Regional differences in the association of local food environment and sodium intake

Introduction: Sodium intake has been linked to increased risk of hypertension. Although prior studies have shown a link between local food environment and overall diet quality, none have examined sodium. Our study examined the association between food environment and sodium intake. Methods: We assessed sodium intake among adults aged ≥20 years using the National Health and Nutrition Examination Survey (NHANES), 2005-2008. Usual sodium intake was calculated using 24-hour dietary recalls. Food environment was defined by the modified retail food environment index (mRFEI), which measures the number of healthy and unhealthy food retailers within a mile radius of a census tract. Tracts were categorized into quintiles by mRFEI scores, with higher scores indicating more access to healthy food retailers. We tested the association between mRFEI and sodium intake using linear regression. Results: There was statistically significant interaction between mRFEI and region. In the Midwest, sodium intake was 204.8mg lower (p<.05) in quintile 4 (15<mRFEI≤25) compared to quintile 1 (mRFEI=0). In the West, sodium intake was 156.1mg lower in quintile 2 (0<mRFEI≤8) compared to quintile 1 (p=.05). In the Northeast, sodium intake was 259.0mg and 144.5mg higher (p<.05) among those in quintiles 4 and 5 (mRFEI>25) respectively compared to quintile 1. In the South there were no differences in sodium intake by mRFEI. Discussion: These analyses reveal regional differences in the association between the food environment and sodium intake among adults. Interventions targeted at sodium reduction should consider regional variation in the retail food environment and potential links with consumer behavior.