Herbal Monograph
Maca
Lepidium meyenii Walp.
Brassicaceae (Cruciferae)
Andean adaptogenic root for vitality, fertility, sexual function, and menopausal support
Overview
Plant Description
Maca is a small, herbaceous, biennial or annual cruciferous plant growing as a compact rosette close to the ground. The above-ground portion consists of a low mat of frilly, pinnately divided leaves, typically 12-20 cm in diameter, that lie flat against the soil surface as an adaptation to the extreme wind and cold of its high-altitude habitat. The leaves are continually regenerated from the center of the rosette. The plant produces inconspicuous, small, self-fertile, white to off-white flowers on a central raceme. The primary organ of interest is the swollen hypocotyl-root complex (commonly called the 'root' or 'tuber'), which develops below ground and is the storage organ that constitutes the edible and medicinal portion. This hypocotyl is roughly turnip-shaped or radish-shaped, typically 3-6 cm in diameter and 3-5 cm in length, though size varies with growing conditions. The external skin color varies significantly among ecotypes (landraces) and ranges from creamy yellow (the most common) to red, purple, black, white, pink, orange, grey, and mixed patterns. The internal flesh is typically white to cream-colored in all ecotypes. The taste of fresh maca is mildly pungent (reminiscent of radish or turnip, consistent with its Brassicaceae family) with a sweet, butterscotch-like flavor that intensifies upon drying. The species name honors German botanist Franz Julius Ferdinand Meyen (1804-1840) who first described the plant during his South American travels.
Habitat
Maca is uniquely adapted to one of the most extreme agricultural environments on Earth: the high-altitude puna grasslands of the central Peruvian Andes, between 3,800 and 4,500 meters (12,500-14,800 feet) above sea level. At this elevation, the plant endures intense UV radiation, wide diurnal temperature fluctuations (from below freezing at night to moderate warmth during the day), strong winds, poor rocky soils of volcanic origin, and a short growing season. The region typically has a mean annual temperature of 4-7 degrees Celsius and receives approximately 500-700 mm of rainfall annually. Maca thrives in these harsh conditions that exclude most other crop plants, growing in shallow, well-drained, slightly acidic soils rich in volcanic minerals. It is one of the highest-altitude food crops in the world.
Distribution
Maca cultivation is historically concentrated in the Junin and Pasco departments of central Peru, particularly around Lake Junin (Chinchaycocha) and the Meseta de Bombon plateau at approximately 4,000-4,300 meters elevation. This remains the primary commercial growing region. Limited cultivation has been attempted in other Andean regions of Peru and Bolivia, as well as in the highlands of Yunnan Province, China (above 3,000 m), where commercial maca farming expanded significantly in the 2010s. Attempts to cultivate maca at lower altitudes generally result in poor hypocotyl development, indicating that the extreme high-altitude conditions (UV intensity, cold temperature cycling, and specific soil mineral profile) are essential for optimal growth and phytochemical production. Peru declared maca a national heritage crop and has imposed restrictions on the export of raw maca genetic material to protect its monopoly on production.
Parts Used
Hypocotyl-root (dried maca root)
Preferred: Dried powder (raw or gelatinized); concentrated extract capsules; traditionally consumed cooked in porridges, beverages, and baked goods
The swollen hypocotyl-root storage organ is the exclusively used medicinal and food part. This is commonly referred to as 'maca root' in commerce, though botanically it is primarily a swollen hypocotyl (the transition zone between root and stem) rather than a true root. It is used either as raw dried powder, gelatinized (pre-cooked) powder, or as various solvent extracts. The different ecotypes (color varieties: yellow, red, black, purple, etc.) have overlapping but somewhat distinct phytochemical profiles and may be preferentially selected for specific indications. Yellow maca is the most commonly cultivated and commercially available variety.
Key Constituents
Macamides (N-benzylamide fatty acid derivatives)
Macamides are the most pharmacologically distinctive constituents of maca, unique to this species. Their identification as FAAH inhibitors (Wu et al., 2013) links maca's traditional uses for mood, energy, and sexual function to modulation of the endocannabinoid system. By inhibiting the enzyme that degrades anandamide (an endogenous cannabinoid), macamides may elevate endocannabinoid tone, influencing mood, pain modulation, appetite, and reproductive physiology. Macamide content is used as a marker for maca extract quality and authenticity. These compounds are lipophilic and concentrated in hexane or ethyl acetate extracts.
Macaenes (unsaturated fatty acids)
Macaenes are unique fatty acid constituents that were among the first bioactive compounds identified in maca (Zheng et al., 2000). Early studies attributed maca's fertility-enhancing and sexual function effects to the combined macamide-macaene fraction. While more recent research has focused on macamides as the more pharmacologically active components, the macaenes may contribute to the overall lipid-mediated bioactivity of whole maca preparations.
Glucosinolates and isothiocyanates
Glucosinolates are the quantitatively most abundant class of secondary metabolites in maca and are characteristic of the Brassicaceae family. They contribute to maca's pungent taste and are responsible for cancer chemoprotective properties similar to those documented for other cruciferous vegetables (broccoli, cauliflower). The glucosinolate-isothiocyanate system provides documented anticarcinogenic, antioxidant, and antimicrobial activity. Glucosinolate content varies among ecotypes: red and purple maca tend to have higher glucosinolate concentrations than yellow maca. Gelatinization (heat processing) reduces glucosinolate content due to thermal degradation and myrosinase inactivation.
