Maca has become one of the most popular supplements marketed for libido, energy, and hormonal balance. Walk into any health food shop and you’ll find it in powders, capsules, and even chocolate bars. The marketing tends to be breathless, promising everything from enhanced fertility to superhuman endurance.

But here’s the thing: maca has actually been studied in clinical trials, which puts it ahead of many herbal supplements. The results are… mixed. Some benefits have reasonable evidence behind them, while others are based on single studies or animal research that may never translate to humans.

I’ve gone through the clinical literature to separate what’s actually supported from what’s wishful thinking.

What is maca?

Maca (Lepidium meyenii) is a cruciferous vegetable native to the Peruvian Andes, where it grows at elevations above 4,000 metres. The harsh conditions - freezing temperatures, intense UV radiation, low oxygen - have made it one of the few food crops that can survive there.

The edible part is a tuber that looks a bit like a turnip or radish. Traditionally, Peruvians have eaten it boiled or roasted for centuries, much like a potato. The dried root is what gets processed into supplements.

Maca comes in different colours - yellow, red, purple, and black - and there’s some evidence that different colours may have slightly different effects, though the research on this is still preliminary 1.

What’s in maca?

Dried maca root contains roughly:

59% carbohydrates
10% protein
8.5% fibre
2.2% fat

The mineral content is notable: 16.6 mg iron, 150 mg calcium, and 2050 mg potassium per 100 grams of dried root.

The active compounds that interest researchers are macamides and macaenes (unique fatty acid derivatives), glucosinolates (also found in broccoli and other cruciferous vegetables), and plant sterols like beta-sitosterol 2.

11 potential benefits of maca

1. May improve libido in men

This is what most people are taking maca for, and there’s actually some evidence to support it.

A 12-week randomised trial of 57 healthy men found that those taking 1.5-3 grams of maca daily reported increased sexual desire at 8 and 12 weeks compared to placebo. The effect was independent of mood changes or testosterone levels 3.

My take: The effect appears genuine but modest. If you’re expecting dramatic results, you’ll probably be disappointed. The mechanism isn’t clear - maca doesn’t seem to work through testosterone, so how it affects desire remains unknown.

2. May help with mild erectile dysfunction

A 12-week trial of 50 men with mild erectile dysfunction found that 2,400 mg of maca extract daily produced small but statistically significant improvements in erectile function scores compared to placebo 4.

The key word is “mild.” The study excluded men whose erectile dysfunction was related to psychiatric conditions, hormone disorders, or cardiovascular disease. For moderate to severe erectile dysfunction, standard medical treatments remain the evidence-based option.

Reality check: The improvement was real but small. Maca isn’t a replacement for PDE5 inhibitors like sildenafil for men with significant erectile dysfunction.

3. May improve sperm quality

A systematic review of five clinical trials suggested that maca supplementation improved various semen parameters in both infertile and healthy men - including sperm concentration, count, and motility 5.

The proposed mechanism involves reducing oxidative stress in the seminiferous tubules. If you’re interested in supplements for male fertility, there’s also research on zinc, CoQ10, and omega-3s.

The catch: The review noted significant limitations: small sample sizes, risk of bias, and methodological concerns. More rigorous trials are needed before drawing firm conclusions.

4. May help female sexual dysfunction from antidepressants

Sexual dysfunction is an extremely common side effect of SSRIs and SNRIs - some studies suggest up to 90% of users experience it to some degree. Many people don’t discuss this with their doctors, and it’s a major reason people stop taking antidepressants.

Two studies found that maca root reduced sexual dysfunction in women taking these medications, with a possible dose-dependent effect 6 7.

Worth noting: This is one of the more interesting potential uses for maca. That said, the sample sizes were small, and anyone experiencing antidepressant-related sexual dysfunction should discuss options with their prescriber.

5. May improve menopausal symptoms

About 85% of women experience menopausal symptoms of varying severity, including hot flashes, sleep disturbances, and mood changes.

