No use of maca is proven to work. Maca is a Peruvian plant related to the cabbage family, sold as powder, capsules and tablets. Human studies are few and small: two systematic reviews call the evidence for sexual function and menopause symptoms limited, and a 2022 meta-analysis calls the semen-quality evidence unclear.
Quick facts about maca root
| Item | What the research shows |
|---|---|
| Plant | Lepidium meyenii, also called Lepidium peruvianum |
| Forms | Capsules, tablets and powders, per the Memorial Sloan Kettering herb guide; MedicineNet also lists liquid extracts |
| Doses used in trials | 1.5 g and 3.0 g per day |
| Study lengths reported in these trials | 12 weeks in the 2003 men’s trial, and four months in a small study MedicineNet describes |
| Human trials in the reviews | 4 randomized trials (2010 review), 4 (2011 review), 5 (2022 meta-analysis) |
| Main studied uses | Sexual desire and function, menopause symptoms, semen quality, sexual side effects of antidepressants, physical performance |
| Strength of evidence | Limited to unclear, according to the reviews below |
What the human evidence shows
The sections below summarize the main uses studied in human trials.
Sexual desire and sexual function
The 2010 systematic review of sexual function looked at four randomized trials comparing maca with placebo. The populations were healthy menopausal women, healthy adult men, healthy cyclists, and men with erectile dysfunction. Two trials, in healthy menopausal women and in healthy adult men, found a significant positive effect on sexual dysfunction or sexual desire. A trial in healthy cyclists found no effect. A trial in men with erectile dysfunction showed significant effects on the IIEF-5 score. The authors called the evidence limited, because the number of trials, their total sample size and their quality were too small for firm conclusions.
A 2009 double-blind trial in men with mild erectile dysfunction measured subjective effects on well-being and sexual performance. The Memorial Sloan Kettering herb guide summarizes its preliminary findings as suggesting maca may enhance subjective sexual well-being in men.
Menopause symptoms
The 2011 menopause systematic review included four randomized trials that compared maca with placebo in healthy perimenopausal, early postmenopausal and late postmenopausal women. The trials used the Kupperman Menopausal Index and the Greene Climacteric Score. All four favored maca. The authors also said there have been very few rigorous trials, the total sample was too small for firm conclusions, and safety has not been proved yet.
Sexual dysfunction linked to antidepressants
A 2008 double-blind, randomized pilot study gave 20 people in remission from depression, 17 of them women with a mean age of 36, either 1.5 g or 3.0 g of maca per day. These people had sexual dysfunction caused by SSRI antidepressants. Ten completed the study. In the 9 people on 3.0 g, analyzed on an intent-to-treat basis, scores on two sexual function scales improved significantly: the ASEX fell from 22.8 to 16.9 and the MGH-SFQ fell from 24.1 to 17.0. The 1.5 g group did not show that change. The authors wrote that maca was well tolerated and that the effect may be dose-related. With 20 people, this is a first look, not confirmation. The Memorial Sloan Kettering guide also lists a 2015 placebo-controlled trial in women and says several studies suggest maca improves antidepressant-related sexual dysfunction. If you take an antidepressant, talk to your prescriber before any change, and do not adjust it on your own.
Semen quality and male fertility
The 2022 semen quality meta-analysis searched nine databases and included five randomized trials. Three trials in men with infertility gave mixed results on semen quality, including sperm concentration and motility. Two trials in healthy men were also mixed. Pooled, maca did not clearly raise sperm concentration compared with placebo: the mean difference was 2.22, with a 95% confidence interval of -2.94 to 7.37. That range includes zero, so there was no clear difference. The authors called the effects unclear and the trials too few and too small for firm conclusions.
MedicineNet describes a four-month study in nine healthy men who took maca tablets and had higher seminal volume, sperm count and motility. That is one small study, and it sits beside the 2022 review’s mixed results. The 2003 men’s hormone trial is covered in the safety section below.
Physical performance and energy
The 2024 systematic review and meta-analysis in the journal Nutrients included 21 studies and pooled 16 of them. The studies were in animals and humans. The main outcomes were tests such as the forced swimming test, rota-rod test, grip strength, and blood and lactic acid levels. The pooled effects were large for all outcomes. The authors concluded that maca’s compounds, mainly macamides, increase physical performance, with a greater effect at higher doses. Because the review pools animal and human studies together, its large effects cannot be read as a human result alone. The Memorial Sloan Kettering guide notes that animal studies suggest maca may increase endurance, and that only a few small trials have been done in humans.
Women’s fertility and other animal findings
For women’s fertility, the work the Memorial Sloan Kettering guide describes is in animals. In female rats, maca powder raised luteinizing hormone during the LH surge in a dose-dependent way. A 2021 randomized, double-blind, placebo-controlled trial in infertile patients is listed in the same guide’s references, so its full abstract is the place to check the result. The guide also lists animal studies on memory deficits, endurance and sexual function. These are animal findings, not human results.
Doses used in studies
These are the amounts researchers gave in the trials above. They are not a recommendation for you.
| Study | Dose | Length | Who took it |
|---|---|---|---|
| 2008 pilot, SSRI-related sexual dysfunction | 1.5 g/day or 3.0 g/day | — | 20 people in remission from depression, 17 women |
| 2003 hormone trial | 1.5 g or 3.0 g/day of gelatinized maca | 12 weeks | Healthy men aged 21 to 56 |
| Small study described by MedicineNet | 1,500 or 3,000 mg/day, as tablets | Four months | Nine healthy men |
The 2024 review found a greater effect at higher doses in its pooled analysis. The trials above report daily totals. For timing, check the label or ask your clinician.