Alkaloids
Maca contains a small but distinctive group of imidazole alkaloids (macaridine, lepidilines) that are unique to the species. While present in trace amounts, these compounds may contribute synergistically to maca's overall pharmacological profile. The alkaloid content has been proposed as one factor distinguishing maca's effects from those of other cruciferous vegetables that share its glucosinolate chemistry. Total alkaloid content is very low and does not raise safety concerns at food-level consumption.
Phytosterols
Phytosterols are well-characterized bioactive compounds present in meaningful concentrations in maca. Beta-sitosterol's effects on prostate health are clinically documented (from studies on other plant sources) and may contribute to the observed prostate-protective effects of red maca in animal models (Gonzales et al., 2005). The phytosterol fraction also contributes to mild cholesterol-lowering properties and anti-inflammatory activity.
Flavonoids and polyphenols
The polyphenol content, particularly anthocyanins, varies dramatically among maca ecotypes and is believed to contribute to the differential clinical effects of colored varieties. Black maca's superior neuroprotective and spermatogenic effects and red maca's prostate-protective effects may be partly attributable to their unique polyphenol profiles. The anthocyanin content also provides significant antioxidant capacity.
Nutritional constituents
The nutritional density of maca underpins its millennia-long use as a sustaining food crop at extreme altitude. The combination of high-quality protein, bioavailable minerals (especially iron and calcium), and complex carbohydrates makes maca a significant dietary source of nutrition in a habitat where few other crops survive. Some of maca's traditional energizing and vitalizing effects may be partly attributable to its exceptional nutritional profile rather than solely to specific phytochemicals.
Herbal Actions
Helps the body adapt to stress and restore homeostasis
Maca is classified as an adaptogen based on its traditional use as a sustaining, energy-enhancing tonic at extreme altitude and modern evidence of stress resilience support. Unlike classic adaptogens such as Panax ginseng or Rhodiola rosea, maca does not appear to directly modulate the HPA axis through cortisol pathways. Instead, its adaptogenic mechanism is proposed to work through nutritional support, endocannabinoid system modulation (via macamide FAAH inhibition), and endocrine-balancing effects. Multiple clinical studies demonstrate improvements in subjective energy, stamina, and well-being without stimulant-like side effects. Brooks et al. (2008) found maca improved mood and reduced anxiety in postmenopausal women, consistent with adaptogenic stress-buffering.
[1, 2, 10, 12]Supports and calms the nervous system
Maca demonstrates mood-enhancing and anxiolytic effects in clinical studies. Brooks et al. (2008) found that 3.5 g/day of maca powder significantly reduced anxiety and depression scores in postmenopausal women compared to placebo over 6 weeks. Dording et al. (2015) demonstrated that maca at 3 g/day improved sexual dysfunction in women on SSRIs, indirectly supporting nervous system activity. The macamide-mediated FAAH inhibition may elevate anandamide levels, influencing mood regulation through the endocannabinoid system. Black maca ecotype has shown neuroprotective effects in animal models, improving memory and learning.
[10, 11, 16]Prevents or slows oxidative damage to cells
Maca demonstrates significant antioxidant activity attributable to its glucosinolate-derived isothiocyanates, polyphenols (particularly anthocyanins in pigmented ecotypes), and macamide constituents. In vitro studies show free radical scavenging (DPPH, ABTS) and ferric reducing antioxidant power. Colored maca ecotypes (red, purple, black) demonstrate substantially higher antioxidant capacity than yellow maca due to their anthocyanin content. The antioxidant activity likely contributes to neuroprotective, hepatoprotective, and general cytoprotective effects observed in preclinical studies.
[1, 2]Modulates and balances immune function
Preliminary evidence suggests maca may modulate immune function. Polysaccharide fractions from maca have demonstrated immunostimulant activity in vitro, enhancing macrophage activity and cytokine production. The glucosinolate-isothiocyanate system provides indirect immune support through enhancement of phase II detoxification and chemoprotective mechanisms. Traditional Andean use as a sustaining food to maintain health and vitality at high altitude implies a general tonic effect on immune resilience, though direct immunological clinical studies are limited.
[1, 2]Enhances cognitive function, memory, and mental performance
Black maca ecotype has demonstrated neuroprotective and cognitive-enhancing effects in animal models. Rubio et al. (2006) showed that black maca improved memory acquisition and retention in mice (scopolamine-induced amnesia model and water maze tests). The mechanism may involve antioxidant protection of neural tissue, acetylcholinesterase inhibition, or endocannabinoid system modulation. Human cognitive outcome data is limited, but the animal evidence is consistent across multiple study designs and supports further clinical investigation.
[1, 16]Therapeutic Indications
Reproductive System
Male sexual dysfunction and low libido
Multiple RCTs demonstrate that maca improves subjective sexual desire and erectile function in men. Gonzales et al. (2002) showed that maca at 1.5-3 g/day increased self-perceived sexual desire in healthy men after 8 weeks of treatment, independent of serum testosterone or estradiol changes. Shin et al. (2010) systematic review of 4 RCTs concluded there was suggestive evidence for maca's effectiveness in improving sexual function. Zenico et al. (2009) found maca effective for mild erectile dysfunction. The mechanism does not appear to involve direct hormonal changes; modulation of the endocannabinoid system via macamide FAAH inhibition and nutritional support of reproductive physiology are proposed mechanisms.
[1, 5, 8]Female sexual dysfunction (including SSRI-induced)
Dording et al. (2015) conducted a double-blind RCT showing that maca root 3 g/day significantly improved sexual dysfunction scores (Arizona Sexual Experiences Scale and Massachusetts General Hospital Sexual Function Questionnaire) in women experiencing SSRI/SNRI-induced sexual dysfunction compared to placebo over 12 weeks. An earlier pilot study by the same group (Dording et al., 2008) had shown similar trends. Brooks et al. (2008) found improvements in sexual dysfunction measures in postmenopausal women taking maca.
