Japanese Intake of Flavonoids and Isoflavonoids from Foods

Abstract

The intake of flavonoids and isoflavonoids was estimated based upon a preliminary database of 40 food items, covering at least 80% of total food consumption. Fifty volunteer women in "I-City" recorded the weight of all dietary intake for 3 days in September 1996, and received a health check-up, as well as laboratory examination. The data was analyzed in relation to the various food factors. Average daily intake per capita of flavonoids was as follows: 4.9 mg kaempferol, 8.3 mg quercetin, 1.5 mg rutin, 0.6 mg myricetin, 0.3 mg luteolin, 0.01 mg myricitrin, 0.4 mg fisetin, and 0.3 mg eriodictyol. Total intake from vegetables and fruits was less than 10 mg 16.2 mg (range: 3.18-35.61 mg) and 23.27 mg (4.62-52.12 mg) of isoflavones, such as daidzein and genistein, respectively, were taken per day, and total isoflavone intake was 39.46 mg (7.80-87.73 mg). Chief component analysis on ingested vitamins, flavonoids and isoflavonoids was carried out. Factor 1 was mainly composed of flavonoids and antioxidant vitamins. Factor 1 was positively associated with age and the level of HDL cholesterol and negatively related to the level of triglycerides. Factor 2, which was mainly composed of isoflavonoids, was positively associated with creatinine and uric acid levels. So far, these factors did not show a significant association with bone density and other health indices, such as BMI and blood pressure.

Dietary soy isoflavone intake in older Japanese American women

“…Because the glycitein content was not available for several of the soy foods we examined, it was not included in our estimation of soy isoflavone intake. This was also consistent with other studies that have estimated dietary soy isoflavone intake in various populations 6,8,10,11,13 . Table 2 summarises the genistein and daidzein contents for each soy food used for this analysis.…”

Intakes and sources of soya foods and isoflavones in a UK population cohort study (EPIC-Norfolk)

“…However, these values are still considerably lower than in Asian populations. Recent studies in Japanese adults have estimated daily isoflavone intakes to be in the range of 30-50 mg (Kimira et al, 1998;Arai et al, 2000;Kikuchi et al, 2001).…”

Soy isoflavone intake inhibits bone resorption and stimulates bone formation in menopausal women: meta-analysis of randomized controlled trials

“…It is well known that the incidence of osteoporosis-related fracture is significantly lower in Southern and Eastern Asian women than in Western women (Ho et al, 1993;Tham et al, 1998). One possible reason for this difference is high intake of phytoestrogens; Asian people consume soy 10-20 times more than Western people (Kimira et al, 1998;Ho et al, 2003). Soy isoflavones comprise mainly genistein, daidzein and glycitein, which have structures similar to that of 17b-estradiol, a potential alternative to HRT (Knight and Eden, 1996).…”