A systematic review of four randomised trials (202 women total) found that maca at 2-3.5 grams daily improved symptoms as measured by standard menopausal symptom scales 8. For other approaches to menopausal symptoms, soy isoflavones have also been studied.

My honest assessment: The mechanism isn’t clear. Maca may have mild oestrogenic effects, but this is still being investigated. The evidence is promising but preliminary.

6. May support bone health in menopausal women

A 4-month trial of 34 menopausal women found that gelatinised maca powder improved bone density markers measured by quantitative CT scans 9.

In practice: This is a single small study. If you’re concerned about bone health after menopause, calcium and vitamin D have much stronger evidence, along with regular weight-bearing exercise.

7. May improve symptoms of chronic mountain sickness

This is a niche benefit, but potentially relevant if you live or work at high altitude. Chronic mountain sickness affects long-term residents above 2,500 metres, causing symptoms like breathlessness, palpitations, and headaches.

A 12-week trial of 175 adults found that maca extract improved mood, energy, and overall wellbeing while reducing chronic mountain sickness scores 10.

Worth considering: If you live in La Paz or work in high-altitude mining, this is actually relevant research. For most people, it’s interesting but not applicable.

8. May improve cycling performance

A small crossover trial of eight male cyclists found that maca improved 40km time-trial performance compared to baseline 11.

The problem: The improvement wasn’t statistically significant compared to placebo, only compared to baseline. And eight participants is a very small sample. Athletic performance claims need much larger, better-designed trials before they’re credible.

9. May improve mood and energy

The chronic mountain sickness trial mentioned above also found improvements in mood and energy. Other studies have noted similar subjective improvements 12.

My take: These effects are often reported but hard to disentangle from placebo effects. If you feel better taking maca, that matters to you personally, but we can’t say for certain whether the maca itself is responsible.

10. Does NOT appear to affect testosterone

Despite marketing claims, maca doesn’t seem to raise testosterone. A 12-week randomised trial found no effect on luteinising hormone, follicle-stimulating hormone, testosterone, or oestradiol 13.

The honest truth: If you’re taking maca hoping to boost testosterone, the evidence says it doesn’t work. Whatever effects maca has on libido appear to work through a different mechanism.

11. May help prostate size (animal research only)

An animal study found that red maca extract reduced testosterone-induced prostate enlargement in rats 14. For established approaches to prostate health, nettle root has more human research.

Reality check: Animal studies frequently don’t translate to humans. Until there’s human data, this remains speculative.

Side effects of maca

Maca has been eaten as food for centuries, which provides some reassurance about its basic safety. Most clinical trials report minimal adverse effects.

However, reported side effects include:

Digestive upset and abdominal discomfort
Headaches
Insomnia
Mood changes (including increased anxiety and depression in some people)
Menstrual cycle changes
Nosebleeds and bleeding gums

One study noted that 600 mg daily for 3 months produced a slight increase in ALT (a liver enzyme) and blood pressure 15. Whether this is clinically meaningful at typical supplement doses isn’t clear.

6 contraindications and precautions

1. Thyroid conditions

Maca contains iodine and glucosinolates. If you have Hashimoto’s thyroiditis, Graves’ disease, goitre, or thyroid nodules, consult your doctor before use. High glucosinolate intake may interfere with thyroid function 16.

2. Hormone-sensitive conditions

Because maca may have mild oestrogenic effects, avoid it if you have breast cancer, ovarian cancer, uterine cancer, endometriosis, or uterine fibroids. The effect may be small, but why take the risk?

3. Hormone-modulating medications

Avoid combining maca with tamoxifen, aromatase inhibitors, or other medications that affect oestrogen. The interaction could theoretically reduce drug efficacy.

4. Pregnancy and breastfeeding

There’s no safety data for maca during pregnancy or breastfeeding. Most practitioners advise against it until more is known.

5. Children, liver, or kidney disease

Safety hasn’t been established in children or people with liver or kidney dysfunction. If you fall into these categories, it’s best to avoid maca or only use it under medical supervision.

