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Immune function declines with age, putting older adults at increased risk of infections such as pneumonia. Zinc is an essential nutrient that has been shown to regulate the function of white blood cells and increase immunity. Findings of a study in older adults demonstrate a link between low serum zinc and an increased incidence of pneumonia and antibiotic use.

T cells are white blood cells that mature in the thymus, a gland located in the chest that decreases in size and function after adolescence. Zinc deficiency has been shown to accelerate thymic shrinking, reduce T cell proliferation, and suppress antibody production. Low serum zinc levels are associated with poor immune function in older adults; however, the association between zinc levels and pneumonia incidence and severity is unknown.

The authors collected data from a trial in which 600 participants who were residents of a long-term care facility were randomly assigned to receive a vitamin E supplement (200 international units per day) for one year or a placebo. All participants were given a supplement containing 50 percent of the recommended dietary allowance of essential nutrients, including zinc, in an effort to make individuals easier to compare as a group. The authors measured the incidence and duration of pneumonia, number of antibiotic prescriptions, days of antibiotic use, death due to pneumonia, and death due to any cause.

At baseline, risk of death due to any cause was 39 percent lower in participants with normal serum zinc levels (greater than or equal to 70 micrograms per deciliter) compared to low serum zinc levels (less than 70 micrograms per deciliter); however, zinc levels were not significantly associated with any of the pneumonia-related variables. After one year of supplementation, the incidence of pneumonia and number of new antibiotic prescriptions were about 50 percent lower in participants with normal zinc levels. These participants also experienced about four fewer days of pneumonia illness and three fewer days of antibiotic use.

Among older adults living in residential care facilities, normal serum zinc levels reduced pneumonia incidence and severity and antibiotic use. Learn more about the role of zinc in health and longevity and which foods contain zinc in our overview article.

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