[8, 10, 11]Male infertility and poor semen quality
Gonzales et al. (2001) demonstrated that maca treatment (1.5-3 g/day for 4 months) significantly increased sperm count, sperm motility, and semen volume in healthy adult men. A subsequent study (Gonzales et al., 2003) confirmed increased sperm count and motility without altering serum reproductive hormone levels (FSH, LH, testosterone, estradiol). Black maca ecotype has shown the strongest spermatogenic effects in comparative animal studies (Gonzales et al., 2006). The mechanism appears to involve nutritional support and direct effects on spermatogenesis rather than hormonal stimulation.
[1, 6, 7]Fertility support (general, both sexes)
Traditional Andean use of maca as a fertility-enhancing food spans over 2,000 years. Andean communities report enhanced fertility in both humans and livestock (maca was traditionally fed to animals before mating). Modern evidence strongly supports effects on male semen parameters and sexual function in both sexes, but large-scale fertility outcome trials (conception rates) in humans are lacking.
[1, 3, 6]Endocrine System
Menopausal symptoms (hot flushes, mood changes, sleep disturbance)
Stojanovska et al. (2015) conducted a double-blind, placebo-controlled RCT in early postmenopausal women and found that maca (3.3 g/day for 6 weeks, as gelatinized powder) significantly reduced physiological and psychological menopausal symptoms as measured by the Greene Climacteric Scale and the Kupperman Menopausal Index. Significant reductions were observed in hot flushes, night sweats, anxiety, depression, and sleep disturbance. Brooks et al. (2008) similarly found reduced anxiety and depression with maca in postmenopausal women. Importantly, maca did not alter serum estradiol, FSH, LH, or SHBG levels, suggesting the mechanism is not through direct estrogenic activity but rather through other pathways (possibly endocannabinoid modulation, nutritional support, or effects on hypothalamic function).
[9, 10, 13]Endocrine balance and hormonal support (non-specific)
Maca is traditionally described as an endocrine tonic that supports overall hormonal balance without containing plant hormones or directly altering serum hormone levels. Multiple clinical studies have confirmed that maca improves symptoms associated with hormonal dysfunction (sexual dysfunction, menopausal symptoms, fatigue) without measurably changing serum testosterone, estradiol, FSH, LH, or other reproductive hormones. This distinguishes maca from phytoestrogenic herbs. The endocrine-modulating mechanism may involve effects at the hypothalamic-pituitary level, local tissue-level effects, or nutritional support of steroidogenic pathways.
[1, 5, 13]Nervous System
Anxiety and depression (including menopausal mood changes)
Brooks et al. (2008) found that maca (3.5 g/day for 6 weeks) significantly reduced anxiety (Hamilton Anxiety Rating Scale) and depression (Greene Climacteric Scale psychological subscore) in postmenopausal women compared to placebo. This mood-improving effect occurred without changes in serum hormone levels. Stojanovska et al. (2015) confirmed reductions in anxiety and depression subscores. The anxiolytic mechanism may involve macamide-mediated endocannabinoid system modulation via FAAH inhibition, elevating anandamide levels in mood-regulating brain circuits.
[9, 10]Cognitive function and neuroprotection
Black maca ecotype has shown neuroprotective effects in multiple animal models. Rubio et al. (2006) demonstrated that black maca improved memory and learning in mice, and protected against scopolamine-induced cognitive impairment. In vitro studies show antioxidant protection of neural tissue and acetylcholinesterase inhibitory activity. Human clinical data on cognitive outcomes is very limited, and this remains a preliminary indication requiring clinical trials.
[1, 16]Fatigue and low energy
Multiple clinical trials report subjective improvements in energy, stamina, and vitality with maca supplementation. Stone et al. (2009) pilot study in competitive cyclists found that maca supplementation improved self-rated energy and 40-km cycling time trial performance. Gonzales-Arimborgo et al. (2016) reported improvements in subjective energy in high-altitude residents. Traditional use as an energy-sustaining food at extreme altitude supports this indication. The mechanism likely involves both nutritional support and pharmacological activity of macamides.
[1, 3, 12]Musculoskeletal System
Bone density support (postmenopausal osteoporosis prevention)
Red maca has demonstrated bone-protective effects in ovariectomized rat models, preserving bone mineral density and bone structure comparable to estradiol treatment. Gonzales et al. (2010) showed that red maca prevented bone loss in estrogen-deficient animal models. Maca's high calcium and mineral content may also contribute to skeletal health. Human clinical data on bone density outcomes is not yet available. The combination of menopausal symptom relief and potential bone protection makes red maca of particular interest for postmenopausal health.
[1, 15]Urinary System
Benign prostatic hyperplasia (BPH) support
Red maca ecotype specifically has demonstrated prostate-protective effects in preclinical studies. Gonzales et al. (2005) showed that red maca reduced prostate size in testosterone-induced BPH rat models, while yellow and black maca had no significant effect. The effect was attributed to glucosinolate and beta-sitosterol content. The phytosterol fraction, particularly beta-sitosterol, has independently documented efficacy for BPH symptoms from studies on other plant sources. Human clinical trials specific to maca and BPH are needed.
[1, 14]Immune System
General immune support and vitality enhancement
Traditional Andean use of maca as a health-sustaining food at extreme altitude implies immune-supportive properties. The glucosinolate-isothiocyanate system provides chemoprotective and phase II enzyme-inducing activity relevant to immune defense and detoxification. Preliminary in vitro evidence of polysaccharide-mediated immunostimulant activity. The high nutritional density (iron, zinc, vitamin C) supports immune function through nutritional pathways. Large-scale immunological clinical studies are lacking.
