Price and convenience: The influence of supermarkets on consumption of ultra-processed foods and beverages in Brazil.

OBJECTIVE: To evaluate the influence of convenience and price of ultra-processed foods and beverages on purchases at supermarkets.

METHODS: The study used data on food and beverage acquisition for household consumption from the Brazilian Household Budget Survey, performed in a random sample of 55,970 households between 2008 and 2009. Foods and beverages were categorized into four groups, according to characteristics of food processing. Retail stores were grouped into supermarkets and other food stores. Proportion of calories from foods and beverages purchased at supermarkets and other food stores, and respective mean prices (R$/1000 kcal), were calculated according to households' geographical and socioeconomic characteristics. Effect of convenience in household purchases at retail stores was expressed by the acquisition of several food items at the same store. The influence of convenience and prices of ultra-processed products on purchases at supermarkets was analyzed using log-log regression model with estimation of elasticity coefficients.

RESULTS: The mean prices of foods and beverages purchased at supermarkets were 37% lower in comparison to other food stores. The share of ultra-processed foods and beverages in purchases made at supermarkets was 25% higher than at other food stores. An increase of 1% in prices of ultra-processed food items led to a 0.59% reduction in calorie acquisition at supermarkets (R2  = 0.75; p < 0.001). On the other hand, an increase of 1% in the number of food items purchased at supermarkets resulted in 1.83% increase in calorie acquisition of ultra-processed foods and beverages (p < 0.001).

CONCLUSION: Convenience and lower relative prices of food items purchased at supermarkets, in comparison to other food stores, are relevant to explain higher share of purchases of ultra-processed foods and beverages at supermarkets.