(HealthDay News) — Vitamin D supplementation does not reduce cold severity or frequency among adults with mild-to-moderate asthma, according to a study published online Nov. 5 in the American Journal of Respiratory and Critical Care Medicine.
Loren C. Denlinger, M.D., Ph.D., from the University of Wisconsin in Madison, and colleagues examined whether vitamin D supplementation reduced cold symptom occurrence and severity among adults with mild-to-moderate asthma. Colds were assessed among 408 adults randomized to receive placebo or cholecalciferol for 28 weeks.
The researchers found that 203 adults had one or more colds. Vitamin D supplementation had no effect on the average peak Wisconsin Upper Respiratory Symptom Survey-21 scores (62.0 for placebo versus 58.7 for vitamin D; P = 0.39), despite achieving 25-hydroxyvitamin D levels of 41.9 ng/mL by 12 weeks. There was no between-group difference seen in the rate of colds (rate ratio, 1.2; 95 percent confidence interval, 0.9 to 1.5); however, an increased rate of colds was seen among African-Americans receiving vitamin D versus placebo (rate ratio, 1.7; 95 percent confidence interval, 1.1 to 2.7; P = 0.02).
“In patients with mild-to-moderate asthma undergoing an ICS dose-reduction, these results do not support the use of vitamin D supplementation for the purpose of reducing cold severity or frequency,” the authors write.