Table 1.

Overview of implemented supermarket interventions in the Supreme Nudge trial

Intervention strategies	Components	Explanation of intervention	Targeted product groups	Static or dynamic
Placement nudges	Healthy shelf layout	Healthy products placed at eye level	Shelves including pasta and rice products, bread substitutes, and breakfast cereals	Static
	Healthy checkout	One check-out till presenting only healthy products	Sugar-free beverages, nuts, snack vegetables, dried fruits, whole-grain crackers, instead of confectionery products	Static
	Healthy end of aisle	Promoting only healthy products on a prominent end of aisle; monthly product switch	Whole-grain products, oils, canned fish/legumes/ tomatoes, nuts, natural peanut butter, sugar-free beverages	Dynamic
	Healthy aisle baskets	Three to four aisle baskets filled with healthy products; monthly product switch	Nuts, canned fish/legumes/tomatoes, whole-grain products	Dynamic
Property nudges	Shelf-labels	Symbols which highlighted the product’s tastiness (smiley symbol), convenience (stopwatch symbol indicating ease of preparation) or popularity (thumbs-up symbol)	All healthy products across a range of food groups (i.e. vegetables, fruits, all whole-grain products, fish, milk and yogurt, cheese, legumes, butters and oils, nuts, sugar-free bottled beverages, and tea)	Static
	Shelf feedback strips	Positive feedback strip with popularity symbol	Underneath whole-grain bread, fresh fish and snack vegetables	Static
	Shelf-stoppers	Shelf cards highlight one healthy product per product group; monthly product switch	At each shelf including the shelf-labels	Dynamic
	Healthy suggestions shelf-banners	Seasonal shelf-banners suggesting different healthy product combinations using the convenience symbol	Whole-grains, legumes and bread substitutes	Static
	Explanation of nudging symbols	The symbols are introduced on the shopping cart handles, and also shown on shopping cart/baskets boards and the checkout divider bars	N/A	Static
Pricing strategies	Price reductions	Price reductions were − 25% or − 10% when combined with price increases in the same food group; three-weekly product switch	Healthy product groups: vegetables, fruit, whole-grain products, fresh fish, low and medium-fat dairy, low-salt legumes, butters and oils with unsaturated fats, unsalted nuts, sugar-free beverages	Dynamic
	Price increases	Price increases were + 15%; three-weekly product switch	Unhealthy product groups: non-whole-grain products, processed/salted fish, high fat and sugary dairy, high-salt legumes, butters and oils with saturated fats, salted nuts, sugary beverages	Dynamic

Static Intervention targeting the same food group(s) for the complete trial period, Dynamic Interventions altered over targeted products or food group(s) during the trial period. N/A Not applicable