Does diet modify the effects of air pollution on lung function? A large cross-sectional study

BACKGROUND: Air pollution and diet both affect lung health and may interact. We investigated whether a healthy diet may modify associations between air pollution and lung function in adults. METHODS: Modelled annual-average concentrations of nitrogen dioxide (NO₂) and particulate matter with aerodynamic diameters ≤10 μm (PM₁₀) and ≤2.5 μm (PM_2.5) were linked to residential address points of 260,982 individuals in the UK Biobank cohort. Averaged air pollution concentrations in the year of spirometry and two years prior to spirometry measurements were used. The healthy diet score (HDS) was calculated based on dietary data collected at baseline. Effect modifications by HDS and individual food components (fruit and vegetables) on the associations of air pollution and lung function were investigated. RESULTS: Participants in the highest HDS group had higher forced expiratory volume in 1-second(FEV₁) and forced vital capacity(FVC) than those in the lowest group in both males and females. Interactions between HDS and air pollution were not seen. Suggestive evidence of total fruit intake effect modification on PM_2.5-FEV₁ was observed in females. Exposure to PM_2.5 per 5 μg/m³ increment was associated with reduced FEV₁ in the low of -14.4 mL(95%CI: -26.8, -2.2) but not in medium and high fruit intake groups (+2.9 mL(95%CI: -13.8,19.7) and +9.7 mL(95%CI: -4.1,23.6), respectively). A similar pattern was observed for FVC. CONCLUSIONS: We found suggestive evidence that higher consumption of fruit may partially reduce the adverse effects of air pollution on lung function in females. These findings merit investigation to see if they replicate in other cohorts.