Association Between Serum Folate and Lung Function in People with and without Chronic Obstructive Pulmonary Disease: Results from NHANES 2007–2012.

Abstract Background The relationship between serum folate and pulmonary function in individuals with chronic obstructive pulmonary disease (COPD) remains unclear. Our study aims to explore the potential correlation between serum folate levels and pulmonary function. Methods We analyzed cross-sectional data from the National Health and Nutrition Examination Survey (NHANES 2007–2012), including individuals aged 40 years and above (n = 1062) with complete post-bronchodilator lung function data and serum folate measurements. COPD was diagnosed based on a post-bronchodilator FEV 1 /FVC ratio of less than 0.70. Using a multivariable adjusted linear model, we assessed the association between serum folate levels and lung function indices, stratified by COPD status. Results Our study included 493 COPD patients and 569 individuals without spirometry-defined COPD. There were no significant differences in serum folate levels between the two groups. Adjusting for multiple factors, we observed that each 1 nmol/L increase in serum folate was significantly associated with improvements in FEV 1 (2.54 mL, 95% confidence interval [CI] 0.58 to 4.5), FVC (3.58 mL, 95% CI 0.9 to 6.27), and PFE (7.73 mL, 95% CI 2.17 to 13.29) among COPD patients. However, no significant correlation was found between lung function and serum folate levels in non-COPD individuals. Conclusions Elevated serum folate levels are associated with better lung function in COPD patients, while folate levels do not significantly impact lung function in individuals without COPD.