Critical evaluation of the questionnaires assessing adherence to the Mediterranean diet that are based on servings

Background and aims: The Mediterranean Diet (MD) is characterized by a high intake of vegetables, fruit, legumes, nuts, and olive oil, and moderate fish, dairy, and wine intake. A high adherence to MD has been associated with numerous health benefits, including reduced risk of chronic diseases such as cardiovascular disease, cancer, and type 2 diabetes. The clinical assessment of MD adherence is complicated by the absence of a univocally accepted tool and by the abundance of questionnaires developed to determine adherence, whose reliability and validity is uncertain. In this inter-associative document, we critically evaluated servings-based questionnaires for the assessment of MD adherence, aiming to identify the most valuable tool for the use in clinical practice. Methods and results: For each questionnaire, we analyzed the structure, evidence on health-related outcomes and agreement with the recommendations of MD. We found that most questionnaires do not accurately reflect the principles of MD in terms of the food groups and their optimal consumption frequency. Additionally, the comparison of questionnaires revealed low agreement and some concerns with regard to the scoring assumptions. Conclusions: Among the available questionnaires, we suggest the use of the 15-Items Pyramid based Mediterranean Diet Score (PyrMDS), which is the one with fewer flaws and a strong supporting body of theoretical and scientific evidence. The use of the PyrMDS may facilitate the assessment of MD adherence in clinical practice, which is instrumental in reducing the risk of non-communicable chronic diseases.