The potential role of dietary patterns in modifying the association between ambient PM 2.5 exposure and mortality in elderly Hong Kong Chinese.

Abstract

BACKGROUND: The potential of dietary patterns to modify the associations between long-term ambient fine particulate matter (PM2.5) exposure and all-cause, respiratory, and circulatory mortality remains unclear. METHODS: A total of 3,937 older adults (≥ 65 years) living in the community were enrolled in a prospective cohort study from 2001 to 2003 in Hong Kong. Assessment of the Diet Quality Index-International (DQI-I), Dietary Inflammatory Index (DII), the Mediterranean-DASH Intervention for Neurodegenerative Delay (MIND) diet was carried out utilizing a 280-item food frequency questionnaire. Annual PM2.5 concentrations were estimated via land use regression models. Mortality outcomes were sourced from official death registry. Time-varying Cox proportional hazards models were applied to estimate hazard ratios (HRs) and their 95% confidence intervals (CIs). RESULTS: During a median of 16.8 years follow-up, 1,856 deaths were recorded. PM2.5 exposure significantly increased the risks of all-cause mortality, respiratory and circulatory mortality. The MIND diet interacted with PM2.5 exposure on all-cause (p-interaction = 0.008) and respiratory mortality (p-interaction = 0.022). Higher MIND diet scores (≥ median) attenuated the adverse PM2.5 exposure-mortality association, showing lower risks for all-cause (HR: 1.18, 95% CI: 1.06–1.32) and respiratory mortality (HR: 1.14, 95% CI: 0.91–1.41). In contrast, those with lower MIND scores (< median) had elevated mortality risks, with HRs of 1.45 (95% CI: 1.27–1.65) for all-cause mortality and 1.60 (95% CI: 1.24–2.06) for respiratory mortality. No significant interaction was observed for circulatory mortality. Besides, no interaction was found between PM2.5 exposure with DQI-I or DII in relation to mortality. CONCLUSIONS: Adherence to MIND diet may mitigate the detrimental effects of long-term exposure to PM2.5 on all-cause and respiratory mortality in older adults, whereas overall diet quality or an anti-inflammatory diet showed no protective effects.