Maca: Benefits, Forms, Dosing, and Side Effects

Overview

Maca (Lepidium meyenii), also known as Peruvian ginseng, is a starchy root vegetable in the Brassicaceae (cruciferous) family, native to the high-altitude central Andes of Peru at elevations between 4,000 and 4,500 meters [1][2]. The edible portion is a fleshy, radish-like underground tuber (technically a fused hypocotyl and taproot) measuring 10–14 cm in length and 3–5 cm in width when fresh [1]. Maca has been cultivated for over 2,000 years in the Peruvian Andes, with archaeological evidence of domestication dating back approximately 1,300–2,000 years in the Junín region [1][2].

Maca is consumed as a traditional food in Peru and neighboring Andean countries, where it is boiled, roasted in earthen ovens (huatia), ground into flour for porridges and baked goods, or fermented into a mildly alcoholic beverage (chicha de maca) [2]. Historically, the Incas valued maca highly, reportedly feeding it to soldiers before battle to enhance stamina and endurance, and using it as a form of tribute and currency [2]. Spanish colonial records from 1653 document its use for enhancing fertility in both humans and livestock at high altitudes [1][2].

The nutritional profile of maca is similar to grains such as rice and wheat. On a dry weight basis, maca root contains 55–73% carbohydrates (primarily starch and polysaccharides), 8.9–21% protein, 8.2–25.6% dietary fiber, and 0.6–2.2% lipids [3]. It provides approximately 325 kcal per 100 g of dried powder and is a source of essential minerals including iron, calcium, potassium, and iodine, along with B vitamins and vitamin C [3][4]. Compared to other root vegetables, maca has notably higher protein content than potatoes (approximately 8–10% dry basis) [3].

Beyond its nutritional value, maca contains several unique bioactive compounds that may contribute to its biological effects. The most distinctive are macamides — N-benzylamide fatty acid derivatives structurally similar to the endocannabinoid anandamide — and macaenes (unsaturated variants of macamides), which are found exclusively in dried maca hypocotyls [5][6]. Maca also contains glucosinolates (sulfur-containing compounds typical of Brassicaceae plants, primarily glucotropaeolin and m-methoxyglucotropaeolin), polyphenols with antioxidant activity, alkamides, and a beta-carboline alkaloid called MTCA (1-methyl-1,2,3,4-tetrahydro-β-carboline-3-carboxylic acid) [5][7][8]. The relative concentrations of these bioactive compounds vary by root color, growing conditions, and processing method [3][9].

Maca has been promoted for a wide range of uses, including increasing energy, stamina, and sexual ability, improving mood, boosting the immune system, and alleviating menopausal symptoms [10]. These claims are based largely on traditional use and several small clinical studies, most of which were short-term (12 weeks or less), had small sample sizes, and some lacked placebo controls. The potentially active components of maca have not been definitively determined, and no official guidelines (such as those set by the USP) have been established regarding the amounts of macamides or other compounds to be expected of authentic maca products [10]. Larger, well-controlled, long-term studies are needed to confirm most claimed benefits.

Peru remains the world's leading producer and exporter of maca, with exports reaching approximately 1,830 tons valued at USD 14 million in the first eight months of 2023, supporting thousands of small-scale farmers in highland regions [11]. Global demand has surged since the 1990s, with export values growing from USD 1.415 million in 2001 to USD 6.17 million by 2010 [1]. However, this growth has also raised biopiracy concerns, particularly regarding unauthorized cultivation of Peruvian maca varieties in China's Yunnan Province and foreign patents on maca propagation methods [12][13].

Table of Contents

• Overview
• Forms and Bioavailability
• Evidence for Benefits
• Recommended Dosing
• Safety and Side Effects
• Drug Interactions
• Dietary Sources
• References

Forms and Bioavailability

Root Color Varieties

Maca root grows in a variety of colors, with the most common being yellow, red, and black. These vary in their chemical and nutrient composition and are sometimes promoted for different uses [10][3].

