The SALSA Questionnaire: creation and validation of a tool to assess people’s self-perceived barriers and facilitators to follow a sustainable and healthy diet

A transition towards sustainable and healthy diet(SHD) is crucial for both population and planetary health. However, changing consumer’s behaviour is challenging due to the many factors influencing food choices. Tools that comprehensively assess these factors are paramount, yet none are available in Spain. Hence, we created and validated the SALSA questionnaire to capture self-perceived barriers and facilitators for SHD. The process involved three phases: First, item development combining insights from a scoping review and content validity with experts(n = 9) and the target population(n = 38); Second, scale development by pre-testing the questionnaire(n = 4), administering it through an online survey to two samples(Dimensionality-Sample, n = 516; Reliability-Sample, n = 61), and applying exploratory factor analysis for factors extraction and item reduction; Third, scale evaluation by testing its dimensionality through confirmatory factor analysis, its reliability through Cronbach’s alpha and McDonald’s omega, and intra-class correlation coefficient, and construct validity through discriminant validity, convergent validity, and correlation analysis. Results yielded a questionnaire with 27 items grouped into four dimensions: personal factors, sociocultural factors, external factors, and meat and plant-based meat alternatives. The psychometric analysis revealed that the SALSA questionnaire is a reliable instrument to identify behavioural determinants.