Lepidium meyenii, also known as maca, is an herbaceous biennial plant of the Brassicaceae family, maca is native to Andean region of Peru (over 3000 meters altitude), where has been harvested and used by humans for centuries. Dried maca has a good nutritional value, comparable to cereal grains such as rice and wheat. Maca has gained a lot on popularity lately, however, it seems its horrible taste created a barrier for the further propagation of this food as a vegetable.
Maca as aphrodisiac and testosterone booster
Lepidium meyenii (Maca), is traditionally used to improve energy, sexuality and fertility . Oral administration of maca significantly improved the sexual behavior in male rats and mice [1,2,3]. More recently, it has been demonstrated that maca improves sperm production in male rats , however, its effect on sperm production in men is not well-known.
G. F. Gonzales, A. Córdova et al.  treated nine men with maca (1500 or 3000 mg/day) for 4 months. Treatment with maca resulted in increased seminal volume, sperm count per ejaculum, motile sperm count, and sperm motility. Serum hormone levels were not modified with maca treatment. Increase of sperm count was not related to dose of maca. This results are in concordance with study by Cicero and associates  which concluded that oral administration of maca significantly improved both acute and chronic sexual performance parameters in male rats. Gonzales and associates  were the first to show beneficial effect on spermatogenesis in male rats in their study from 2001 where significantly increased testicular weight was evident in rats treated with Lepidium meyenii.
In 2003 Gonzales and associates  conducted a 12-week, double-blind, placebo-controlled, randomized, parallel trial to further evaluate aphrodisiac effect of maca. Compared to placebo, maca (at doses of 1,5 g or 3,0 g) improved sexual desire in healthy men. Serum testosterone levels were not affected by treatment with maca at any of the times studied.
Maca has been used lately in quite a few popular testosterone boosters with claims that it enhances hormonal output. However, scientific evidence shows that maca improves sperm production and sperm motility by mechanisms not related to serum luteinizing hormone, follicle stimulating hormone, prolactin, testosterone or estradiol [4,5].
Since testosterone usage is not suggested method to improve sexual desire in men with normal testosterone levels, maca may be an interesting alternative.
Zheng, Bo Lin, et al. “Effect of a lipidic extract from Lepidium meyenii on sexual behavior in mice and rats.” Urology 55.4 (2000): 598-602.
Cicero, Arrigo F. G., E. Bandieri, and R. Arletti. “Lepidium meyenii Walp. improves sexual behaviour in male rats independently from its action on spontaneous locomotor activity.” Journal of ethnopharmacology 75.2 (2001): 225-229.
Gonzales, G. F., et al. “Effect of Lepidium meyenii (maca) roots on spermatogenesis of male rats.” Asian J Androl 3.3 (2001): 231-233.
Gonzales, G. F., et al. “Effect of Lepidium meyenii (maca) on sexual desire and its absent relationship with serum testosterone levels in adult healthy men.” Andrologia 34.6 (2002): 367-372.
Gonzales, G. F., et al. “Effect of Lepidium meyenii (Maca), a root with aphrodisiac and fertility-enhancing properties, on serum reproductive hormone levels in adult healthy men.” Journal of Endocrinology 176.1 (2003): 163-168.