distance to supermarkets as well as other store types. Collectively, these results indicate an association between high-deprivation neighborhoods and both low access and limited transportation to supermarkets in a rural area.

In response to a request from Congress, USDA conducted a comprehensive 1-year study to assess the impact of limited access to food on local populations and outline recommendations for addressing the problem (Ver Ploeg et al., 2009). The study included two conferences on food deserts and a set of commissioned studies carried out in cooperation with the National Poverty Center at the University of Michigan, as well as reviews of the existing literature, a national-level assessment of access to supermarkets and large grocery stores, analysis of the economic and public health effects of limited access, and a discussion of existing policy interventions. Table 4-5 shows the study findings on access to supermarkets according to individual factors of low-income and underserved population groups in the United States. Data in the table indicate that the median distance to a supermarket for low-income, minority, and elderly populations is comparable to that for higher-income populations. However, as data in Table 4-6 indicate, the percentage of households without a vehicle is higher in low-income areas. For example, 2.5 to 3.3 percent of urban and 7.4 percent of rural low-income households live more than a mile from a supermarket and lack access to a vehicle. Research has shown that inadequate transportation is a significant barrier to access to supermarkets for residents of economically disadvantaged African American neighborhoods (Zenk et al., 2005).

Impact of Disparities in Access on Health Outcomes

The committee identified a number of studies examining associations between disparities in access to healthy foods and food insecurity, obesity, and obesity-related chronic disease. On the whole, the evidence supports a positive relationship between food insecurity and risk for obesity that is strongest among women (Dinour et al., 2007; Frongillo et al., 1997; Jilcott et al., 2011; Jones and Frongillo, 2006; Larson and Story, 2011; Velasquez-Melendez et al., 2011) and stronger among African American and Hispanic groups than whites (Fitzgerald et al., 2011; Sharkey and Schoenberg, 2005). The evidence reviewed was inconsistent as to significant associations between food insecurity and obesity in children (IOM, 2011).

A review of 54 studies examining associations between neighborhood differences in access to healthy food and risk for obesity identified an association between better access to convenience stores and higher risk for obesity (Larson et al., 2009). An observational study that analyzed data collected from a telephone survey found increased odds of obesity associated with distance to a supermarket in metropolitan but not in nonmetropolitan areas (Michimi and Wimberly, 2010). In contrast, another analysis of data



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