(HealthDay News) — Maintaining normal zinc concentrations in the blood may help prevent pneumonia in elderly nursing home residents, a new study shows.

A team at Tufts University looked at 617 people 65 and older in 33 nursing homes in the Boston area.

They found that those with normal blood zinc concentrations were about 50 percent less likely to develop pneumonia than those with low concentrations.

The study, published in the October issue of the American Journal of Clinical Nutrition, also found that people with normal zinc concentrations had a 39 percent lower rate of death from all causes.

“Not only did (people with lower zinc concentrations) have a higher risk of developing pneumonia, when they did become sick, they did not recover as quickly and required a longer course of antibiotics, ” corresponding author Simin Nikbin Meydani, director of the nutritional immunology laboratory at the U.S. Department of Agriculture’ s Human Nutrition Research Center on Aging at Tufts, said in a prepared statement.

The Tufts researchers took blood samples from the participants at the start and conclusion of the one-year study. All the participants received daily supplements containing 50 percent of the recommended dietary allowance of several vitamins and minerals, including zinc, for one year.

“Zinc is already known to strengthen the immune system; however, there needs to be further investigation of zinc and its effect on pneumonia development and prevention in nursing homes. The next step would be a clinical trial,” Meydani said.

Red meat, poultry, whole grains, beans, dairy products, and oysters are examples of foods that provide zinc.