Fast food restaurants and food stores - Longitudinal associations with diet in young to middle-aged adults: The CARDIA study

Background: A growing body of cross-sectional, small-sample research has led to policy strategies to reduce food deserts - neighborhoods with little or no access to healthy foods - by limiting fast food restaurants and small food stores and increasing access to supermarkets in low-income neighborhoods. Methods: We used 15 years of longitudinal data from the Coronary Artery Risk Development in Young Adults (CARDIA) study, a cohort of US young adults (aged 18-30 years at baseline) (n = 5115), with linked time-varying geographic information system-derived food resource measures. Using repeated measures from 4 examination periods (n = 15 854 person-examination observations) and conditional regression (conditioned on the individual), we modeled fast food consumption, diet quality, and adherence to fruit and vegetable recommendations as a function of fast food chain, supermarket, or grocery store availability (counts per population) within less than 1.00 km, 1.00 to 2.99 km, 3.00 to 4.99 km, and 5.00 to 8.05 km of respondents' homes. Models were sex stratified, controlled for individual sociodemographic characteristics and neighborhood poverty, and tested for interaction by individual-level income. Results: Fast food consumption was related to fast food availability among low-income respondents, particularly within 1.00 to 2.99 km of home among men (coefficient, 0.34; 95% confidence interval, 0.16-0.51). Greater supermarket availability was generally unrelated to diet quality and fruit and vegetable intake, and relationships between grocery store availability and diet outcomes were mixed. Conclusion: Our findings provide some evidence for zoning restrictions on fast food restaurants within 3 km of low-income residents but suggest that increased access to food stores may require complementary or alternative strategies to promote dietary behavior change.