From Science Daily:

Vitamin D supplements do not reduce the number or severity of colds in asthma patients, according to a new study published online ahead of print publication in the American Thoracic Society’s American Journal of Respiratory and Critical Care Medicine.

Loren C. Denlinger, MD, PhD, associate professor of medicine at the University of Wisconsin, and colleagues conducted a randomized, controlled trial of adults with mild-to-moderate asthma. Among African Americans in the study, those receiving supplemental vitamin D, rather than a placebo, experienced more colds.

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 hypothesized that vitamin D supplementation would reduce colds and cold severity.

“Other studies of vitamin D and colds have produced mixed results,” Dr. Denlinger said. “Most of those studies were conducted among healthy patients. We wanted to ask the same question of a patient population in which the impact of a cold carries greater risk.”

The researchers followed asthma patients who were undergoing inhaled corticosteroid (ICS) tapering, Denlinger added, to test the hypothesis that vitamin D might bolster the potency of the ICS.

The multi-center AsthmaNet Vitamin D Add-on Therapy Enhances Corticosteroid Responsiveness (VIDA) trial enrolled 408 adults with mild-to-moderate asthma whose vitamin D levels were insufficient or deficient (25-OH-D3 < 30 ng/mL). Those enrolled had asthma symptoms despite low-dose ICS therapy. The patients were randomized to…

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