Methods to Evaluate Adherence to Mediterranean Diet: A Review on Epidemiologic Studies

Background: Mediterranean dietary pattern can have a considerable role in overcoming adverse environmental changes. The purpose of this study was to review the methods that several epidemiologic studies used to evaluate the adherence of different populations to the Mediterranean dietary pattern. Methods: In order to perform this literature review, terms related to Mediterranean diet adherence were searched in PubMed. Published studies until 2011 were considered. Reference lists in identified relevant papers were cross-checked manually to ensure that all relevant papers were identified. Finally, among 105 performed investigations that evaluated different outcomes, 35 papers with different scoring patterns were selected. Findings: The reviewed evaluation methods could be classified into four categories: 1) those based on a positive or negative scoring of the components; 2) those that added or subtracted standardized components; 3) those based on a ratio between components; and 4) a mixed of two or more mentioned methods. In a useful scoring method, energy intake should be adjusted, so the estimations will be independent of the variations present in energy intake. Based on the objectives of the study, confounding variables must be adjusted as well. The scores constructed by quantiles can discriminate better between the variations of intakes within the study population. Moreover, each Mediterranean diet component should be given an appropriate weight in the final score based on its contribution in outcomes of the study. A combined score based on the recommended intakes in Mediterranean diet pyramid, with a penalty for excess intake and considering a weighting factor for energy from non-Mediterranean foods can reflect Mediterranean diet adherence of the population very well. The content validity of this score can be approved against expected nutritional and biochemical biomarkers. Accompanying serum folate levels can be useful as a complementary tool for evaluating Mediterranean diet adherence. Conclusion: A more precise and quantitative definition of the Mediterranean diet is required if the adherence to such a dietary pattern is intended in order to include all aspects of the Mediterranean diet indices. Therefore, typical Mediterranean foods need to be included and the dietary pattern approach needs to be validated using biomarkers. Keywords: Mediterranean diet, Scoring, Dietary patterns