Encouraging healthier choices as side dishes

What happened in this trial?

In this trial, four bagged salad products were shelved above Italian ready meals in 23 stores over a 12-week period between July and October 2021. This shelving space was previously used for dishes in the M&S Italian range such as ultra-thin pizzas. Throughout the trial period, salad items also remained available to purchase from the usual locations in-store.

Using sales data from the retailer for 2 years prior to the intervention, the 12-week intervention period and the 9-months post-intervention, we examined the effect of placing salad items next to ready meals on salad and total fruit and vegetable sales. Interrupted time series analysis was used to quantify changes in store-level daily sales of promoted salads versus a predicted counterfactual. Analysis was repeated in control stores.

What did we find?

During the first three weeks of the intervention, sales of promoted sales increased by 35.74% compared with what was predicted without the intervention. Across the full 12-week period, sales were 18.3% lower than expected. A similar pattern was seen in control stores, suggesting changes were not directly due to the intervention.

Before the intervention, customers fruit and vegetable purchases at this retailer were already broadly aligned with the Eatwell Guide. This suggests that shoppers already had relatively healthy purchase patterns, which may have limited the potential impact of the intervention.