SOYBEAN DIET AND BREAST DENSITY

本子项目是利用由NIH/NCRR资助的中心赠款提供的资源的众多研究子项目之一。子项目和研究者（PI）可能已经从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。列出的机构是中心的，不一定是研究者的机构。食用大量大豆的人群，如在许多亚洲国家，卵巢激素水平较低，乳腺癌发病率较低，与食用典型西方饮食的人群相比，乳房x光检查密度也较低。我们发现大豆喂养有利于降低绝经前妇女卵巢激素25-45%。我们建议检验这样一种假设，即食用大豆会降低卵巢类固醇激素（雌二醇、雌酮、硫酸盐和黄体酮），并导致乳腺密度相应降低，而这些效果可以通过不含异黄酮的大豆饮食来实现。目的1确定饮食中添加不含异黄酮的大豆对卵巢激素水平和乳腺密度的影响。目的2评估这种干预的安全性。这些目标将通过一项随机双盲研究进行验证，该研究分为两组，每组100名绝经前妇女。具有50%乳腺致密组织的绝经前妇女将被随机分配，每天服用不含异黄酮的豆浆（治疗）或牛奶（安慰剂）作为膳食补充剂，持续2年。将对两组患者在饮食干预前、干预期间和干预后2年的卵巢类固醇、激素和乳腺密度的比较水平进行评估。降低乳腺密度可以通过两种机制降低乳腺癌风险，即减少癌症发展风险的靶组织的体积和提高乳房x光检查对早期筛查发现的敏感性。长期目标是确定大豆是否可以作为第二种乳腺癌的替代和补充预防措施。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Populations consuming high levels of soy, as in many Asian countries, have lower levels of ovarian hormones, lower rates of breast cancer, and reduced mammographic density than populations consuming typical Western diets. We found that soy feeding favorably lowered ovarian hormones by 25-45% in premenopausal women. We propose to test the hypothesis that consumption of soya reduces ovarian steroid hormones (estradiol, estrone, sulfate, and progesterone) and results in a corresponding reduction in breast density and that these effects can be achieved with a soy diet that does not contain isoflavones. Aim 1 determines the effects of a diet supplemented with isoflavone-free soy on ovarian hormone levels and breast density. Aim 2 assesses the safety of this intervention. The aims will be tested by conducting a randomized, double-blind study, with two arms and 100 premenopausal women in each arm. Premenopausal women with 50% of dense breast tissue will be randomly allocated to take soymilk without isoflavones (treatment) or cow milk (placebo) as dietary supplements daily for 2 years. The comparative levels of ovarian steroids, hormones and breast density will be assessed before, during and after 2 years of dietary interventions in both groups. Reducing breast density can be expected to reduce breast cancer risk by two mechanisms, i.e., reducing the volume of target tissue at risk for cancer development and improving the sensitivity of mammography for early screening detection. A long-term objective is to determine if soy can be an alternative and complementary preventive measure for a second breast cancer.