Zinc

A trace mineral used in immune function, wound healing, taste and smell, and the making of DNA. There is no meaningful store, so intake matters continuously rather than occasionally.

A cofactor for hundreds of enzymes. Central to immune function, wound healing, taste and smell, and DNA synthesis.

• Oysters — by far the richest source
• Beef and lamb
• Pumpkin seeds
• Chickpeas and lentils
• Cashews
• Whole grains

Soaking, sprouting and fermenting grains and legumes reduces phytate and improves absorption.

11 mg (men) · 8 mg (women) for most adults. The upper limit, past which harm becomes likely, is 40 mg.

Reference intakes are population figures. Pregnancy, illness, age and medication all move an individual’s needs, which is one of several reasons this page is information rather than advice.

Most at risk: Vegetarians and vegans — phytates in grains and legumes bind it. Also alcohol use, gut disease, and pregnancy.

Diets high in unleavened wholegrains and legumes, where phytate binds zinc; vegetarian and vegan diets without attention to it; malabsorption; alcohol dependence; and prolonged diarrhoea. Requirements rise in pregnancy and breastfeeding.

Poor wound healing, frequent infections, hair loss, loss of taste and smell, and in children, stunted growth.

Every sign here has other, often likelier, explanations. A list of symptoms is a reason to look into something, never a diagnosis.

Plasma zinc is the usual measure but falls with any inflammation and with recent eating, so it is unreliable in isolation. A trial of adequate intake is often more informative than a single number.

Oysters are far and away the richest source; meat, shellfish, pumpkin seeds, cashews, chickpeas and lentils follow. Soaking, sprouting and leavening reduce phytate and improve absorption from plant foods appreciably.

Zinc competes with copper: sustained high doses can produce a copper deficiency, which is one of the more common self-inflicted nutritional problems. Taken on an empty stomach it frequently causes nausea. Intranasal zinc has been linked with lasting loss of smell and is best avoided.

Sustained high intake causes copper deficiency, which produces anaemia and nerve damage. Zinc nasal sprays have caused permanent loss of smell and should be avoided entirely.

Interactions: Competes with copper and iron. Reduces absorption of some antibiotics.