Development of a food frequency questionnaire to monitor protein intake in Flanders, Belgium

BACKGROUND: To improve planetary and dietary health, the Flemish government adopted the ‘Green Deal Protein Shift on our plate’ policy which aims to reverse the ratio between animal-based and plant-based protein-rich products in our diet to 40/60 by 2030. The Green Deal provides a platform for actions that unites players from across the food system. To guide the development of actions and assess their effectiveness it is crucial to closely monitor the protein consumption of the population. METHODS: We developed a semi-quantitative Food Frequency Questionnaire (FFQ) to be self-completed annually (2023-2030) by a representative sample of 1000 adults (18-65 years). The food list of the FFQ was developed using a stepwise approach based on the Belgian food consumption survey 2014, selecting the 90% most contributing foods to protein intake. New foods retrieved from a market research and expected innovations were added. Similar foods were combined into survey items, and portion size questions added. Protein intake was estimated using the weighted mean protein intake of the 90% most consumed foods represented in each item. A content validation study was performed to assess question comprehension, food identification and quantification. Results will allow to estimate average protein intake and evolution of protein sources over time. RESULTS: The FFQ includes 60 food items. The average completion time was 16 minutes. The content validation let to re-ordering of food items and reformulation of portion descriptions. CONCLUSIONS: The newly developed FFQ will strengthen the Flemish public health surveillance system: monitoring protein intake and the ratio of animal-based versus plant-based and alternative protein will allow to guide actions and track progress towards policy objectives of the ‘Green Deal Protein Shift on our plate'. KEY MESSAGES: • This study highlights the role of public health surveillance systems in monitoring new policy actions and progress towards policy objectives. • This study highlights the development of rapid screening tools using a database approach and market research data.