Measuring Micro-Level Effects of a New Supermarket: Do Residents Within 0.5 Mile Have Improved Dietary Behaviors?

BACKGROUND: Local and national policies to encourage supermarket opening or expansion are popular strategies for improving access to healthy food for residents in neighborhoods lacking these types of stores, yet few evaluations of such initiatives exist.

OBJECTIVE: Our aim was to test whether a newly opened supermarket in the Bronx, NY, changed household availability of healthy and unhealthy food items and reported daily consumption of these items among respondents residing in close proximity (≤0.5 mile) to the new supermarket.

DESIGN: This quasi-experimental study evaluated changes in purchasing and consumption habits of residents within 0.5 mile of the new supermarket as compared to residents living more than 0.5 mile from the supermarket. Data were collected through street intercept surveys at three different times: once before the store opened (March to August 2011) and in two follow-up periods (1 to 5 months and 13 to 17 months after the store opened). This study analyzed a subset of successfully geocoded resident intersections from the larger study.

PARTICIPANTS/SETTING: We surveyed 3,998 residents older than the age of 18 years in two Bronx neighborhoods about their food-purchasing behaviors before the store opened and in two follow-up periods. Responses from residents whose intersections were successfully geocoded (N=3,378) were analyzed to examine the consumption and purchasing behaviors of those in close proximity to the new store.

INTERVENTION: A new supermarket opened in a low-access neighborhood in the Bronx with the help of financial incentives through New York City's Food Retail Expansion to Support Health (FRESH) program.

MAIN OUTCOME MEASURES: The primary outcome evaluated was the change in percent of respondents reporting that the following food items were "always available" in the home: milk, fruit juice, soda, pastries, packaged snacks, fruits, and vegetables. As a secondary outcome, we explored changes in self-reported daily servings of these items.

STATISTICAL ANALYSIS PERFORMED: A difference-in-difference analysis was performed, controlling for age, education, marital status, income, sex, race, and ethnicity.

RESULTS: Residents within 0.5 mile of the store had increased household availability of both healthy and unhealthy foods. After the introduction of the supermarket, the percent of residents in close proximity to the store who reported always having produce available in the home increased by 8.8% compared to those living >0.5 mile from the store in the first post-period and by 10.6% compared to those living >0.5 mile from the store in the second post-period. A similar positive increase in household availability of salty snacks and pastries was observed. Residents living in close proximity also reported greater consumption of healthy foods like produce and water, and lower intake of soft drinks and pastries.

CONCLUSIONS: Given the financial support at the national and local levels to encourage supermarket development and expansion in high-need communities, it is imperative to evaluate the impact of such initiatives. Although the findings have so far been equivocal, our findings give weight to the argument that, at a micro-level, the siting of a new supermarket can indeed impact local purchasing and consumption behavior. Although purchasing for both healthy and unhealthy food items increased, reported consumption showed an increase in servings of healthy items (water, vegetables, and fruit) and a decrease in servings of unhealthy foods (soft drinks, salty snacks, and pastries).