Maca Root

Gustavo F Gonzales (2011) · Evidence-based complementary and alternative medicine : eCAM

This 2012 review looked at maca (Lepidium meyenii), a root vegetable that has grown in the high Andes of Peru and Bolivia for more than 2,000 years, where it has long been used as both food and a traditional fertility remedy. Written by a Peruvian researcher who has studied maca extensively, the review asked a simple question: does the science actually back up maca's traditional reputation? At the time, Peru's maca exports had grown more than fourfold in a decade, making that question increasingly practical. As a review of existing research rather than one new experiment, there is no single group of people or animals studied. The material available here covers the review's introduction, its round-up of reproduction-focused animal experiments, and its closing remarks, and it leans heavily on rat and mouse studies rather than human trials. How maca is prepared matters: traditional use involves boiling the root or extracting it in alcohol, and the review notes that a simple water extract only works after the pulverized root has been boiled first. In male rats, different doses of maca had inconsistent effects on sexual behavior between two studies, but more reliably increased sperm count and movement, an effect strongest with black maca, weaker with yellow, and absent with red. Red maca extract reduced prostate enlargement caused by testosterone treatment in rats and mice, in a dose-related way, likely due to a plant compound called benzylglucosinolate acting at a step after testosterone's usual hormone receptor rather than by lowering testosterone itself. In female animals, maca did not change estrogen levels but did improve embryo survival in mice, and red and black maca protected bone strength in rats whose ovaries had been removed (a standard aging-and-bone-loss model) without acting like estrogen on the uterus. The review's abstract also states that human clinical trials found maca helpful for sexual difficulties and for sperm count and motility, though the specific numbers behind that claim sit in parts of the original article not available in this record. The author concludes that more chemical and mechanistic research is needed, pointing out that macamides (compounds unique to maca) may explain some of its effects on sexual behavior, though extracts with almost no macamides worked too, meaning other compounds are likely involved as well. Because most of what is captured here comes from animal studies rather than human trials, these findings are best read as promising groundwork pointing toward further human research, useful for understanding why maca is traditionally valued, but not as settled clinical guidance for treating any specific condition today.

Dongho Shin et al. (2023) · The world journal of men's health

This randomized, double-blind, placebo-controlled trial with 80 men explored whether Maca (Lepidium meyenii), a root vegetable traditionally grown high in the Peruvian Andes and eaten as a nutritional "superfood," can ease late-onset hypogonadism (LOH), the cluster of low-testosterone-type symptoms, such as fatigue, low mood, reduced libido, and erectile difficulty, that many men develop with age even when their blood testosterone level is technically normal. Because standard testosterone replacement therapy carries cardiovascular and prostate-cancer risks, researchers wanted to know whether Maca, long used as a folk aphrodisiac and fertility aid, could offer relief without those risks. Eighty men over 40, recruited as outpatients at two South Korean hospitals and randomly split into two groups, took either 1,000 mg Maca tablets or an identical-looking placebo, two tablets three times a day before meals (about 5 grams of Maca daily), for 12 weeks. Neither the men nor the study staff knew who was getting the real supplement. Researchers tracked symptoms with four standard questionnaires covering overall aging-male symptoms, androgen deficiency, erectile function, and urinary symptoms, and ran blood tests for testosterone, cholesterol, and other safety markers at baseline, 4 weeks, and 12 weeks. Only the Maca group showed real improvement: overall symptom scores dropped by nearly 11 points from baseline (p<0.0001), while placebo barely moved (statistically unchanged, p=0.5007), and the difference between groups was highly significant (p<0.0001). Androgen-deficiency screening flipped from mostly positive to mostly negative in the Maca group (70.7% down to 56.1% at 12 weeks, p<0.0001 versus placebo). Erectile function scores rose by 14 points with Maca (p<0.0001, meaning a clear improvement) while the placebo group's scores actually fell, and urinary symptom scores improved with Maca too (p=0.0025) with no such change on placebo. Notably, none of this tracked with testosterone levels, which barely budged in either group, suggesting Maca works through some other pathway the study did not pin down. Only two participants reported mild stomach upset, and no serious safety issues turned up in blood work or vital signs. In men who were not candidates for testosterone therapy, this study found Maca well tolerated, with its effects on sexual and urinary symptoms rather than on lab-measured testosterone itself. The trial ran only 12 weeks, so it cannot say whether benefits last, and every participant was Korean, so results may not generalize to other populations. The researchers themselves flag that the biological mechanism behind Maca's effect is still unknown and call for longer, more mechanistic follow-up studies.

Norka Ulloa Del Carpio et al. (2024) · Frontiers in pharmacology

This 2024 review pulled together the science on maca (Lepidium meyenii), an Andean root long eaten as food and used as a traditional remedy. Maca's chemical makeup varies with the plant's ecotype, growing conditions, and processing, giving rise to a complex mix of bioactive compounds called macamides, macaenes, and glucosinolates. Rather than running one new experiment, the authors gathered evidence from lab studies, animal research, and human clinical trials to map out what science currently knows, and does not yet know, about maca's effects and safety. Because this is a literature review rather than a single study, there is no one group of participants or one experimental design to describe. Instead, the authors drew on a mix of test-tube studies, rodent experiments, and human trials identified across the maca research, including safety data submitted for the United States Pharmacopeia's evaluation of maca as a dietary ingredient for the National Formulary, covering root powder, gelatinized powder, and various purified extracts sold as supplements. The review's central finding is that maca appears to act as an adaptogen (a substance that helps the body handle stress) by influencing the hypothalamus-pituitary-adrenal axis (the body's central stress-response system), likely through macamide compounds working via serotonin and cannabinoid-receptor pathways. Lab and animal studies point to neuroprotective, anti-inflammatory, and antioxidant effects, including in models of prostate enlargement and lung and liver inflammation. In humans, the review describes maca research as concentrated on sexual health, with reported improvements in sexual desire, erectile function, and general wellbeing in men, plus some evidence for easing menopausal symptoms in women and improving physical performance, though the review does not provide the specific numbers behind these findings. Safety testing found generally low toxicity, though a small number of people reported side effects such as stomach upset, headache, and irritability, and rare reports of vaginal bleeding or a manic episode. The authors are candid that inconsistent study designs, doses, and treatment lengths across the maca research make results hard to compare directly, and they call for more standardized studies to pin down maca's mechanisms and confirm its benefits before firmer guidance can be offered. This review is best read as a map of where maca's promising leads are, especially sexual health and neuroprotection, rather than as proof of any specific effect on any one condition.