Also Known As: Maca, Lepidium meyenii
Lepidium meyenii, known commonly as maca, is an herbaceous biennial plant or annual plant (some sources say a perennial plant) native to the high Andes of Peru and Bolivia. It is grown for its fleshy hypocotyl (actually a fused hypocotyl and taproot), which is used as a root vegetable and a medicinal herb. Its Spanish and Quechua names include maca-maca, maino, ayak chichira, and ayak willku.
Maca is consumed as food for humans and livestock, suggesting any risk from consumption is rather minimal. It is considered as safe to eat as any other vegetable food. However, maca does contain glucosinolates, which can cause goiters when high consumption is combined with a diet low in iodine. This being said, darker colored maca roots (red, purple, black) contain significant amounts of natural iodine, a 10-gram serving of dried maca generally containing 52 µg of iodine. Though this is common in other foods with high levels of glucosinolate, it is uncertain if maca consumption can cause or worsen a goiter. Maca has been shown to reduce enlarged prostate glands in rats.
Small-scale clinical trials performed in men have shown that maca extracts can heighten libido and improve semen quality. A small double-blind, randomized, parallel group dose-finding pilot study has shown that Maca root may alleviate SSRI-induced sexual dysfunction. A 12-week randomized, double-blind, placebo-controlled study in 56 subjects found that Maca has no effect on sex hormone levels in men, including LH, FSH, prolactin, 17-OH progesterone, testosterone or estradiol. In addition, maca has been shown to increase mating behavior in male mice and rats. A recent review states "Randomized clinical trials have shown that maca has favorable effects on energy and mood, may decrease anxiety and improve sexual desire. Maca has also been shown to improve sperm production, sperm motility, and semen volume."