Mediterranean diet and health status: an updated meta-analysis and a proposal for a literature-based adherence score

Objective: To update previous meta-analyses of cohort studies that investigated the association between the Mediterranean diet and health status and to utilize data coming from all of the cohort studies for proposing a literature-based adherence score to the Mediterranean diet. Design: We conducted a comprehensive literature search through all electronic databases up to June 2013. Setting: Cohort prospective studies investigating adherence to the Mediterranean diet and health outcomes. Cut-off values of food groups used to compute the adherence score were obtained. Subjects: The updated search was performed in an overall population of 4 172 412 subjects, with eighteen recent studies that were not present in the previous meta-analyses. Results: A 2-point increase in adherence score to the Mediterranean diet was reported to determine an 8% reduction of overall mortality (relative risk (0.92; 95% CI 0.91, 0.93), a 10% reduced risk of CVD (relative risk (0.90; 95% CI 0.87, 0.92) and a 4% reduction of neoplastic disease (relative risk (0.96; 95% CI 0.95, 0.97). We utilized data coming from all cohort studies available in the literature for proposing a literature-based adherence score. Such a score ranges from 0 (minimal adherence) to 18 (maximal adherence) points and includes three different categories of consumption for each food group composing the Mediterranean diet. Conclusions: The Mediterranean diet was found to be a healthy dietary pattern in terms of morbidity and mortality. By using data from the cohort studies we proposed a literature-based adherence score that can represent an easy tool for the estimation of adherence to the Mediterranean diet also at the individual level.