Effect of Vitamin D on Chronic Obstructive Pulmonary Disease: A Systematic Review of Randomized Controlled Trials

Objective: To evaluate the clinical and biological effects of vitamin D supplementation in patients with chronic obstructive pulmonary disease, based on evidence from randomized controlled trials. Materials and Methods: A systematic review was conducted in accordance with the PRISMA guidelines. Three databases (PubMed/MEDLINE, Scopus, and Web of Science) were searched for randomized controlled trials published until June 2025. Studies were included if they assessed the effects of vitamin D supplementation in patients with chronic obstructive pulmonary disease and reported clinical or biological outcomes. Results: Twelve randomized controlled trials involving 6626 participants from diverse regions, with wide variability in sample sizes (36 to 5 110 participants).