Development and validation of a multicriteria measure to assess the sustainability characteristics of diets: the Diet Sustainability Score.

PURPOSE: This cross-sectional study aims to develop and validate the Diet Sustainability Score (DSS), a multicriteria measure designed to evaluate the sustainability of diets by integrating nutritional, environmental, economic, and sociocultural dimensions. METHODS: Dietary data from 2287 adults (18 + years) who completed two non-consecutive 24-h dietary recalls during the National Food, Nutrition, and Physical Activity Survey (IAN-AF 2015/2016) were used to assess the psychometric properties of the DSS. Content validity was assessed through expert evaluation. Reproducibility was tested using the intraclass correlation coefficient (ICC), and construct validity was examined by testing conceptually derived hypotheses. RESULTS: The DSS demonstrated robust content validity through expert assessment and alignment with established frameworks. Reproducibility was supported by an ICC of 0.407 and construct validity by confirming 78% of conceptually derived hypotheses. The DSS showed positive associations with females, older ages, higher education, and higher income, as well as healthier lifestyle behaviours, including non-smoking, non-alcohol consumption, greater organic food intake, and less frequent eating out-of-home habits. Participants with higher DSS consumed more vegetables, fruits, fish, white meat, and olive oil and less red and processed meat, sweets, and salty snacks, aligning with Portuguese Mediterranean dietary guidelines. CONCLUSION: The DSS effectively captures the multidimensional nature of sustainable diets, offering a reliable tool for research and policy to promote more sustainable eating practices.