Maca root

What it is

Maca is a root vegetable grown at high altitude in the Peruvian Andes, related to radishes and turnips. It has been eaten there for centuries. The dried root is sold as powder or capsules and comes in colour types: yellow, red and black.

People take it for libido, sexual function, energy, mood and fertility. It is often marketed as a natural testosterone booster, but studies have not shown that it changes testosterone levels.

It is sold as a food in the UK and is widely available.

How it works

The mechanism is unclear. Maca does not appear to contain hormones or alter hormone levels in most studies. Proposed effects involve its unique plant compounds (macamides, macaenes and glucosinolates) acting on the brain or mood pathways, but this is not established.

What the evidence says

• Limited Sexual desire
  A few small randomised trials suggest a modest rise in libido after several weeks, but sample sizes are small.
• Limited Antidepressant-related sexual dysfunction
  One small trial in women reported improvement; needs more confirmation.
• Weak Mood and energy
  Self-reported improvements in small studies, but difficult to separate from placebo.
• Weak Sperm quality
  Small trials suggest some improvement in semen measures, but the evidence is thin.

Evidence ratings are our plain-English summary of how much good human research exists, not a promise of results. How we rate evidence.

Dosage and timing

• Trials commonly use 1.5 to 3 g daily of powder, sometimes up to 5 g.
• Take with food, often in the morning.
• Gelatinised maca (heated to remove starch) can be easier on the stomach than raw.
• There is no NHS reference intake. Check the label and current guidance.

Forms and what to look for

• Gelatinised maca powder: often better tolerated.
• Raw powder: cheaper but can cause bloating.
• Capsules: convenient and easier to dose.
• Colour types (yellow, red, black) are marketed for different aims, but the evidence for those distinctions is limited.

What to expect, and when

• Do not expect anything in the first couple of weeks.
• Trials typically measure effects at 8 to 12 weeks.
• Many people notice no change; it is reasonable to stop if nothing happens in three months.

Side effects

• Bloating or stomach discomfort, particularly with raw powder.
• Insomnia or restlessness in some people.
• Headache.
• Mood changes or irritability in a small number of people.

Interactions

• Thyroid medication: maca contains glucosinolates, which in theory may affect thyroid function.
• Hormone therapies or contraception: effects not well studied.
• Blood pressure medicines: some reports of added effect.
• Antidepressants: limited data, so mention to a clinician.

Who should avoid it

• People with thyroid conditions, unless advised by a clinician.
• Pregnant or breastfeeding women, as safety data is limited.
• People with hormone-sensitive cancers, as a precaution.
• Anyone with a history of sensitivity to cruciferous vegetables.

Risks and safety

• Lead and other heavy-metal contamination has been reported in some root products from soil.
• Products may be adulterated with cheaper ingredients or stimulants in some markets.
• Not WADA-prohibited, but athletes should choose batch-tested products.

Buying well: quality and testing

• Look for Lepidium meyenii and Peruvian origin on the label.
• Prefer brands that publish heavy metal testing.
• Third-party certification is a good sign.
• Avoid blends with undisclosed amounts or exaggerated testosterone claims.

Bottom line

Maca is a low-risk, food-like root with small, uncertain benefits for libido. It suits adults who want a gentle option and accept that it may do nothing. It is not a testosterone booster, and anyone with persistent sexual or hormonal problems should see a GP rather than rely on supplements.