Maca
EVIDENCE: WEAKAlso sold as: Lepidium meyenii, Peruvian ginseng, maca root, gelatinized maca
Maca is a Peruvian root vegetable with small human studies suggesting modest libido benefits. Research commonly uses gram-level amounts. The evidence is more limited than its broad supplement reputation suggests.
Compiled by iSupplementReviews editorial team ·Updated 2026-10-13 · 5 sources
- Type
- Botanical root
- Studied dose
- 1.5–3 g/day
- Best form
- gelatinized powder or standardized extract — gelatinization improves digestibility and concentration
- Our rating
- WEAK — Mostly small, animal, or traditional evidence
What is maca?
Maca (Lepidium meyenii) is a root vegetable related to radish, grown at high altitude in the Peruvian Andes. It has a long history as food. Supplement research mainly concerns libido and vitality at gram-level amounts.
The forms that matter
| Form | What it is | Notes |
|---|---|---|
| Gelatinized maca | Starch-removed powder | More concentrated, easier to digest — the quality pick |
| Raw maca powder | Whole ground root | Starchier; the bulk form |
| Standardized extract | Concentrated active ingredients | Less common; less trial basis than powder |
| Color grades (yellow/red/black) | Root phenotypes | Distinctions are mostly animal-data and marketing |
Where does it come from?
Exclusively the high Andes of Peru (and a little Bolivia): 4,000+ meters up, where almost nothing else grows. Its status as an everyday food is the strongest safety evidence it has.
How does maca work in the body?
Unresolved. It contains unique compounds (macamides, macaenes) and glucosinolates, and trials show libido effects without hormonal changes, implying a non-endocrine pathway. Mechanistically interesting, commercially inconvenient: nobody can tell you exactly why it works.
What is maca claimed to do?
Libido (both sexes), erectile function, semen quality, mood and energy, menopausal symptoms, and prostate support (red maca; animal data only).
What does the research show?
| Claim | Evidence | Dose studied | Verdict |
|---|---|---|---|
| Libido in men | Small trials + systematic review | 1.5–3 g/day | Modest positive |
| Mood/sexual function, postmenopausal women | Small trial (Brooks 2008) | 3.5 g/day | Early positive |
| Erectile function | One pilot (Stone 2009) | 2.4 g/day | Weak |
| Semen parameters | Small trials, inconsistent | 1.5–3 g/day | Mixed |
| Testosterone levels | Consistent nulls | any | Not shown |
| Energy/athletic performance | Anecdote + animal | — | Insufficient |
Libido — the main ingredient (and its limits)
Gonzales et al. (2002, Andrologia): 57 men, 1.5 or 3 g/day for 12 weeks: self-reported libido up ~40% at weeks 8–12 versus placebo, with no change in testosterone or estradiol. Every later trial repeated the pattern: desire up, hormones flat. The mechanism isn’t endocrine.
The systematic review’s grade
Shin et al. (2010, BMC Complement Altern Med) reviewed the sexual-function trial base and rated it “limited evidence”: small trials, short durations, positive but low-powered. That’s the correct academic verdict on maca: a real signal, a thin base.
Women, too
Brooks et al. (2008, Menopause): 3.5 g/day for 6 weeks reduced anxiety, depression, and sexual-dysfunction scores in postmenopausal women, again without hormone changes.
What doesn’t maca do?
It doesn’t raise testosterone (consistent nulls), doesn’t reliably improve erections (one tiny positive), and gram-level dosing means sub-gram label amounts are below the studied range: 250 mg cannot reach the 1.5 g floor where trials start.
What dose was studied?
| Goal | Dose | Duration |
|---|---|---|
| Libido | 1.5–3 g/day | 8–12 weeks |
| Postmenopausal mood/sexual | 3.5 g/day | 6 weeks |
| Mild ED (pilot) | 2.4 g/day | 12 weeks |
Consistently gram-level: the single most important number in maca’s review.
Side effects
Mild digestive upset (the starch, in raw powder). Generally safe; it’s food. Theoretical flag: raw maca carries goitrogenic glucosinolates, relevant only to iodine-deficient heavy users of raw product.
Drug interactions
None well-documented; its food status means a short interaction list. Thyroid caution is theoretical for raw, high-dose use.
Who should not take maca?
Almost nobody. People with hormone-sensitive conditions sometimes avoid it by convention (despite no demonstrated hormonal effect); thyroid patients should prefer gelatinized.
What the authorities say
MSKCC’s About Herbs entry records the libido/fertility claims alongside the “insufficient evidence” grade, consistent with the systematic review. No authority endorses a hormonal mechanism because none has been shown.
What to know about maca
Small human studies suggest modest libido effects at about 1.5–3 g daily. A much smaller blend amount does not establish the same result. Its history as food should be distinguished from claims about concentrated preparations.
Frequently asked questions about Maca
Does maca increase libido?
A little, probably. Small trials (Gonzales et al., 2002 onward) found improved self-reported desire at 1.5–3 g/day versus placebo, and a systematic review (Shin 2010) rated the evidence positive but limited. Small trials, short durations, modest effect: real but not dramatic.
Does maca raise testosterone?
No, and that's the interesting part. The libido effect appears without testosterone changes; trials consistently show no hormonal shifts. Whatever maca does for desire, it isn't a hormone mechanism.
What is gelatinized maca?
Maca powder that's been heat-processed to remove starch: more concentrated per gram and easier to digest than raw powder. 'Gelatinized' on a label is a legitimate quality marker.
Are red, black, and yellow maca different?
Different root phenotypes with different traditional uses: black for male fertility/memory claims, red for prostate-size effects (rat studies showed reduced prostate size), yellow the common type. Human trials almost never distinguish them; treat color claims as marketing refinements.
Does maca help erectile dysfunction?
One small pilot (Stone et al., 2009) found a modest erectile-function score improvement at 2.4 g/day in men with mild ED; a single small trial, so 'possible' rather than 'proven.'
References
- [1]Gonzales GF et al. — Maca (Lepidium meyenii) on sexual desire in healthy men, RCT (Andrologia, 2002)
- [2]Brooks NA et al. — Maca for psychological symptoms and sexual dysfunction in postmenopausal women (Menopause, 2008)
- [3]Shin BC et al. — Maca for sexual function: systematic review (BMC Complement Altern Med, 2010)
- [4]Zenico T et al. — Maca extract on well-being and sexual performance in mild ED, pilot trial (Andrologia, 2009)
- [5]Memorial Sloan Kettering — Maca (About Herbs database)
Products we reviewed containing Maca
Based on recorded labels or seller-described formulas. Inclusion does not establish a match to the strains, preparations or amounts studied here; check each review's disclosure limits.