Zinc Fact Sheet
Zinc is a mineral essential for growth, metabolism, detoxification and healing. Yet 75% of Australians don’t receive their RDI of zinc. This is more of a problem because, unlike iron, we do not store zinc in our bodies, so we need a daily fix to maintain our levels.
Zinc and Aging
The effect of zinc supplements on aging is unclear, although some studies suggest that supplements may reduce the risk of oesophageal cancer and age-related damage (macular degeneration) to the retina.
Do I Have a Deficiency of Zinc?
Low levels of zinc can lead to lethargy, delayed healing of wounds and increased susceptibility to infection. Other groups at high risk of low zinc levels include alcoholics and those with digestive diseases.
Zinc concentrations are correlated with sperm-count, with the lowest zinc concentrations found in infertile men. When zinc levels are low, our sense of taste and smell may also be impaired. This principle is utilized in the simple zinc taste test in which a dilute solution of zinc sulphate is used to test our sense of taste. If an immediate, strong and unpleasant taste is experienced, then our levels are OK. But if the response is not immediate or we don’t taste anything it could indicate low zinc levels.
How Can I Add Zinc to my Diet?
The best sources are seafood (oysters, crab, lobster), meat and poultry. Many cereals and other products are fortified with zinc. Although whole grains, legumes and nuts contain lesser amounts of zinc, fiber in plants may partially inhibit zinc absorption, so strict vegetarians need to take twice as much zinc in a vegetarian diet.
Zinc is widely used in multivitamins, as well as over-the-counter preparations that reduce the duration and severity of cold symptoms. These are fine to maintain our levels. However, correcting deficiency may take a higher dose than can be provided by ordinary supplements, due to zinc blockade (where low zinc levels impair the absorption of all minerals).
How Much Zinc Should I Take?
Zinc is available from fresh food, fortified food, multivitamins, and even over the counter cold remedies. The recommended dietary allowances for zinc are 11 mg for males and 8 mg for females per day.
A high zinc intake can result in loss of appetite, nausea, vomiting, cramps, diarrhea and headaches. The tolerable upper limit for zinc intake is 40 mg per day.
Zinc supplements may react with quinolone and tetracycline antibiotics, diuretics (water tablets), and penicillamine – used to treat rheumatoid arthritis.