Abstract
Introduction : Although recent evidence suggests that regular consumption of soybean is useful for preferable bone health, the optimal amounts of soybean needed are not yet clear. This cross-sectional study attempts to propose the optimal amount for postmenopausal women to prevent osteoporosis in consideration of the upper limitation of daily soy isoflavone intake (74mg, corresponding to 52.7-gram soybean) presented by Food Safety Commission of Japan in 2006.
Methods : The 50-year-old or older women whose bone mineral density (BMD) was measured at our clinic were selected. After exclusion of those who have moved on, those who were dead or demented, those who have long history of corticosteroid administration, ex-smokers, inadequate reporter on soybean consumption and excessive soybean eaters, 50 postmenopausal women were eligible in the study. Under the conditions that the hypothetic thresholds for quantity of soybean intake needed are 20, 25 and 30 grams, the correlation between exposure and the rate of sufficient-bone-mineral-density group was investigated respectively.
Results : The bone was healthier significantly in the groups consuming 30 grams or more soybean (p<0.01). The threshold of 20 or 25 grams didn't show a significant bone-sparing effect in the exposure groups.
Conclusion : The optimal amount of daily soybean needed to support bone health is suggested to be 30 grams or more, not exceeding the upper limitation of 52.7 grams.