Color	Characteristics	Promoted Uses
Yellow	Most common variety; sweetest flavor; lower polyphenol and anthocyanin content	General health; most widely available; used in the majority of clinical studies
Red	Higher anthocyanin content; intermediate macamide levels	Prostate health (animal data); bone density (animal data); antioxidant support
Black	Sweet-bitter flavor profile; elevated macamide levels; highest polyphenol content among some analyses	Sperm count and motility (animal data); memory and cognition (animal data); physical endurance
Purple	Highest anthocyanin content	Limited research; antioxidant properties

Important caveat: Most evidence for the differential effects of maca colors comes from laboratory and animal studies, not human clinical trials [10]. For example, red maca (but not black or yellow) reduced prostate weight in rats (Gonzales, Reprod Biol Endocrinol, 2005) [14]. Black maca increased sperm count and motility in rats compared to red or yellow maca (Gonzales, J Ethnopharmacol, 2006) [15]. Yellow maca increased fertility measures in female mice, though other colors were not tested (Ruiz-Luna, Reprod Biol Endocrinol, 2005) [16]. No human studies have directly compared the effects of different maca colors, and most clinical trials do not specify which color was used [10].

One clinical study in postmenopausal women used a branded formula (Maca-GO) containing a specific blend of colors (16% black, 48% yellow, 9% red, and 27% other colors) and found increases in estrogen levels and reductions in FSH and hot flashes compared to placebo — but it is unknown how this blend compares to single-color products or other combinations (Meissner, Int J Biomed Sci, 2006) [17].

Processing Forms

Raw maca powder: The dried root is ground into a fine powder, retaining the full spectrum of nutrients and bioactive compounds including fiber, starch, macamides, glucosinolates, and micronutrients [18][19]. Raw powder has a malty, somewhat sweet, slightly burnt taste. This is the form used in most clinical studies [10].

Gelatinized maca powder: A process using heat and pressure to remove fibrous starch material, breaking starches down into simpler sugars [10][18]. Gelatinization is believed to make the powder easier to digest and may concentrate the remaining bioactive constituents. This is particularly beneficial for individuals with digestive sensitivity to maca's natural fiber content [18]. Despite the name, gelatinization does not involve gelatin — it refers to the starch gelatinization process.

Maca extract: Concentrated preparations obtained through solvent processing to isolate specific bioactive compounds. Extracts are available as liquids, powders, or capsulated products [13]. There is considerably less clinical evidence for extracts compared to whole root powder, and because the active components of maca have not been definitively identified, it is unclear which type of extract would be most therapeutically appropriate [10].

Capsules: Pre-measured doses of either powder or extract in capsule form. Convenient for standardized dosing but typically require multiple capsules per day due to the relatively high doses used in clinical studies (1,500–3,000 mg) [10][13].

Maca flour (harina de maca): Fine flour from ground dried roots, used in baking to add nutritional value and a nutty flavor to breads and other foods. This form has been promoted for enhancing the antioxidant properties of baked products [20].

Bioavailability Considerations

The potentially active components of maca responsible for its reported effects have not been conclusively determined. Macamides are the most studied candidates, as they are structurally similar to the endocannabinoid anandamide and are unique to maca [5][6]. However, no standardization exists for macamide content in commercial products [10].

Gelatinized vs. raw powder: Gelatinization may improve digestibility and concentrate non-starch bioactive compounds, but direct bioavailability comparisons in human studies are lacking. Both forms have been used in clinical research with positive outcomes [10][18].

Powder vs. extract: Most positive clinical evidence comes from whole root powder (loose or in capsules), not concentrated extracts. Given the uncertainty about which components drive maca's effects, whole root powder appears to be the more evidence-supported form [10].

Dose-form practical considerations: The typical effective dose of maca is relatively high (1,500–3,000 mg per day). Loose powder mixed with water, juice, milk, or blended into a smoothie may be preferable for individuals who do not wish to take multiple capsules daily [10].