[1, 3]Energetics
Temperature
warm
Moisture
slightly dry
Taste
Tissue States
cold/depression, damp/stagnation
In Western herbal energetics, maca is classified as warm and slightly dry, reflecting its ability to stimulate metabolic function, enhance energy, and counter cold-deficient states (fatigue, low libido, poor circulation) without being overtly heating or stimulating. The sweet taste corresponds to its nutritive, tonic quality and high carbohydrate/mineral content, while the pungent taste (characteristic of Brassicaceae) reflects the glucosinolate/isothiocyanate chemistry that stimulates circulation and metabolism. Maca is best suited for individuals with cold, depleted constitutions -- those presenting with fatigue, low vitality, decreased libido, and sluggish metabolism. It addresses cold/depressed tissue states (immune deficiency, endocrine hypofunction, fatigue, low reproductive drive) and damp/stagnant states (metabolic sluggishness, congestion). It may be less appropriate for constitutionally hot, excess individuals. In Andean tradition, maca is considered a warming, strengthening food essential for surviving the cold, harsh high-altitude environment. CAVEAT: Herbal energetics are interpretive frameworks within Western herbalism and traditional systems, not standardized across all practitioners.
Traditional Uses
Peruvian Andean (Inca and pre-Inca peoples, 2,000+ years)
- Cultivated as a primary food crop at extreme altitude (3,800-4,500 m) where few other crops survive, sustaining Andean communities nutritionally
- Used as a fertility enhancer for both humans and livestock; maca was reportedly fed to animals before mating to improve conception rates
- Consumed to increase strength, endurance, and energy for agricultural labor and military campaigns at high altitude
- Given to warriors before battle by Inca armies to enhance stamina and ferocity (reportedly restricted after conquest of a city to protect the conquered population)
- Used as a sexual tonic to enhance libido and sexual performance in both men and women
- Prepared as a fermented beverage (maca chicha) for ceremonial and social occasions
- Traded as a valuable commodity between highland and lowland communities; exchanged for rice, corn, and other lowland products
- Used to support adaptation to the cold, harsh high-altitude environment and promote general vitality
"Spanish colonial chronicles, including those by Cieza de León (1553) and Cobo (1653), documented maca's importance as a food and medicine among Andean peoples. Cieza de León noted that inhabitants of the Chinchaycocha region (Junin) 'made use of a certain root which they call maca' for sustenance and vitality. Father Cobo wrote that maca 'grows in the most frigid and windswept areas of the sierra where no other cultivated plant can survive' and that it 'increases fertility, in both humans and animals.' The earliest archaeological evidence of maca cultivation dates to approximately 1600 BCE from the Junin region."
South American folk medicine (colonial and post-colonial era)
- Continued use as a fertility tonic and aphrodisiac throughout the colonial and republican periods in Peru
- Consumed as dried maca porridge (mazamorra de maca) prepared by boiling dried maca in water or milk with sweetener
- Prepared as maca-based beverages (maca juice, maca chicha) for energy and vitality
- Applied for menstrual irregularities and menopausal complaints in women
- Used to enhance memory, mental clarity, and cognitive endurance
- Given to children and elderly for general nutritional support and strengthening
- Used for anemia and nutritional deficiency due to its high iron and mineral content
"Peruvian folk medicine traditions maintain the use of dried maca as a nutritive tonic and energy food. The preparation methods passed down through generations include boiling dried maca in milk to make 'jugo de maca' (maca juice) and preparing sweet porridges. Local healers in the Junin region recommend maca for 'building blood' (anemia support), enhancing memory in students, and supporting reproductive health across the lifespan."
Modern Research
Systematic review of maca for sexual function
Systematic review assessing the clinical evidence for the efficacy of maca (Lepidium meyenii) in improving sexual function. Searched multiple databases and identified 4 randomized clinical trials meeting inclusion criteria.
Findings: Four RCTs were included (n=131 total participants, 3 trials in men, 1 in menopausal women). Two RCTs showed significant improvement in sexual dysfunction scores with maca compared to placebo. One trial showed improvement in self-perceived sexual desire in healthy men without changes in serum testosterone. The review concluded that there is 'limited evidence suggesting the effectiveness of maca in improving sexual dysfunction' and that 'rigorous, larger-scale trials are needed to confirm these findings.' Maca appeared to be well tolerated in all studies.
Limitations: Small number of included RCTs (4 trials). Very small total sample sizes (n=131 across all trials). Short treatment durations (6-12 weeks). Heterogeneous study populations (healthy men, men with ED, postmenopausal women). Different maca preparations and dosages used. Mostly single-center studies from Peru.
[8]
Effect of maca on sexual desire in healthy men
Double-blind, randomized, placebo-controlled trial evaluating the effect of Lepidium meyenii (maca) on self-perceived sexual desire in healthy adult men. Fifty-seven healthy men received maca (1.5 g/day or 3 g/day) or placebo for 12 weeks.
Findings: Treatment with maca improved sexual desire beginning at week 8 of treatment. Both 1.5 g/day and 3 g/day doses showed improvement, though the 3 g dose showed a trend toward greater effect. Sexual desire improvement was not correlated with changes in serum testosterone, estradiol, or sex hormone-binding globulin levels, which remained unchanged in all groups. Depression and anxiety scores (measured by Hamilton Depression and Anxiety Rating Scales) also did not change significantly. The lack of hormonal changes suggests maca's effect on libido operates through a non-hormonal mechanism.
