Dietary intakes of flavonols, flavones and isoflavones by Japanese women and the inverse correlation between quercetin intake and plasma LDL cholesterol concentration

The intake of flavonols, flavones and isoflavones by Japanese women was cal culated from our food-phytochemical composition table. The relationship bet ween intake of these phytochemicals and various anthropometric and blood ch emistry data was analyzed in a cross-sectional study. The subjects were 115 women volunteers, aged 29-78 y, living in the northern part of Japan. Each subject completed a 3-d dietary record and received a health check up, inc luding urine and blood sampling for biochemical analysis. Total mean intake s of flavonoids (sum of flavonols and flavones) and isoflavones were 16.7 a nd 47.2 mg/d, respectively. The major source of flavonoids was onions (45.9 %) and that of isoflavones was tofu (37.0%). Total intake of isoflavones ex ceeded that of other dietary antioxidants, such as flavonoids, carotenoids (3.5 mg/d) and vitamin E (8.2 mg/d), and was approximately one half of the vitamin C intake (109 mg/d). The total intake of flavonoids was inversely c orrelated with the plasma total cholesterol concentration (TC) (r = -0.236, P < 0.05) and plasma LDL cholesterol concentration (LDL-C) (r = -0.220, P < 0.05), after the adjustment for age, body mass index and total energy int ake. As a single component, quercetin was inversely correlated with both TC (r = -0.261, P < 0.01) and LDL-C (r = -0.263, P < 0.01). Among Japanese, f lavonoid and isoflavone intake is the main component among nonnutrient phyt ochemicals with antioxidant potential in the diet. These results suggest th at a high consumption of both flavonoids and isoflavones by Japanese women may contribute to their low incidence of coronary heart disease compared wi th women in other countries.