Growing Region and Quality Concerns

Maca is traditionally grown in Peru and Bolivia. More recently, it has been cultivated in China's Yunnan Province at elevations of 2,500–3,500 meters [21]. Concerns exist about potential differences in bioactive compound profiles between Andean-grown and Chinese-grown maca due to variations in altitude, UV exposure, soil conditions, and climate [21][22]. Additionally, concerns about industrial pollutants and heavy metals in Chinese growing regions have been raised [10]. Maca grows poorly when cultivated below 3,500 meters or where summer temperatures exceed 24°C, often resulting in reduced root development and potentially lower concentrations of bioactive compounds [22].

Evidence for Benefits

Sexual Desire (Libido)

Sexual desire enhancement is the most widely studied and traditionally promoted use of maca. Several small clinical trials have shown promising but preliminary results.

Men — positive evidence for libido:

A randomized, double-blind, placebo-controlled trial in men aged 21–56 found that gelatinized maca tablets (Maca Gelatinizada La Molina, Laboratorios Hersil, Peru) taken daily for 8 weeks at either 1,500 mg or 3,000 mg per day significantly increased self-reported sexual desire compared to placebo. Notably, the higher dose did not produce more benefit than the lower dose. There were no changes in blood levels of testosterone or estradiol, and no improvement in depression or anxiety scores (Gonzales, Andrologia, 2002) [23]. This study is significant because it demonstrated that maca's effect on sexual desire appears to be independent of sex hormone levels.

A study of 47 healthy men and women aged 18–53 found that 2,100 mg per day of a patented blend of black and red maca powders (Lepidamax, Nutrition21) taken as three 700 mg capsules daily for 28 days improved self-reported sexual functioning (including arousal and satisfaction) in men. Some improvement was also observed in women, but this did not reach statistical significance (Jiannine, J Exerc Nutr, 2019) [24].

A pilot study in trained male cyclists found that 14 days of maca extract supplementation (2 g/day) significantly increased self-reported sexual desire (Stone, 2009) [25].

Women — mixed evidence for libido:

A randomized, double-blind, placebo-controlled crossover trial in 14 postmenopausal women found that 3,500 mg of maca powder daily for 6 weeks produced a 34.6% decrease in measures of sexual dysfunction compared to placebo (Brooks, Menopause, 2008) [26]. This included improvements in sexual desire and satisfaction. No significant changes in blood levels of estradiol, FSH, LH, or sex-hormone-binding globulin (SHBG) were observed, again suggesting maca's effects on sexual function are not mediated through direct hormonal changes.

A study in 17 women and 3 men with SSRI-associated sexual dysfunction found that 3,000 mg of maca root powder significantly improved sexual desire (libido) and number of enjoyable sexual experiences compared to the lower 1,500 mg dose (Dording, CNS Neurosci Ther, 2008) [27]. However, this study did not include a placebo group, making it impossible to rule out placebo effects. A small number of adverse events including headache, stomach upset, sleep disruption, and increased sweating were reported.

The Lepidamax study (Jiannine, J Exerc Nutr, 2019) noted some improvement in women's sexual functioning, but the changes were not statistically significant compared to placebo [24].

Mechanism: Importantly, multiple human studies have consistently shown that maca does not significantly alter serum hormone levels — including testosterone, estrogen, FSH, or LH — despite improvements in sexual desire and sexual function [23][26][28]. This suggests maca acts through non-hormonal mechanisms, potentially related to its macamide content and structural similarity to endocannabinoids, or through effects on the central nervous system [5][28]. Black maca in particular has been studied for potential non-hormonal effects on spermatogenesis and libido [28].

Erectile Dysfunction

A randomized, double-blind, placebo-controlled trial in young men (average age 36) with mild erectile dysfunction found that 2,400 mg of dried maca extract daily for 12 weeks produced a slight but statistically significant improvement in erectile function compared to placebo (Zenico, Andrologia, 2009) [29]. Those with the most erectile dysfunction at baseline experienced the greatest improvement. Men taking maca also reported significant improvements in physical and social performance measures of daily life satisfaction compared to the placebo group.

