A daily zinc supplement may significantly reduce infections in the elderly, says a new trial from the US that may have implications for boosting "healthy ageing".
The elderly currently make up 10 per cent of the global population - a figure that is expected to double by 2050, placing increasing demands on public health systems and medical and social services.
The randomized, double-blind, placebo-controlled trial, by researchers from Wayne State University School of Medicine and the University of Michigan, suggests that zinc supplements may reduce the incidence of infections, and may also improve the overall antioxidant status of this section of the population.
Lead researcher Ananda Prasad and her collaborators recruited 50 healthy subjects from both sexes (age range 55 to 87) and randomly assigned them to receive either a daily supplement of zinc in the form of zinc gluconate providing 45 mg of elemental zinc per day, or placebo for 12 months.
At the start of the study, the researchers report that the older subjects generally had significantly lower blood zinc levels and higher levels of oxidative stress than their younger counterparts.
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.
At the end of one year of supplementation the number of infections recorded in the zinc supplemented group was found to have significantly decreased, compared to placebo.
Blood samples showed that levels of tumour necrosis factor alpha (TNF-alpha), a marker for inflammation, and oxidative stress markers were also reduced in the zinc-supplemented subjects.
"After zinc supplementation, the incidence of infections was significantly lower, plasma zinc was significantly higher, and generation of tumour necrosis factor-alpha and oxidative stress markers was significantly lower in the zinc-supplemented than in the placebo group," concluded the researchers in the American Journal of Clinical Nutrition.
A report published this week by the International Alliance of Dietary/Food Supplement Associations (IADSA) highlighted the need for action in addressing nutrition in the elderly.
Report author Professor David Richardson told NutraIngredients.com that as people age their energy intake declines, making it much more difficult to ensure the micronutrient intake of diet as a whole. Such a deficit in micronutrient intake offers an opportunity for food supplements, he said.
Source: American Journal of Clinical Nutrition
March 2007, Volume 85, Number 3, Pages 837-844
"Zinc supplementation decreases incidence of infections in the elderly: effect of zinc on generation of cytokines and oxidative stress"
Authors: A.S. Prasad, F.W.J. Beck, B. Bao, J.T. Fitzgerald, D.C. Snell, J.D. Steinberg and L.J. Cardozo