Limitations: Moderate sample size (n=57). Self-reported outcome (sexual desire questionnaire). Healthy young men; results may not generalize to individuals with established sexual dysfunction or older populations. Single-center Peruvian study. 12-week duration.
[5]
Maca and spermatogenesis in healthy men
Clinical study examining the effect of maca supplementation on semen parameters in healthy adult men. Nine healthy men received 1.5-3 g/day of dried maca hypocotyl for 4 months, with semen analysis performed at baseline, 2 months, and 4 months.
Findings: Maca treatment resulted in significant increases in sperm concentration (beginning at 2 months), sperm motility, and semen volume compared to baseline values. Mean sperm count increased from baseline. Serum testosterone, estradiol, FSH, and LH levels did not change significantly during the treatment period, indicating that the spermatogenic effects are not mediated through changes in systemic reproductive hormone levels. A dose-response trend was observed, with 3 g/day showing numerically greater effects than 1.5 g/day.
Limitations: Very small sample size (n=9). No placebo control group (pre-post design only). Open-label. Single-center. Short duration relative to the full spermatogenesis cycle (74 days). Serum hormone levels measured but not intratesticular hormone concentrations.
[6]
Maca for menopausal symptoms in early postmenopausal women
Randomized, double-blind, placebo-controlled, crossover trial evaluating the effect of maca (3.3 g/day as gelatinized powder) on menopausal symptoms, lipid profiles, and body composition in 28 early postmenopausal Chinese women over two 6-week treatment periods with a 6-week washout.
Findings: Maca significantly reduced menopausal symptoms as measured by the Kupperman Menopausal Index and Greene Climacteric Scale. Significant reductions were seen in hot flushes and night sweats (vasomotor symptoms), anxiety, depression, and sexual dysfunction subscores. Blood pressure (both systolic and diastolic) decreased significantly. Serum estradiol was slightly increased and FSH decreased, though these hormonal changes were not statistically significant in the main analysis. Body weight and BMI were not significantly affected. Serum lipid profiles showed trends toward improvement.
Limitations: Small sample size (n=28 completers). Short treatment periods (6 weeks per phase). Crossover design may have carryover effects despite 6-week washout. Chinese postmenopausal population; may not generalize to other ethnicities. Gelatinized maca powder; results may differ with other preparations.
[9]
Maca for reduction of SSRI-induced sexual dysfunction in women
Double-blind, randomized, placebo-controlled trial evaluating maca root (3 g/day) for the treatment of antidepressant-induced sexual dysfunction in 45 women on SSRI or SNRI antidepressants over 12 weeks.
Findings: Maca treatment was associated with significant improvement in sexual function as measured by the Arizona Sexual Experiences Scale (ASEX) and the Massachusetts General Hospital Sexual Function Questionnaire (MGH-SFQ) compared to placebo. Significant improvements were seen in libido, orgasm, and overall sexual satisfaction scores. Remission rates (achieving normal sexual function scores) were significantly higher in the maca group. The effect was independent of changes in depression scores (Hamilton Depression Rating Scale), which did not differ between groups. Maca was well tolerated with no serious adverse events.
Limitations: Moderate sample size (n=45). Single-center study at Massachusetts General Hospital. SSRI/SNRI-mediated sexual dysfunction is a specific subpopulation. 12-week duration. Effects on male SSRI-induced sexual dysfunction were studied in a separate earlier pilot (Dording et al., 2008) but the definitive trial focused on women.
[11]
Maca and mood/anxiety in postmenopausal women
Randomized, double-blind, placebo-controlled trial examining the psychological and hormonal effects of maca powder (3.5 g/day for 6 weeks) in postmenopausal women, with a focus on mood outcomes.
Findings: Maca significantly reduced anxiety (Hamilton Anxiety Rating Scale) and depression (Greene Climacteric Scale psychological subscore) compared to placebo. The anxiolytic and antidepressant effects were observed independently of changes in serum sex hormone levels (estradiol, FSH, LH, SHBG all unchanged), suggesting a non-hormonal mechanism of mood improvement. Blood pressure showed trends toward reduction. The results support maca's use as a mood-supportive intervention in menopausal women beyond its effects on vasomotor symptoms.
Limitations: Small sample size (n=29 completers). Short treatment period (6 weeks). Postmenopausal women only; may not generalize to premenopausal populations. Self-reported psychological measures. Single-center study.
[10]
Ecotype-specific effects: Red maca and prostate size
In vivo study comparing the effects of yellow, red, and black maca ecotypes on prostate size in rats with testosterone-induced benign prostatic hyperplasia (BPH).
Findings: Red maca ecotype significantly reduced prostate size in the testosterone-induced BPH model, with the effect comparable to finasteride (a pharmaceutical 5-alpha reductase inhibitor used for BPH). Yellow and black maca ecotypes did not significantly reduce prostate size. The prostate-protective effect of red maca was attributed to its higher glucosinolate content and phytosterol (beta-sitosterol) concentration. This was among the first studies to demonstrate that different maca ecotypes have distinct pharmacological profiles.
Limitations: Animal model only (rats); human clinical data for BPH not available. Testosterone-induced BPH model may not fully replicate the pathophysiology of age-related human BPH. Specific ecotype (red maca) may not be representative of commercial maca products, which are predominantly yellow maca.
[14]
Ecotype-specific effects: Black maca and neuroprotection/memory
In vivo study examining the effects of different maca ecotypes on learning and memory in mice using the Morris water maze and the scopolamine-induced amnesia model.