A 2024 systematic review and meta-analysis confirmed that maca supplementation shows potential benefits for sexual function including erectile dysfunction in mild cases, though the evidence is limited by small sample sizes and methodological issues [30][31].

Sperm Quality and Male Fertility

An early study in 9 men reported that maca tablets (1,500 mg or 3,000 mg daily) significantly increased semen volume, total sperm count, motile sperm count, and certain measures of sperm motility (Gonzales, Asian J Androl, 2001) [32]. However, this study did not include a control group, limiting the strength of its conclusions.

A 2016 systematic review of clinical trials concluded that maca supplementation improves semen quality parameters, including sperm concentration and motility, in healthy adult men based on evidence from multiple randomized controlled trials [33]. However, the review noted that most individual studies were small and short-term.

Animal studies have provided supporting evidence: black maca in particular has been found to increase sperm count and motility in rats compared to red or yellow maca (Gonzales, J Ethnopharmacol, 2006) [15]. Animal models have also demonstrated enhanced sexual behavior and mounting frequency with maca extracts [28].

Female Fertility

Yellow maca was reported to increase measures of fertility in female mice, although other colors of maca were not tested for comparison (Ruiz-Luna, Reprod Biol Endocrinol, 2005) [16]. No well-designed human clinical trials have specifically investigated maca's effects on female fertility outcomes such as conception rates, ovulation, or IVF success.

Menopausal Symptoms

Psychological symptoms: The Brooks (2008) crossover trial in 14 postmenopausal women found that 3,500 mg of maca powder daily for 6 weeks significantly reduced psychological symptoms including anxiety (27.3% decrease) and depression (26.8% decrease) compared to placebo, as measured by the Greene Climacteric Scale [26]. No changes in serum estradiol, FSH, LH, or SHBG were observed, suggesting the mood improvements occurred through non-hormonal pathways.

Hot flashes and hormonal markers: The Maca-GO study (Meissner, Int J Biomed Sci, 2006) using a multi-color maca blend in postmenopausal women found increases in serum estrogen levels, reductions in FSH, and decreases in hot flashes compared to placebo [17]. A 2013 clinical study reported that maca may modulate endocrine function by balancing hormones along the hypothalamus-pituitary-ovarian axis, including increasing serum estrogen in postmenopausal women [34].

Systematic review evidence: A 2011 systematic review of randomized controlled trials found limited evidence that maca alleviates menopausal symptoms such as hot flashes and mood disturbances, though results were inconclusive due to small sample sizes and methodological limitations across the available studies [35].

Important distinction: Maca is not a true hormone replacement therapy (HRT). Most human studies show no significant alteration of serum hormone levels, and it does not provide the same degree or type of symptom relief as established HRT. There are no direct head-to-head studies comparing maca with conventional HRT [36]. Maca should not be used as a substitute for HRT in women with clinically significant menopausal symptoms without medical guidance.

Mood — Anxiety and Depression

Postmenopausal anxiety and depression: The Brooks (2008) trial demonstrated significant reductions in anxiety (27.3%) and depression (26.8%) in 14 postmenopausal women taking 3,500 mg maca daily for 6 weeks versus placebo [26].

SSRI-associated mood changes: The Dording (2008) study found a small but significant decrease in depression and anxiety measures in the group taking 3,000 mg maca daily, though the absence of a placebo control limits this finding [27].

Anecdotal reports: User reports on maca's effects on anxiety are mixed, with some individuals reporting reduced symptoms and others reporting worsened anxiety or even triggered panic attacks [37]. Rare case reports have documented manic episodes associated with maca use [37].

Panic disorder: There is no scientific evidence from clinical trials that maca is effective for treating or alleviating panic disorder or panic attacks. No dedicated clinical research has investigated this specific application [37].

Synthesis: Preliminary evidence suggests maca may reduce anxiety and depression in postmenopausal women, but the data consists of very small trials. The conflicting anecdotal reports and absence of large-scale mood disorder trials mean maca cannot be recommended as a treatment for clinical anxiety or depression.

