Zinc deficiency

Zinc is needed for immunity, wound healing, taste and smell. Clear zinc deficiency is uncommon in people with a varied diet. It is usually linked to bowel conditions, alcohol or a very restricted diet.

Symptoms

Most signs are non-specific:

• food tastes bland or “off”, a dulled sense of smell;
• cuts and scrapes heal slowly;
• a red, scaly rash around the mouth, nose, eyes, hands or feet;
• hair loss.

Changes in taste and smell often follow a cold or COVID-19, and zinc has nothing to do with them.

Who is at risk

• coeliac disease, Crohn’s disease, chronic diarrhoea, bowel surgery;
• heavy alcohol use;
• a vegetarian diet (zinc from plants is less well absorbed);
• very restrictive eating;
• liver or kidney disease;
• diuretics;
• pregnancy and breastfeeding.

Which test to ask for

Plasma or serum zinc, but usually only when a doctor suspects deficiency for other reasons.

The test is unreliable: the result shifts after meals, through the day, with inflammation and with low albumin. A normal number does not rule out deficiency, and a low one does not always mean it.

What not to do

Do not take zinc long-term without a reason. Excess zinc causes copper deficiency, which leads to anaemia and nerve damage resembling B12 deficiency.