Associations of Serum Vitamin A and E Concentrations with Pulmonary Function Parameters and Chronic Obstructive Pulmonary Disease

Background/Objectives: Oxidative stress, an imbalance between oxidants and antioxidants, is known to affect pulmonary function (PF), thereby leading to the development of chronic obstructive pulmonary disease (COPD). However, data on the associations of serum vitamin A and E concentrations with PF parameters and COPD are inconsistent. The present cross-sectional study aimed to investigate these associations, considering inflammatory status. Participants/Methods: This study included 2005 male and female adults aged ≥40 years who had participated in a population-based national survey. Spirometry without a bronchodilator was conducted to yield PF parameters, such as forced expiratory volume in one second (FEV1), forced vital capacity (FVC), and the FEV1/FVC ratio, which were used to define COPD. Serum vitamin A (retinol) and E (α-tocopherol) concentrations were assayed. Multivariable regression analysis was performed after adjusting for potential confounding variables. Results: Serum vitamin A concentration was positively associated with FEV1 (p for trend < 0.01) among all participants. In addition, the odds ratio (95% confidence interval) of the highest serum vitamin A concentration tertile for the prevalence of COPD, which was defined by the FEV1/FVC ratio < 0.7, was 0.53 (0.31, 0.90) compared with that of the lowest tertile (p for trend < 0.05). Analysis stratified by a cutoff point of 1 mg/L serum high-sensitivity C-reactive protein (hs-CRP) revealed that such associations with FEV1 and COPD prevalence were stronger in participants with lower hs-CRP levels (p for trend < 0.05). In contrast, serum vitamin E concentration was associated with neither PF parameters nor COPD prevalence. Conclusions: These findings suggest that serum vitamin A concentration may be important in preventing the progressive decline in PF parameters that results in COPD. Further epidemiological investigations are warranted to evaluate the causal associations of antioxidant vitamin status with PF parameters and COPD.