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As we age, our immune systems tend to quiet down, leaving us more vulnerable to infections and other health problems. Luckily, a study found supplementing with zinc may elevate low serum zinc concentrations (a measure of zinc in the blood), and increase the number of important immune cells known as T cells, in older people. Published in the American Journal of Clinical Nutrition, the double-blind study included 31 older people with low serum zinc concentrations (below 70 micrograms per decilitre) living in a nursing home. For three months, the older people received either 30 mg of zinc per day or a placebo containing very small amount of zinc (5 mg per day). When researchers measured the participants' serum zinc concentrations and immune cell activity at the beginning and end of the study, here is what they found:

• Average serum zinc rose 16% in participants taking the zinc supplement compared with those taking the placebo.
• The number of T cells also rose significantly more in participants taking the zinc supplement.

While these findings suggest zinc supplements could be beneficial for older people with low serum zinc concentrations, larger, long-term studies will help us understand if zinc supplementation, with its apparent benefits for the immune system, actually helps reduce the risk of infection in older people. It is known, however, that zinc is an essential mineral linked to normal immune function, healthy reproductive function, and growth and development in children. While this study focused on zinc supplements, you can also get zinc from foods such as oysters, eggs, black-eyed peas, pumpkin seeds, and tofu.

Source: American Journal of Clinical Nutrition