Barriers and Facilitators Associated with the Adoption of and Adherence to a Mediterranean Style Diet in Adults: A Systematic Review of Published Observational and Qualitative Studies

The Mediterranean diet (MedDiet) has been linked with physical and mental health benefits. Previous research, however, suggests that adoption and adherence to a Mediterranean diet might be difficult for people who live outside of the Mediterranean region. The aim of this systematic review was to investigate the factors that influence adoption and adherence to a Mediterranean style diet in adults aged 18 years old and over, as identified in published observational and qualitative studies. Following registration of our protocol on PROSPERO (ID: CRD42018116515), observational and qualitative studies of adults' perceptions and experiences relevant to following a Mediterranean style diet were identified using systematic searches of databases: MEDLINE, the Cochane Library, CINAHL, Web of Science and Scopus, over all years of records until February 2022. A narrative synthesis was then undertaken. Of 4559 retrieved articles, 18 studies fulfilled our inclusion criteria and were included. Factors influencing adoption and adherence to a MedDiet were identified and categorized as: financial, cognitive, socio-cultural, motivational, lifestyle, accessibility & availability, sensory & hedonic and demographic. Similar barriers and facilitators are often reported in relation to healthy eating or the consumption of specific healthy foods, with a few exceptions. These exceptions detailed concerns with specific components of the MedDiet; considerations due to culture and traditions, and concerns over a cooler climate. Suggestions for overcoming these barriers and facilitators specific to adoption and adherence to the Mediterranean diet are offered. These data will inform the development of future studies of robust methodology in eating behaviour change which offer pragmatic approaches for people to consume and maintain healthy diets.