ZMA

Marketing claim· human data

Also known as: Zinc, magnesium aspartate, B6

The testosterone- and strength-boosting claims don't hold up in people who aren't deficient.

What it is

ZMA is a branded combination of zinc, magnesium aspartate and vitamin B6, sold as a night-time recovery and "testosterone support" supplement. It's really just two minerals and a vitamin in one capsule.

What the evidence shows

Testosterone and strength. Marketing claim This is the headline claim, and it doesn't hold up. In people who aren't deficient in zinc or magnesium — most people who train and eat reasonably — controlled studies do not show meaningful increases in testosterone or strength.

Recovery and sleep. Preliminary· human data Any benefit here traces back to correcting a genuine zinc or magnesium shortfall (see magnesium), not to ZMA as a special formula.

Correcting a real deficiency. Well-supported· human data Zinc and magnesium do matter, and fixing a true deficiency has value — but that's an argument for the individual minerals where needed, not for ZMA's marketing.

Who it suits

Realistically, few people specifically need ZMA. If you're low in zinc or magnesium, addressing that directly is more sensible than buying the branded combination for its testosterone promise.

Practical notes

You can get the same nutrients from food or plain zinc and magnesium. If you try it, the muscle-building marketing is the part to ignore — judge it only on whether you had a deficiency worth correcting.

Sources

Frequently asked questions

Does ZMA boost testosterone?
In men who aren't deficient in zinc or magnesium — which is most people who train and eat reasonably — controlled studies do not support meaningful testosterone or strength increases. That's the headline claim, and it doesn't hold up.
So is ZMA useless?
Not entirely: if you're genuinely low in zinc or magnesium, correcting that has value. But that's a case for fixing a deficiency, not for ZMA's marketed muscle-building promise.
Is it just zinc and magnesium?
Yes — ZMA is zinc, magnesium and vitamin B6 in a branded combination. You can get the same nutrients from food or plain zinc/magnesium if needed.

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Written and reviewed by Mathew Beale — MSc Biotechnology, University of Reading.

Last reviewed: