While explorer Ponce de Leon was looking for a fountain of youth in what is now Florida, South American natives already knew of the maca plant and its purported energy-boosting and aphrodisiac qualities.1 Maca, or Lepidium meyenii, grows mostly in the high Peruvian Andes and has been referred as one of the “lost crops of the Incas.”

Background

Maca is a member of the radish family and classified as a cruciferous plant whose primary usable part is its potatolike tuberous root. Although maca was nearly extinct at one time, its rapidly expanding popularity as an herbal medicine has revived its status to that of a large commercial crop.2

Maca appears as a short, leafy-topped plant whose thin, frilly leaves eventually produce a central, off-white flower. After maturing, the flower leaves a seedpod, which breaks open and scatters seeds that quickly germinate in the thin, mountainous soil. The fleshy underground part of maca appears as a pear-shaped extension of the central taproot.3

Science

Maca contains a complex grouping of sugars, proteins, and fiber as well as minerals and essential fatty acids.3 Although much of the basis for maca’s energy-boosting and libido-enhancing actions is still unknown, researchers feel the key lies in the action that some of the alkaloid components have on the hypothalamic-pituitary axis.1

Research centers on maca’s potential for enhancing libido and sexual performance. In one trial, 56 healthy men aged 21 to 56 years were given either maca or placebo. Subjective ratings of sexual desire as well as scores on the Hamilton depression and anxiety scales were recorded at four, eight, and 12 weeks. Serum testosterone levels were also measured. The results were statically significant for increased libido in the treatment group, and there were no changes in serum testosterone levels.4 This finding was corroborated by a study specifically designed to test the presence or absence of androgenic agents in maca. The results indicated that there are compounds in maca that mimic testosterone and are able to bind to androgen receptors, thus triggering androgenic actions.5

A similar trial using maca and placebo involved postmenopausal women. Participants completed a 14-week study and were rated on the Greene Climacteric Scale and subjective assessments of sexual dysfunction. Those treated with maca scored lower on climacteric symptoms and showed significant reduction in symptoms of sexual dysfunction. Serum levels of the female hormone estradiol did not change, leading researchers to speculate that the same chemicals that mimicked androgens also pose as estrogenic compounds capable of binding to receptor sites.6

Another very interesting potential indication for maca is in the reduction of sexual dysfunction side effects related to selective serotonin reuptake inhibitor (SSRI) therapy. Rates of sexual dysfunction in SSRI therapy have been estimated to be as high as 50% to 75%.7 In a clinical trial to determine if maca might be useful in counteracting these side effects, participants were enrolled in a randomized trial and given either placebo or one of two different doses of maca. At the end of the trial, the participants at the higher dose of maca had significant improvement in their sexual functioning, but the lower dose and placebo groups did not.8 While this is the only indication for maca that has shown such dose-response specificity, the results are still quite impressive considering that an estimated 10% of Americans use some form of SSRI.9

Safety, interactions

Aside from the ever-present potential for an allergic reaction, maca has so far proven to have almost no known drug or herbal interactions.10

Dose, how supplied

Most commercially available maca is in the form of a gelatin-filled capsule. The average dosage in the clinical trials was 1.5 g/day.10 The exception to this dose is when treating sexual dysfunction secondary to SSRI use, in which case the successful dose range was 3.0-3.5 g/day.8

Summary

Although not all the data are in yet, in terms of large-scale, rigorous clinical trials, maca root appears to have practically no downside and possesses tremendous market potential. With the usual precautions of medication monitoring and patient education to report any unusual side effects, maca will no doubt find its way into many providers’ herbal toolboxes—much to the delight of the multitude of patients with sexual dysfunction. 

Ms. Sego is a staff clinician at the VA Hospital in Kansas City, Mo., where she practices adult medicine and women’s health. She also teaches at the nursing schools of the University of Missouri and the University of Kansas.

References

  1. Piacente S, Carbone V, Plaza A. Investigation of the tuber constituents of maca (Lepidium meyenii Walp.). J Agric Food Chem. 2002;50:5621-5625.
  2. National Research Council. Maca In: The Lost Crops of the Incas: Little-known Plants of the Andes With Promise for Worldwide Cultivation. Washington, D.C.: National Academy Press; 1989:57-66.
  3. Skyfield Tropical. Maca (lepidium peruvianum).
  4. Gonzales GF, Córdova A, Vega K, et al. Effect of Lepidium meyenii (Maca), a root with aphrodisiac and fertility-enhancing properties, on serum reproductive hormone levels in adult healthy men. J Endocrinol. 2003;176:163-168.
  5. Bogani P, Simonini F, Iriti M, et al. Lepidium meyenii (Maca) does not exert direct androgenic activities. J Ethnopharmacol. 2006;104:415-417.
  6. Brooks NA, Wilcox G, Walker KZ, et al. Beneficial effects of Lepidium meyenii (Maca) on psychological symptoms and measures of sexual dysfunction in postmenopausal women are not related to estrogen or androgen content. Menopause. 2008;15:1157-1162.
  7. Kauffman RP. Persistent sexual side effects after discontinuation of psychotropic medications. Prim Psychiatry. 2008;15:24.
  8. Dording CM, Fisher L, Papakostas G, et al. Lepidieum meyenii for the management of SSRI-induced sexual dysfunction: A double-blind, randomized, pilot dose-finding study of maca root (L. meyenii) for the management of SSRI-induced sexual dysfunction. CNS Neurosci Ther. 2008;14:182-191.
  9. Olfson M, Marcus SC. National patterns in anti­depressant medication treatment. Arch Gen Psychiatry. 2009;66:848-856.
  10. Natural Medicines Comprehensive Database. Maca.

All elecronic documents accessed July 15, 2010.