Inadequate levels of vitamin D have been linked to lower immunity and an increased risk of upper respiratory infections. We have written about these links here and here.
Do Vitamin D Supplements Make a Difference?
A new study shows, however, that vitamin D supplements did not reduce the number of colds that people with asthma caught, nor did they lower the severity of these colds. Needless to say, these results are disappointing, although they follow other recent studies demonstrating little benefit from vitamin D supplements. (You can read about them here, here and here.)
How the Study Worked:
The study included 400 adults with mild to moderate asthma. They were randomized to receive placebo pills or a loading dose of 100,000 IU of vitamin D3 (cholecalciferol) followed by 4,000 IU of the vitamin daily. The double-blind trial lasted seven months.
What the Investigators Found:
About half the volunteers caught at least one cold during the trial. Even though the majority of those taking vitamin D had adequate blood levels of 25-hydroxyvitamin D after three months (defined as 40 ng/mL or higher), it made no difference in the number of colds they caught.
Why It Matters:
The scientists were interested in reducing the number of colds because such infections can worsen asthma symptoms and may mean patients need to use more asthma medication or even be hospitalized to control an exacerbation. Learning that vitamin D supplements do not reduce this risk is valuable, even though it means one possible tool that doctors and patients might have used to protect asthma patients simply may not work.
American Journal of Respiratory and Critical Care Medicine, online Nov.5, 2015
Is There Any Hope?
We said in the preceding paragraph that vitamin D supplements may not work in keeping asthma patients healthier. They did not work in this study, but other studies may be needed to confirm this finding. Not every study gives the same result.
In the meantime, we offer our Guide to Vitamin D Deficiency for more information on vitamin D, and Dr. David Hahn’s book, A Cure for Asthma? What Your Doctor Isn’t Telling You and Why for an interesting angle on a different approach that may help some asthma patients.