How long before it works?
The 2003 men’s trial measured hormones at 2, 4, 8 and 12 weeks. MedicineNet reports that in one study sexual desire improved after eight weeks of gelatinized maca, and in another it improved after as few as 14 days with a maca extract. The semen studies measured sperm, not pregnancy, so they cannot tell you how long conception takes. None of the trials on this page reported weight gain as an outcome, and the cited sources give no weight-gain data.
Safety, side effects and medicine interactions
The safety picture is incomplete. The sources below give the cautions, and they do not always agree.
What is the downside to maca?
The reported downsides are menstrual changes, mood changes, cramps, stomach upset, sleep problems, and a few lab and hormone effects. The table lists them by concern.
| Concern | What the sources say |
|---|---|
| Reported side effects | The Memorial Sloan Kettering guide lists subjective reports of altered menstrual cycles, moodiness, cramps, gastritis and insomnia. Flu-like symptoms and vomiting were reported in one study, but it is unclear if maca caused them. The same guide opens by saying side effects have not been reported, so read both statements together. |
| Case report, hormones | The Memorial Sloan Kettering guide describes a woman in her thirties who took maca powder, one teaspoon daily, and had prolonged bleeding between periods and elevated testosterone. |
| Menstrual bleeding | MedicineNet says some women have reported heavy and prolonged menstrual bleeding. |
| Lab tests | Maca may interfere with testosterone immunoassays. Tell your clinician if you took maca before testosterone labs. |
| Medicines | In hypertensive rats, maca enhanced the blood pressure-lowering effect of losartan. The Memorial Sloan Kettering guide says clinical relevance has yet to be determined. MedicineNet says there are no known interactions with medicines, herbs or supplements. The sources disagree, so tell your clinician about any medicine you take. |
| Thyroid | MedicineNet says people with thyroid conditions should avoid maca because it may cause thyroid enlargement (goiter). |
| Metabolic syndrome | MedicineNet says maca may cause a moderate elevation of AST (aspartate aminotransferase) and of diastolic blood pressure in patients with metabolic syndrome. |
| Pregnancy and breastfeeding | The Memorial Sloan Kettering guide says maca may not be safe if you are pregnant or breastfeeding. |
Does maca lower estrogen?
The evidence does not settle whether maca changes estrogen in people. The Memorial Sloan Kettering guide says lab extracts of maca showed estrogenic activity, and MedicineNet says maca extracts can act like estrogen. In the 2003 men’s trial, estradiol did not change. A 2008 study in postmenopausal women reported benefits on psychological symptoms and sexual dysfunction, and its title says those benefits were not related to estrogen or androgen content.
Does maca root bloat you?
The reported digestive effects are gastritis and cramps in the Memorial Sloan Kettering guide. A supplement site’s guide adds stomach pain, diarrhea and nausea, which it says usually ease when the dose is lowered.
Who should talk to a clinician first
- Anyone who is pregnant or breastfeeding.
- Anyone with a hormone-sensitive condition, such as breast, uterine or ovarian cancer, uterine fibroids or endometriosis. The Memorial Sloan Kettering guide says maca may affect cancer treatment.
- Anyone with a thyroid condition or metabolic syndrome.
- Anyone taking a medicine, especially a blood pressure medicine such as losartan.
- Anyone taking an antidepressant. Talk to your prescriber first, and do not change your medicine on your own.
- Anyone who has a testosterone test planned.
What is still unknown
Most human trials are small, many are short, and the reviews rate the evidence as limited, mixed or too small. Safety with long-term use has not been proved. The Memorial Sloan Kettering guide says doctors have not studied maca’s other uses to see if they work. One study MedicineNet describes found that black maca, but not red or yellow, raised sperm production and motility. Which color matters is unsettled.
Does maca help belly fat, curves, buttocks or weight gain?
None of the human trials above measured body fat, weight or body shape. The uses the Memorial Sloan Kettering guide lists are energy and strength, fertility, sex drive and menopause symptoms. Belly fat, curves and buttock size are not on that list. Claims about body shape are not part of the research, so treat them as marketing.
Is maca better than ashwagandha?
Nothing on this page compares maca with ashwagandha, and the studies here test maca alone. Each herb has its own trials, so compare them by the outcome you care about, the dose studied and the people studied.
Fermented beet with maca for men: what is the research?
The studies above test maca on its own, not with fermented beet. For beet root on its own, see our beet root benefits evidence page.
How to read a maca label
Use this table to check any product that lists maca.
| Label item | What to check |
|---|---|
| Amount per serving | Compare the grams or milligrams with the 1.5 g and 3.0 g studied. Check whether a serving is one capsule, one scoop or one tablet. |
| Form | Powder, capsule, tablet or extract. The 2003 trial used gelatinized maca. MedicineNet reports that in one comparison maca extract seemed to work better than gelatinized maca or maca flour for male sexual desire. |
| Color | Yellow, red, purple or black. The Memorial Sloan Kettering guide notes that the colors may have different biological effects. |
| Proprietary blends | If maca sits in a blend, the label may not show how much maca is in each serving. Ask the maker for that amount before you buy. |
| Warnings | Read any warnings and tell your clinician about the product, including before any testosterone test. |
Herbal supplements are stronger than herbs used in cooking, the Memorial Sloan Kettering guide notes, so food amounts will not help you judge a dose. To test a label’s claims against the evidence, read ingredient evidence vs marketing claims.
By ClinicalStudyConnect.com Research Desk
This article is for general information purposes only and does not constitute medical advice. Consult your doctor or qualified healthcare provider before making changes to your health routine.