Physical Performance and Energy

Maca has traditionally been used to enhance energy, stamina, and physical endurance, earning it the "Peruvian ginseng" designation [1][2].

Cycling performance: A pilot study in trained male cyclists found that 14 days of maca extract supplementation (2 g/day) significantly improved 40 km cycling time trial performance (Stone, 2009) [25].

Hand-grip strength: The Lepidamax study (Jiannine, 2019) found that 2,100 mg of black and red maca blend taken daily for 28 days improved hand-grip strength and reduced self-reported fatigue in men. Improvements in women did not reach statistical significance [24].

Anti-fatigue mechanisms: In vitro and in vivo research supports maca's anti-fatigue effects by demonstrating its ability to prevent mitochondria-mediated muscle damage and reduce oxidative stress during exercise [38]. The antioxidant properties of macamides are proposed as a mechanism for these effects [28].

Systematic review evidence: A 2024 systematic review and meta-analysis of 21 studies (including animal and human data) confirmed maca's positive impact on physical performance and stamina, with large effect sizes observed for endurance, strength, and reduced lactic acid accumulation. However, the review emphasized the need for larger, high-quality randomized trials to validate these benefits beyond short-term observations [30][31].

Oxidative stress: A 2024 systematic review and meta-analysis confirmed that maca supplementation positively affects cellular oxidative stress markers, which may underlie some of its purported anti-fatigue and performance effects [39].

Osteoarthritis

Although maca is sometimes promoted for joint pain, the evidence is limited and of low quality.

A laboratory study showed that a branded maca extract (RNI 249) increased levels of IGF-1 (insulin-like growth factor) in cartilage cells from patients with knee osteoarthritis (Miller, BMC Complement Altern Med, 2006) [40].

A clinical trial found that a combination supplement (Reparagen, Rainforest Nutritionals Inc.) containing 1,500 mg of RNI 249 maca extract plus 300 mg of cat's claw, taken twice daily for 8 weeks, reduced pain in adults with knee osteoarthritis similarly to treatment with 1,500 mg of glucosamine sulfate. Ninety-four percent of the Reparagen group and 89% of the glucosamine group achieved at least a 20% reduction in knee pain (Mehta, BMC Complement Altern Med, 2007) [41].

Critical limitations: This study did not include a placebo group, so it is impossible to determine whether either treatment was truly effective beyond natural symptom fluctuation. Additionally, the supplement contained cat's claw in addition to maca, and cat's claw alone has been shown in at least one clinical trial to reduce knee osteoarthritis pain. Therefore, the maca component's contribution cannot be isolated [10][41].

Prostate Health

Red maca (but not black or yellow) was found to reduce prostate gland weight in rats with experimentally enlarged prostates (Gonzales, Reprod Biol Endocrinol, 2005) [14]. This has led to promotion of red maca for prostate health, but no human clinical trials have investigated maca's effects on prostate enlargement (BPH), PSA levels, or prostate cancer risk.

Bone Density

Animal studies have suggested that red maca may help maintain bone mineral density, potentially relevant for postmenopausal osteoporosis. However, no human clinical data exists for this indication [14].

Neuroprotection and Cognition

Animal studies have demonstrated that black maca may improve memory and learning in rodent models, attributed to its macamide and polyphenol content [28]. However, no well-designed human clinical trials have investigated maca's effects on cognitive function, memory, or neuroprotection. Broader systematic reviews mention neuroprotection as a potential benefit, but the evidence remains limited to preclinical data [30].

Diabetes and Blood Sugar

Based on animal research, maca has been promoted for blood sugar regulation and diabetes management. However, there is insufficient evidence from human clinical trials for these uses [10]. One clinical study noted that 600 mg of maca powder daily for 3 months or longer may cause a small but significant increase in alanine aminotransferase (ALT) levels, which is notable because liver health is relevant to glucose metabolism (Valentova, Food Chem Tox, 2008) [42]. This finding warrants caution rather than supporting a therapeutic role.

