Why people follow a gluten-free diet? An application of health behaviour models

Purpose: To understand factors affecting adherence to GFD by celiac and non-celiac people through the application of behavioural theories, Integrative Model (IM) and Multi Theory Model (MTM). Methods: Analyses were conducted for a sample of 308 subjects, majority females, celiac and non-celiac. Adherence to GFD was measured considering two scales, self-declared adherence and scored adherence, in order to discern possible inconsistencies between what subjects believe and what they really do. Subsequently, adherence to GFD was modelled by considering constructs of MTM and IM. Moreover, the constructs were designed based on literature review. Ordered logit (OL) model was used to test the IM and MTM theoretical models. Results: The findings show that adherence to GFD is affected mainly by attitudes towards GFD, self-efficacy, injunctive norms, knowledge about GFD and perceptions that GF products are expensive. Between the two models, IM and MTM, results show that all constructs of IM explain the behavior. Contrary, for MTM, results indicate only some constructs of the MTM explain adherence to GFD. Conclusions: Results of this study should be considered for improving the adherence to GFD for celiac people. Furthermore, it is important to consider the non-celiac people’s perceptions for GFD and GF products. In other words an accurate information about the diet and products it is relevant for supporting people to make healthier food choices. Finally, as the results show, IM explain adherence to GFD better than MTM.