Findings: Black maca ecotype showed the most significant improvement in memory and learning performance compared to yellow and red maca ecotypes. Black maca reversed scopolamine-induced memory impairment and improved escape latency in the Morris water maze. The neuroprotective effect was proposed to involve antioxidant protection of hippocampal neurons and possible acetylcholinesterase inhibition. Yellow and red maca showed intermediate and lesser effects, respectively, on cognitive parameters.
Limitations: Animal model only (mice). The scopolamine model is specific to cholinergic memory pathways and may not represent all forms of cognitive decline. No human clinical data on maca and cognitive function available. Ecotype-specific findings require confirmation in human studies.
[16]
Comprehensive ethnobotanical and pharmacological review of maca
Comprehensive narrative review of Lepidium meyenii covering ethnobotany, traditional uses, phytochemistry, pharmacology, clinical evidence, and safety. Published in the journal Evidence-Based Complementary and Alternative Medicine.
Findings: Documented maca's 2,000+ year history of cultivation and use in the Peruvian Andes. Reviewed the phytochemical profile including macamides (unique to maca), macaenes, glucosinolates, alkaloids, sterols, and nutritional components. Summarized clinical evidence for effects on sexual function, fertility, menopausal symptoms, mood, and energy. Highlighted the importance of ecotype differences (yellow, red, black maca) for specific clinical applications. Confirmed an excellent safety profile with no significant adverse effects reported in clinical trials or traditional use.
Limitations: Narrative review without formal systematic methodology. Predominantly authored by researchers from the Universidad Peruana Cayetano Heredia who have conducted much of the primary maca research, with potential for selection bias. Many of the reviewed clinical studies had small sample sizes.
[1]
Maca athletic performance pilot study in cyclists
Pilot study evaluating the effect of maca supplementation on cycling performance and subjective measures in trained male cyclists.
Findings: Maca supplementation (2 g/day for 14 days) resulted in a significant improvement in 40-km cycling time trial performance compared to baseline. Self-rated sexual desire also increased significantly. The performance effect was modest but statistically significant. Maca was well tolerated with no adverse effects reported.
Limitations: Pilot study with very small sample size (n=8). Short supplementation period (14 days). Time trial comparison to baseline rather than placebo group. Trained cyclists may not represent the general population. Specific performance measure (cycling time trial) may not generalize to other forms of physical performance.
[12]
Maca and spermatogenesis: hormonal independence
Follow-up clinical study confirming that maca's effects on sperm production occur without changes in serum reproductive hormone levels, providing further evidence for a non-hormonal mechanism of action on male fertility.
Findings: Maca supplementation (1.5-3 g/day for 12 weeks) significantly increased sperm count and motility compared to placebo in healthy men. Serum testosterone, LH, FSH, estradiol, and prolactin levels remained unchanged throughout the study period, confirming that maca's spermatogenic effects do not operate through systemic hormonal modulation. The dissociation between improved sperm parameters and unchanged hormone levels suggests a direct effect on spermatogenic tissue, possibly through nutritional support, antioxidant protection of germ cells, or local paracrine mechanisms.
Limitations: Moderate sample size. Healthy young men; results may not generalize to men with clinical infertility. Specific preparation (dried maca powder); results may differ with other preparations. No long-term follow-up on fertility outcomes (conception rates).
[7]
Preparations & Dosage
Capsule / Powder
Strength: Gelatinized powder: typically 500-750 mg per capsule (4:1 to 6:1 concentration from raw). Standardized extract: varies by manufacturer, commonly 4:1 to 10:1 DER standardized to >= 0.6% macamides or >= 0.6% glucosinolates
Dried maca hypocotyl, finely powdered, encapsulated. Available as raw maca powder (dried and ground) or gelatinized maca powder (pre-cooked by extrusion at high temperature and pressure to remove starch, improve digestibility, and concentrate bioactive compounds). Gelatinized maca is preferred for therapeutic use as it has improved bioavailability and reduced potential for digestive discomfort associated with raw maca starch. Standardized extracts concentrated to specified levels of macamides and/or glucosinolates are also available in capsule form.
Gelatinized powder: 1.5-3.3 g per day (matching clinical trial doses). Raw powder: 3-6 g per day (higher dose needed as gelatinization concentrates actives). Standardized extract: follow manufacturer specifications, typically 450-1500 mg per day depending on concentration ratio.
Once to three times daily with meals. Clinical trials have typically divided the total daily dose into 2-3 doses taken with food.
Clinical trials used 6-16 weeks of continuous supplementation. Effects on sexual desire typically emerge by week 6-8. Effects on spermatogenesis require at least 2-4 months. Traditional use supports long-term consumption as a food. Reassess therapeutic need periodically.
Not well established. Traditional use includes dietary consumption by children in Andean communities. Therapeutic doses not recommended for children under 12 without practitioner guidance.
Capsules are the most common commercial form in Western markets and the form used in the majority of published clinical trials. Gelatinized maca is strongly preferred over raw maca powder for therapeutic use: the gelatinization process (high-temperature extrusion) removes the indigestible starch fraction (which constitutes up to 60% of raw maca), concentrates the bioactive compounds by 3-4 fold, and significantly improves digestibility. Raw maca powder may cause bloating, gas, and digestive discomfort in some individuals due to its high starch content. Product labeling should specify whether the product contains raw or gelatinized powder and whether derived from a specific ecotype (yellow, red, black) or mixed.
