Maca
Lepidium meyenii, also sold as Lepidium peruvianum, from the mustard family
A root vegetable grown high in the Peruvian Andes, eaten there as food and sold dried as a powder, and studied mostly for sexual function, menopause, semen quality and sport. Here is every study in people we could find, sorted from each study's summary.
- Part used: root
- Most tested: 2,000 mg a day
- Usually 12 weeks
From every paper to the studies that matter
Most research on maca is in the lab, in animals or about the plant's chemistry. Only a small share tests it in people, and that is what this page is about.
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1,305 papers mention maca.Every record in PubMed, all years
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41 are about people.The rest: 515 lab and animal studies, 84 reviews, 665 on chemistry, farming and more
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24 give maca on its own.3 more test it inside a blend
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18 are randomised against a placebo.Randomised controlled trials In a randomised controlled trial, people are put into groups by chance, one taking the treatment and one a placebo or other comparison. Chance spreads differences such as age and health evenly, so a difference between the groups is more likely to be down to the treatment., the strongest kind of study
Bar lengths use a square-root scale so the small numbers stay visible.
How much research there is
- 24 studies giving maca to people
- 18 of them randomised against a placebo A placebo-controlled trial compares a real treatment with a dummy that looks the same, the placebo. People often feel better when they expect to, so comparing against a placebo shows how much of the change comes from the treatment itself.
- 924 people taking part, where studies say
- 20 systematic reviews A systematic review searches for every study on a question in a set, written-down way, judges the quality of each and sums up what they show together. Many include a meta-analysis. The Atlas lists these as pooled reviews. pooling the trials
Studies in people, by year published
Maca on its own.
What the studies looked at
Each study can measure several things. Choose a topic to see its studies in the list below.
Studies in people with a diagnosed condition are counted here and listed with their population. We describe what they measured, not what they might treat. Most studies also report safety; see below.
What was tested, and how much
Most studies gave dried maca root as a powder, often gelatinised (heat-treated), a few grams a day. Others used extracts made in different ways, and yellow, red or black maca, so the same number of milligrams doesn't always mean the same amount of root. Most gave it every day for about 12 weeks.
Daily amount, one dot per study
Studies per extract
Named extracts are the maker's brand. "Not named" means the study didn't say.
Have a label with a %? Work out the macamides in your own label
All studies in people
Filter the list, then open a study on PubMed. Each row comes from the study's published summary.
| Study | Who took part | People | Extract and daily dose | Length |
|---|---|---|---|---|
| Weng 2025RCT, placebo | Healthy men | 20 | Not named, 4,500 mg | 12 weeks |
| Wu 2025Crossover, placebo | Well-trained male basketball players | 10 | Not named, 2,000 mg | 2 weeks |
| Ross 2024Other | Two men with low testosterone or infertility | 2 | Maca-OG | – |
| Shin 2023RCT, placebo | Men with late-onset hypogonadism symptoms | 80 | Gelatinized maca, 6,000 mg | 12 weeks |
| Lee 2023Single-arm or open-label | Male elite athletes | 44 | Black maca extract, 5,000 mg | 8 weeks |
| Kang 2023Crossover, placebo | Elite female adolescent handball players | 8 | Black Maca, 2,500 mg | 4 weeks |
| Melnikovova 2021RCT, placebo | Infertile men | 50 | Yellow maca | 16 weeks |
| Alcalde 2020RCT, placebo | Men with mild asthenozoospermia or oligozoospermia | 69 | Not named, 2,000 mg | 12 weeks |
| Gonzales-Arimborgo 2016RCT, placebo | Adults at low and high altitude | 175 | Black and red maca spray-dried extracts, 3,000 mg | 12 weeks |
| Dording 2015RCT, placebo | Women with antidepressant-induced sexual dysfunction | 45 | Not named, 3,000 mg | 12 weeks |
| Stojanovska 2015Crossover, placebo | Postmenopausal Chinese women | 29 | Not named, 3,300 mg | 6 weeks |
| Melnikovova 2015RCT, placebo | Healthy adult men | 20 | Not named, 1,750 mg | 12 weeks |
| Benites Goñi 2014Single-arm or open-label | Patients with functional dyspepsia | 29 | Not named, 3,000 mg | 4 weeks |
| Zenico 2009RCT, placebo | Men with mild erectile dysfunction | 50 | Maca dry extract, 2,400 mg | 12 weeks |
| Stone 2009Crossover, placebo | Trained male cyclists | 8 | Maca extract | 2 weeks |
| Dording 2008RCT, active or other control | Remitted depressed outpatients with SSRI sexual dysfunction | 20 | Not named | – |
| Brooks 2008Crossover, placebo | Postmenopausal women | 14 | Not named, 3,500 mg | 6 weeks |
| Meissner 2006RCT, placebo | Early-postmenopausal women | 168 | Maca-GO (pre-gelatinized), 2,000 mg | – |
| Meissner 2006Crossover, placebo | Early-postmenopausal women | 34 | Maca-GO (pre-gelatinized), 2,000 mg | 16 weeks |
| Meissner 2006Crossover, placebo | Perimenopausal women | 20 | Maca-GO (pre-gelatinized), 2,000 mg | 16 weeks |
| Meissner 2005Other | Early-postmenopausal women | 20 | Maca-GO (gelatinized), 2,000 mg | – |
| Gonzales 2003RCT, placebo | Healthy adult men | – | Maca Gelatinizada | 12 weeks |
| Gonzales 2002RCT, placebo | Healthy adult men | – | Maca Gelatinizada | 12 weeks |
| Gonzales 2001Single-arm or open-label | Healthy adult men | 9 | Not named | 17 weeks |
What's known about safety
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In trials
No serious side effects were reported in a 12-week trial of 175 adults taking 3 g of extract a day. Reviews say the trials so far are small and its safety hasn't been properly tested. Changes to periods, moodiness, cramps, stomach upset and poor sleep have been reported.
Gonzales-Arimborgo 2016, 175 adults; Lee 2011, review of 4 trials; MSK About Herbs, updated June 2023
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In the UK
Maca root was used as food in Europe before 1997, so it isn't a novel food and can be sold as food and in food supplements. EU decisions on this made before 2021 still apply in Great Britain.
EU Novel Food Status Catalogue (tubers, not novel in food); FSA novel foods authorisation guidance, Oct 2026
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Check first
Its safety in pregnancy and breastfeeding isn't known, and people with a hormone-sensitive cancer, such as breast or womb cancer, are advised to speak to their doctor first. It can upset some testosterone blood tests, and one case report found lead in a maca root powder. Speak to a pharmacist or doctor first if any of this applies or you take regular medicines.
MSK About Herbs, updated June 2023; Srikugan 2011 and Johnson-Arbor 2018, case reports
Where these studies come from
We list every published study of maca in people. Only Lepidium meyenii counts, including maca sold as Lepidium peruvianum, and other Lepidium species are left out. This first version is built from each study's summary; full-paper checks come next.
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We search
PubMed, the world's main library of medical research, for every paper on L-theanine.
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We keep studies in people
Lab and animal work is counted but left out of the list, because it doesn't tell you what happens in people.
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We note the basics
Who took part, how many, how much and for how long, from each study's published summary. A second check corrects what the first read gets wrong.
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We read them in full
Results appear once we've read the whole paper and checked every number. The date at the top shows when this entry was last updated.
Download the study list
Every study in people as a spreadsheet, 24 rows, free to reuse with a link back.
Versions
Each update to the data gets a new version number, so you can tell what changed and when.
See every version
1.0 · 24 Oct 2026. First release. Every published study giving maca on its own to people is listed from its summary. None is read in full yet.
