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

Abstract

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.

Figure 1

Concentric areas in which food resource availability was measured. *Asterisk indicates location of respondent residence. Food resource availability was measured within each concentric area: within 1km, between 1 and 3 km, between 3 and 5 km, and between 5 and 8.05 km.

Figure 2

Summary of study retention and exclusions Coronary Artery Risk Development in Young Adults (CARDIA) Study (1985–2000) *Retention incorporates loss to follow-up and mortality

Figure 3

Estimated effectsa of fast food availability within concentric areas around residential locations on weekly frequency of fast food consumption, by individual-level income ^aEstimated using fixed effects Poisson regression modeling fast food consumption (times per week) as a function of fast food restaurant availability (fast food restaurant counts per 10,000 population) in the areas within 1k and between 1 and 3k, 3 and 5k, and 5 and 8k of each Coronary Artery Risk Development in Young Adults (CARDIA) Study (1985–2000) respondent’s home, adjusting for time-varying age, income, marital status, children in household and percent of persons below 150% of federal poverty level; race, education, and study center are time invariant and therefore omitted from fixed effects models. Income-specific estimates were obtained from models containing income interactions with fast food restaurant availability within each neighborhood area. Coefficients can be interpreted as the percent change in fast food consumption expected from a 1% change in fast food restaurant availability. Error bars represent 95% confidence intervals.

Figure 4

Estimated effectsa of grocery store availability within concentric areas around residential locations on diet quality, by individual-level income ^aEstimated using fixed effects linear regression modeling diet quality index as a function of grocery store availability (grocery store counts per 10,000 population) in the areas within 1k and between 1 and 3k, 3 and 5k, and 5 and 8k of each Coronary Artery Risk Development in Young Adults (CARDIA) Study (1985–2000) respondent’s home, adjusting for time-varying age, income, marital status, children in household and percent of persons below 150% of federal poverty level; race, education, and study center are time invariant and therefore omitted from fixed effects models. Income-specific estimates were obtained from models containing income interactions with grocery store availability within each neighborhood area. Coefficients can be interpreted as change in DQI expected from a 1% change in grocery store density. Error bars represent 95% confidence intervals.