Exploring the chemical and pharmacological variability of Lepidium meyenii: a comprehensive review of the effects of maca.

The short version

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.

Key findings

• Maca (Lepidium meyenii) is a nutrient-dense Andean root whose chemical makeup, including macamides, macaenes, and glucosinolates, varies depending on how and where it is grown and processed.
• This review found the strongest evidence for maca's traditional adaptogenic reputation in its effects on neuroprotection and men's sexual health, including improved sexual desire, erectile function, and general wellbeing.
• Some evidence also points to eased menopausal symptoms in women and improved physical performance, though the review does not report the specific numbers behind these findings.
• Safety data across animal and human studies suggest maca is generally well tolerated at typical supplement doses, with only occasional mild side effects like stomach upset or headache, and rare reports of vaginal bleeding or a manic episode.
• Because study designs, doses, and treatment lengths vary widely across the maca research, the authors call for more standardized studies before firm treatment recommendations can be made.

Common questions