The effect of vitamin D therapy on airway reactivity and airway inflammation in asthmatic children

Background : Cross-sectional studies have reported association of vitamin D deficiency with increased asthma prevalence and severity, and with allergy. The effect of vitamin D as a sole therapy on bronchial hyperreactivity (BHR) and airway inflammation has not yet been reported. Aim : To evaluate the effect of vitamin D therapy on BHR, Fractional Exhaled Nitric Oxide (FeNO), and exhaled breath condensate cytokines. Patients : Children aged 6–18 years with a clinical diagnosis of mild to moderate asthma not receiving anti-inflammatory therapy and with low vitamin D levels. Methods : Randomized, double-blind, placebo-controlled study assessing the effect of six weeks treatment with either oral vitamin D 14000 units once weekly or placebo on these parameters. Results : Twenty patients received vitamin D treatment and 19 received placebo . Vitamin D replacement resulted in significant increase of vitamin level (20.8±1.5 vs . 33.1±2.1 ng/mL) and remained unchanged in the placebo. However, similar improvement in BHR was observed in the two groups. There was no change in IgE, eosinophil count, CRP, or FeNO levels following treatment. There was a similar change in exhaled breath condensate cytokines (IL4, IL5, IL10, IL17) and gamma interferon in both vitamin D and placebo groups. Conclusions : In our small group of children with mild to moderate asthma, treatment with vitamin D as a sole treatment had a similar effect as placebo in spite of significant increase in vitamin D blood levels. Further larger studies are needed to evaluate the possible additive effect of vitamin D to steroid therapy.