The overall aim of the project VEGANScreener is the prevention and early detection of nutritional deficiencies in the diet of European individuals who have adopted mostly plant-based dietary patterns and particularly in the vegan population. To achieve this goal, we will develop and validate a standardized and brief web- and app-based dietary screening tool to assess and monitor dietary intake among vegans, and we will take first steps towards end-user application. A particular challenge for conducting dietary studies in vegans is the accurate and comprehensive assessment of the consumption of vegan and vegetarian foods, such as plant-based milks, meat alternatives, algae, and calcium-rich mineral water and meat alternatives. These foods are not sufficiently inquired about in FFQs of existing cohort studies, such as the NutriNet Sante, Nurses’ Health Study and UK Biobank. Therefore, extracting vegans from those cohorts would not allow for assessing vegan dietary patterns of today. In order to reach the research aims of the current proposal pertaining to the validation of a novel vegan diet screener, 400 vegans across four European countries (Belgium Czech Republic, Germany, Spain) will be newly recruited. The number of subjects needed for the validation of a diet screener is based on our previous experience. We will, however, make use of existing data already collected among vegans, such as the cohorts available in the Czech Republic and Germany whenever possible, i.e. for developing and pre-testing the diet quality metrics. Further, novel biomarker approaches including metabolomics will be applied to work towards identifying vegan subtypes. Lastly, in a first step towards broader end-user acceptability, digital applications geared toward health care providers (informational and educational website) and the enduser vegans (app to self-assess vegan’s diet quality), will be developed and piloted for acceptability and use.