To switch or not to switch? Examining the complexity of store choice when a new supermarket opens

Background. Improving access to healthy foods in underserved areas is the cornerstone of US policies designed to change diet behavior and reduce obesity. The assumption is that by increasing the number of supermarkets in underserved neighborhoods access to healthier foods is improved, and this will lead to diet change and better health outcomes. However, critical gaps exist in the measurement of neighborhood food environments and our understanding of store-switching behavior.

Methods.We use data from the Neighborhood Food, Diet and Health Intervention Study (Philadelphia) on store patronage and journeys to the stores. The addresses of the participants (Follow-up=651) and the main food stores used were geocoded using GIS. We examine the associations between diet and switching behavior.

Results. Neighborhood resident identified numerous primary food stores, with average distance from home exceeding 3km. Over 60% of participants in the intervention site switched stores, with less than half switching to the new store. Those switching to the new store were more likely to live closest to it (a distance decay effect). Switching stores occurred in approximately 50% of participants in the control site.

Conclusions. Store patronage is complex, and store switching common. On average participants traveled outside their local neighborhood to their main grocery store. Adding a new store led to some store switching; especially among those living closest to the site. Neighborhood residents also switched between existing stores but a third did not switch store.  Understanding switching and non-switching behavior is important and has implications for policy recommendations targeting food access and diet behavior.