Everyone needs zinc, which is essential for enzymes that do everything from manufacturing DNA to healing wounds. It's a crucial component of a strong immune system and it fights the common cold. Yet a surprising number of people don't get enough of this vital nutrient.
What it is?
An essential mineral required by every cell in the body, zinc is concentrated in the muscles, bones, skin, kidneys, liver, pancreas, eyes and, in men, the prostate. It is plentiful in fish and seafood, and some meat. Because your body does not produce zinc, it depends on external sources for its supply.
What it does?
Zinc plays a critical role in hundreds of body processes – from cell growth to sexual maturation and immunity – and is even important for taste and smell. Consequently, everyone who takes a daily multivitamin and mineral supplement should make sure that it contains zinc. Individual zinc supplements are also available for specific complaints.
Necessary for the proper functioning of the immune system, zinc helps to protect the body against colds, flu, conjunctivitis and other infections. In a study of 100 people in the initial stages of a cold, those who sucked on zinc lozenges every couple of hours recovered from their illness about three days earlier than those who sucked on placebo lozenges. Zinc lozenges may also speed the healing of mouth ulcers and sore throat. Taken in pill form, zinc may aid in treating more serious illnesses, such as rheumatoid arthritis, lupus, fibromyalgia and possibly multiple sclerosis, as well as other conditions such as AIDS, that are associated with an improperly functioning immune system.
Zinc exerts beneficial effects on various hormones, including the sex and thyroid hormones. It shows promise for enhancing fertility in both women and men. Zinc may also shrink an enlarged prostate. In addition, it may be effective for those with an underactive thyroid and, because it improves insulin levels, it may help people with diabetes.
Because zinc affects so many body systems, it has many other uses. It stimulates the healing of wounds and skin irritations, making it useful for acne, burns, eczema, psoriasis and rosacea, and promotes the health of the hair and scalp. Zinc has also been shown to slow vision loss in people with macular degeneration, a common cause of blindness in those over the age of 50. And in a recent Japanese study, tinnitus (ringing in the ears) improved with zinc supplementation. Zinc may also be useful for osteoporosis, haemorrhoids, inflammatory bowel disease and ulcers.
Fights colds, flu, other infections.
Treats a wide range of chronic ailments, from rheumatoid arthritis and underactive thyroid to fibromyalgia and osteoporosis.
Heals skin ailments and eases digestive complaints.
May boost fertility, build healthy hair and diminish ringing in ears.
- Don't take too much zinc: more than 100 mg daily can, over the long term, impair immunity. It can also interfere with copper absorption, leading to anaemia.
- Reminder: If you have a medical condition, talk to your doctor before taking supplements.
How much you need?
The RDI for zinc is 12 mg daily for adults. Higher doses are usually reserved for specific complaints.
If you get too little:
Severe zinc deficiency is rare in Australia and New Zealand, but a mild deficiency can lead to poor wound healing, more colds and flu, a muted sense of taste and smell, and skin problems such as acne, eczema and psoriasis. It also can result in impaired blood sugar tolerance (and an increased diabetes risk) and a low sperm count.
If you get too much:
Long-term use of more than 100 mg a day has been shown to impair immunity and lower the level of HDL ('good') cholesterol. One study reported a connection between excess zinc and Alzheimer's, though the evidence is scant. Larger doses (more than 200 mg a day) can cause nausea, vomiting and diarrhoea.
How to take it?
The usual dosage is 30 mg once a day. Taking zinc for longer than a month may interfere with copper absorption, so add 2 mg of copper for every 30 mg of zinc. For colds or flu, use zinc lozenges every two to four hours for a week; don't exceed 150 mg a day.
Guidelines for use:
Take zinc an hour before or two hours after a meal. If it causes stomach upset, have it with a low-fibre food. If you also use iron supplements, don't take them at the same time as zinc. Take zinc at least two hours after taking antibiotics. Zinc is better absorbed if it's taken at night.
When looking for foods rich in zinc, think protein. It's abundant in beef, port, liver, poultry (especially dark meat), eggs and seafood (especially oysters). Pumpkin seeds, beans, nuts and wheatgerm are other good sources, but the zinc in these foods is less easily absorbed than the zinc in meat.
- Zinc supplements are available as either pills or liquids in the form of zinc gluconate, zinc chelate or zinc sulphate. All are well absorbed and easy on the stomach. When shopping for lozenges to treat colds or flu, preparations containing zinc gluconate are your best bet.
- Zinc may be especially beneficial for older people, who are often deficient in this mineral, according to a recent study of 118 elderly but relatively healthy nursing home residents in Rome, Italy. Those given 25 mg of zinc daily for three months showed improved immune systems. Experts think that zinc may revitalize the thymus gland, which manufactures immune cells.
- Studies show that exercisers lose zinc in perspiration and urine. That may be one reason why, although moderate exercise boosts immunity, long bouts of intense exercise are linked with lowered immunity.
Did you know?
Sunflower seeds are a rich source of zinc for vegetarians, who may be deficient in it: 115 g provides about 6 mcg – half the RDI.