Diet quality and cardiovascular outcomes : A systematic review and meta-analysis of cohort studies

Aims: To evaluate relationships between diet quality and cardiovascular outcomes. Methods: Six databases were searched for studies published between January 2007 and October 2021. Eligible studies included cohort studies that assessed the relationship between a priori diet quality and cardiovascular disease mortality and morbidity in adults. The Academy of Nutrition and Dietetics Checklist was used to assess the risk of bias. Study characteristics and outcomes were extracted from eligible studies using standardised processes. Data were summarised using risk ratios for cardiovascular disease incidence and mortality with difference compared for highest versus lowest diet quality synthesised in meta-analyses using a random effects model. Results: Of the 4780 studies identified, 159 studies (n = 6 272 676 adults) were included. Meta-analyses identified a significantly lower cardiovascular disease incidence (n = 42 studies, relative risk 0.83, 95% CI 0.82–0.84, p < 0.001) and mortality risk (n = 49 studies, relative risk 0.83, 95% CI 0.82–0.84, p < 0.001) among those with highest versus lowest diet quality. In sensitivity analyses of a high number of pooled studies (≥13 studies) the Mediterranean style diet patterns and adherence to the heart healthy diet guidelines were significantly associated with a risk reduction of 15% and 14% for cardiovascular disease incidence and 17% and 20% for cardiovascular disease mortality respectively (p < 0.05). Conclusions: Higher diet quality is associated with lower incidence and risk of mortality for cardiovascular disease however, significant study heterogeneity was identified for these relationships.