Association of air pollution with ischemic heart disease, stroke, diabetes, COPD, lung cancer, and all-cause mortality: Effect modification by pro-inflammatory diet

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 (PM_2.5, PM₁₀, NO₂, NO_X, 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.