Lepidium meyenii Walp. (or the closely related Lepidium peruvianum L.) — a root vegetable grown at extreme altitude in the Peruvian Andes, traditionally used for energy and fertility, studied as an adaptogen with effects on libido and sexual function, and at the center of a documented case of agricultural biopiracy.
Maca grows in the Andes Mountains at an altitude of roughly 5,000 meters, mainly in Peru — one of the world records for a cultivated crop grown at altitude. Its edible part is a tuber resembling a large white radish.
The Inca used maca to toughen their warriors, and it has likely been cultivated and used for several millennia in the Andean highlands, where it remains one of the world's highest-altitude cultivated crops.
Maca's modern history includes a documented, often-cited case of biopiracy: the root was exported from Peru by a university ethnobotanist and sold to a company that filed patents on its effects — patents later ruled illegitimate. The United States has never signed the Convention on Biological Diversity, and the root was reportedly resold at roughly 100 times its original purchase price, with no share of those profits returned to Peru, the country of origin.
⚠ A Patent, and a Conflicting Independent Finding
A U.S. patent specifically claims maca raises testosterone. Independent research has since found maca does not exert direct androgenic activity, and a separate human trial found no relationship at all between maca's effect on sexual desire and serum testosterone. See Mode of Action and Safety & Precautions.
Two compound families named directly after the plant itself — unique to maca and central to its research story.
Macamides — including N-benzyl-5-oxo-6E,8E-octadecadienamide and N-benzylhexadecanamide — are a class of alkamides found specifically in maca.[3]
Macaenes are unique unsaturated fatty acid derivatives also specific to this root.[3]
Maca additionally contains steroids structurally similar to sex hormones — part of the basis for its traditional and commercial reputation around sexual function.
Macaridine (1,2-dihydro-N-hydroxypyridine) is a specific alkaloid marker compound, alongside lepidilines A and B and lepidine.[3]
⚠ Effects on Desire Without a Hormonal Signature
Maca's effect on sexual desire has been shown to be independent of testosterone.
A human trial found maca improved sexual desire with no relationship at all to serum testosterone levels — meaning whatever maca's active compounds are doing, raising this particular hormone does not appear to be how they're doing it.[15]
Only the root is used, prepared as a flour from carefully selected tubers.
Maca is processed into a flour made from the tubers, which must be hard and free of cracks. Commercial products are most commonly sold as gelatinized powder (the form used in most clinical trials) or as a dry extract in capsule form.
Documented across three separate human trials, each targeting a different outcome.
These are the specific doses used in the trials cited above, targeting different outcomes — not one universal recommendation. Confirm dosing with a healthcare provider.
A genuinely food-like nutritional profile alongside several plant-specific bioactive compound families.
Documented adaptogenic activity for the root.[4]
Antidepressant effect and improved learning ability in ovariectomized mice.[5]
Neuroprotective activity is documented, with research exploring possible relevance to Parkinson's disease specifically flagged as uncertain in the primary literature.[6][7][8][9]
Maca polysaccharides are antioxidant, anti-fatigue, antitumoral, immunomodulating, and hepatoprotective.[2][10][11]
An extract improves symptoms associated with age-related androgen deficiency, including erectile function, without prostate-related adverse effects, and improves subjective general and sexual well-being in treated patients.[12][13]
A systematic review concludes that maca's sexual-function-stimulating properties require further confirmation.[14]
Increases sexual desire in adult healthy men, in a trial that specifically found no relationship between this effect and serum testosterone levels.[15]
Improves spermatogenesis in male rats, improves fertility, inhibits altitude-induced spermatogenesis alterations, stimulates progesterone and testosterone in mice, and increases sexual performance in male rats.[16][17][18][19][20][21]
A U.S. patent claims oral maca powder combined with deer or elk antler velvet (used in Traditional Chinese Medicine) raises testosterone levels in men.[22]
The antler velvet component of that combination contains glycosaminoglycans, epidermal growth factor, and polypeptides that support fracture healing by stimulating chondrocyte and osteoblast precursor proliferation — properties of the antler, not maca itself.[23][24][25]
Alkaloids are proposed as possible hypothalamic regulators modulating LH, FSH, HCG, and prolactin secretion, and possible stimulants of calcitonin, parathyroid hormone, and testosterone — all explicitly flagged as uncertain in the primary literature.
An independent study found that maca does not exert direct androgenic activity — a finding that sits in direct tension with the patented commercial claim above.[31]
Oral administration of black or red maca extract is associated with safety and efficacy for altitude-sickness prevention, normalizing polycythemia in highland residents when hemoglobin levels are abnormal.[28][29]
Reviewed among herbal medicines studied for polycystic ovary syndrome (PCOS).[26][27]
From menopause and fatigue to altitude sickness — a genuinely varied indication list for a single root.
A proposed hypothalamic-hormonal mechanism, explicitly marked as uncertain in the primary literature.
Maca's alkaloids are proposed to act as hypothalamic regulators, modulating the secretion of luteinizing hormone (LH), follicle-stimulating hormone (FSH), human chorionic gonadotropin (HCG), and prolactin.
The same alkaloids are also proposed to stimulate calcitonin, parathyroid hormone, and testosterone — but the primary literature itself flags each of these specific claims with a question mark, reflecting genuine scientific uncertainty rather than established fact.
A favorable safety profile, helped by centuries of use as an actual food.