Abstract
Background The role of interactions of diet and air pollution in health outcomes remain unclear. This study investigated the combined effects of a pro-inflammatory diet and long-term air pollution exposure on the risk of five common diseases and all-cause mortality. Methods We included 120,000 UK Biobank participants with ≥2 Oxford WebQ 24-h dietary assessments. Cox proportional hazards models were employed to examine the associations between two exposures - Dietary Inflammatory Index (DII) scores and seven air pollutants (PM2.5, PM10, NO2, NOX, SO2, CO, and benzene) - with six outcomes: ischemic heart disease (IHD), stroke, diabetes (all diabetes types encompassing insulin- and non-insulin-dependent, and others), chronic obstructive pulmonary disease (COPD), lung cancer, and mortality. Non-linear exposure-response associations were modeled using shape-constrained health impact functions and penalized splines. Multiplicative interaction effects between DII and air pollutants were evaluated via likelihood-ratio tests. Results Our findings indicated exposure to air pollutants were associated with increased risks of diabetes, COPD, IHD, and stroke (hazard ratios 1.004-1.049). Higher DII predicted 1.034-1.086 fold greater risk of diabetes, COPD, lung cancer, and mortality. Significant multiplicative interactions (P for interaction <0.05) indicated that the effects of air pollutant on diabetes, COPD, and mortality were amplified among participants with higher DII, whereas no significant air pollutant-outcome associations were seen in those with low or intermediate DII. Conclusions A pro-inflammatory diet may amplify the adverse health effects of air pollution, highlighting potential for dietary interventions to complement environmental regulations.</p>