Vitamin D supplements do not reduce the number of or severity of colds in asthma patients, according to a new study published in the American Journal of Respiratory and Critical Care Medicine.
In a randomised controlled trial of 408 adults with mild-to-moderate asthma undergoing inhaled corticosteroid (ICS) tapering and whose vitamin D levels were insufficient or deficient, participants were given either a vitamin D supplement or a placebo for 28 weeks. The study aimed to test the hypothesis that vitamin D might increase the positive effect of the ICS.
82% of those who received the supplements achieved vitamin D sufficiency within 12 weeks. However, this made no difference in the number of colds they experienced or how severe their colds were. In addition, African Americans in the group who received the supplements actually experienced more colds than African Americans in the placebo group.
The results were unexpected for the team from the University of Wisconsin who had previously published research showing a 40% reduction in asthma exacerbations when vitamin-D deficient patients took supplements to achieve normal levels.
Loren C. Denlinger, associate professor of medicine at the University of Wisconsin, said: “Other studies of vitamin D and colds have produced mixed results. 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.”
There are other reasons to recommend vitamin D supplements for asthma patients but Denlinger said, “we can’t recommend vitamin D for the prevention of colds.”
Read the full study in the American Journal of Respiratory and Critical Care Medicine.