Effect of the Mediterranean diet on incidence of heart failure in European countries: a systematic review and meta-analysis of cohort studies

Introduction: Heart failure (HF) is one of the most common cardiovascular disorders, and its prevalence is increased due to age, genetics, and lifestyle factors. Emerging evidence suggests that the Mediterranean Diet (Med Diet) is linked to lower all-cause mortality in patients with increased cardiovascular disease risk, such as those with HF. Objective: To conduct a systematic review and meta-analysis of observational studies into the relationship between the Med Diet on HF risk. Design: Several databases (PubMed, Scopus, Web of Science and Cochrane Library) until the 01^st of May 2023 were searched. Our research was conducted based on the updated 2020 Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Data were reported as risk ratios (RRs) with their 95% confidence intervals (CIs) as results of multivariate or univariate analyses. Results: From the original 1206 studies collected, six observational prospective studies were included, with a total of 216,385 European participants without evidence of HF at baseline. Over a mean period of 11 years of follow-up, a 1-point increase in the Med Diet score was associated with a significantly lower risk of HF (RR = 0.940; 95% CI: 0.912–0.969, p < 0.0001; I² = 42.9%). Categorised by sex, a higher adherence to Med Diet was associated with a significantly lower incidence of HF in women (RR = 0.942; 95% CI: 0.912-0.973, p = 0.001; I² = 41.8%), but not in men. The overall quality of included studies was good. Conclusions: Higher adherence to Med Diet across European countries is associated with lower risk of HF, particularly in women.