The Opticourses project aims to improve the nutritional quality/price (NQP) ratio of the food purchases of people claiming to be facing financial problems. Following one of the main principles of the French National Nutrition and Health Program (PNNS), the project starts from the principle that to modify food consumption favourably and durably, one must act on both the demand and the supply (see figure). The "demand" part of the project is based on participatory workshops, and the "supply" part relies on intervention of social marketing in shops.

The demand part of the project is based on intervention sessions consisting in five two-hour workshops with about ten participants. The workshops were based on the people's actual purchases and notably on their till receipts. During the five sessions, the receipts were used as intervention tools: participants and research staff discussed the receipts brought in by them all, and exchanged ideas and experiences around food purchasing behaviors.

• First workshop: Opticourses intervention presentation, discussion about grocery shopping strategies, explanation of protocol for receipt collection and annotation, two quiz on nutritional knowledge, food shopping exercise on a catalog;
• Second workshop: discussion about the receipt collection and help to participants encountering difficulties, food groups teaching;
• Third workshop: till receipts delivery by each participant, food with a high nutritional quality for their price teaching;
• Fourth workshop: individual return on the nutritional quality of food purchase on the basis of till receipts analysis, individual objectives to improve the nutritional quality of food purchase at no additional cost, discussion about discount food representations, two quiz on nutritional knowledge, food shopping exercise on a catalog;
• Fifth workshop: assessment of the Opticourses intervention with the participants, discussion about their behavioral modification regarding grocery shopping.

The supply part of the project aims at influencing the supply by means of social marketing. The research team intervenes in two "discount" shops (DIA retailer) in the northern districts in order to influence the food supply. In collaboration with the agency Link Up, a specialist in social marketing, a campaign to promote foods with a good NQP ratio has been launched (from January until June 2014). This public health campaign has the aim of making good NQP foods visible, available and attractive. For 6 months, all the foods with a good NQP ratio in the shop (identified by the research team) are put at the front of the shelves. Consumers can spot them thanks to a logo, "EAT TOP", accompanied by the claim "Nutritious and inexpensive; that's TOP". Good NQP foods are presented with the support of flyers and recipes, simple and accessible to everyone. Also, placing at the head of the gondola and in-store exhibitions are planned around star foods of the month. During the first two months, fish and canned foods will be given the most prominence. Consumers will find in the flyers made available: nutritional information, tips and tricks for cooking them, simple cheap recipes (less than 1€ per person) combining these good NQP foods (sardine rillettes, tuna pâté, etc.) and a TOP selection of good NQP foods available in the store.

Inclusion Criteria:

• living in the northern districts of Marseille
• willingness to be involved in an intervention session aimed at improving the nutritional quality of food purchases under budgetary constraints

Exclusion Criteria:

• none