Poor food choices have been shown to contribute to the rise of major chronic diseases, including overweight and obesity. In academic and policy circles, as well as in the public eye, the local food environment has been associated with food choices and diet-related health consequences. Limited food access is considered especially worrisome for underserved, predominantly low-income areas, which are believed to be disproportionately subject to health and income disparities. The Food, Conservation, and Energy Act of 2008 (the 2008 Farm Act), refers to such areas as “food deserts.” In February 2010, the Obama Administration proposed a $400 million Healthy Food Financing Initiative that would eradicate food deserts by improving food access. Several States have launched policy efforts to increase access to healthy food.
The concern in policy circles is that there may be insufficient availability and affordability of healthy food in these areas that may cause poor dietary choices. The literature in various disciplines of social science, marketing, management and nutrition sciences has addressed the issue of food access and choice from distinct, albeit overlapping angles. The empirical evidence from these disciplines lacks consensus as to whether the food deserts exist and why.
The gaps in the literature on whether food deserts exist appear to be related to the inconclusive evidence on the linkage between accessibility and food choice due to data limitations and methodological weaknesses. Overall, it appears that the focus of much of the previous research is on supply-side factors, creating an implicit underlying assumption that food deserts as a supply-side market failure and therefore motivating policy intervention to correct such market inefficiencies. But the contradictory empirical evidence in the previous literature about such complex phenomena as food deserts highlights the need for a more comprehensive approach.
In this research project, both supply- and demand-side factors affecting the associations among food access, affordability, and food choices are analyzed. These factors may give rise to or, at the least, compound the adverse dietary and health effects associated with food deserts. This research steps in to fill the aforementioned gaps in the literature. The focus of this research is on 10 healthy and unhealthy food groups mentioned in the literature, with an emphasis on fruits and vegetables. The food access measure in this project is the food store density at the county level. The research questions to answer are whether: (1) the availability of different types of food retail outlets affects the probability of patronizing that particular type of outlet for purchasing fruits and vegetables (F&V); (2) food access or affordability or a combination thereof plays a major role in purchasing fruits and vegetables; (3) household-level heterogeneity confounds the true effects of increased access to supermarkets; and (4) the demands for 10 major food groups (healthy and unhealthy) are elastic or responsive to a proportional increase in supermarket availability.
To explore these hypotheses, national-level purchase data on at-home food purchases (Nielsen HomeScan Panel data) are utilized to overcome most the data-related issues in the literature. The Economic Census conducted by the U.S. Census Bureau, is the source for data on the retail food availability for at-home and away-from-home consumption. A nonlinear, multinomial logit model is used to estimate hypothesis (1). A series of mixed effects models are used to simultaneously model the effects of supermarket availability and income on F&V purchases, while accounting for household heterogeneity (hypothesis (2)). To eliminate the self-selection bias in the nonexperimental data, difference-in-difference models are used to estimate the true effects of supermarkets on F&V purchases in hypothesis (3). Finally, a system of demand equations (almost ideal demand system, AIDS) is used to estimate not only the effects of food access on F&Vs, but also other important foods, accounting for substitution and complementation effects in the process. This formally constitutes testing hypothesis (4).
The results from hypothesis (2) suggest that the availability of supermarkets is inversely related to the likelihood of patronizing these specific types of food stores when purchasing F&Vs. The availability of convenience stores, on the other hand, does in fact induce higher probability of purchasing F&Vs from this type of store. This finding suggests perhaps a whole new direction of policy intervention emphasizing reliance on smaller, more flexible store types.
The findings from the mixed models in hypothesis (2) demonstrate that the availability of supermarkets or other store types do not have significant effects on F&V purchases. The results also suggest that increases in income, as opposed to supermarket density, can result in a mild increase in F&V purchases. A different modeling approach in hypothesis (3) completely supports these findings.
From the AIDS estimations it would appear that an increase in the supermarket availability would induce increased healthy food (fruits and whole grains) and decrease “unhealthy” food (alcohol) demands in the high-income groups. In the low-income groups, an increase in the supermarket availability appears to have no effect on any healthy food demand, and have ambiguous effects on unhealthy food (carbonated soft drinks and other sugary fruit drinks, and sweet and savory snacks) demand. These suggest that increased availability will possibly have ambiguous effects on diet, especially that of the population in the low-income groups.
Overall, the effect of supermarket availability on F&V purchases in isolation is insignificant, regardless of the income level. The results for a “food basket” rather than F&Vs alone, suggest that supermarket availability induces significant positive effects in “healthy” food demand in the high-income groups. The effect on the “healthy” food purchases by low income population is insignificant. On the other hand, the effects of increased availability on “unhealthy” food consumption are ambiguous for the low-income population.
These findings will help to design appropriate policy interventions to address heterogeneous strata disproportionately affected by inadequate food access.