Air Pollution, Diet, and Mortality in the NIH-AARP Cohort

Abstract

Background/Aim: Oxidative stress and systemic inflammation are suggested pathways for air pollution-mediated adverse health outcomes. Recent evidence from dietary supplementation intervention studies suggests that foods rich in antioxidant and anti-inflammatory nutritional content offer protection against air pollution exposures. Methods: Potential interactive effects of long-term air pollution (PM2.5, NO2, and O3) exposures and dietary habits (daily total fat, meat, fruit, vegetable, dairy, fish, and grain consumption) on mortality risks were evaluated in the NIH-AARP Diet and Health Study, a cohort of approximately half million subjects across the contiguous US. The cohort was linked to census tract estimates for PM2.5 and NO2 for 1999-2008, and O3 (8-hr daily maximum) for 2007-2011. Associations between air pollutants and risk of cause-related mortality were evaluated using multivariate Cox proportional hazards models, adjusted for both individual (age, sex, race, education, marital status, smoking history, BMI, diet, and alcohol consumption) and census-level contextual covariates (median census tract household income, % of census tract population with less than a high school level education), and effect modification by diet was assessed by evaluating statistical significance of air pollution-dietary variable interaction terms and conducting stratified analyses. Results: Associations between PM2.5 and NO2 exposures and total cardiovascular disease, ischemic heart disease, and diabetes mortality were found to be significantly reduced (p interaction<0.05) among those who consumed higher levels of fruits, while associations between O3 and total respiratory disease and COPD mortality were observed to be significantly reduced among those who consumed higher levels of vegetables. Conclusions: The results from this analysis reveal that increased intake of natural antioxidants found in fruits and vegetables attenuate mortality risks associated with long-term air pollution exposure, suggesting that promotion of healthy dietary habits can potentially provide an alternative, cost-efficient public health strategy to ameliorate the considerable health and economic burdens imposed by ambient air pollution.