Does Vitamin D₃ Supplementation Improve Exercise Tolerance of D₃ Deficient Chronic Obstructive Lung Disease Patients? - A Randomized Controlled Trial.

Newer functional aspects of vitamin D₃ have been revealed in tissue and organs other than bones. In several studies, vitamin D₃ supplementation showed significant improvement in exercise tolerance in various co-morbid patients but precise connection is not clear, in Chronic Obstructive Pulmonary Disease (COPD) patients. This study aimed to evaluate the effects of vitamin D₃ supplementation on exercise tolerance in D₃ deficient patients with COPD. A double-blinded randomized controlled trial was carried out on 40 D₃ deficient [serum 25(OH)D <30 ng/ml], male, smoker (>4 pack years), stable COPD (post-bronchodilator FEV1/FVC <0.70) patients (age 40 to 80 years) and randomly allocated as study (n=20) and control (n=20). Their baseline exercise tolerance [6 minute walk distance (6MWD), dyspneic score, fatigue score] variables were measured. Then oral capsules of D₃ [80,000IU/week for 13 weeks, followed by 40,000 IU per one to six weeks for further 13 weeks, according to serum 25(OH)D and calcium] and placebo were provided to 'Study' and 'Control' patients, respectively, for consecutive 26 weeks. Additionally, all patients of both groups were also advised to have sunlight exposure (within 11am to 4pm) at least for 5 to15 minutes daily. On 26th week of follow-up, all the exercise tolerance variables were again measured. Results were expressed as mean±SD and percentage. The data were statistically analyzed by SPSS (Version 16.0), using independent sample 't'-test and paired Student's 't-test, where p≤0.05 level was accepted as significant. Statistically significant improvement was observed in 6MWD (p<0.05), dyspneic score (p<0.001) and fatigue score (p<0.001) in our D₃ supplemented patients than those with a placebo after 26 weeks of follow-up. This study reveals that Vitamin D₃ supplementation can improve exercise tolerance but not ventilatory variables in D₃ deficient stable patients of COPD.