The effects of vitamin D supplementation on airway functions in mild to moderate persistent asthma

Background: Vitamin D is hypothesized to have some roles in innate and adaptive immunity, inflammation reduction, and remodeling; therefore, it is supposed to affect the asthma phenotype, severity, and response to inhaled corticosteroid (ICS). Objective: To explore the synergistic effects of vitamin D supplementation in addition to asthma controllers (ICS or ICS plus long-acting beta-agonist) on airway functions. Methods: A randomized clinical trial was conducted in 130 individuals aged 10 to 50 years who lived in Tehran during a 24-week period. Data on age, sex, body mass index, stage of asthma, serum total IgE, history of allergic rhinitis, atopic dermatitis, food allergy, and urticaria were collected. Spirometric parameters (forced expiratory volume in 1 second [FEV1] and ratio of FEV1 to forced vital capacity) and serum vitamin D measurement were obtained before and 8 and 24 weeks after the intervention. Patients were divided in 2 groups randomly. Both groups received asthma controllers (budesonide or budesonide plus formoterol) according to their stage, but the intervention group received vitamin D supplementation (100,000-U bolus intramuscularly plus 50,000 U orally weekly) in addition to asthma controllers. Results: FEV1 improved significantly in both groups after 8 weeks, but no significant difference was found between the 2 groups at baseline (P = .20) or after 8 weeks (P = .99); however, a significant improvement was seen in the intervention group in the last 16 weeks, and FEV1 was significantly better in the intervention group than the other group after 24 weeks (P < .001). Conclusion: Vitamin D supplementation associated with asthma controllers could significantly improve FEV1 in mild to moderate persistent asthma after 24 weeks. (C) 2014 American College of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.