Flavonoid intake and coronary mortality in Finland: a cohort study

Abstract

Objective: To study the association between dietary intake of flavonoids and subsequent coronary mortality. Design: A cohort study based on data collected at the Finnish mobile clinic health examination survey from 1967-72 and followed up until 1992. Settings: 30 communities from different parts of Finland. Subjects: 5133 Finnish men and women aged 30-69 years and free from heart disease at baseline. Main outcome measure: Dietary intake of flavonoids, total mortality, and coronary mortality. Results: In women a significant inverse gradient was observed between dietary intake of flavonoids and total and coronary mortality. The relative risks between highest and lowest quarters of flavonoid intake adjusted for age, smoking, serum cholesterol concentration, blood pressure, and body mass index were 0.69 (95% confidence interval 0.53 to 0.90) and 0.54 (0.33 to 0.87) for total and coronary mortality, respectively. The corresponding values for men were 0.76 (0.63 to 0.93) and 0.78 (0.56 to 1.08), respectively. Adjustment for intake of antioxidant vitamins and fatty acids weakened the associations for women; the relative risks for coronary heart disease were 0.73 (0.41 to 1.32) and 0.67 (0.44 to 1.00) in women and men, respectively. Intakes of onions and apples, the main dietary sources of flavonoids, presented similar associations. The relative risks for coronary mortality between highest and lowest quarters of apple intake were 0.57 (0.36 to 0.91) and 0.81 (0.61 to 1.09) for women and men, respectively. The corresponding values for onions were 0.50 (0.30 to 0.82) and 0.74 (0.53 to 1.02), respectively. Conclusion: The results suggest that people with very low intakes of flavonoids have higher risks of coronary disease. Key messages The protective effect of flavonoids was associated with a diet high in intake of apples and onions The effect may be mediated through prevention of oxidation of low density lipoproteins but other mechanisms could be involved Flavonoids offer an explanation for the suggested beneficial effect of fruits and vegetables in coronary heart disease Further studies should concentrate on the effects of various flavonoid compounds and on populations with different intakes