Recommended Dosing

Clinical Trial Doses

No official dosing guidelines for maca have been established by regulatory bodies. The following doses have been used in clinical studies [10]:

Indication	Dose	Form	Duration	Study
Sexual desire (men)	1,500–3,000 mg/day	Gelatinized powder	8 weeks	Gonzales 2002 [23]
Sexual desire and fatigue (men and women)	2,100 mg/day (3 × 700 mg)	Black/red maca blend (Lepidamax)	28 days	Jiannine 2019 [24]
Erectile dysfunction	2,400 mg/day	Dried maca extract	12 weeks	Zenico 2009 [29]
Menopausal symptoms (psychological)	3,500 mg/day	Maca powder	6 weeks	Brooks 2008 [26]
SSRI-related sexual dysfunction	3,000 mg/day	Maca root powder	—	Dording 2008 [27]
Sperm quality	1,500–3,000 mg/day	Gelatinized maca tablets	—	Gonzales 2001 [32]
Cycling performance	2,000 mg/day	Maca extract	14 days	Stone 2009 [25]

General Recommendations

Typical dose range: 1,500 to 3,000 mg per day of maca root powder is the most commonly studied and used dose [10].

Starting dose: Beginning with 500 mg per day and gradually increasing to the target dose over 1–2 weeks may help minimize gastrointestinal side effects [10].

Daily doses from 500 mg to 3,500 mg of maca root powder have been used in clinical studies for improving mood and sexual desire and reducing sexual dysfunction [10].

Form selection: Most clinical studies used whole root powder (loose or in capsules), not concentrated extracts. Because the active components of maca remain unidentified, whole root powder appears to be the safest choice aligned with the existing evidence [10].

Timing: No specific timing relative to meals has been established. Maca is traditionally consumed with food as part of meals.

Duration of use: Most clinical trials lasted 4–12 weeks. Long-term safety data beyond 12 weeks of supplementation are limited [10][43].

Traditional Consumption

In Andean populations where maca is a staple food, daily consumption of dried maca exceeds 20 grams per day as part of the regular diet, far exceeding typical supplement doses [1]. This long history of food-level consumption provides some reassurance about the safety of lower supplement doses, though supplement forms may differ in composition and concentration from traditionally prepared maca.

Safety and Side Effects

General Safety Profile

Maca has been consumed as a food for millennia in Andean populations, and clinical studies using maca root powder have not reported serious adverse effects [10][43]. However, most studies were short-term (12 weeks or less) and had small sample sizes, limiting their ability to detect rare or delayed adverse effects.

Reported Side Effects

Side effects reported in clinical trials and anecdotal reports include [10][27][37]:

• Gastrointestinal: Stomach upset, digestive discomfort (occasionally reported)
• Headache (reported in the Dording 2008 study)
• Sleep disruption (reported in the Dording 2008 study)
• Increased sweating (reported in the Dording 2008 study)
• Anxiety or mood changes: Anecdotal reports are mixed — some users report reduced anxiety, while others report worsened anxiety or triggered panic attacks. Rare case reports have documented manic episodes [37]

Liver Enzyme Effects

A clinical study found that daily consumption of 600 mg of maca powder for 3 months or longer caused a small but statistically significant increase in alanine aminotransferase (ALT) levels, high levels of which are associated with liver dysfunction (Valentova, Food Chem Tox, 2008) [42]. Individuals with existing liver conditions should exercise caution and monitor liver enzymes if taking maca long-term.

Blood Pressure Effects

The same study by Valentova (2008) found that 600 mg of maca daily caused a moderate increase in systolic and diastolic blood pressure specifically in women [42]. Individuals with hypertension or cardiovascular conditions should monitor blood pressure when supplementing with maca.

Thyroid Considerations

Maca contains glucosinolates, sulfur-containing compounds that can exhibit goitrogenic effects — meaning they may interfere with iodine uptake by the thyroid gland and potentially impair thyroid function [44][45]. Individuals with existing thyroid conditions (hypothyroidism, Hashimoto's thyroiditis, Graves' disease) should exercise caution with maca and consult their healthcare provider before use. This concern is particularly relevant for individuals with marginal iodine status, as glucosinolates are most likely to cause thyroid disruption when iodine intake is inadequate.

