Zinc Supplementation May Decrease Incidence of Infections in the Elderly

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March 13, 2007 — Zinc supplements reduce the incidence of infection in elderly patients, according to the results of a small, randomized, double-blind trial reported in the March issue of the American Journal of Clinical Nutrition.

"Zinc deficiency, cell-mediated immune dysfunction, susceptibility to infections, and increased oxidative stress have been observed in elderly subjects (ie, those > 55 y old)," write Ananda S. Prasad, from the Wayne State University School of Medicine in Detroit, Michigan, and colleagues. "Zinc is an effective anti-inflammatory and antioxidant agent."

At a senior center, a group of 49 healthy adults aged 55 to 87 years and inclusive of all ethnicities were randomized to zinc supplementation (zinc gluconate, 45 mg of elemental zinc per day) or placebo orally for 12 months. Outcome measures included incidence of infections during the study; generation of inflammatory cytokines, T helper 1 and T helper 2 cytokines, and oxidative stress markers; and plasma concentrations of zinc at baseline and after supplementation.

Compared with a group of younger adults, the older subjects had significantly lower baseline levels of plasma zinc, higher ex vivo generation of inflammatory cytokines and interleukin 10, and higher plasma oxidative stress markers and endothelial cell adhesion molecules.

Compared with the placebo group, the zinc-supplemented group had a significantly lower incidence of infections and ex vivo generation of tumor necrosis factor–alpha and plasma oxidative stress markers, and significantly higher plasma zinc and phytohemagglutin-induced interleukin 2 messenger RNA in isolated mononuclear cells.

The main limitation of this study is the small sample size.

"After zinc supplementation, the incidence of infections was significantly lower, plasma zinc was significantly higher, and generation of tumor necrosis factor alpha and oxidative stress markers was significantly lower in the zinc-supplemented than in the placebo group," the authors write. "We hope that our results will stimulate larger zinc trials in the elderly."

The National Institutes of Health and Labcatal Laboratories (Paris, France) supported this study. None of the authors have disclosed any relevant financial relationships.

Am J Clin Nutr. 2007;85:837-844.

Source: http://www.medscape.com/viewarticle/553524?src=mp