Maca

Metadata

Approved Indications

European Regulatory Bodies

Maca has not been assessed by any of the three major European phytotherapy regulatory bodies:

• Commission E (Germany): No monograph exists. Maca is not part of the European herbal tradition evaluated by Commission E.
• ESCOP: No monograph. Not within the scope of European scientific cooperative assessment.
• EMA/HMPC: No assessment report or monograph. The herb is not listed in the EU herbal substances inventory for medicinal use.

This is not a negative assessment — these bodies simply never evaluated maca, as it originates from the South American (Andean) food and medicinal tradition rather than the European phytotherapy tradition.

EU Novel Food Status

• EU Novel Food Regulation: Maca root powder was approved as a novel food ingredient in the EU in 2014 (Commission Implementing Decision 2014/155/EU), permitting its sale as a food and food supplement within the European Union.
• Classified as food, not medicine within the EU regulatory framework.

Peruvian Tradition

• Traditional status: Maca has been cultivated and consumed as a staple food crop in the Peruvian Andes for at least 2000 years, grown at altitudes of 4000-4500m in the Junin Plateau — among the highest altitude food crops in the world.
• Traditional indications: Energy, stamina, fertility enhancement, libido, adaptation to high-altitude conditions.
• National cultural heritage: Recognized as a culturally significant crop by the Peruvian government.

United States

• Dietary supplement: Available as a dietary supplement under DSHEA (Dietary Supplement Health and Education Act of 1994).
• No FDA GRAS notice: Maca does not have explicit GRAS status, but it is widely sold as a supplement and food ingredient.

Conditions Treated

Primary (Moderate Evidence)

• Sexual desire and libido (both sexes) — The most consistent clinical finding. Gonzales et al. (2002) demonstrated improved sexual desire in men at 8 weeks with 1.5-3g/day. Brooks et al. (2008) and Dording et al. (2015) showed benefit in SSRI-induced sexual dysfunction. Effect appears independent of hormone levels.
• Male fertility (spermatogenesis) — Gonzales et al. (2001) and Gonzales et al. (2003) demonstrated increased sperm count, motility, and volume. Black maca appears most effective for this indication.

Secondary (Preliminary Evidence)

• Menopausal symptoms — Stojanovska et al. (2015) reported reduced psychological symptoms (anxiety, depression) and sexual dysfunction scores in postmenopausal women. Meissner et al. (2006) demonstrated beneficial effects on hormonal balance markers.
• Exercise performance and energy — Stone et al. (2009) showed improved cycling time-trial performance. Traditional use for stamina and energy at high altitude is consistent with adaptogenic properties.

Emerging/Preclinical

• Cognitive function — Black maca specifically has shown neuroprotective and memory-enhancing effects in animal models (Rubio et al. 2011). Mechanism may involve acetylcholinesterase inhibition and antioxidant effects.
• Bone health — Red maca has demonstrated bone-protective effects in ovariectomized rat models (Gonzales et al. 2010), suggesting potential for osteoporosis prevention.
• Mood and well-being — Preliminary data suggests improvements in depression and anxiety scores as secondary endpoints in several trials, possibly related to adaptogenic properties.

Mechanism of Action

Key Pharmacological Distinction

Maca does not alter circulating levels of testosterone, estradiol, follicle-stimulating hormone (FSH), or luteinizing hormone (LH). This has been consistently demonstrated across multiple clinical trials (Gonzales et al. 2002, 2003; Dording et al. 2008). This distinguishes maca from hormonal supplements (such as DHEA or tribulus) and suggests an entirely different mechanism for its effects on sexual function and fertility.

Primary Mechanisms

1. Endocannabinoid system modulation (FAAH inhibition): Macamides — the unique N-benzylated fatty acid amides found only in maca — are structural analogs of endocannabinoids (anandamide). They act as fatty acid amide hydrolase (FAAH) inhibitors, preventing the breakdown of endogenous anandamide and thereby enhancing endocannabinoid signaling. FAAH inhibition has been linked to anxiolytic effects, mood enhancement, and modulation of reproductive function. This represents the most mechanistically compelling explanation for maca’s effects on subjective desire and well-being.

2. Hypothalamic-pituitary modulation without hormonal alteration: Maca appears to influence subjective sexual desire and energy through effects on hypothalamic function or neurotransmitter signaling without measurably altering circulating sex hormone levels. The precise mechanism remains unclear but may involve subtle neuroendocrine signaling or changes in receptor sensitivity rather than hormone concentration.

3. Glucosinolate-mediated antioxidant effects: As a Brassicaceae family member, maca is rich in glucosinolates (particularly glucotropaeolin and its breakdown products, benzyl isothiocyanate). These compounds activate the Nrf2-ARE antioxidant response pathway, upregulating endogenous antioxidant enzymes (SOD, catalase, glutathione peroxidase). This antioxidant activity may protect spermatozoa from oxidative damage and support overall cellular health.

