Higher dietary inflammatory index is associated with reduced lung function in non-COPD adults: A cross-sectional...

The association between lung function and dietary inflammatory index (DII) in non-chronic obstructive pulmonary (non-COPD) population is currently unknown. We hypothesized that higher DII is associated with lower lung function measures, particularly forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC). Data from 7990 NHANES (2007-2012) participants (48.5% men, 51.5% women; mean BMI 29.1±6.6 kg/m²) were analyzed. The DII scores were calculated from 24-hour dietary recall and divided into tertiles. After adjusting for confounders, multivariable linear regression analysis revealed that each unit increase in DII score was associated with a 23.16 mL reduction in FEV1 and a 34.95 mL reduction in FVC (p < .001). When DII was analyzed as a categorical variable, participants in the higher tertiles (T2 and T3) had significantly lower FVC and FEV1 compared with those in the lowest tertile (T1) (p < .001). Restricted cubic spline analysis indicated a linear association between DII and lung function parameters (FEV1 and FVC), with the P-value for nonlinearity > .05. In our study, subgroup analyses revealed weaker associations between DII and lung function in obese individuals. Specifically, FEV1 was reduced by 14.17 mL (significant interaction, P = .015), and FVC was reduced by 24.51 mL (interaction approaching significance, P = .056). In conclusion, pro-inflammatory diets (higher DII) negatively affect lung function in middle-aged non-COPD populations, with weaker associations in obese individuals.