MTCA Concerns

Maca contains a beta-carboline alkaloid called MTCA (1-methyl-1,2,3,4-tetrahydro-β-carboline-3-carboxylic acid), which has properties as a monoamine oxidase inhibitor. In 2002, the French food safety agency (AFSSA) issued a warning about potential neurotoxic and mutagenic effects of MTCA in powdered maca root [7][46]. However, subsequent research demonstrated that MTCA is a natural constituent of maca with no observed toxicity upon consumption at typical doses, and that its activity may be deactivated by heat processing during traditional preparation methods [7][46].

Hormone-Sensitive Conditions

Although most human studies show that maca does not significantly alter serum hormone levels, theoretical concerns exist based on in vitro evidence of estrogenic activity. Cell studies have shown that maca extract upregulates MMP-1 expression and stimulates migration in triple-negative breast cancer cells [47]. Consequently, maca is generally cautioned against in individuals with hormone-sensitive cancers (breast, uterine, ovarian, endometrial cancer) or conditions such as endometriosis or uterine fibroids. Consultation with a healthcare provider is recommended for anyone with a history of hormone-sensitive conditions [47][48].

Body Composition Claims

There is no reliable scientific evidence from clinical trials that maca enhances body curves, enlarges hips, buttocks, or breasts, or alters fat distribution. Such claims are marketing-based and not supported by research [36][28].

Pregnancy and Lactation

Long-term safety studies on maca supplementation in pregnant or nursing women have not been conducted. Use during pregnancy or breastfeeding is not advised due to insufficient safety data [10][43].

Psychiatric Effects

Rare case reports have documented manic episodes associated with maca use [37]. Individuals with bipolar disorder, a history of mania, or other psychiatric conditions should exercise caution with maca supplementation.

Long-Term Safety

Long-term safety studies on maca supplement use in humans have not been conducted. Most clinical trials lasted 12 weeks or less [10][43]. While traditional food-level consumption (>20 g/day) over centuries provides some reassurance, concentrated supplement forms may have different safety profiles. As of 2024, a working group of EU member states has proposed restrictions on maca in food supplements due to identified safety risks [45].

Contaminant Concerns

Heavy metal contamination is a concern with maca supplements, particularly those sourced from regions with industrial soil contamination. Products grown in China's Yunnan Province have raised specific concerns about heavy metal levels [10][22]. Independent testing has found lead contamination in some maca products, including those labeled as sourced from Peru [10]. Choosing products from reputable sources with third-party testing for heavy metals is advisable.

Drug Interactions

Limited pharmacokinetic data is available on maca, which complicates the full assessment of potential drug interactions [44]. The following interactions are based on the known properties of maca's bioactive compounds:

Anticoagulant/Antiplatelet Medications

Maca has a high concentration of vitamin K and it is therefore possible that it could adversely affect bleeding control in people taking anticoagulant medication such as warfarin (Coumadin) (USP Dietary Supplement Compendium, 2012) [49]. Individuals on blood thinners should consult their healthcare provider before taking maca and may need more frequent INR monitoring.

Hormone Therapies

Maca's potential adaptogenic properties may influence estrogen or testosterone levels, although human evidence for significant hormonal changes is inconsistent [36][28]. Theoretical interactions exist with:

• Hormone replacement therapy (HRT): Maca may theoretically interact with estrogen or progesterone therapy, though no clinical interaction studies have been conducted
• Oral contraceptives: Theoretical concern based on potential estrogenic activity in vitro
• Anti-estrogen medications (tamoxifen, aromatase inhibitors): Caution warranted given in vitro estrogenic activity [47]

Thyroid Medications

Due to the glucosinolate content and potential goitrogenic effects, maca may theoretically interfere with thyroid hormone replacement therapy (levothyroxine) or anti-thyroid medications. Individuals taking thyroid medications should consult their healthcare provider [44][45].

