Adequate Zinc Levels Help Quell Pneumonia in Elderly

BOSTON, Oct. 23 -- For nursing home elderly, a little zinc every day may stave off pneumonia or lessen its severity and duration, nutrition researchers here reported. In an observational study, they found that those of nearly 600 nursing home residents (ages 84.6 + 7.6) with normal serum zinc concentrations had lower occurrence rates of pneumonia, fewer new prescriptions for antibiotics, a shorter duration of pneumonia, and fewer days of antibiotic use compared with patients who had low zinc levels.
Patients with normal zinc levels also had a 39% lower all-cause mortality rate than patients with low levels, reported Simin N. Meydani, D.V.M., Ph.D., of the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts, and colleagues, in the October issue of the American Journal of Clinical Nutrition.
"Results from our study indicate that supplementation with <80 mg of zinc daily might reduce mortality in the elderly," they wrote.
Other studies have shown a reduced occurrence rate of all-cause mortality in older patients and in other populations, the investigators noted. In the Age-Related Eye Disease Study, for example, the risk of death was reduced by 27% among those who received 80 mg of zinc daily in a supplement.
"In addition, zinc supplementation has been shown to reduce overall mortality by as much as 51% in children with diarrhea and by as much as 68% in infants born full-term and those small-for-gestational age," they wrote.
The authors conducted an observational study to determine whether serum zinc concentrations in elderly nursing home residents are associated with the incidence and duration of pneumonia, total antibiotic use and duration of use, and pneumonia-associated and all-cause mortality.
The participants were residents of 33 Boston nursing homes who were part of a one-year randomized, double-blind, placebo-controlled trial of vitamin E supplementation. As part of that trial, participants all were given daily doses of 50% of the recommended dietary allowance of essential vitamins and minerals, including zinc.
In the analysis, the Tufts group included 578 participants with baseline zinc level measurements and 420 with end-of-study values, including seven with only end-of-study levels. The cutoff points they chose were less than 70 µg/dL to indicate low serum zinc concentrations, and 70 µg/dL or higher to indicate normal levels.
"Although there is no consensus that zinc status can be easily defined by serum zinc values, it is the most widely used biochemical indicator of zinc status and is the only biochemical indicator of zinc status for which adequate reference data are available," the authors wrote. "In addition, several studies in the elderly have shown that serum zinc concentrations do respond to zinc supplementation."
The investigators found that compared with the patients who had low zinc levels, patients with normal levels had a 53% lower rate of death from pneumonia, although this difference was not statistically significant (P=0.198). However, the all-cause mortality rate was 39% lower among patients with normal zinc levels, and this difference was significant (P=0.049).
When the authors controlled for between-group differences in congestive heart failure and other potential confounders, they found that the statistical significance of the differences in mortality rates remained largely unchanged.
Serum zinc concentrations at the end of the study were strongly associated with the incidence and duration of pneumonia and with the number of new antibiotic prescriptions and days of antibiotic use (P<0.004 for all).
Both the occurrence rate of pneumonia and the total number of new antibiotic prescriptions to treat pneumonia were about 50% lower in those with end serum zinc concentrations of at least 70 µg/dL than in those with lower concentrations.
Duration of pneumonia was 3.9 days shorter and days of antibiotic use were 2.6 fewer among patients with normal zinc levels versus low zinc, and these differences remained significant when the authors controlled for various factors, including baseline serum albumin and change in serum albumin concentrations.
The authors concluded "that an adequately powered randomized, double-blind, controlled trial seems to be the likely next step. Such a study is needed to determine the efficacy of zinc supplementation as a potential low-cost intervention to reduce morbidity and mortality due to pneumonia in this vulnerable population."
The study was supported by the National Institute on Aging, the USDA, and a grant for preparation of the study capsules from Hoffmann-La Roche Vitamins and Fine Chemicals Division. All authors declared that they had no conflicts of interest. Primary source: American Journal of Clinical NutritionSource reference: Meydani SN, et al "Serum zinc and pneumonia in nursing home elderly" Am J Clin Nutr 2007; 86: 1167-73.