Can zinc supplementation really boost testosterone levels?

Zinc is often included in supplements marketed to support testosterone. There is a scientific reason for this: zinc contributes to normal reproductive function, and inadequate zinc can affect testosterone production.

But whether a supplement helps depends partly on your starting point. Correcting a deficiency can improve testosterone levels; taking extra zinc when you already have enough has not consistently shown the same benefit. [1] [2]

Why zinc matters

Zinc is an essential mineral involved in making new cells and enzymes, processing nutrients and wound healing. Foods including meat, shellfish, dairy products, bread and cereals supply it.

UK guidance puts daily requirements at approximately 9.5 mg for men aged 19–64 and 7 mg for women. Most people should be able to meet their needs through a varied diet. [3]

Its involvement in testosterone production makes adequate intake important. However, a nutrient being necessary for a process does not mean that adding more continually increases that process.

What does the research show?

A systematic review published in 2023 examined 38 studies: eight human studies and 30 animal studies. The authors concluded that zinc deficiency can reduce testosterone and that supplementation can improve levels. They also highlighted that the response depends on factors including initial zinc and testosterone levels, dose, formulation and treatment duration.

Those details matter. Most of the included studies involved animals, and the review does not establish that every man will benefit from a zinc supplement. Its findings support paying attention to zinc status, rather than treating zinc as a universal testosterone booster. [1]

Correcting low zinc may help

One frequently cited human study, published in 1996, investigated both zinc restriction and supplementation.

In four young men, restricting dietary zinc for 20 weeks was associated with a substantial fall in testosterone.

A separate group of nine older men with marginal zinc deficiency received approximately 30 mg of elemental zinc daily, supplied as zinc gluconate. After six months, average testosterone increased from 8.3 to 16.0 nmol/L.

These results suggest that inadequate zinc can contribute to low testosterone and that correcting it may help. However, these were very small groups, and the supplementation findings were a before-and-after comparison rather than a large placebo-controlled trial. The increase should not be presented as an expected result for everyone taking zinc. The study dose is also not a general recommendation. [4]

What if you already get enough zinc?

The evidence is less convincing when zinc intake is already sufficient.

A study of 14 healthy, regularly exercising men aged 22–33 tested ZMA, a supplement containing zinc, magnesium and vitamin B6. Their usual zinc intake was approximately 12–23 mg daily.

Supplementation increased blood zinc, but researchers found no significant increase in total or free testosterone.

The study was small and tested a combined supplement rather than zinc alone. Nevertheless, it illustrates an important distinction: raising zinc levels does not necessarily raise testosterone. [2]

More zinc is not automatically better

High zinc intakes can reduce copper absorption, potentially leading to anaemia and weakened bones.

NHS guidance advises not taking more than 25 mg of zinc from supplements daily unless advised by a doctor. That is a supplemental limit, not a target to aim for.

Check the combined amount if you use a multivitamin alongside a separate zinc supplement or testosterone-support product. [3]

What if you suspect low testosterone?

Persistent low libido, fewer morning erections or other concerning symptoms deserve proper assessment. Symptoms alone cannot establish testosterone deficiency.

UK specialist guidance recommends interpreting symptoms alongside blood tests, with a low testosterone result confirmed on a separate occasion. Testing is generally performed in the morning, ideally fasting and when you are not acutely unwell. [5] [6]

Zinc can be relevant where intake or status is inadequate. It should not replace investigating why testosterone is low.

The practical message: ensure you get enough zinc, address a deficiency where present, and be cautious about promises that extra zinc will boost already-normal testosterone.