Store-directed price promotions and communications strategies improve healthier food supply and demand: impact results from a randomized controlled, Baltimore City store-intervention trial

OBJECTIVE: Small food store interventions show promise to increase healthy food access in under-resourced areas. However, none have tested the impact of price discounts on healthy food supply and demand. We tested the impact of store-directed price discounts and communications strategies, separately and combined, on the stocking, sales and prices of healthier foods and on storeowner psychosocial factors. DESIGN: Factorial design randomized controlled trial. SETTING: Twenty-four corner stores in low-income neighbourhoods of Baltimore City, MD, USA. SUBJECTS: Stores were randomized to pricing intervention, communications intervention, combined pricing and communications intervention, or control. Stores that received the pricing intervention were given a 10–30 % price discount by wholesalers on selected healthier food items during the 6-month trial. Communications stores received visual and interactive materials to promote healthy items, including signage, taste tests and refrigerators. RESULTS: All interventions showed significantly increased stock of promoted foods v. control. There was a significant treatment effect for daily unit sales of healthy snacks (β=6·4, 95 % CI 0·9, 11·9) and prices of healthy staple foods (β=–0·49, 95 % CI –0·90, –0·03) for the combined group v. control, but not for other intervention groups. There were no significant intervention effects on storeowner psychosocial factors. CONCLUSIONS: All interventions led to increased stock of healthier foods. The combined intervention was effective in increasing sales of healthier snacks, even though discounts on snacks were not passed to the consumer. Experimental research in small stores is needed to understand the mechanisms by which store-directed price promotions can increase healthy food supply and demand.