Vitamin D Supplementation, Chronic Obstructive Lung Disease and Asthma Exacerbations, and Lung Function Decline

It remains unclear whether supplementation with vitamin D reduces risk of acute exacerbations of chronic obstructive lung disease (COPD) or asthma, major contributors to the world-wide burden of disease.

To compare effects of vitamin D with placebo supplementation for the prespecified primary endpoints 1) acute exacerbations of COPD and 2) decline in pulmonary function measures of airflow obstruction. Prespecified secondary endpoints included asthma exacerbations and control.

Lung VITamin D and OmegA-3 TriaL (VITAL) is an ancillary study of VITAL, a United States nationwide, randomized, placebo-controlled trial with a 2-by-2 factorial design of vitamin D₃ (2000 IU/d) and marine n-3 fatty acids (1 g/d) among men 50 y and women 55 y of age or older. Of 25,871 randomly divided participants, 3632 at risk for respiratory exacerbations, including 1977 with COPD by diagnosis or symptoms and 1654 with self-reported asthma diagnosis, were followed annually for 5 y by self-administered respiratory questionnaire. Spirometry was performed at baseline and 2 y after randomization by 1648 participants from 12 urban centers. Decline in forced expiratory volume in 1 s (FEV₁) and FEV₁/forced vital capacity was measured between baseline and follow-up.

Supplementation with vitamin D was not associated with lower risk of any primary or secondary end point. Over the 5-y follow-up, the number of COPD exacerbations was 0.27/y in the vitamin D group and 0.25/y in the placebo group (rate ratio 1.10; 95% confidence interval, 0.93, 1.29). Over the 2-y follow-up, supplementation was not associated with slower decline (mL/y) in FEV₁.

Supplementation with vitamin D, compared with placebo, did not result in a lower rate of COPD exacerbations or improved pulmonary function in community-dwelling adults not selected for vitamin D deficiency. This trial was registered at Lung VITAL clinicaltrials.gov as NCT01728571 with Protocol ID 2010-P-000622 (https://prevention.cancer.gov/clinical-trials/clinical-trials-search/nct01728571).