Secondary Mechanisms

4. Color-specific bioactivity profiles: Different maca ecotypes (distinguished by hypocotyl color) contain varying ratios of bioactive compounds:

   • Black maca: Highest effect on spermatogenesis and cognitive function; richest in glucosinolates.
   • Red maca: Greatest effect on prostate size reduction and bone density; highest anthocyanin content.
   • Yellow maca: Most common commercially; general adaptogenic and libido effects.

5. Nutritional density: Maca root is nutrient-dense (approximately 60% carbohydrate, 10% protein, 8.5% fiber) and rich in iron, calcium, potassium, copper, manganese, and essential amino acids. As a high-altitude staple food, its energizing effects may be partly attributable to nutritional fortification.

6. Alkaloid activity: Maca-specific alkaloids (macaridine, lepidiline A, lepidiline B) have been isolated but their pharmacological contribution is not yet fully characterized.

Clinical Evidence Summary

Clinical evidence for maca consists of several small but generally well-designed randomized controlled trials, with the most consistent findings for sexual desire/libido.

Libido and Sexual Function

Male Fertility

Menopausal Symptoms and Women’s Health

Exercise Performance

Evidence Limitations

• Sample sizes are consistently small (n=8-168, most under 60).
• Many studies originate from one research group (Gonzales laboratory, Peru), raising questions about independent replication.
• Duration of most trials is 6-12 weeks; long-term efficacy data is lacking.
• Heterogeneity in maca preparations (raw, gelatinized, extract, different colors) makes cross-study comparison difficult.
• The 2002 Gonzales libido trial — the landmark study — used self-reported sexual desire as a primary endpoint, which is subjective.
• A 2010 systematic review (Shin et al., BMC Complementary and Alternative Medicine) concluded that evidence was “limited” but “suggestive” for sexual function.

Safety Profile

General Assessment

Maca has an excellent safety profile, supported by a long history of use as a staple food crop in Peru (consumed in quantities of 20-100g/day as a food) and by the absence of serious adverse events in clinical trials. EU novel food approval (2014) further supports its safety for general consumption.

Contraindications

• Hormone-sensitive conditions: Although maca does not directly alter circulating sex hormone levels, a precautionary approach is recommended for individuals with hormone-sensitive conditions (estrogen receptor-positive breast cancer, endometriosis, uterine fibroids) due to incomplete mechanistic understanding.
• Thyroid conditions: Maca contains glucosinolates, which are goitrogenic compounds. Individuals with hypothyroidism or iodine deficiency should exercise caution, as glucosinolate metabolites (thiocyanates, isothiocyanates) can interfere with iodine uptake by the thyroid gland. This concern is most relevant for raw maca consumed in large quantities; gelatinized maca has reduced glucosinolate content.
• Pregnancy and lactation: Maca is considered safe in pregnancy by Peruvian traditional practice and has been consumed as a food by pregnant women in the Andes for centuries. However, there are no controlled clinical studies evaluating safety during pregnancy or lactation. A conservative approach is to avoid concentrated extracts during pregnancy while acknowledging the long traditional food use.

Drug Interactions

• No clinically documented drug interactions. Maca has no known significant interactions with pharmaceutical drugs.
• Theoretical: Given glucosinolate content, theoretical interaction with thyroid medications (levothyroxine) cannot be excluded, though no clinical cases have been reported.
• CYP450: No significant CYP450 inhibition or induction has been demonstrated at typical doses.

Side Effects (at recommended doses)

• Common: Generally very well-tolerated. Mild GI discomfort (bloating, gas) reported occasionally, particularly with raw (non-gelatinized) maca powder.
• Uncommon: Insomnia or increased energy if taken late in the day (reported anecdotally); mild headache.
• No hepatotoxicity signal has been observed in any clinical trial or post-market surveillance.

Toxicology

• No acute toxicity at doses far exceeding therapeutic range (traditional consumption of 20-100g/day as food).
• Subchronic toxicity studies in animals at doses up to 1g/kg showed no adverse effects on organ function, hematology, or histopathology (Valentova et al. 2006).
• No genotoxicity or mutagenicity in standard assays.

Clinical Dosage

Gelatinized Maca Powder (Most Studied Form)

• Standard dose: 1.5-3g/day (the dose range used in the landmark Gonzales et al. 2002 trial)
• Gelatinization involves heating and pressurizing to remove starch, concentrating bioactives and improving digestibility; reduces glucosinolate content (relevant for thyroid safety)
• This is the most clinically supported dose form

Raw Dried Maca Powder

• Typical dose: 3-5g/day
• Traditional Peruvian consumption involves much higher doses (20-100g/day) as a food staple, typically boiled, roasted, or prepared as a fermented beverage (maca chicha)
• Higher glucosinolate content than gelatinized form; goitrogenic potential is greater

Concentrated Extracts

• Dose varies depending on extraction ratio (typically 4:1 to 10:1 concentrates)
• Equivalent dose: Adjust to approximate 1.5-3g of gelatinized powder equivalent
• Standardization is not uniform across commercial products; look for macamide content when available

Color-Specific Recommendations

• Black maca: Preferred for cognitive function and spermatogenesis based on preclinical and preliminary clinical data
• Red maca: Preferred for prostate health and bone density based on animal studies
• Yellow maca: Most widely available and the most commonly used in clinical trials; general-purpose use for libido and energy

