Ethnobiology and Ethnopharmacology of Lepidium meyenii (Maca), a Plant from the Peruvian Highlands.

The short version

This 2012 review looked at maca (Lepidium meyenii), a root vegetable that has grown in the high Andes of Peru and Bolivia for more than 2,000 years, where it has long been used as both food and a traditional fertility remedy. Written by a Peruvian researcher who has studied maca extensively, the review asked a simple question: does the science actually back up maca's traditional reputation? At the time, Peru's maca exports had grown more than fourfold in a decade, making that question increasingly practical. As a review of existing research rather than one new experiment, there is no single group of people or animals studied. The material available here covers the review's introduction, its round-up of reproduction-focused animal experiments, and its closing remarks, and it leans heavily on rat and mouse studies rather than human trials. How maca is prepared matters: traditional use involves boiling the root or extracting it in alcohol, and the review notes that a simple water extract only works after the pulverized root has been boiled first. In male rats, different doses of maca had inconsistent effects on sexual behavior between two studies, but more reliably increased sperm count and movement, an effect strongest with black maca, weaker with yellow, and absent with red. Red maca extract reduced prostate enlargement caused by testosterone treatment in rats and mice, in a dose-related way, likely due to a plant compound called benzylglucosinolate acting at a step after testosterone's usual hormone receptor rather than by lowering testosterone itself. In female animals, maca did not change estrogen levels but did improve embryo survival in mice, and red and black maca protected bone strength in rats whose ovaries had been removed (a standard aging-and-bone-loss model) without acting like estrogen on the uterus. The review's abstract also states that human clinical trials found maca helpful for sexual difficulties and for sperm count and motility, though the specific numbers behind that claim sit in parts of the original article not available in this record. The author concludes that more chemical and mechanistic research is needed, pointing out that macamides (compounds unique to maca) may explain some of its effects on sexual behavior, though extracts with almost no macamides worked too, meaning other compounds are likely involved as well. Because most of what is captured here comes from animal studies rather than human trials, these findings are best read as promising groundwork pointing toward further human research, useful for understanding why maca is traditionally valued, but not as settled clinical guidance for treating any specific condition today.

Key findings

• Maca (Lepidium meyenii) is a root vegetable grown for over 2,000 years in the high Peruvian and Bolivian Andes, traditionally eaten as food and used to support fertility.
• In rat studies, maca most reliably increased sperm count and motility, with black maca showing the strongest effect and red maca showing none, while effects on sexual behavior itself were inconsistent between studies.
• Red maca reduced testosterone-driven prostate enlargement in rats and mice through a mechanism that did not involve lowering testosterone, suggesting a different pathway than standard prostate medications.
• Maca extracts also protected bone strength in rats with removed ovaries, a standard model for postmenopausal bone loss, without acting like estrogen on other reproductive tissue.
• Nearly all of the specific findings in the available text come from animal studies, so while the review's abstract states human clinical trials also showed benefits for sexual dysfunction and sperm quality, the itemized human data were not present in this record to verify directly.

Common questions