Zinc is one of those minerals that quietly does a lot of heavy lifting. It’s involved in hundreds of enzymatic reactions — including the fact that zinc contributes to normal protein synthesis — which is why athletes, particularly those who train hard or eat a restricted diet, are worth paying attention to their intake. Not because zinc is a performance-enhancer in any dramatic sense, but because falling short of it will quietly undermine things that matter.
What zinc actually does in the body
Zinc is an essential trace mineral, meaning the body can’t make it and must get it from food. It’s involved in a surprisingly wide range of processes:
- Protein synthesis — zinc contributes to the normal building and repair processes that follow every training session.
- Immune function — zinc contributes to the normal function of the immune system, relevant for anyone whose training load is high enough to dent immunity temporarily.
- Testosterone maintenance — zinc contributes to the maintenance of normal testosterone levels in the blood. This one is worth reading carefully (more on it below).
- Oxidative stress — zinc contributes to the protection of cells from oxidative stress, a by-product of intense exercise.
- Macronutrient metabolism — zinc contributes to normal macronutrient metabolism, supporting how the body processes carbohydrates, fats and proteins.
- DNA synthesis — zinc contributes to normal DNA synthesis, which underpins cell division and repair.
- Bone maintenance — zinc contributes to the maintenance of normal bones, a concern for long-term athletic health.
The EU Nutrient Reference Value (NRV) for zinc is 10 mg per day.
Zinc and testosterone — what the evidence actually says
This is where a lot of supplement marketing goes wrong, so let’s be direct: the authorised claim is that zinc contributes to the maintenance of normal testosterone levels. That’s a meaningful distinction.
What it means in practice: if you’re zinc-deficient, your testosterone levels may fall below normal — and getting your intake back up to adequate restores normal function. That’s genuinely useful to know.
What it does not mean: supplementing zinc when you’re already getting enough will push testosterone above its normal range or make you stronger. The evidence for zinc or ZMA (the zinc–magnesium–B6 combination) improving performance, muscle mass or body composition in well-fed, non-deficient athletes is weak. The honest summary: if you’re replete, more zinc won’t move the needle on testosterone. If you’re short, it might.
Why athletes may be more at risk of low zinc intake
The general population eating a varied diet tends to get enough zinc. Athletes are a slightly different story, for a few reasons:
Sweat losses
Zinc is lost in sweat. Heavy sweaters — endurance athletes, those training in the heat, anyone putting in long sessions — lose more than sedentary people. It’s rarely dramatic, but it adds up across weeks of hard training, especially if dietary intake is already modest.
Low-meat or plant-heavy diets
Zinc from animal sources (meat, shellfish, dairy) is more readily absorbed than zinc from plant foods. The reason is phytates — compounds in wholegrains, legumes, seeds and nuts that bind zinc in the gut and reduce how much you absorb. This doesn’t make plant foods bad (they’re still worthwhile sources), but it does mean vegetarians and vegans may need to be more attentive to intake, and that soaking or fermenting legumes can help.
Calorie restriction or low food variety
Athletes cutting weight, eating very “clean”, or relying on a narrow set of foods are more likely to come up short on zinc than those eating broadly and plentifully.
Food sources of zinc
The best dietary sources, roughly in order of bioavailable zinc:
- Oysters — exceptionally rich; a small serving provides many times the daily NRV
- Red meat and lamb — one of the most practical everyday sources
- Shellfish (crab, prawns, mussels)
- Poultry
- Dairy (cheese, milk)
- Eggs
- Pumpkin and hemp seeds
- Legumes (lentils, chickpeas, kidney beans) — decent amounts, lower absorption due to phytates
- Wholegrains, nuts and fortified cereals
If you eat meat and dairy regularly and have a varied diet, you’re probably fine. If you’re plant-based or calorie-restricted, it’s worth a closer look at what you’re actually eating.
What about ZMA?
ZMA is a combination supplement containing zinc, magnesium and vitamin B6. It’s popular in sports-nutrition circles, often marketed with fairly bold claims. The reality is more measured: ZMA may be worth considering if you’re genuinely low in both zinc and magnesium — not an unusual combination for athletes with high sweat losses or poor diets — but the evidence that it improves sleep, recovery or performance in people who are already adequately nourished is not convincing. If ZMA appeals to you, the magnesium component may be doing as much useful work as the zinc. Our guide to magnesium for athletes covers that side of the equation.
How much to take, and is more better?
The NRV is 10 mg per day. Most adults eating a reasonably varied diet will hit this through food. If you’re considering a supplement, typical doses in sports products range from 10–25 mg — matching or modestly exceeding the NRV. The NHS advises not exceeding 25 mg of supplemental zinc per day unless under medical guidance.
High doses — roughly above 40 mg per day sustained over time — can interfere with copper absorption, because zinc and copper compete for the same absorption pathway. Getting more zinc than you need doesn’t add benefit; it just shifts the risk profile. More is not better here.
Practical takeaways
Zinc is a foundational micronutrient, not a performance supercharger. The athletes most likely to benefit from paying closer attention to it are those with high training volumes, heavy sweat losses, plant-heavy diets or restricted calorie intake. For everyone else, consistent eating of a varied, protein-containing diet — the same diet that serves muscle gain, recovery and long-term health — will keep zinc status where it needs to be.
If you’re curious about the broader micronutrient picture for athletes, vitamin D and vitamin C are worth reading alongside this. And if you want to see what CapyFuel’s range offers for training support, the shop is a good place to start.
Related: Magnesium for athletes · Vitamin D for athletes · Vitamin C for athletes · Rest & recovery.
Frequently asked questions
Does zinc boost testosterone?
Not exactly — and the distinction matters. The authorised claim is that zinc contributes to the maintenance of normal testosterone levels. If you're zinc-deficient, your levels may dip below normal and correcting the deficiency restores them. In people who already have adequate zinc, supplementing more does not push testosterone above normal or improve muscle gain. The 'zinc boosts T' headline is a simplification the evidence doesn't support.
How much zinc do athletes need per day?
The EU Nutrient Reference Value is 10 mg per day — the same for athletes as for everyone else. Athletes with high sweat losses, plant-heavy diets or restricted calorie intake may find it harder to consistently hit this through food, which is when a modest supplement (up to 25 mg/day) can make sense. Beyond that, high doses risk interfering with copper absorption without adding benefit.
Is zinc in plant foods as good as zinc in meat?
Plant foods — legumes, wholegrains, seeds, nuts — contain meaningful amounts of zinc, but also phytates, which bind zinc in the gut and reduce absorption. Zinc from meat, shellfish and dairy is more readily absorbed. Vegetarians and vegans can still meet their needs through food, but may need a wider variety of zinc-containing foods, and soaking or fermenting legumes can improve absorption.
Does ZMA improve sleep or recovery?
ZMA combines zinc, magnesium and vitamin B6. In people genuinely low in zinc and magnesium — possible in athletes with heavy sweat losses or restricted diets — correcting those shortfalls supports normal function. But the evidence that ZMA improves sleep or performance in people who are already adequately nourished is not convincing. The magnesium component is at least as relevant as the zinc.