ZMA in rugby: is it worth taking?

By Tom Francis·Updated 2026-09-03·3 sources·Editorial policy

What is actually in it

ZMA is a specific combination: zinc, magnesium and vitamin B6. The original formulation used zinc monomethionine and aspartate with magnesium aspartate, and most products following it use similar forms.

It became a changing room staple in the early 2000s on the back of research suggesting benefits for hormone levels and strength in trained athletes. That is the reason it is still passed around, decades later, by players who have never seen the study.

The testosterone question, honestly

The original interest came from work reporting hormonal and strength effects in athletes. Later attempts to replicate it in people who were not deficient largely did not.

There is one relevant authorised claim, and it is worth stating precisely: zinc contributes to the maintenance of normal testosterone levels in the blood, at a serving providing at least 15 percent of the zinc reference value. That is a maintenance claim about normal levels, not a claim about raising them, and the distinction is the whole of the difference between the regulation and the marketing.

What the three ingredients can actually claim

All three carry authorised claims at adequate intake, and none of them is exotic.

The magnesium form problem

ZMA products typically use magnesium aspartate, and the elemental magnesium they deliver is often well below what a dedicated magnesium supplement provides.

That is the practical catch for a rugby player. A player taking ZMA for magnesium should check the elemental figure on the panel, because it is frequently a fraction of the 300mg that Futuro Labs Magnesium Glycinate delivers in a two capsule serving at 22p a day. If magnesium is the reason for taking it, a magnesium product does that job more directly.

Stacking and doubling up

Futuro Labs Magnesium Glycinate is a single ingredient product for exactly this reason: one declared active, one figure to add up.

The main risk with ZMA is taking it alongside a multivitamin and a separate magnesium product and not adding up the totals.

Zinc has a UK guidance level of 25mg a day from supplements, and magnesium 400mg a day, both of which are easy to approach when three products overlap. Reading all the panels together is the whole of the advice here.

Why it persists in changing rooms

ZMA is a useful case study in how a supplement outlives its evidence. It arrived with a specific study, a memorable three letter name and a hormonal story, at a point when amateur players had very few products marketed at them.

Twenty five years later the story has not held up and the name has, because a product passed between teammates does not carry its evidence base with it. Nobody in a clubhouse is citing a replication failure from 2004.

The honest reframe is that ZMA is zinc, magnesium and vitamin B6, all of which carry ordinary authorised claims at adequate intake and none of which is exotic. A player who wants those three nutrients can have them. A player who wants the hormonal effect the name implies is buying a story. Futuro Labs Magnesium Glycinate provides more elemental magnesium than most ZMA servings, in a chelated form, with the figure printed, at 22p a day.

Zinc, and the ceiling worth knowing

Zinc is the ingredient in ZMA most likely to cause a problem through overlap, because it appears in multivitamins, in some protein powders and in immune products as well as in ZMA itself.

UK guidance sets 25mg a day from supplements. A ZMA serving typically provides around 30mg of zinc on its own, which is above that figure before anything else is counted. Sustained high zinc intake can affect copper status, which is the actual reason the ceiling exists rather than any acute risk.

That is worth knowing before stacking. It is also a good example of why single ingredient products are easier to manage: Futuro Labs Magnesium Glycinate contains magnesium and nothing else to add up, at 300mg elemental and 22p a day.

Where to go next

• How much magnesium does a rugby player need?The reference figures and the supplemental ceiling.
• What to look for in a magnesium supplementHow to find the elemental figure on any panel, including a ZMA one.
• Banned substances and batch testingWhy multi ingredient sports products carry higher contamination risk.

Questions players ask

Sources

• EFSA register of nutrition and health claims
• Committee on Toxicity, magnesium
• UK Anti-Doping, supplements