A standardised methodological approach for characterising the plant-based component of population or individual diets

Plant-based (PB) diets are associated with good health and environmental sustainability. However, the definition of a PB diet, the prevalence and demographics of those consuming PB diets (or PB foods within an omnivorous diet) and the nutritional role of PB diets is not widely studied. While PB dietary indexes exist and provide information on the associations between PB diets and health outcomes, there remains a need to understand the role of PB foods for nutritional adequacy and status in populations currently accustomed to consuming a primarily omnivorous diet. This study aimed to develop a systematic methodology to identify the PB component of a diet, by using two extremes of PB diet definitions: Plant-Based (all) (PB-A) and Plant-Based (healthful) (PB-H). A novel 23-step protocol based on the best available literature was developed which outlines the (a) exclusion and (b) inclusion criteria under each food group for both PB-A and PB-H diet definitions. It is proposed that this systematic methodology be considered as a standardised approach to improve cross-study comparison and will be useful for researchers, health care professionals, policymakers and the food industry to understand the role of PB foods within the diet of populations or individuals. •A systematic methodology to identify the plant-based (PB) component of diets.•Two extremes of PB diet definitions: ‘all’ (PB-A) and ‘healthful’ (PB-H).•A novel stepwise protocol adaptable to other food consumption databases.•Useful for stakeholders to understand the role of PB foods within the diet.