Introduction. Both socioeconomic status and supermarket choice have been associated with diet quality. This study aimed to assess the contributions of: (1) supermarket choice and (2) shopping behaviors to (a) the healthfulness of purchases and (b) social patterning in purchases.

Methods. Observational panel data on purchases of fruit and vegetables and less healthy foods/beverages from 2010 were obtained for 24,879 households, stratified by occupational social class (analyzed 2014). Households’ supermarket choice was determined by whether they ever visited market-defined high-price and/or low-price supermarkets. Analyses also explored extent of use within supermarket choice groups. Shopping behaviors included trip frequency, trip size, and number of store chains visited.

Results. Households using low-price (and not high-price) supermarkets purchased significantly lower percentages of energy from fruit and vegetables and higher percentages of energy from less healthy foods/beverages than households using high-price (and not low-price) supermarkets. When controlling for socioeconomic status and shopping behaviors, the effect of supermarket choice was largely maintained for fruit and vegetables, but reduced for less healthy foods/beverages. The extent of use of low- or high-price supermarkets had limited effects on outcomes. More frequent trips and fewer small trips were associated with healthier purchasing for both outcomes, while visiting more store chains was associated with higher percentages of energy from fruit and vegetables.

Conclusions. While both supermarket choice and shopping behaviors influence healthfulness of purchases, neither appeared to contribute to socioeconomic differences. Moreover, differences between supermarket environments may not be primary drivers of the influence of supermarket choice.