Decreased lung function is associated with vitamin D deficiency in apparently health, middle aged Koreans: the Kangbuk Samsung Health Study

Background/Objectives There has been inconsistent relationships between serum vitamin D levels and lung function in previous studies. However, previous studies included patients with medical diseases, affecting both vitamin D levels and lung function. Considering this view of potential confounders, we investigated if vitamin D deficiency (VDD) is linked to lung function in health screening examinee without overt medical conditions. Subjects/Methods We conducted a cohort study on 68,457 healthy Koreans (36,759 males, mean age: 37.7 years) with a health examination in 2015. Measured forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) were categorized in quartiles. To examine the relationships between VDD and lung function, adjusted odds ratios (aORs) for VDD were estimated by logistic regression. Results Median vitamin D level was 14.9 ng/mL. The prevalence of VDD (defined as