Maca Root

With supplements

1. Tongkat Ali — reported to work through testosterone elevation (SHBG reduction, aromatase inhibition, cortisol modulation), a hormonal mechanism distinct from maca's reported non-hormonal one.
2. L-citrulline — reported to work through nitric-oxide-mediated vasodilation, a vascular mechanism distinct from maca's.
3. Ashwagandha — an overlapping adaptogen mechanism (HPA-axis cortisol modulation); no trial identified for this page has tested the combination.
4. Zinc — a mineral cofactor for testosterone synthesis, relevant to fertility applications rather than maca's own mechanism.
5. SSRI/SNRI antidepressants — Dording 2008's trial population was recruited specifically for SSRI-induced sexual dysfunction; the trial did not test maca as a general antidepressant adjunct.

Reported in the cited trials

1. No significant adverse events were reported in the cited trials at 1.5–3.5 g/day for 6–12 weeks.
2. Mild GI discomfort with raw (non-gelatinized) maca is reported in the broader supplement literature, not specifically measured as an adverse event in the cited trials.

Reported outside the cited trials

1. Thyroid interaction at high doses in iodine-deficient users. Maca contains glucosinolates, compounds reported elsewhere in the nutrition literature to theoretically affect thyroid function at high doses in iodine-deficient individuals; this was not directly measured in a maca trial identified for this page.
2. Pregnancy and breastfeeding. No trial identified for this page enrolled pregnant or breastfeeding participants.
3. Hormone-sensitive condition history. The trials above measured no hormonal change from maca; no trial identified for this page enrolled participants with active hormone-sensitive cancer, so the reproductive-tissue effects noted in the mechanism section above have not been characterized in that population.
4. Heavy-metal content. Maca is grown in the mineral-rich Andean soils of Peru; independent testing of botanical products grown in similar conditions has documented lead and cadmium accumulation as a category-wide consideration, not specific to a maca trial identified for this page.

Drug and supplement interactions

1. SSRI / SNRI antidepressants. Dording 2008 studied maca specifically in this population and reported no clinically significant pharmacokinetic interaction; the trial did not report adverse interactions with the antidepressants its participants were already taking.
2. Thyroid medications — no interaction documented in a trial identified for this page; a theoretical concern at very high doses in iodine-deficient users is reported in the broader nutrition literature (see above).
3. Hormone-sensitive condition medications (tamoxifen, aromatase inhibitors, GnRH agonists) — no trial identified for this page tested this combination.
4. Other adaptogens (ashwagandha, rhodiola) — no trial identified for this page tested the combination.

Does maca root raise testosterone?

No trial identified for this page found a testosterone-raising effect. Multiple human RCTs have measured serum testosterone, estrogen, LH, and FSH before and after maca supplementation and found no significant hormonal changes (Gonzales 2002 is the foundational study reporting libido improvement without testosterone change). Maca's libido-enhancing effects are reported to operate through different mechanisms — proposed dopaminergic and noradrenergic neurotransmitter pathways, plus adaptogenic effects on stress-hormone balance. For a compound with reported testosterone-elevating evidence, see Tongkat Ali, which has trial evidence for testosterone elevation in eugonadal-low and late-onset-hypogonadal men.

What's the difference between black, red, and yellow maca?

All three are the same species (Lepidium meyenii); the color variation reflects different cultivars and growing conditions, and the trial evidence differs by color. Yellow maca has the broadest evidence base, since most trials used yellow or mixed-color maca. Black maca specifically has trial evidence for male fertility — sperm count, motility, and seminal volume improvements (Gonzales 2001 series, Melnikovova 2015). Red maca has been studied for benign prostatic hyperplasia (BPH) in a testosterone-induced rat model (Gonzales 2012), which reported reduced prostate weight and prostate zinc levels — no human RCT was identified for this page.

What doses have been studied?

1.5–3 g daily of maca powder or extract, across the cited human trials. Gonzales 2002 tested 1.5 g and 3 g arms — both produced libido improvements, with no clear dose-response difference reported between them. Dording 2008 tested 1.5 g versus 3 g for SSRI-induced sexual dysfunction and reported the 3 g arm performed better. Brooks 2008 used 3.5 g/day. Gonzales 2012's red maca prostate research is a rat study, not a human dosing trial. Gelatinized maca (starch-removed) is the form the cited human trials predominantly used.

What does the evidence say about maca for SSRI-induced sexual dysfunction?

A 2008 RCT by Dording et al. in remitted-depression patients with SSRI-induced sexual dysfunction reported that high-dose maca (3 g/day for 12 weeks) significantly improved sexual function scores compared to the 1.5 g/day arm. SSRI-induced sexual dysfunction is a common side effect of antidepressant therapy with limited established treatments; the trial's authors note maca's non-hormonal mechanism is relevant here since some patients on SSRIs have additional reasons to avoid hormonal interventions. The reported effect size is modest. This trial did not test maca as a replacement for prescriber-directed changes to antidepressant therapy.

Does maca have trial evidence in postmenopausal women?

Yes. A 2008 RCT by Brooks et al. in postmenopausal women reported that 3.5 g/day maca for 6 weeks reduced anxiety, depression symptoms, and sexual dysfunction scores compared to placebo, without affecting serum estradiol or other hormones. A 2015 trial in Chinese postmenopausal women reported similar sexual-function and mood improvements. Postmenopausal sexual dysfunction has limited non-hormonal treatment options in the broader clinical literature; the trial authors frame maca's non-hormonal mechanism as relevant to that gap.

How long do the cited trials run before reporting an effect?

The cited trials range from 6 to 12 weeks. Gonzales 2002 used a 12-week protocol; Brooks 2008 used 6 weeks; Dording 2008 used 12 weeks. No trial identified for this page measured effects before 4 weeks or established a non-response threshold.

What does the safety data show?

The cited trials, at 1.5–3.5 g/day for 6–12 weeks, report no significant adverse events. Maca has a long history of use as a food in Peru, which supports a favorable traditional-use safety record, though this is distinct from randomized-trial safety data at supplemental doses over multi-year periods, which was not located for this page. Maca contains glucosinolates, compounds also found in other cruciferous plants (broccoli, cauliflower, kale) that are reported in the broader nutrition literature to theoretically affect thyroid function at high doses in iodine-deficient individuals; no trial identified for this page measured this directly in maca users. Gelatinized maca is reported to have lower glucosinolate content than raw maca. Pregnancy and breastfeeding safety at supplemental doses is not characterized in a trial identified for this page.

What other compounds have overlapping or complementary mechanisms?

Tongkat Ali is reported to work through testosterone elevation (SHBG reduction, aromatase inhibition, cortisol modulation) — a hormonal mechanism distinct from maca's. L-citrulline is reported to work through nitric-oxide-mediated vasodilation — a vascular mechanism. No trial identified for this page has tested maca combined with either compound.