Effectiveness of Mediterranean diet for the primary prevention of cardiovascular diseases: A systematic review and meta-analysis featured in the Italian National Guidelines "La Dieta Mediterranea"

Background: Cardiovascular diseases (CVDs) are among the leading causes of premature mortality in Europe, with unhealthy diets a major contributing factor. The Mediterranean diet (MD), characterized by high intake of plant-based foods and healthy fats, has been associated with reduced cardiovascular risk. This systematic review and meta-analysis aimed to assess the effectiveness of MD in the primary prevention of CVDs. Methods: This review was conducted in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 and Meta-analysis of Observational Studies in Epidemiology guidelines. A comprehensive search of PubMed/MEDLINE, Scopus, Embase, and Cochrane Library was performed up to February 28, 2024. Study quality was assessed using the Newcastle-Ottawa Scale, and the certainty of evidence was evaluated with the NUTRIGRADE approach. Pooled effect sizes were computed using a random-effects model and expressed as risk ratios, hazard ratios (HR), or odds ratios, as appropriate. Results: A total of 87 studies, encompassing over 1.4 million participants, were included. Higher adherence to the MD was consistently associated with a reduced risk of peripheral artery disease (HR-from 0.34 to 0.54), coronary heart disease (HR: 0.95), atrial fibrillation (HR: 0.65), cerebrovascular disease (HR: 0.97), hypertension (HR: 0.97), and CVDs mortality (HR: 0.97). Even a one-point increase in MD adherence score conferred a statistically significant benefit. The strongest evidence emerged from high-quality RCTs, notably the PREDIMED study. Conclusions: The MD is an effective strategy for the primary prevention of CVDs. These findings suggest the importance of adherence to MD and support incorporating MD-based recommendations in national dietary guidelines and public health initiatives.