and Alternative Medicine (2010) 10:44
Stone, M. et al. "A Pilot Investigation into the Effect of Maca Supplementation on Physical Activity and Sexual Desire in Sportsmen," Journal of Ethnopharmacology (2009) 126:574.
Zenico, T. et al. "Subjective Effects of Lepidium Meyenii Extract on Well-Being and Sexual Performance in Patients with Mild Erectile Dysfunction: A Randomized, Double-Blind Clinical Trial," Andrologia (2009) 41:95.
