The healthy food marketing strategies study: design, baseline characteristics, and supermarket compliance.

Identifying effective strategies to promote healthy eating and reduce obesity is a priority in the USA, especially among low-income and minority groups, who often have less access to healthy food and higher rates of obesity. Efforts to improve food access have led to more supermarkets in low-income, ethnically diverse neighborhoods. However, this alone may not be enough to reduce food insecurity and improve residents' diet quality and health. This paper summarizes the design, methods, baseline findings, and supermarket in-store marketing strategy compliance for a randomized trial of the impact of healthy food marketing on the purchase of healthier "target" food items. Thirty-three supermarkets in low-income, high-minority neighborhoods in the metropolitan Philadelphia area were matched on store size and percentage of sales from government food assistance programs and randomly assigned to the intervention or control group. Healthy marketing strategies, including increased availability of healthier "target" products, prime shelf-placement and call-out promotion signs, and reduced availability of regular "comparison" products, were implemented in 16 intervention stores for an 18 month period for over 100 individual food items. Six product categories were studied: bread, checkout cooler beverages, cheese, frozen dinners, milk, and salty snacks. The primary outcome measure was weekly sales per store in each product category for 1 year preintervention and 18 months during the intervention. Compliance with the marketing strategies was assessed twice per month for the first 6 months and once a month thereafter. Store and neighborhood characteristics were not significantly different between control and intervention stores. Intercept surveys with customers to assess shopping habits and grocery marketing environment assessments to examine the food promotion environment were completed in the same six food categories. In intercept surveys, 51.0% of shoppers self-identified as overweight and 60.6% wanted to change their weight. Shoppers who typically purchased one type of food over another commonly did so out of habit or because the item was on sale. Findings revealed that preintervention sales of healthier "target" or regular "comparison" items did not differ between intervention and control stores for 1 year prior to intervention implementation. Rates of compliance with the healthy marketing strategies were high, averaging 76.5% over the first 12 months in all 16 stores. If healthy in-store marketing interventions are effective in this scaled-up, longer-term study, they should be translated into wider use in community supermarkets.