Association between neighborhood food measures and diet and obesity among California adults

Background: While the neighborhood food environment has been hypothesized to influence dietary intakes and obesity, empirical results from previous research remain inconclusive. Aim: This study examines whether the association between residential neighborhood food measures and dietary intakes among California adults differs by how neighborhood size is defined. Methods: A cross-sectional study is conducted to analyze data of 98,210 adults ages 18 and older from the 2007 and 2009 waves of California Health Interview Survey. Food outlet data are obtained from the 2008 release of InfoUSA. The data are geocoded to latitude/longitude and overlaid over circular buffers with four different radii (0.1, 0.5, 1.0, and 1.5 miles), centered at individuals' homes. Monthly consumption frequencies of fruits, vegetables, sugar-sweetened beverages, fried potatoes, and fast-foods, and body mass index (BMI) are regressed against counts of various types of food outlets, including fast-food restaurants, full service restaurants, convenience stores, small food stores, grocery stores, and large supermarkets within each buffer radius, controlling for individual and neighborhood socio-demographic characteristics. Results: No robust evidence is found to support the hypotheses that proximity to supermarkets, or less exposure to fast-food restaurants or convenience stores improve diet quality or reduce body weight, nor that particular distances are more important. There are isolated significant coefficients, but they are sensitive to model specifications, and lose significance after adjusting for multiple comparisons. Conclusions: Within the range of distances studied (from much smaller to much larger than urban census tracts), we did not find evidence that density or type of food outlets predict diet or BMI. A likely reason is that the vast majority of people have access to motorized transportation, and shopping patterns are no longer related to neighborhoods.