Adequate Zinc Vital to Healthy Immune Response

As cold and flu season nears, now is a good time to take stock of zinc intake, because adequate zinc is essential to immune response. In a study funded by the U.S. Department of Agriculture's (USDA) Agricultural Research Service (ARS), a group of older adults with relatively low blood zinc concentrations boosted their immune function by raising their zinc levels.

Researchers observed an increase in T cells in blood that was challenged with a stimulus that mimicked infectious agents. T cells are white blood cells that play a key immune role. The researchers noted that the greater the blood zinc concentrations, the greater the increase in T cells.

The study was led by Simin Nikbin Meydani, director of the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University in Boston, Massachusetts.

For the study, researchers recruited participants 65 or older from Boston-area nursing facilities. More than 30 percent of the participants tested low in zinc. Researchers divided the zinc-deficient participants into two groups. For three months, one group consumed 30 milligrams (mg) of additional zinc via a daily multivitamin supplement, and a control group received a similar supplement that contained 5 mg of zinc. While the recommended dietary intake is 8-11 mg daily, the higher level was used because many volunteers had low blood zinc levels.

The researchers then retested the participants' blood zinc levels and T cell numbers. They found that the participants who took 30 mg of supplemental zinc had higher blood zinc concentrations and higher T-cell counts as well as better T-cell function than those in the control group.

Good sources of zinc include oysters and other shellfish, fortified breakfast cereals, beef, pork and beans. A personalized nutrient-intake assessment that includes a zinc-intake audit is available at www.supertracker.usda.gov.