Immunity: How a zinc deficiency raises the risk of pneumonia in the elderly

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New research findings have revealed that low blood levels of zinc may be linked to an increased risk of pneumonia amongst the elderly, suggesting the benefits of supplements for this at risk population.
 
Lead researcher Simin Meydani said: ‘Normal serum zinc concentrations in nursing home elderly are associated with a decreased incidence and duration of pneumonia, a decreased number of new antibiotic prescriptions, and a decrease in the days of antibiotic use. Zinc supplementation to maintain normal serum zinc concentrations in the elderly may help reduce the incidence of pneumonia and associated morbidity.’
 
Zinc is one of the most plentiful trace elements in the body, second only to iron. It mediates many physiological functions and is believed to be essential for maintaining a healthy immune system.

Assessing the results

The researchers, from the US Department of Agriculture, Tufts University, and Boston University, investigated the effect of low serum zinc concentrations on the incidence of pneumonia in elderly men and women (average age 84.6) living in nursing homes. The research was part of a study to evaluate the effect of vitamin E supplements on respiratory infections. 
 
Over the course of 12 months, the subjects received vitamin E and a supplement containing half of the recommended dietary allowances (RDA) of other essential micronutrients, including zinc. 
 
Meydani and co-workers report that participants with low zinc levels at the end of the study, defined as having levels less than 70 micrograms per decilitre, had increased incidence of pneumonia, longer pneumonia episodes, about 50 per cent more new antibiotic prescriptions, and more days of antibiotic use.
 
Commenting on the findings Meydani said: ‘Our finding of a significantly lower all-cause mortality rate (by 39 per cent) in those with normal baseline serum zinc concentrations than in those with low baseline serum zinc concentrations suggests that zinc may play a crucial role in influencing mortality in the elderly.
 
Other studies have suggested that zinc deficiency may be a risk factor for immune deficiency and subsequent infection relapses in the elderly, based on zincs role in membrane integrity and DNA synthesis. The mineral also acts a cofactor to more than 300 enzymes. 
 
The researchers said: ‘The results from our current study, in addition to these earlier findings, suggest that elderly with low serum zinc concentrations might benefit from zinc supplementation.
 
‘Such a measure has the potential to reduce not only the number of episodes and duration of pneumonia and the number of new antibiotic prescriptions and days of antibiotic use due to pneumonia but also all- cause mortality in the elderly. An adequately powered randomised, 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.

 

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