Mediterranean diet and its components in relation to all-cause mortality: meta-analysis

The beneficial association of the Mediterranean diet (MedDiet) with longevity has been consistently demonstrated, but the associations of MedDiet components have not been accordingly evaluated. We performed an updated meta-analysis of prospective cohort studies published up to 31 December 2017, to quantify the association of adherence to MedDiet, expressed as an index/score (MDS) and of its components with all-cause mortality. We estimated summary relative risks (SRR) and 95% CI using random effects models. On the basis of thirty studies (225 600 deaths), SRR for the study-specific highest/lowest and per 1SD MDS increment were 0.79 (95% CI 0.77, 0.81, I-2 = 42%, P-heterogeneity 0.02) and 0.92 (95% CI 0.90, 0.94, I-2 56%, P-heterogeneity <0.01), respectively. Inversely, statistically significant associations were evident in stratified analyses by country, MDS range and publication year, with some evidence for heterogeneity across countries overall (P-heterogeneity 0.011), as well as across European countries (P = 0.018). Regarding MDS components, relatively stronger and statistically significant inverse associations were highlighted for moderate/none-excessive alcohol consumption (0.86, 95% CI 0.77, 0.97) and for above/below-the-median consumptions of fruit (0.88, 95% CI 0.83, 0.94) and vegetables (0.94, 95% CI 0.89, 0.98), whereas a positive association was apparent for above/below-the-median intake of meat (1.07, 95% CI 1.01, 1.13). Our meta-analyses confirm the inverse association of MedDiet with mortality and highlight the dietary components that influence mostly this association. Our results are important for better understanding the role of MedDiet in health and proposing dietary changes to effectively increase adherence to this healthy dietary pattern.