Zinc

Zinc has a wide range of functions in the body. It helps with the healing of wounds and is a vital component of many enzyme reactions. Zinc is particularly important for healthy skin and a healthy immune system.
Zinc plays a crucial role in growth and cell division, in insulin activity, in the metabolism of the ovaries and testes, and in liver function. Zinc is involved in the metabolism of proteins, carbohydrates, lipids and energy.
Our body contains about 2-3g of zinc. There are no specific storage sites known for zinc and so a regular supply in the diet is required. Zinc is found in all parts of our body. Particularly high concentrations are in the prostate gland and semen. Men need more zinc than women because semen contains 100 times more zinc than is found in the blood. The first signs of zinc deficiency are impairment of taste, a poor immune response and skin problems. Other symptoms of zinc deficiency can include hair loss, diarrhoea, fatigue, delayed wound healing, and decreased growth rate and mental development in infants. It is thought that zinc supplementation can help skin conditions such as acne and eczema, prostate problems, anorexia nervosa, alcoholics and those suffering from trauma or post-surgery.
Zinc is present in a wide variety of foods, particularly protein foods. Good sources of zinc include meat (particularly organ meats like liver), dairy products, beans and lentils, yeast, nuts, seeds and wholegrain cereals. Pumpkin seeds provide one of the most concentrated vegetarian food sources of zinc.
Dietary fibre and phytic acid, found in bran, wholegrain cereals, pulses and nuts, inhibit zinc absorption. Phytic acid forms a highly insoluble complex with zinc which the body cannot absorb. Cooking processes, including baking, can reduce the adverse effects of both phytic acid and dietary fibre on zinc absorption. High levels of the toxic mineral cadmium can also prevent zinc absorption because these two minerals compete for absorption. Conversely high levels of zinc in the diet can prevent the absorption of cadmium. Various chemicals added to many processed foods can also reduce zinc absorption. A deficiency of zinc in the diet means zinc absorption is improved.
Zinc is lost via the faeces, urine, hair, skin, sweat, semen and also menstruation.
Pregnant women do need extra zinc, but it is thought that demands are met by increased absorption from the gut. Breast milk contains over 2mg of zinc in the first four months and women need an extra 6mg a day to cover these demands. Breast feeding women must include a generous serving of at least one good source of zinc in their diet each day.
Iron supplements may compromise zinc status. This is because of competition for absorption.
Excess zinc is toxic. Too much zinc will interfere with the metabolism of other minerals in the body, particularly iron and copper. Symptoms of acute zinc toxicity occur after ingestion of 2g of or more and include nausea, vomiting and fever.