Vital for healthy immune systems, with low levels during pregnancy increasing the chances of having a premature or low weight baby.

Good food sources include oysters, fortified cereals, baked beans and beef. Diabetics and the elderly are most likely to be deficient in zinc.

The RDA of zinc is between 5.5mg and 9.5mg for men and between 4mg and 7mg for women.

The FSA advises taking no more than a 25mg daily dose of zinc as higher intake can block other essential nutrients such as iron.