Monoamine Oxidase Inhibitors (MAOIs)

The MTCA content of maca has monoamine oxidase inhibitory properties [7]. Although the clinical significance at typical supplement doses is likely minimal (and may be reduced by heat processing in gelatinized products), a theoretical interaction exists with MAO inhibitor medications (phenelzine, tranylcypromine, selegiline). Caution is advisable if combining maca with MAOIs.

SSRI Antidepressants

One small study specifically investigated maca in combination with SSRIs for sexual dysfunction (Dording, 2008) [27]. At 3,000 mg/day, maca appeared to improve SSRI-related sexual dysfunction without reported significant adverse interactions. However, given maca's MTCA content and potential serotonergic effects, individuals taking SSRIs should discuss maca use with their prescriber.

Stimulant Medications

Drug interaction databases report no known interactions between maca and methylphenidate (Concerta) or other ADHD stimulants (e.g., Adderall), although the absence of documented interactions does not rule out the possibility of effects in some individuals [50]. Consulting a healthcare provider is advised before combining maca with prescription stimulants.

Blood Pressure Medications

Given the finding that maca may modestly increase blood pressure in some individuals (particularly women), those taking antihypertensive medications should monitor blood pressure when adding maca supplementation (Valentova, 2008) [42].

Summary Table

Drug Class	Concern	Recommendation
Anticoagulants (warfarin)	Vitamin K content may affect INR	Consult provider; monitor INR
Hormone therapies (HRT, OC, tamoxifen)	Theoretical estrogenic activity	Consult provider; avoid with hormone-sensitive cancers
Thyroid medications	Glucosinolate goitrogenic effects	Consult provider
MAO inhibitors	MTCA has MAO inhibitory properties	Exercise caution; discuss with prescriber
SSRIs	Limited data; MTCA content	Discuss with prescriber
Antihypertensives	May modestly raise blood pressure	Monitor blood pressure

Dietary Sources

Maca is not commonly found in Western diets outside of supplement form. In its native Andes region, it is consumed as a whole food.

Traditional Preparations

Preparation	Description
Boiled maca	Hypocotyls are boiled to soften and eaten directly, or added to soups and stews
Roasted maca (huatia)	Roots baked underground with hot stones in traditional earthen ovens; produces a caramelized flavor
Maca flour (harina de maca)	Dried roots ground into fine flour for bread, porridges (mazamorra), and other baked goods
Chicha de maca	Fermented mildly alcoholic beverage made from dried roots; traditional brewing technique
Maca juice	Blended fresh or dried root with water or milk
Maca leaves	Edible leaves consumed raw in salads or cooked like spinach

Nutritional Content of Dried Maca Root

Per 100 g of dried maca powder [3][4]:

Nutrient	Amount
Calories	~325 kcal
Carbohydrates	55–73%
Protein	8.9–21%
Dietary fiber	8.2–25.6%
Fat	0.6–2.2%
Iron	Rich source
Calcium	Rich source
Potassium	Rich source
Iodine	Present
Vitamin C	Present
B vitamins (B1, B2)	Present

Modern Dietary Use

Outside of the Andes, maca is most commonly consumed as:

• Powder added to smoothies — the most popular preparation method; the malty flavor blends well with banana, cacao, and nut-based smoothies
• Powder mixed into beverages — water, juice, milk, or coffee
• Capsules — convenient for those who dislike the taste
• Added to oatmeal, yogurt, or energy balls — as a nutritional booster
• Baked goods — maca flour added to breads, muffins, and pancakes

Traditional Consumption Levels

In Andean populations, daily consumption of dried maca commonly exceeds 20 grams per day — roughly 7–13 times the typical supplement dose of 1,500–3,000 mg [1]. This represents one of the highest daily intakes of any single plant food in traditional Andean diets. The roots were historically so valued that they were traded for lowland goods such as salt, corn, and fish, and served as tribute payment during both Inca and Spanish colonial periods [2].

References

1. Grokipedia. "Maca." Accessed 2026. https://grokipedia.com/page/Maca

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