Ambient air pollution, healthy diet and vegetable intakes, and mortality: a prospective UK Biobank study

Recent studies suggest potential interactions of air pollutants with dietary factors and genetic susceptibility on mortality risk; however, evidence from prospective studies is still lacking. We aimed to assess the association between air pollution and mortality, and investigate the modification effects of a healthy diet and genetic susceptibility.

A total of 386 937 participants were enrolled from 2006 to 2010 and followed up to 2018 in the UK Biobank study. The annual average air pollutant concentrations of particulate matter (PM) with diameters ≤2.5 (PM2.5), ≤10 (PM10) and between 2.5 and 10 µm (PM2.5-10) and nitrogen oxides (NO2 and NOx) were calculated and linked to participants' residential addresses. Healthy dietary patterns were evaluated by a healthy diet score (HDS) based on intakes of vegetables, fruit, fish, unprocessed red meat and processed meat. We also calculated genetic risk score (GRS) of the lifespan. We examined potential interactions by setting variable cross-product terms of air pollutants with diets or GRS in the models.

We identified 11 881 deaths [2426 from cardiovascular diseases (CVD), 1211 from coronary heart disease (CHD) and 466 from stroke] during a median follow-up of 8.9 years. We found that PM2.5 [hazard ratio (HR), 1.27; 95% CI, 1.05-1.55], PM10 (HR, 1.18; 95% CI, 1.04-1.34), NO2 (HR, 1.05; 95% CI, 1.01-1.08), and NOx (HR, 1.02; 95% CI, 1.01-1.03) were associated with all-cause mortality. PM2.5 was also associated with increased risks of CVD mortality (HR, 1.68; 95% CI, 1.10-2.56) and CHD mortality (HR, 2.08; 95% CI, 1.16-3.75). In addition, we found that adherence to healthy dietary patterns modified associations of PM2.5, NO2 and NOx with all-cause mortality (P-interaction = 0.006, 0.006 and 0.02, respectively). Among the individual dietary components, vegetable intakes showed interactions with PM2.5, NO2 and NOx (P-interaction = 0.007, 0.004 and 0.02, respectively). The associations between air pollutants and increased risks of all-cause mortality were attenuated among participants with higher vegetable intakes. We did not observe interactions between air pollutants and HDS on CVD, CHD or stroke mortality (P-interaction > 0.05). Besides, we did not find interactions between air pollutants and genetic risk for lifespan on mortality risk.

This study provides evidence linking long-term exposure to various air pollutants to the risk of all-cause, CVD and CHD mortality, and the potential attenuation of a healthy diet, especially high vegetable intakes, on such relations. Our findings highlight the importance of adherence to a healthy diet in lowering ambient air-pollution-related mortality risk.