Tincture
Strength: 1:5, 45-55% ethanol (dried hypocotyl)
Use dried, coarsely ground maca hypocotyl. Standard maceration: 1:5 ratio in 45-55% ethanol. Macerate for 4-6 weeks with regular agitation. Press and filter. A higher alcohol percentage (55-60%) may improve extraction of lipophilic macamides. Glycerite alternatives (1:5 in vegetable glycerin) are available for those avoiding alcohol.
3-5 mL (60-100 drops) two to three times daily
Two to three times daily
May be used long-term. Assess response after 6-8 weeks.
Not recommended in tincture form for children due to alcohol content
Tincture is not the traditional Andean preparation method but is commonly prepared by Western herbalists. Hydroalcoholic extraction captures both water-soluble constituents (glucosinolates, polyphenols, amino acids) and lipophilic compounds (macamides, macaenes, sterols). The tincture form may offer more efficient macamide extraction than simple water preparations. However, the majority of clinical evidence is based on whole powder or gelatinized powder rather than tincture preparations. The taste is mildly pungent and earthy.
[1]
Decoction
Strength: 15-30 g dried maca per 500 mL liquid; approximately 1:15-1:30 ratio
Traditional Andean preparation: Add 15-30 g (1-2 tablespoons) of dried maca powder or small pieces of dried maca hypocotyl to 500 mL of water or milk. Bring to a gentle boil and simmer for 15-20 minutes. Strain and serve. Traditionally sweetened with honey, raw cane sugar (panela), or flavored with cinnamon, vanilla, or cacao. In traditional preparation, dried maca chips are boiled until soft and the resulting liquid is consumed as 'jugo de maca' (maca juice).
15-30 g dried maca per day, prepared as decoction in 500-750 mL liquid. Drink in 1-2 servings.
Once to twice daily, typically in the morning for energy support
Traditional daily use as a food beverage. May be consumed indefinitely.
Traditional Andean use includes giving diluted maca beverages to children. Use 5-10 g in milk or porridge for older children under parental discretion.
This is the closest preparation to traditional Andean consumption methods. Boiling the dried maca in water or milk extracts the water-soluble constituents (glucosinolates, amino acids, minerals, polysaccharides) and softens the starchy matrix. Milk-based preparations are traditional and may improve absorption of lipophilic compounds. This method does not concentrate macamides as effectively as alcoholic extraction but provides the full spectrum of nutritional and water-soluble bioactive compounds. The traditional preparation essentially makes a thick, nutritious beverage rather than a concentrated medicine.
Standardized Extract
Strength: Common DER 4:1 to 10:1. Standardization markers: macamides >= 0.6%, glucosinolates >= 1%, or combined profiles
Commercially prepared concentrated extracts, typically using gelatinization (high-temperature extrusion) followed by solvent extraction. Products may be standardized to minimum macamide content (commonly >= 0.6% macamides), glucosinolate content, or both. Some products use proprietary extraction processes to concentrate specific constituent classes. Ecotype-specific standardized extracts (red maca, black maca) are available for targeted applications.
Varies by concentration ratio and standardization. Typical dose: 450-1500 mg per day of standardized extract. Products standardized to >= 0.6% macamides: follow manufacturer's directions, typically 1-3 capsules daily. Gelatinized concentrated powder (4:1): 750-1500 mg per day.
Once to three times daily with meals
Clinical trial durations have ranged from 6-16 weeks. Long-term use appears safe based on traditional food consumption.
Not established for concentrated extract forms
Standardized extracts offer the most reproducible dosing and are increasingly used in clinical research and commerce. Key quality considerations: (1) Extraction method should preserve both water-soluble (glucosinolates, polyphenols) and lipophilic (macamides, sterols) constituents; (2) Source ecotype should be specified, as different colored maca varieties have distinct phytochemical and pharmacological profiles; (3) Third-party testing for macamide content provides the best authenticity and quality marker, as macamides are unique to Lepidium meyenii; (4) Products derived from gelatinized maca are preferred for digestibility. Country of origin matters: high-altitude Peruvian-grown maca is generally considered to have a superior phytochemical profile compared to lower-altitude cultivated material.
Safety & Interactions
Class 1
Can be safely consumed when used appropriately (AHPA Botanical Safety Handbook)
Contraindications
Individuals with confirmed allergy to maca or other cruciferous vegetables (broccoli, cauliflower, cabbage, mustard) should avoid maca. Allergic cross-reactivity within the Brassicaceae is possible though rarely reported.
While clinical studies consistently show that maca does NOT alter serum estrogen, testosterone, or other reproductive hormone levels, its traditional use as a fertility and sexual function enhancer raises theoretical concerns for individuals with hormone-sensitive conditions (estrogen-receptor-positive breast cancer, endometriosis, uterine fibroids). The clinical evidence does not support a direct estrogenic mechanism, but as a precautionary measure, individuals with hormone-sensitive conditions should consult their oncologist or specialist before using therapeutic doses of maca.
