Bottom Line: While some compounds in Maca have anticancer properties, it has not been shown to be effective against cancer.
Maca root is in the same family as cabbage, cauliflower and broccoli. Plants in this family contain chemicals called, "glucosinolates." These glucosinolates can be converted in the body to a substance that has been reported to inhibit certain kinds of cancer in animals. Maca has traditionally been used to improve sexual performance and as a treatment for infertility. Studies have shown that maca is able to improve sexual performance, however it does so without affecting serum hormone levels in the blood. It is possible that maca affects the receptors that these hormones bind to. Because maca affects the body through these hormones, it is assumed that it can produce effects in members of both sexes. Further study is warranted.
Sexual performance: Fifty-seven male subjects aged 21-56 years participated in a study of the effect of maca in increasing sexual desire. For twelve weeks subjects received either 500 mg maca three times a day, 500 mg maca six times a day or placebo. Subjects reported subjectively about their sexual desire. Nobody in the placebo group reported increased sexual desire, however 40% of the subjects receiving maca reported increased sexual desire. The study contains a number of statistical flaws which weaken the results.
In another study, twelve healthy men aged 24-44 participated in a four-month study of the effect of maca on sperm production and motility. Subjects received either 1,500 or 3,000 mg of maca per day. Sperm count and mobility increased during the course of the study, however the levels of certain hormones which produce such effects in the body remained unchanged. Because the trial was not randomized, results may be skewed.
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A nutritionally valuable native Peruvian plant that grows in a harsh climate above 4,000 feet. Maca has been used traditionally to enhance fertility and sexual performance in both men and women and to relieve menopausal symptoms (1). It has been purported to treat cancer and to improve stamina in cancer patients. Although animal studies show increased sexual function (2), few human trials have been performed. One human study showed increased libido (3), while another showed improved sperm production and sperm motility (4). Both studies showed that physiologic effects were not due to serum hormone levels. The hexanic extract of maca appears to be more effective at improving sexual performance in rats than methanolic and chloroformic extracts (5). Data also indicates that maca increases endurance in rats (6). Dried maca was shown to have lower content of the suspected active metabolite than fresh maca. It is also available as a liquor, tonic and mayonnaise, although health benefits of these derivatives seem minimal (7). The therapeutic dose and toxicity of maca are unknown.
Maca root contains far greater amounts of glucosinolates than other members of the Brassicacae family, such as cabbage, cauliflower and broccoli. Fertility-enhancing properties of maca are thought to be due to aromatic isothiocyanates hydrolyzed from these glucosinolates. Furthermore, benzyl isothiocyanate has been reported to inhibit breast, stomach and liver cancer in rats. Aphrodisiacal properties are attributed to the prostaglandins, sterols and amides of polyunsaturated fatty acids (7). The most confounding question about maca's effect is its ability to influence sexual performance without affecting serum hormone levels such as luteinizing hormone, follicle stimulating hormone, prolactin, testosterone and estradiol (9). It is therefore assumed that maca acts on the receptors for these hormones (4). Both methanolic and acqueous extracts of Maca exhibit estrogenic activity in vitro (10). Alkaloids purified from the maca root are thought to affect the hypothalamic-pituitary axis, explaining why maca can induce effects in both sexes (6).
Gonzales GF, Cordova A, Vega K, Chung A, Villena A, Gonez C et al. Effect of Lepidium meyenii (MACA) on sexual desire and its absent relationship with serum testosterone levels in adult healthy men. Andrologia 2002;34:367-72. Fifty-seven male subjects aged 21-56 years participated in a study of the effect of maca in increasing sexual desire. Subjects were randomized into one of three groups. Thirty subjects received 500 mg maca three times a day (1,500 mg/day), another fifteen subjects received 500 mg maca six times a day (3,000 mg/day) and the remainder received placebo for twelve weeks. Subjects were asked to report subjectively about level of sexual desire at 4, 8 and 12 weeks. 40% of men receiving maca reported an increase in sexual desire and eight and twelve weeks. None of the placebo group reported an increase in sexual desire. Results did not appear to be dose-dependent. The study appears to contain a number of statistical flaws which weaken the results. Larger, better run studies are warranted.
Gonzales GF, Cordova A, Gonzales C, Chung A, Vega K, Villena A. Lepidium meyenii (Maca) improved semen parameters in adult men. Asian J Androl 2001;3:301-3. 12 healthy men aged 24-44 participated in a four-month study of the effect of maca on sperm production and motility. Three subjects dropped out for personal reasons. Subjects received either 1,500 or 3,000 mg of maca per day. After four months semen volume, total sperm count, motile sperm count and sperm motility were significantly increased. Serum levels of leuteinizing hormone, follicle stimulating hormone, prolactin, testosterone and estradiol hormones were unaffected. Because the trial was not randomized, observation bias may have been introduced, weakening the results. Further study is warranted.
Li G, Ammermann U, Quiros CF. Glucosinolate Contents in Maca (Lepidium peruvianum chacon) Seeds, Sprouts, Mature Plants and Several Derived Commercial Products. Economic Botany 2001;55:255-62.