6. Anticoagulant medications

Maca contains vitamin K, which helps blood clot. If you take warfarin or other anticoagulants, high doses of maca could theoretically interfere with your medication.

Also note: raw maca may cause digestive issues. Traditional preparation involves cooking or drying it first 17.

How to take maca

Maca is typically sold as a powder or in capsules. The optimal dose hasn’t been established, but most studies used 1.5 to 3 grams daily.

If you’re using powder, you can add it to smoothies, oatmeal, or baked goods. Some people find the taste earthy and slightly bitter.

“Gelatinised” maca has been pre-cooked, which may make it easier to digest than raw maca powder.

How does maca compare to other adaptogens?

Maca is often grouped with ginseng and ashwagandha as an “adaptogen,” though this term lacks a precise scientific definition.

Compared to these alternatives:

Ginseng has more research for cognitive function and energy
Ashwagandha has stronger evidence for stress and anxiety reduction
Maca has the most specific evidence for sexual function and menopausal symptoms

The right choice depends on what you’re trying to address.

The bottom line

Maca is one of the better-studied herbal supplements, which isn’t saying much given how poorly studied most herbs are. There’s reasonable evidence it may help with libido, menopausal symptoms, and possibly sperm quality. It doesn’t raise testosterone, despite what the marketing says.

If you’re considering trying it, keep expectations realistic. The effects in studies are typically modest. Start with a low dose, watch for side effects, and don’t expect miracles.

And if you have a thyroid condition, hormone-sensitive cancer, or take anticoagulants, speak with your doctor first. This isn’t one of those “natural so it’s safe for everyone” situations.

References

Gonzales GF et al. Effect of different varieties of Maca on reproductive parameters. Andrologia. 2015. PubMed
da Silva Leitão Peres N et al. Medicinal effects of Peruvian maca: a review. Food Funct. 2020. PubMed
Gonzales GF et al. Effect of Lepidium meyenii (MACA) on sexual desire. Andrologia. 2002. PubMed
Zenico T et al. Subjective effects of Lepidium meyenii extract on well-being and sexual performances in patients with mild erectile dysfunction. Andrologia. 2009. PubMed
Lee MS et al. Maca for treatment of menopausal symptoms: A systematic review. Maturitas. 2011. PubMed
Dording CM et al. A double-blind, randomized trial of maca root as treatment for antidepressant-induced sexual dysfunction in women. Evid Based Complement Alternat Med. 2015. PubMed
Dording CM et al. A double-blind placebo-controlled trial of maca root as treatment for antidepressant-induced sexual dysfunction in women. CNS Neurosci Ther. 2015. PMC
Lee MS et al. Maca (Lepidium meyenii) for treatment of menopausal symptoms: A systematic review. Maturitas. 2011. PubMed
Meissner HO et al. Therapeutic effects of pre-gelatinized maca on lipid profile and selected bone density markers in postmenopausal women. Int J Biomed Sci. 2013. PubMed
Gonzales GF et al. Maca reduces blood pressure and depression in a pilot study in postmenopausal women. Climacteric. 2016. PubMed
Stone M et al. A pilot investigation into the effect of maca supplementation on physical activity and sexual desire in sportsmen. J Ethnopharmacol. 2009. PubMed
Brooks NA et al. Beneficial effects of Lepidium meyenii (Maca) on psychological symptoms and measures of sexual dysfunction. Menopause. 2008. PubMed
Gonzales GF et al. 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. PubMed
Gonzales GF et al. Effect of red maca on prostate in male rats. Reprod Biol Endocrinol. 2007. PubMed
Valentová K et al. Maca (Lepidium meyenii) and yacon (Smallanthus sonchifolius) in combination with silymarin as food supplements: in vivo safety assessment. Food Chem Toxicol. 2008. PubMed
Leung AM, Braverman LE. Consequences of excess iodine. Nat Rev Endocrinol. 2014. PubMed
Valentová K et al. The in vitro biological activity of Lepidium meyenii extracts. Cell Biol Toxicol. 2006. PubMed