The study, conducted by researchers at Nova Southeastern University in Florida, investigated the potential health properties of a standardized maca root extract called Lepidamax, marketed by ingredient supplier Nutrition 21 (the researchers reported that the supplier did not fund the study).
Though study participants included both men and women, only the male participants exhibited significant improvements in the measured outcomes from baseline compared to placebo.
“We’re excited to see that these clinical study results support Lepidamax’s ability to effectively enhance various end-points related to men’s health, enabling end-users to break through potential performance barriers,” said Joe Weiss, president of Nutrition 21.
“This study confirms our previous understandings around this ingredient and has exceeded our expectations regarding the possible applications for Lepidamax.”
Study details and results
Forty-seven participants, both men and women, completed the study. The sample size consisted mostly of college students and lasted for 28 days.
Researchers randomized the participants into two groups. The treatment group, with 25 people consumed 2.1 g of maca-containing product, while 22 of the participants consumed the placebo. Both treatments and placebo were divided into three daily, similar-looking pills.
Before and after the 28 days, participants conducted three tests to help the researchers measure the study’s main outcomes. This included measurement of handgrip strength using a Jamar hand grip device, as well as two standard questionnaires, one to measure fatigue and the other to measure sexual function.
“Due to the sensitive nature of sexual behaviors, sexual functioning was self-reported. Thus, there is an inherent concern regarding the construct validity of self-report measures,” the authors wrote.
“However, if responses were exaggerated, they would be expected to be inflated across persons in both the treatment and placebo group.”
Additionally, the researchers noted that significant increases compared to placebo in the primary outcomes were only noticed among male participants.
“It is unclear as to why maca was effective for men but not women. Some studies indicate that maca can cause changes in hormonal levels while others indicate that serum testosterone and oestradiol levels are not different in men treated with maca,” they wrote.
“Further studies need to examine maca’s effects on testosterone levels and sex differences in maca treatment.”
Consider the maca
Maca (Lepidium meyenii) also goes by the name Peruvian ginseng, which hints at the plant’s origins. It has been cultivated as a food item for over two millennia. In the 1990s, it started booming in the US as a supplement ingredient.
It is often marketed as an ingredient for libido and stamina. Some marketers say ‘indigenous knowledge’ inform its use for sexual desire, though a paper published by Biodiversity International on the plant argued that there are very few references pre-dating the maca boom of the 1990s surrounding a functional use of maca among indigenous Peruvians other than nourishment.
Nevertheless, the link between maca root extract and a man’s stamina and libido is a subject of interest among researchers in the nutrition space.
A search for ‘maca root’ and ‘sexual’ on PubMed, a database of published studies registered with the US National Library of Medicine, returned four results. Two were randomized, placebo-controlled trials with mostly women participants. Its researchers found a positive link between maca root supplementation and improved ‘sexual dysfunction.’
A third study, on rodents, also found a positive link. The fourth study was a 2010 systematic review by researchers from South Korea who argued that there is still “limited evidence for the effectiveness of maca” and “more rigorous studies are warranted.”
The plant’s popularity in recent years has led to large amounts being grown in China from roots smuggled out of Peru, leading to much uncertainty about supply volume and pricing, according to a bulletin published by the Botanical Adulterants Program.
According to the most recent annual “Herb Market Report” by the American Botanical Council, US retail sales exceeded $15 million in the natural and mainstream channels combined in 2017. Maca ranked 8th in the natural channel and 36th in the mainstream channel.
Source: Journal of Exercise and Nutrition
Published online, Open Access
“The Effects of Lepidium Meyenii on Grip Strength, Fatigue, and Sexual Behavior”
Authors: Lia Jiannine, Jose Antonio