... Different approaches were used to categorize followers of plant-based diets in observational studies. For instance, studies asked participants to self-identify their dietary pattern (22,24,27,29,30,34,35,38,41,46,47,49,50,53,55,56,61,64,(85)(86)(87)(88)(89), to indicate the animal-based foods that they consumed or avoided (32,39,40,45,51,52,62,84,90,91), or to complete a questionnaire about their frequency of meat consumption (26,60,65,92,93). Other studies applied a combination of the above (25,28,33,36,37,43,44,54,57,59,79,82,94). ...