Vitamin D in chronic obstructive pulmonary disease and asthma in Indian population

Abstract

Rajaram et al. in their hospital-based study among 18–50-year-old South Indian patients with bronchial asthma demonstrated the effects of genetic polymorphisms in Vitamin D metabolic pathway on Vitamin D level and asthma control.[5] They concluded that Vitamin D receptor polymorphism (rs2228570) was found to be protective against asthma exacerbations. There were poor correlations and insignificant associations of single-nucleotide polymorphisms and serum 25-hydroxyvitamin D levels among asthma patients and healthy controls. The Global Initiative for Asthma guidelines do not support the supplementation of Vitamin D for the prevention of exacerbation of asthma.[11] A systematic review and meta-analysis of individual participant data from seven randomized controlled trials by Jolliffe et al. studied the pooled estimate of the protective effects of Vitamin D against asthma exacerbations requiring treatment with systemic corticosteroids.[12] It also investigated the effect of Vitamin D supplementation on risk of asthma exacerbation according to baseline 25-hydroxyvitamin D concentrations. All these seven randomized controlled trials were conducted at secondary and tertiary care levels, among children and adults. The Vitamin D supplementation dosage and schedule varied among the studies. All the studies gave oral Vitamin D3 supplementation to participants in the intervention arm. Minimum dose given was 500 IU/day to a maximum of 4000 IU/day. Three of the randomized controlled trials also gave a bolus dose of Vitamin D3 ranging from 100000 IU to 120000 IU.[13-15] The authors concluded that Vitamin D supplementation reduced asthma exacerbations treated with oral corticosteroids when compared with placebo. Nevertheless, differences across subgroups, including baseline 25-hydroxyvitamin D status, did not reach statistical significance. Therefore, which group of patients will have preventive effects of Vitamin D supplementation is still not known.