Can supermarkets coax people into buying healthier food?

Restricting supermarket placement of less healthy items and increasing the availability of healthier alternatives in these stores may be promising interventions to encourage healthier purchasing behaviors. Those are the conclusions of two new studies publishing March 24^th in PLOS Medicine by Carmen Piernas and colleagues of University of Oxford, UK.

Dietary targets for saturated fat, dietary fiber, sugar, and salt intake are currently not being met in the UK. Poor diets are an important risk factor for chronic diseases, and many socioeconomic inequalities remain when it comes to diet. Evidence from systematic reviews has suggested that grocery store interventions may be effective at changing diet, but evidence in real supermarkets has been lacking.

In the first new study, the researchers evaluated six interventions involving the availability, placement, promotions, and signage of healthier products within three major chains of UK grocery stores. They found that increasing the availability of healthier options within a category was associated with significant changes in purchasing. For instance, stocking low-fat chips next to regular chips decreased the sales of regular chips (-23% in intervention stores vs. -4% in control stores, p=0.001). Stocking more lower calorie biscuits increased sales by 18% and decreased purchases of regular, higher calorie biscuits by 4%.

In the second study, Piernas and colleagues evaluated a grocery store intervention to remove seasonal chocolates and candy from prominent locations within a major UK supermarket in the 7 weeks leading up to Easter. In 34 intervention stores, free-standing promotional displays of seasonal chocolate confectionery products were removed, although the candies were available elsewhere in the store. The researchers found an attenuation in the usual seasonal increase in confectionery sales; units of confectionery sales increased by 18% in the control stores during the pre-Easter period but only 5% in the intervention stores (p<0.001). The absolute difference in confectionery sales between control and intervention stores was approximately 21 kilograms per store per week, which translated in fewer total calories in customers baskets.

Together, the papers offer new evidence on how legislation can help shape consumers’ diets with the goal of improving health. “This research has important implications for the development of policies by retailers or governments to bring dietary intakes closer to recommendations for good health,” the authors write. “Strategies aiming at informing customers about healthier options are unlikely to work in isolation.”

Regarding the first study, Piernas adds, “The Government in England has announced new legislation to restrict promotions of foods high in sugars, salt and saturated fat (HFSS) in prominent locations. This project established a partnership with a large UK food retailer to evaluate an intervention to remove seasonal chocolate confectionery from prominent areas of the store, specifically end-of-aisles and entrance areas, over 7 weeks before the Easter period. These results from a ‘real world’ intervention provide promising evidence that the proposed legislation in England to restrict promotions of less healthy items in prominent locations may help reduce over-consumption.” 

Regarding the second study, Piernas adds, “In this multi-retailer partnership, we conducted an independent evaluation of six in-store interventions within three major UK food retailers aimed at improving food purchasing behaviours. We reported that some choice architecture interventions implemented within stores, such as availability and promotions, were associated with short-term changes in food purchasing behaviours. However, the effect of promotions on consumer behaviour may diminish with time and are less likely to be sustainable for retailers over longer time periods.”

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In your coverage, please use this URL to provide access to the freely available papers in PLOS Medicine:

http://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1003951

http://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1003952

Citation 1: Piernas C, Harmer G, Jebb SA (2022) Removing seasonal confectionery from prominent store locations and purchasing behaviour within a major UK supermarket: Evaluation of a nonrandomised controlled intervention study. PLoS Med 19(3): e1003951. https://doi.org/10.1371/journal.pmed.1003951

Citation 2: Piernas C, Harmer G, Jebb SA (2022) Testing availability, positioning, promotions, and signage of healthier food options and purchasing behaviour within major UK supermarkets: Evaluation of 6 nonrandomised controlled intervention studies. PLoS Med 19(3): e1003952. https://doi.org/10.1371/journal.pmed.1003952

Author Countries: United Kingdom

Funding 1: This study received funding from Guy’s and St Thomas’ Foundation (grant EIC181003). GH, CP and SJ are funded by the National Institute of Health Research (NIHR) Applied Research Collaborations Oxford. SJ is a NIHR Senior Investigator funded by the Oxford Biomedical Research Centre. The funders had no role in designing the study, data collection, analysis, interpretation of data, writing the report, or the decision to submit the report for publication.

Funding 2: This study received funding from Guy’s and St Thomas’ Charity (grant EIC181003). GH, CP and SJ are funded by the National Institute of Health Research (NIHR) Applied Research Collaborations Oxford. SJ is a NIHR Senior Investigator funded by the Oxford Biomedical Research Centre. The funders had no role in designing the study, data collection, analysis, interpretation of data, writing the report, or the decision to submit the report for publication.