What is zinc? A plain guide

Zinc is an essential trace mineral — a nutrient the body needs in small amounts from food or supplements because it can't make its own. It's a cofactor for hundreds of enzymes and is needed for normal immune function, growth, and DNA and protein synthesis, according to NIH's Office of Dietary Supplements. It's separate from metallic zinc, the silvery-blue element used in batteries and galvanized steel — same element, very different context.

Is zinc a metal?

Yes. As a chemical element (atomic number 30, symbol Zn), zinc is a bluish-white metal, and it's the form used industrially — in galvanizing (coating steel to slow rust), brass, and batteries. Zinc metal does corrode, just very slowly, which is exactly why it's used as a sacrificial coating to protect steel underneath. The nutrient you get from food or a supplement is zinc in an ionic, compound form (zinc oxide, gluconate, citrate and so on) rather than the raw metal — this page is about that nutritional role.

How much you need

The adult RDA is 11 mg/day for men and 8 mg/day for women, counting food and supplements together, per NIH's Office of Dietary Supplements. The tolerable upper intake level is 40 mg/day from all sources combined. Zinc dosage covers where those numbers come from and what they mean in practice.

How the body handles zinc

Unlike iron, which the body stores in meaningful reserves in the liver, zinc has no dedicated storage organ — it's distributed in small amounts throughout muscle, bone and other tissue, which is part of why a fairly steady daily intake matters more for zinc than for nutrients the body can bank for later. Absorption happens mainly in the small intestine and isn't fixed: the body absorbs a higher percentage of dietary zinc when intake is low and a lower percentage when intake is already high, a regulatory mechanism NIH's Office of Dietary Supplements describes as homeostatic control.

Where it's found

Oysters are by far the most concentrated food source of zinc — about 74 mg per 3-ounce cooked serving, according to USDA FoodData Central, which is more than six times the adult RDA in one serving. Red meat runs closer to 5-7 mg per 3-ounce serving, poultry and pork somewhat less, and crab and lobster a few milligrams per serving. Beans, chickpeas and lentils provide roughly 1-2.5 mg per cooked cup, and nuts, seeds and dairy contribute smaller amounts. Whole grains and legumes contain zinc too, but also phytates, compounds that bind zinc and reduce how much of it actually gets absorbed — one reason vegetarian and vegan diets sometimes need to plan more deliberately around zinc intake, and why the RDA for strict vegetarians is sometimes set higher in other countries' guidelines than the general figure used on this page.

Zinc in supplements

Supplemental zinc comes as several different compounds — oxide, sulfate, gluconate, citrate, picolinate, and bisglycinate (a chelated form) among them. Each is only partly elemental zinc by weight, so the number on the front of a bottle (the compound weight) isn't the same as the elemental amount that counts toward the RDA and upper limit. How to choose a good zinc covers how to read that.

Zinc oxide outside of supplements

Zinc oxide shows up in places that have nothing to do with a dietary supplement: it's a long-established, FDA-recognized skin-protectant and mineral sunscreen ingredient, and it's the active ingredient in most diaper-rash creams. That's a topical use on the skin's surface, a different product and a different question from an oral zinc supplement, and it isn't covered by the research on dosing and safety elsewhere on this site.

Questions people ask

What is zinc?

An essential trace mineral the body needs from food or supplements for normal immune function, growth, and enzyme activity — and, separately, a metallic chemical element used in industry. This page covers the nutrient.

What does zinc do for the body?

It acts as a cofactor for hundreds of enzymes and supports normal immune function, DNA and protein synthesis, and taste and smell, according to NIH's Office of Dietary Supplements. What extra zinc does beyond an adequate intake is a research question covered separately in zinc benefits: what the research does and doesn't show.

What is zinc oxide?

A zinc compound (roughly 80% elemental zinc by weight) used both as a supplement ingredient and, separately, as a topical skin protectant and mineral sunscreen active — two different products under one chemical name.

What does zinc do for men specifically?

The basic biology — enzyme cofactor, immune function, DNA and protein synthesis — is the same for everyone. Zinc also has a documented role in normal reproductive function. Whether extra zinc affects testosterone in a man who already gets enough is a separate research question, covered with the actual trial data in zinc benefits.

Can zinc help with a cold? Can zinc increase testosterone?

Those are research questions, not basic facts about what zinc is — zinc benefits covers what the actual trials found on both, including the doses used and their limits.

Will zinc rust?

Zinc metal corrodes very slowly rather than rusting the way iron does, which is exactly why it's used as a protective coating on steel. This has nothing to do with zinc as a dietary nutrient.

Related reading: zinc benefits, how much zinc should you take a day, and how to choose a good zinc.