Vitamin D deficiency and lung function decline in healthy individuals: A large longitudinal observation study

Abstract

Aim: A reliable evidence from a comprehensive large-scale study supporting associations between serum vitamin D (25-hydroxyvitamin D) level (SVDL) and lung function decline (LFD) in healthy individuals has been unavailable. Using a well-established health screening database, we assessed the associations between SVDL and LFDs, measured as the forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1) and FEV1/FVC ratio.

Methods: Serial SVDL and lung function data were analyzed using linear mixed models, which were performed in smokers and non-smokers, separately. Vitamin D-deficient individuals (VDDs) were defined when their SVDLs were consistently lower than 20 ng/mL at all measurements.

Results: A total of 1371 individuals were analyzed. The mean FEV1 decline rates of VDDs and vitamin D-normal individuals (VDNs) in smokers were -33.35 mL/year (95% CI: 39.44 to -27.26 mL/year) and -15.61 mL/year (95% CI: 27.29 to -4.21 mL/year) respectively, over a mean of 6.29 years of observation with statistical significance (P < 0.001). However, there was no significant differences observed between decline rates of FEV1 in non-smokers. Similarly, FVC decline rates of VDDs were significantly greater than those of VDNs only in smokers (P < 0.001). However, FEV1/FVC ratio decline rates showed no significant difference between VDDs and VDNs regardless of their smoking status.

Conclusions: Consistently low SVDLs predicted more rapid FEV1 and FVC declines in smokers. However, FEV1/FVC decline rate was not associated with SVDL. SVDL may be used to identify healthy smoking individuals at high risk for accelerated LFD.

Keywords: FEV1; Health screening; Lung function; Serum; Vitamin D.