Intake of specific flavonoids and risk of acute myocardial infarction in Italy

Objective: As intake of flavonoids has been associated with reduced risk of coronary heart disease but data on the relation with specific classes of flavonoids are scarce, we assessed the relation between dietary intake of specific classes of flavonoids and the risk of acute myocardial infarction (AMI) in an Italian population. Design: Case-control study. Dietary information was collected by interviewers on a questionnaire tested for validity and reproducibility. Adjusted odds ratios (OR) and 95% confidence intervals (CI) were obtained by multiple logistic regression models including terms for energy and alcohol intake, as well as sociodemographic factors, tobacco and other major recognised risk factors for AMI. Setting: Milan, Italy, between 1995 and 2003. Subjects: Cases were 760 patients, below age 79 years, with a first episode of nonfatal AMI, and controls were 682 patients admitted to hospital for acute conditions unrelated to diet. Results: A reduced risk of AMI was found for increasing intake of anthocyanidins (OR = 0.45, 95% CI 0.26-0.78 for the highest vs. the lowest quintile, P_trend = 0.003) and flavonols (OR = 0.65, 95% CI 0.41-1.02, P_trend = 0.02). A tendency towards reduced risks, although not significant, was observed for flavan-3-ols (OR = 0.73, 95% CI 0.48-1.10) and total flavonoids (OR = 0.74, 95% CI 0.49-1.14). No meaningful heterogeneity was found between the sexes. No association emerged for other flavonoids, including isoflavones, flavanones and flavones. Conclusions: High intake of anthocyanidins reduced the risk of AMI even after allowance for alcohol, fruit and vegetables, supporting a real inverse association between this class of flavonoids and AMI risk.