Drug Interactions
| Drug / Class | Severity | Mechanism |
|---|---|---|
| Levothyroxine and other thyroid medications (Thyroid hormones) | theoretical | Maca contains glucosinolates (goitrogenic compounds common to all Brassicaceae). Glucosinolate hydrolysis products can theoretically interfere with thyroid iodine uptake and thyroid hormone synthesis. This is the same mechanism by which excessive consumption of raw cruciferous vegetables can affect thyroid function in iodine-deficient individuals. |
| Hormone therapies (estrogen replacement, hormonal contraceptives) (Hormonal agents) | theoretical | Maca is used traditionally as a reproductive tonic and has demonstrated effects on menopausal symptoms and sexual function. While clinical studies consistently show no significant changes in circulating sex hormone levels with maca supplementation, theoretical interactions with exogenous hormone therapies cannot be excluded due to possible local tissue-level effects or hypothalamic modulation. |
| Antihypertensive medications (Antihypertensives) | minor | Stojanovska et al. (2015) observed significant reductions in both systolic and diastolic blood pressure with maca supplementation in postmenopausal women. Additive blood pressure-lowering effects could theoretically occur when combined with antihypertensive medications. |
Pregnancy & Lactation
Pregnancy
likely safe
Lactation
insufficient data
Maca has been consumed as a staple food by Andean populations for millennia, including during pregnancy, with no documented teratogenic or adverse reproductive effects at food-level consumption. The Peruvian traditional practice considers maca a strengthening food appropriate throughout the lifespan including pregnancy. However, no controlled clinical safety studies have been conducted specifically in pregnant women at therapeutic supplement doses. At food-level amounts (up to 20-30 g/day dried maca in traditional consumption), maca is likely safe during pregnancy based on extensive traditional use. Therapeutic supplement doses (concentrated extracts) have not been specifically evaluated for safety in pregnancy and should be used with practitioner guidance. Data on lactation is insufficient; traditional Andean use includes consumption during lactation as a nutritive food, but formal safety studies are lacking. The AHPA class-1 safety rating reflects the herb's overall excellent safety profile, including its long history as a food crop.
Adverse Effects
References
Monograph Sources
- [1] Gonzales GF. Ethnobiology and ethnopharmacology of Lepidium meyenii (Maca), a plant from the Peruvian highlands. Evid Based Complement Alternat Med (2012) ; 2012 : 193496 . DOI: 10.1155/2012/193496 . PMID: 21977053
- [2] Wang Y, Wang Y, McNeil B, Harvey LM. Maca: An Andean crop with multi-pharmacological functions. Food Res Int (2007) ; 40 : 783-792 . DOI: 10.1016/j.foodres.2007.02.005
- [3] Chacón de Popovici G. La maca (Lepidium publicanum sp. nov.) y su habitat. Revista Peruana de Biología (1961) ; 1 : 169-172
- [4] Quirós CF, Aliaga Cárdenas R. Maca (Lepidium meyenii Walp.). In: Hermann M, Heller J (eds). Andean Roots and Tubers: Ahipa, Arracacha, Maca and Yacon. Promoting the conservation and use of underutilized and neglected crops. IPGRI, Rome (1997) : 173-197 . ISBN: 92-9043-351-1
Clinical Studies
- [5] Gonzales GF, Córdova A, Vega K, Chung A, Villena A, Góñez C, Castillo S. Effect of Lepidium meyenii (MACA) on sexual desire and its absent relationship with serum testosterone levels in adult healthy men. Andrologia (2002) ; 34 : 367-372 . DOI: 10.1046/j.1439-0272.2002.00519.x . PMID: 12472620
- [6] Gonzales GF, Córdova A, Gonzales C, Chung A, Vega K, Villena A. Lepidium meyenii (Maca) improved semen parameters in adult men. Asian J Androl (2001) ; 3 : 301-303 . PMID: 11753476
- [7] Gonzales GF, Córdova A, Vega K, Chung A, Villena A, Góñez C. Effect of Lepidium meyenii (Maca), a root with aphrodisiac and fertility-enhancing properties, on serum reproductive hormone levels in adult healthy men. J Endocrinol (2003) ; 176 : 163-168 . DOI: 10.1677/joe.0.1760163 . PMID: 12553872
- [8] 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 . DOI: 10.1186/1472-6882-10-44 . PMID: 20691074
- [9] Stojanovska L, Law C, Lai B, Chung T, Nelson K, Day S, Apostolopoulos V, Haines C. Maca reduces blood pressure and depression, in a pilot study in postmenopausal women. Climacteric (2015) ; 18 : 69-78 . DOI: 10.3109/13697137.2014.929649 . PMID: 24931003
- [10] 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 : 1157-1162 . DOI: 10.1097/gme.0b013e3181732953 . PMID: 18784609
- [11] Dording CM, Schettler PJ, Dalton ED, Parkin SR, Walker RSW, Fehling KB, Fava M, Mischoulon D. 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 . DOI: 10.1155/2015/949036 . PMID: 25954318
- [12] 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 : 574-576 . DOI: 10.1016/j.jep.2009.09.012 . PMID: 19781622
- [13] Meissner HO, Mscisz A, Reich-Bilinska H, Kapczynski W, Mrozikiewicz P, Bobkiewicz-Kozlowska T, Kedzia B, Lowicka A, Barchia I. Hormone-balancing effect of pre-gelatinized organic Maca (Lepidium peruvianum Chacón): (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 : 375-394 . PMID: 23675006
- [14] Gonzales GF, Miranda S, Nieto J, Fernández G, Yucra S, Rubio J, Yi P, Gasco M. Red maca (Lepidium meyenii) reduced prostate size in rats. Reprod Biol Endocrinol (2005) ; 3 : 5 . DOI: 10.1186/1477-7827-3-5 . PMID: 15661081
- [15] Gonzales C, Cárdenas-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 : 137-143 . DOI: 10.1159/000315214 . PMID: 20616517
Traditional Texts
- [16] 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 : 1882-1890 . DOI: 10.1016/j.fct.2007.04.002 . PMID: 17543435
Pharmacopeias & Reviews
- [17] Ministry of Health, Republic of Peru. Norma Técnica de Salud: Listado de Plantas Medicinales (including Lepidium meyenii - Maca). DIGEMID, Lima, Peru (2006)
Last updated: 2026-03-02 | Status: review
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