Endocrine Abstracts

Background: Several studies have reported an association between serum 25-hydroxyvitamin D (25(OH)D) concentrations and pulmonary function in the general population. However, results remain conflicting. In addition, the underlying mechanisms by which vitamin D affects pulmonary function are unknown.

Objective: To assess the relationship of vitamin D status with pulmonary function and whether this relationship is mediated by physical function and/or inflammation. We will also examine potential effect modification of sex and smoking in this relationship.

Methods: We analyzed data from the Longitudinal Aging Study Amsterdam (LASA), an ongoing population-based, prospective cohort study in the Netherlands. Data for this study were obtained from the third cohort (2012/2013). For this study we used data of 551 participants aged between 55 and 65 years, with complete data on serum 25-hydroxyvitamin D (25(OH)D, CRP, IL-6 and pulmonary function tests (Forced Expiratory Volume in one second (FEV₁) and Forced Vital Capacity (FVC). In the regression analyses we corrected for age, sex, BMI, serum creatinine, smoking status, alcohol consumption, educational level, physical activity and season of blood collection. In addition, effect modification of sex and smoking, and mediation by physical performance, IL-6 and CRP was tested.

Results: In men, serum 25(OH)D was associated with pulmonary function: 10 nmol/L higher serum 25(OH)D was associated with 1.01% predicted higher FEV₁ (95%CI: 0.03 to 1.98) and 1.02% predicted higher FVC (95%CI: 0.26 to 1.77). In women no assocation between serum 25(OH)D and FEV₁ (B(95%CI):-0.19 (−1.17 to 0.78)) and FVC (0.12 (−0.74 to 0.97)) was found. No effect modification by smoking was found. Serum 25(OH)D had an indirect effect on FEV₁ through physical performance in women. No mediation effect of physical performance in the relationship between serum 25(OH)D and FVC was seen. In addition, CRP and IL-6 were no mediators in the relationships between serum 25(OH)D and FEV₁ and FVC.

Conclusion: Higher serum vitamin D concentrations were associated with better pulmonary function in men, but not in women. Further studies are needed to elucidate potential mechanisms underlying the difference between men and women.