Also known as: Zinc picolinate, Zinc bisglycinate, Zinc citrate, Zinc gluconate, Zinc oxide, ZMA
MineralsStrong evidence
An essential trace mineral involved in hundreds of enzymes, immune function and hormone production. Effective doses sit close to the safe upper limit, and sustained high intake causes copper deficiency.
Typical dose
10.0–25.0 mg per day
With food; separate from iron, calcium and magnesium
What it is
Zinc is an essential trace mineral required by hundreds of enzymes and by a large family of zinc finger proteins that regulate gene expression. The body has no dedicated storage depot, so regular dietary intake is necessary.
Richest sources are oysters, red meat, shellfish and, less bioavailably, legumes and wholegrains. Phytates in plant foods bind zinc and reduce absorption, which is why vegetarians and vegans have higher requirements and are more likely to have marginal status.
Form affects absorption meaningfully. Picolinate, bisglycinate and citrate are well absorbed. Zinc oxide is poorly absorbed but common in cheap multivitamins because it is inexpensive and high in elemental zinc by weight. As with magnesium, dose by elemental zinc, not by the weight of the compound.
How it works
Zinc serves structural, catalytic and regulatory roles. It stabilises the folding of zinc finger proteins that bind DNA, making it fundamental to gene transcription, and acts as a catalytic cofactor in enzymes across many pathways.
In immune function it is required for development and function of lymphocytes and natural killer cells, and deficiency produces measurable immune impairment relatively quickly.
Zinc is involved in testosterone production, which underpins its presence in ZMA and testosterone support formulas. The important qualifier is that this reflects deficiency correction. Restoring zinc in a deficient man supports normal testosterone; supplementing a man with adequate status does not raise it further.
What the evidence shows
The common cold literature is among the better-studied areas. Meta-analyses of zinc lozenges started within 24 hours of symptom onset report shortened cold duration, with the effect appearing dose-dependent and specific to lozenge formats that release zinc in the throat.
Deficiency correction is well established, with clear benefits to immune function, wound healing and growth in deficient populations. Trials on testosterone tell the expected story: increases in deficient men, no meaningful change in men with adequate status.
The broad pattern is consistent. Zinc is genuinely important and correcting a shortfall matters, but it is not a compound that improves function above normal. ZMA trials in trained athletes with adequate zinc status have generally found no performance or hormonal benefit.
Dosing
Typical supplemental intake is 10-25 mg of elemental zinc daily, on top of dietary intake. Reference intakes sit around 9.5 mg for men and 7 mg for women.
The headroom here is unusually narrow. The tolerable upper intake is 25 mg daily from supplements in European assessment, and 40 mg in some other frameworks, so a 25 mg supplement plus a multivitamin plus dietary intake can exceed sensible limits without the user realising.
Take with food, since zinc on an empty stomach commonly causes nausea. Separate from calcium, iron and magnesium supplements, which compete for absorption. For colds, lozenges rather than swallowed capsules are what the evidence supports.
No dedicated store; status responds to intake over weeks
Timing
With food; separate from iron, calcium and magnesium
Competition status
Permitted — not on the WADA Prohibited List
Category
Minerals
Safety and side effects
Acute effects of excess zinc are nausea, vomiting and stomach cramps, most often when taken on an empty stomach. Taking it with food resolves this for most people.
The significant long-term risk is copper deficiency. Zinc and copper compete for the same absorption route, and sustained high zinc intake, generally above 40-50 mg daily, will push copper down over time. This is a real consequence rather than a theoretical one, and it is the main reason to respect the upper limit rather than treating zinc as harmless.
Zinc also reduces absorption of several types of medicine if taken at the same time. Separating doses by a couple of hours resolves this.
Who should avoid it
Do not exceed the upper intake limit long term, due to the risk of pushing copper levels down. Separate from any medication by at least two hours, since zinc can reduce absorption of several types. Speak to your doctor before use if you take regular medication. Check your total intake across multivitamins and combination products, which is where most people unknowingly exceed the limit.
This entry is provided for information only. Food supplements should not be used as a substitute for a varied and balanced diet and a healthy lifestyle. Consult a qualified healthcare professional before use if you are pregnant, breastfeeding, taking medication or under medical supervision.
