Abstract
BACKGROUND: The adverse effect of tobacco smoke exposure on lung function varies among individuals. We aim to investigate whether diet inflammatory potential modifies the association between tobacco smoke exposure and lung function. METHODS: This was a cross-sectional study of 11,382 adults from the 2007-2012 National Health and Nutrition Examination Survey. Tobacco smoke exposure was measured using serum cotinine level, and dichotomized as low or high level according to the race/ethnicity-specific cut-points. Forced expiratory volume in 1 s percent of predicted (FEV(1)% predicted), forced vital capacity percent of predicted (FVC% predicted) and FEV(1)/FVC were selected to quantify lung function. Diet inflammatory potential was assessed using dietary inflammatory index (DII), and categorized into quartiles. The modification effect of DII on the relationship between tobacco smoke exposure and lung function were evaluated by multivariate linear regression model with interaction term and stratified analysis. RESULTS: DII interacted with serum cotinine level in association with FEV(1)% predicted, FVC% predicted and FEV(1)/FVC (P for interaction < 0.05). In individuals with higher DII, serum cotinine level had stronger inverse associations with FEV(1)% predicted, FVC% predicted and FEV(1)/FVC. More specifically, 23 of 28 DII components showed modification effects on the relationship between serum cotinine level and lung function. CONCLUSIONS: Diet inflammatory potential modifies the effect of tobacco smoke exposure on lung function, and tobacco smoke exposure had a stronger adverse impact on lung function among individuals with high diet inflammatory potential, which should attract more attention.