Vitamin D deficiency causes deficits in lung function and alters lung structure

Rationale: The prevalence of vitamin D defi ciency is increasing. Vitamin D deficiency has been implicated in changing the prevalence and severity of obstructive lung diseases including asthma and COPD. Vitamin D modulates immune function. However, recent data also suggest that vitamin D deficiency is associated with decreased lung function at a population level. The relationship between vitamin D defi ciency and lung function is confounded by the link between physical activity levels and vitamin D status. This study aimed to determine if there is a causal relationship between vitamin D defi ciency and reduced lung function.

Methods: A physiologically relevant model of vitamin D defi ciency in BALB/c mice was developed by dietary manipulation. Vitamin D replete (Vitamin D high; n = 34) and defi cient (Vitamin D low; n = 47) mice were studied for somatic growth, lung function and lung structure at 2 weeks of age. Lung volume and lung mechanics were measured using plethysmography and the forced oscillation technique, respectively, while lung structure was assessed according to ATS/ERS guidelines.

Results: Vitamin D defi ciency decreased lung volume (Vitamin D high, 0.21 (0.04 (SD) mL vs. Vitamin D low, 0.16 (0.03 (SD) mL; p < 0.001) and altered lung mechanics (airway resistance: Vitamin D high, 635 (96 (SD) hPa.s.L−1 vs. Vitamin D low, 834 (125 (SD) hPa.s.L−1 ; p < 0.001). Defi cits in lung function could not be explained entirely by changes in lung volume. There were corresponding changes in lung structure.

Conclusions: This is the fi rst study to demonstrate a direct link between vitamin D defi ciency, altered lung structure and decreased lung function. This may explain the association between vitamin D status and obstructive lung disease.