Validity and Reliability Assessments of a 16-item Food Frequency Questionnaire as a Probiotic and Prebiotic Consumption Scale in People Aged 20 to 40 Years in Tehran

Background and Objectives: Regarding health effects of probiotics and prebiotics in prevention and control of diseases and the lack of standard questionnaires in this field in Iran, objective of the present study was to assess validity and reliability of questionnaires designed to assess validity and reliability of probiotics and prebiotics in individuals aged 20–40 years in Tehran, Iran. Materials and Methods: After verifying content validity of the questionnaires by eight experts in fields of nutrition, psychology and psychometrics, face and construct validities (in two levels of exploratory and confirmatory factor analyses) were assessed and then the tool was validated using Cronbachchr('39')s alpha coefficient (due to the multi-value of the response spectra). Results: The sampling adequacy index was higher than 0.7, which was the premise of exploratory analysis. For all the items, the standard loading factor was higher than 0.3, and the T-value was higher than 1.96. Furthermore, fit indices in confirmatory analysis were at the desired levels (0/9 and greater), and validity was verified. Cronbachchr('39')s alpha value was calculated higher than 0.7, and the reliability of the questionnaire was verified. Conclusions: Results of this study showed that the researcher-prepared food frequency questionnaire developed to assess the level of probiotic and prebiotic consumptions, especially in people aged 20–40 years in Tehran, includes significant validity and reliability.