Administration

• Timing: Usually taken with meals to improve tolerance; morning or early afternoon preferred due to potential energizing effects
• Duration: Clinical effects on libido typically observed after 6-8 weeks of continuous use; spermatogenesis effects may require 3-4 months

Sources

• Gonzales GF, Cordova A, Vega K, et al. Effect of Lepidium meyenii (MACA) on sexual desire and its absent relationship with serum testosterone levels in adult healthy men. Andrologia. 2002;34(6):367-372
• Gonzales GF, Cordova A, Gonzales C, et al. Lepidium meyenii (Maca) improved semen parameters in adult men. Asian J Androl. 2001;3(4):301-303
• Gonzales GF, Nieto J, Rubio J, Gasco M. Effect of Black maca (Lepidium meyenii) on one spermatogenic cycle in rats. Andrologia. 2006;38(5):166-172
• Zenico T, Cicero AF, Valmorri L, Mercuriali M, Bercovich E. Subjective effects of Lepidium meyenii (Maca) extract on well-being and sexual performances in patients with mild erectile dysfunction: a randomised, double-blind clinical trial. Andrologia. 2009;41(2):95-99
• Brooks NA, Wilcox G, Walker KZ, Ashton JF, Cox MB, Stojanovska L. Beneficial effects of Lepidium meyenii (Maca) on psychological symptoms and measures of sexual dysfunction in postmenopausal women are not related to estrogen or androgen content. Menopause. 2008;15(6):1157-1162
• Dording CM, Schettler PJ, Dalton ED, et al. A double-blind placebo-controlled trial of maca root as treatment for antidepressant-induced sexual dysfunction in women. Evid Based Complement Alternat Med. 2015;2015:949036
• Stojanovska L, Law C, Lai B, et al. Maca reduces blood pressure and depression, in a pilot study in postmenopausal women. Climacteric. 2015;18(1):69-78
• Meissner HO, Mscisz A, Reich-Bilinska H, et al. Hormone-balancing effect of pre-gelatinized organic Maca (Lepidium peruvianum Chacon): (III) Clinical responses of early-postmenopausal women to Maca in double blind, randomized, placebo-controlled, crossover configuration, outpatient study. Int J Biomed Sci. 2006;2(4):375-394
• Stone M, Ibarra A, Roller M, Zangara A, Stevenson E. A pilot investigation into the effect of maca supplementation on physical activity and sexual desire in sportsmen. J Ethnopharmacol. 2009;126(3):574-576
• Shin BC, Lee MS, Yang EJ, Lim HS, Ernst E. Maca (L. meyenii) for improving sexual function: a systematic review. BMC Complement Altern Med. 2010;10:44
• Rubio J, Dang H, Gong M, Liu X, Chen SL, Gonzales GF. Aqueous and hydroalcoholic extracts of Black Maca (Lepidium meyenii) improve scopolamine-induced memory impairment in mice. Food Chem Toxicol. 2007;45(10):1882-1890
• Valentova K, Buckiova D, Kren V, Peknicova J, Ulrichova J, Simanek V. The in vitro biological activity of Lepidium meyenii extracts. Cell Biol Toxicol. 2006;22(2):91-99
• Gonzales C, Cardenas-Valencia I, Leiva-Revilla J, Anza-Ramirez C, Rubio J, Gonzales GF. Effects of different varieties of Maca (Lepidium meyenii) on bone structure in ovariectomized rats. Forsch Komplementmed. 2010;17(3):137-143
• Melnikovova I, Fait T, Kolarova M, Fernandez EC, Milella L. Effect of Lepidium meyenii Walp. on semen parameters and serum hormone levels in healthy adult men: a double-blind, randomized, placebo-controlled pilot study. Evid Based Complement Alternat Med. 2015;2015:324369
• Wu H, Kelley CJ, Pino-Figueroa A, Vu HD, Maher TJ. Macamides and their synthetic analogs: evaluation of in vitro FAAH inhibition. Bioorg Med Chem. 2013;21(17):5188-5197
• European Commission Implementing Decision 2014/155/EU. Authorising the placing on the market of maca powder as a novel food ingredient. Official Journal of the European Union. 2014

Connections

• Compare with other men’s health herbs: saw-palmetto (5-alpha-reductase inhibition — prostate focus), nettle-root (SHBG binding — prostate and hormonal)
• Contrast with hormonal supplements: unlike tribulus or DHEA, maca does NOT alter circulating sex hormones — its mechanism is fundamentally different
• Compare with adaptogens for energy and performance: rhodiola (HPA axis modulation, fatigue), eleuthero (Siberian ginseng — endurance, stress adaptation)
• The FAAH inhibition mechanism (macamides) represents a unique pharmacological profile not shared by other commonly used herbal supplements
• Maca’s color-specific bioactivity (black, red, yellow) parallels the concept of chemotype-dependent activity seen in other medicinal plants (e.g., different chemotypes of thyme or basil)
• Maca represents the growing integration of South American traditional plant medicines into the global evidence-based phytotherapy landscape, similar to the trajectory of cat’s claw and pau d’arco