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- Maca (Lepidium meyenii)
- Sexual Function
| Date:
01-14-2011 | HC# 091064-416
|
Re: A Systematic Review of Biological Activity of Maca
Shin BC, Lee MS, Yang EJ, Lim HS, Ernst E.
Maca (L. meyenii) for improving
sexual function: a systematic review. BMC
Complement Altern Med. Aug 6, 2010;10:44. doi: 10.1186/1472-6882-10-44.
Maca (Lepidium meyenii) is a member of the
Brassicaceae family that has a long history of use as a staple food and
medicine in South America. Maca has been
traditionally used to increase fertility in the Andes Mountains.
Animal studies and small clinical trials have provided some evidence that maca
may be effective in treating erectile dysfunction.1 Animal studies
have shown spermatogenic effects, improvements in sexual behavior, and an
enhancement of "androgen-like effects in rats." The bioactive
constituents of maca are not definitively identified, but they may include
macaridine, macamides, macaene, and glucosinolates. The purpose of this review
was to examine the clinical evidence for the effects of maca on "the
improvement of sexual function, including sexual desire and sexual
responses."
The authors
searched the following databases (inception-April 2010): Medline, AMED, CINAHL,
EMBASE, PsycInfo, Cochrane Central Register of Controlled Trials, Cochrane Database
of Systematic Reviews, DARE, Psychology and Behavioral Sciences Collection,
Korean Studies Information, DBPIA, Korea Institute of Science and Technology,
KERIS, KoreaMed, Korean National Assembly Library, CNKI, and The Japanese
Science and Technology Information Aggregator. The authors also performed hand
searches of departmental files and relevant journals.
They included
trials on maca that had at least one measure of sexual function in subjects
with or without sexual dysfunction. The authors read the trials in full and
extracted data, including methods, sample, treatments, and outcome measures. They
applied the Cochrane classification "to evaluate the risk of bias."
It was not possible to conduct a formal meta-analysis, as planned, due to the
"statistical and clinical heterogeneity" of the data.
The authors
recovered 88 articles, and four of them met the inclusion criteria. They were
conducted in Peru, Australia, Italy,
and the United Kingdom.
The study designs were: crossover (n=2), two-armed parallel group (n=1), and three-armed
parallel group (n=1). The trials enrolled a total of 131 subjects. Two studies
used dried maca, and two used gelatinous maca. The studies lasted 2-12 weeks
and employed dosages ranging from 1.5 to 3.5 g. The age ranges of the subjects
were 21-56 years for healthy male subjects, 31-41 years for male subjects with
erectile dysfunction (ED), and 43-65 years for postmenopausal women. Outcome
measures included the International Index of Erectile Dysfunction (IIEF-5),
sexual dysfunction Greene Climacteric Scale, sexual desire rated on a six-point
Likert scale, and the Sexual Desire Inventory. Three of the studies used
commercially available maca products, and one used dried unprocessed maca. None
of the trials reported the method of sequence generation, and none used
allocation concealment. All were double-blinded, and "one trial reported
complete outcome measures." None of the trials reported the presence or
absence of adverse effects.
The one
trial that enrolled patients with ED "showed positive effects of maca on
IIEF-5 in patients with mild ED compared to the placebo control." The
other three RCTs examined the effect of maca on sexual function in healthy
adults. A placebo-controlled trial found positive effects on the sexual
function of postmenopausal women. Another found that high and low doses of maca
(3 g/day and 1.5 g/day, respectively) had beneficial effects on sexual desire
in healthy adult men. The final clinical trial found no positive effects on
sexual desire in male cyclists.
The small
number of trials on maca and sexual function that are currently available makes
it difficult to draw conclusions. The four trials reviewed here had problems that
included failure to report adverse effects, sequence generation for
randomization, allocation concealment, power calculation, and success of
blinding. One of the crossover studies did not include a washout period between
treatments and another had a "poor description of the outcome and was
therefore difficult to interpret." One trial did not use a validated
questionnaire.
More
research is needed to determine the relationship between maca and sexual
function and to determine the optimal dose. Future clinical trials should
report the presence or absence of adverse events and employ large sample sizes
and rigorous study designs.
—Marissa Oppel-Sutter, MS
Reference
1. Milot
B. Subjective effects of maca root extract on men's health. HerbClip. June 30, 2009 (No.
060191-379). Austin, TX: American Botanical Council. Review of
Subjective effects of Lepidium meyenii
(maca) extract on well-being and sexual performances in patients with mild
erectile dysfunction: a randomised, double-blind clinical trial by Zenico T,
Cicero AFG, Valmorri L, Mercuriali M, Bercovich E. Andrologia. 2009;41(2):95-99.
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