Maca and ashwagandha: what the human trials actually found

These are the two ingredients in a men’s formula most likely to have real human data behind them. This is what that data actually measured, how big the trials were, what doses they used, and where the honest limits sit.

What maca and ashwagandha are

Maca (Lepidium meyenii), known in Spanish-speaking markets as maca peruana, is a cruciferous root grown above 4,000 metres in the Peruvian Andes and eaten there as a staple food. Ashwagandha (Withania somnifera) is a root used in Ayurvedic practice and classified in the modern literature as an adaptogen — a plant studied for its effect on the stress response rather than on any single organ.

What the maca trials measured

The single most-cited maca trial randomised healthy adult men to maca or placebo for twelve weeks and measured self-reported sexual desire. Desire scores improved from week eight onward, and the authors reported explicitly that this happened without any change in serum testosterone or oestradiol (Gonzales et al., Andrologia, 2002). That second half is the part marketing leaves out, and it is the more interesting finding: whatever maca does, the trial evidence says it does not do it by raising testosterone.

A systematic review that pooled the randomised maca trials for sexual function concluded that the evidence was suggestive but limited by small sample sizes and methodological weaknesses (Shin et al., BMC Complement Altern Med, 2010). That remains a fair summary. Maca is not an empty ingredient; it is a thinly evidenced one.

What the ashwagandha trials measured

Ashwagandha has the deepest evidence base of any botanical in this category, and almost all of it concerns stress. A frequently cited randomised, double-blind, placebo-controlled trial gave adults a high-concentration full-spectrum root extract for 60 days and reported reductions in stress and anxiety scores against placebo (Chandrasekhar et al., Indian J Psychol Med, 2012). A meta-analysis of ashwagandha and sleep found a small but statistically significant improvement in sleep measures (Cheah et al., PLoS One, 2021), and a more recent systematic review of anxiety and insomnia reached a similar cautious conclusion while flagging the small size and short duration of the underlying trials (Fatima et al., Hum Psychopharmacol, 2024).

The hormone question has been asked directly. A small randomised crossover study in aging, overweight men reported modest increases in testosterone and DHEA-S alongside improvements in fatigue and vitality over eight weeks (Lopresti et al., Am J Mens Health, 2019). It involved around twenty men. That is a signal worth following, not a settled result, and it is a long way from the claims made for ashwagandha in advertising.

Side by side

The dose problem

Trials use specific, standardised preparations at specific amounts — a defined root extract at a stated milligram dose, once or twice daily, for a defined number of weeks. Most consumer formulas do not tell you enough to make that comparison. The MaxForce label is a case in point: it names ashwagandha and maca extract among five ingredients and prints a combined 82 mg per serving, equivalent to approximately 567 mg of dry powders, but no per-ingredient split was published on the pages we reviewed. Without the split, no honest comparison with any trial above is possible. How to read that kind of panel is covered in what a men’s vitality label must tell you, and the same dose arithmetic applied to a third botanical is worked through in what the tongkat ali research actually shows.

What this evidence does not show

It does not show that either plant treats erectile dysfunction, raises testosterone into a clinically meaningful range, or improves fertility. It does not show that combining them multiplies anything. And it does not transfer to a finished product: a trial of a standardised extract is evidence about that extract at that dose, not about a gummy containing an undisclosed fraction of it. The general version of that argument is in do testosterone boosters actually work.

Safety, honestly

Ashwagandha is the one to take seriously here. A case series and literature review documented drug-induced liver injury associated with ashwagandha use (Philips et al., Hepatol Commun, 2023), and a scoping review has since collected the reported cases and their clinical characteristics (McIntyre et al., Cureus, 2026). Thyrotoxicosis following ashwagandha use has also been reported (van der Hooft et al., Ned Tijdschr Geneeskd, 2005). These are uncommon events against wide use, but they are real, and they mean ashwagandha is not a free action if you have liver disease, thyroid disease, or take thyroid medication or sedatives.

How long before either is worth judging?

Both literatures run on an eight-to-twelve-week clock, which is why an honest product page frames its timeline that way rather than promising a first-week effect. The reasoning, and what to track while you wait, is in how long a men’s vitality supplement takes to work.

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