The Individual Association Between Food Store Types and Body Mass Index in Los Angeles County

Using the Los Angeles Family and Neighborhood Survey (L.A. FANS), detailed individual-level data on shopping location, store name, and body mass index are analyzed to assess relationships between body mass index and food store types. The analysis groups similar store brands to create unique food store types, providing finer discrimination than industrial classification or annual sales volume. Seven food store types are created: English-language major supermarket chains, discount food stores with "less", "save", or "bargain" in the name, Spanish-language name supermarkets or grocery stores, specialty stores defined as having fewer locations, smaller format, specific product focus, and/or limited product inventory, and independent, small, and bulk food stores. Documentation within the dataset of shopping locations, home locations, and car ownership allow strict control for distance and transportation. Accounting for these and other individual and neighborhood characteristics using multivariate regression models, body mass index is significantly lower in people who shop in specialty and Spanish-language name food store types compared to major chain food store types in higher poverty neighborhoods. Additional analysis indicates that reported supermarket shopping rates are higher than expected based on the prevalence of supermarkets in home Census tracts. Absence of neighborhood supermarkets (in home Census tracts) is a common state among respondents across all poverty strata, although more common in very poor tracts. In a subgroup of non-movers over a six-year period, opening and closing of stores is associated with change in shopped store type. Because the main results are cross-sectional, causal inference is difficult. Store types may influence body mass index, or individuals may have unobserved characteristics, which explain the association between store types and body mass index. Further research is needed to assess the direction of association. However, these results suggest specific store types should be the focus of policy and research rather than broader categories defined by sales volume or industrial classification. Absence of supermarkets may be an insufficient tool to characterize shopping behavior. Store opening and closing may stimulate change in store type preferences, but whether this change in store type is associated with change in health behaviors or health outcomes is unknown