Thinking of zinc

There is a metal used in coins, makes electrical batteries work and used to slow down rusting of motors. When plants don't get enough of it, they get sick. This metal is also essential to the growth and development of our bodies. It is found mainly in the brain, bones, muscles, liver, prostate glands and eyes. Semen is rich in this metal which helps create new sperm cells.

This metal is exceptionally important in the growth of sexual organs, wound healing, brain functioning, the prostate gland and other reproductive organs. It plays a major role in the activities of the hormone insulin and in over 100 different types of enzymes in our bodies. Our bodies need just a tiny bit of this precious metal (it is called a trace mineral), and we are likely to experience a toxic response if we regularly consume more than our optimal daily dose. Zinc is this metal.

The versatility of zinc

In pharmacies, we find zinc in many dandruff shampoos, sun tan lotions, acne treatments, mouthwashes, eye drops, lozenges and in ointments for diaper rash, bed sores and haemorrhoids (piles). Zinc is also found in first-aid tapes and bandages, and, of course, in multivitamins and supplements.

It is best to get zinc from foods and a balanced diet usually provides enough. We run short on zinc when we eat enough, or if we have one of several chronic illnesses which affect zinc processing or absorption.

People with sickle cell disease and those living with major burns may require more zinc than others. Vegetarians, elderly folk, breastfeeding women and people with kidney and liver diseases tend to be at risk for zinc deficiency, too. In any case, even in healthy people, only about 25 per cent of the zinc consumed is actually absorbed into the blood and tissues.

Diarrhoea can cause zinc deficiency, and it can also be a result of zinc deficiency. Zinc should always be supplemented in people with severe, chronic diarrhoea. Zinc deficiency may lead to symptoms like acne, impairment in the sense of taste and smell, growth impairment, hair loss, infertility and prostate trouble.

Zinc versus iron, calcium, copper

Zinc in excess may cause a metallic taste in the mouth, vomiting, increased stomach acid production, burns in the mouth and throat, lethargy, irritability and anaemia.

Taking excess of zinc for prolonged periods may suppress the absorption of other important minerals like copper, iron and calcium, causing deficiency of these minerals. Calcium, which many people take to prevent osteoporosis, when taken in large amounts reduces absorption of zinc into the body.

How much zinc is too much?

Due to the risks involved with taking excess zinc, a good rule of thumb for supplementation is to take no more zinc than a regular multivitamin would supply (15mg per day). Medical supervision is recommended for those who wish to supplement with higher doses.

Dahlia McDaniel is a pharmacist and final year doctoral candidate in public health at the University of London; email: yourhealth@gleanerjm.com.