Maca is a root vegetable from the Peruvian Andes used primarily to boost libido, support fertility, ease menopause symptoms, and improve energy. It’s sold as a powder or capsule supplement, with most clinical trials using doses between 1.5 and 3.0 grams per day. While maca has a long history as a food crop, modern research has started to clarify which of its popular uses hold up to scrutiny and which remain unproven.
Sexual Desire and Function
The most common reason people take maca is to increase sex drive, and this is also its best-studied use. In a 12-week trial of healthy adult men, those taking maca reported improved sexual desire compared to placebo, with the effect appearing by 8 weeks. Notably, maca did not change testosterone or estradiol levels in these men, suggesting it works through a different pathway than simply raising sex hormones.
Maca has also been studied specifically for sexual side effects caused by antidepressants. In a dose-finding trial of people taking SSRIs, those on 3.0 grams per day saw significant improvements in sexual function scores, while those on 1.5 grams per day did not. A separate placebo-controlled trial in women on antidepressants found that postmenopausal women experienced improved ability to reach orgasm on maca, while premenopausal women saw improvements in arousal. The effects were modest but consistent across multiple measures.
Male Fertility
Beyond desire, maca appears to influence sperm quality. In a 12-week placebo-controlled pilot study of healthy men, those taking maca showed improvements across every measured parameter: sperm concentration rose by 14%, total sperm count by 20%, motile sperm count by 14%, and normal sperm shape by 21%. These were trends rather than statistically significant differences, but they lined up with findings from other research groups.
An earlier study of nine healthy men found larger effects over a longer period. After 16 weeks, sperm concentration increased by 35%, total sperm count by 84%, and the count of actively swimming sperm jumped by 109%. A third study, this one in men with diagnosed infertility, found a more modest but statistically significant 10% increase in motile sperm and 12% improvement in normal sperm shape after 12 weeks. The pattern across studies suggests maca has a real, if variable, effect on sperm quality.
Menopause Symptom Relief
For women in early menopause, maca has shown promise in reducing some of the most disruptive symptoms. A double-blind, placebo-controlled crossover study found that a pre-gelatinized form of maca significantly reduced hot flashes, excessive sweating, interrupted sleep, and nervousness. These improvements were measured using standardized symptom scores and reached statistical significance.
What makes these results interesting is the same finding that shows up in the male studies: maca doesn’t appear to work by directly changing hormone levels. Multiple trials have measured reproductive hormones like estrogen, testosterone, luteinizing hormone, and follicle-stimulating hormone in people taking maca, and none have found significant changes. Whatever maca is doing, it seems to happen downstream of the hormones themselves, possibly by influencing how the body responds to its own hormonal signals.
Energy and Physical Performance
Maca is widely marketed as an energy booster, and the evidence here is mixed but encouraging in certain areas. A study of male cyclists found that 14 days of taking 2 grams of maca per day shaved about one minute off their 40-kilometer time trial, a small but statistically significant improvement. Animal studies consistently show dose-dependent increases in endurance, with higher doses producing larger effects.
For general fatigue, the picture is less clear. One study in adult women measured subjective fatigue on a visual scale and found that while fatigue dropped notably in the maca group (from 7.55 to 5.20 on a 10-point scale), the placebo group improved almost as much. Another study measuring time to exhaustion in healthy men found no difference between maca and placebo. The takeaway: maca may offer a small edge for trained athletes, but it’s unlikely to replace sleep or proper nutrition as an energy strategy.
How Different Colors Compare
Maca roots come in several colors, and research increasingly shows these aren’t just cosmetic differences. The three most studied varieties are yellow, red, and black, each with a distinct chemical profile and somewhat different effects.
- Black maca has the strongest evidence for male fertility, memory, and physical endurance. It contains higher levels of macamides and fatty acids, the compounds most linked to maca’s effects on the nervous system. In studies at high altitude, black maca also reduced blood sugar levels and lowered blood pressure.
- Red maca stands out for prostate health and mood. It reduced prostate size in animal studies where the other colors had little or no effect. Red maca also contains more GABA, a calming brain chemical, and showed the fastest improvement in chronic mountain sickness scores, a general measure of well-being at altitude.
- Yellow maca is the most common variety and has moderate effects across categories. It shows some benefits for sperm production (less than black maca) and has been tested for female fertility with mixed results.
All three colors have shown antidepressant-like effects in research, so mood support appears to be a shared trait rather than color-specific.
What’s Inside Maca
Maca’s effects come from a unique set of plant compounds not found in other foods. The most studied are macamides, which are fatty acid molecules that have demonstrated neuroprotective, anti-fatigue, and hormone-modulating activity. A related group called macaenes is less researched but may contribute additional benefits.
Maca also contains glucosinolates, the same sulfur-containing compounds found in broccoli and other cruciferous vegetables. When broken down by enzymes, these produce isothiocyanates, which have been studied for cancer prevention and hormonal effects. The root also contains alkaloids, plant sterols, and flavonoids, giving it a broad and complex chemical profile that likely explains why its effects touch so many different body systems.
Dosing and Safety
Clinical trials have primarily used doses of 1.5 to 3.0 grams per day, with 3.0 grams showing stronger effects in studies that tested both amounts. Most studies run 8 to 12 weeks before measuring outcomes, so maca is not something that produces overnight results.
Maca has a strong safety record. No fatal adverse effects have been reported, and preclinical studies show low toxicity even at high doses. One study specifically looked at whether maca affects thyroid function by measuring TSH (a thyroid hormone marker) and found no changes. This is relevant because maca belongs to the same plant family as broccoli and cabbage, which contain goitrogens that can theoretically interfere with thyroid function in large amounts. At the doses used in supplements, this does not appear to be a concern. Animal research also found no effects on embryonic development at high doses, though human data on pregnancy and breastfeeding is limited.
The most practical consideration is that maca does not change circulating hormone levels. This is both reassuring (it won’t throw your hormones out of balance) and informative (it won’t show up on blood work). Its effects appear to happen through more subtle mechanisms in how the body processes and responds to its existing hormones.