Discussion
TRANSITION
For the first time, the effectiveness of traffic-light front-of-pack environmental labelling was tested in a randomised controlled trial conducted in a virtual reality supermarket, including a large and diverse range of food products. We demonstrated that the environmental label significantly reduced the environmental impact of food choices at no nutritional, financial or hedonic cost. In the present study, we developed a cross-category environmental label which has been highlighted as a promising tool to substantially reduce the environmental impact of diets [As discussed in a recent review on the effect of environmental labels and based on the COM-B (Capacity Opportunity Motivation Behaviour) framework for understanding behaviour [Application of the COM-B framework to a cross-category traffic-light front-of-pack environmental labelIn the context of a national experimentation phase of environmental labelling in the food sector (2020–2021) coordinated by the French Agency for Ecological Transition (ADEME), the results of the present study contributed to inform the development and future implementation of an environmental labelling system for all food products in France. Numerous stakeholders and experts contributed to this experimentation phase providing guidelines on six aspects 1/ environmental issues that should be considered, 2/ objectives that should be targeted, 3/ data that are needed, 4/ methods for assessing environmental impacts, 5/ environmental scores that should be chosen, 6/ label format that should be proposed [