Impact of Different Front-of-pack Nutrition Labels on Consumer Purchasing Intentions: Randomized Trial in the NutriNet-Santé Study

The purpose of this interventional study is to compare the impact of four different Front-Of-Pack (FOP) nutrition labels on purchasing intentions. This study is nested in the ongoing web-based prospective observational NutriNet-Santé cohort study, including on December 2014 around 150,000 participants. The investigators will perform a five-arm randomized trial where participants will be subjected to different FOP nutrition label formats: Guidelines Daily Amount (GDA), Multiple Traffic Lights (MTL), 5-Color Nutrition Label (5-CNL), Green Tick (Tick) and a 'no label' condition. The impact of front-of-pack nutrition labels on the nutritional quality of the shopping cart will be assessed. Participants from the NutriNet-Santé cohort study will be randomly assigned to one of these five experimental conditions according to their sociodemographic characteristics.

Purchasing intentions will be assessed using an experimental web-based supermarket designed to look like a regular online grocery store. The supermarket includes 269 unique products divided into 4 categories: dairy products, processed meat/delicatessen, savory and breakfast/sugary products. Each category is then separated into specific products families like yogurt, milk, cheese, etc. for the dairy products category. Inside a food family, the selection of foodstuffs will be made to obtain a representative sample of the products commonly sold in French supermarket. For each type of products, at least two variants are proposed. Products are retailers or manufacturers branded. Categories of products that are not usually bought each week, or which are likely to be bought from different sources are not included on the web-based supermarket.

Participants are asked to simulate a shopping situation: they have to select a week worth of food for their family among proposed products. If the user is not able to find a product he/she usually buy, the instruction is to select similar product among proposed ones.

Information provided for each product is: name, price and the picture with the FOP label/or not according to the experimental condition to which the participant is allocated. A brief explanation of the FOP label used is also given.