Vitamin D doesn't cut cold in asthma patients

Taking vitamin D supplements does not reduce the number or severity of cold in asthma patients, suggests new research.

The findings surprised the researchers who had previously published research showing a 40 percent reduction in asthma exacerbations in patients with a vitamin D deficiency who achieved normal levels of the vitamin with supplements.

Because colds often trigger exacerbations, they hypothesised that vitamin D supplementation would reduce colds and cold severity. In fact, the new study found that some participants receiving supplemental vitamin D, rather than a placebo, experienced more colds.

"We cannot recommend vitamin D for the prevention of colds. Although there are many reasons to recommend vitamin D supplements for asthma patients as they are at greater risk for bone weakening,” said one of the researchers Loren Denlinger from University of Wisconsin in the US.

The study enrolled 408 adults with mild-to-moderate asthma whose vitamin D levels were insufficient or deficient. The patients were randomised to receive either vitamin D supplementation once or placebo for 28 weeks.

The researchers found, achieving sufficiency of vitamin D made no difference in number of colds or their severity this group experienced. (The study was published online in the Journal of Respiratory and Critical Care Medicine)