Isoflavones, equol producing status, and breast density in US Chinese women

描述（申请人提供）：异黄酮，主要存在于大豆食品中的植物雌激素，被认为可以预防乳腺癌，但这种作用的流行病学证据不一致。代谢的个体间差异可能解释了一些不一致的结果。20%到60%的人的肠道细菌能够将大豆黄酮（一种主要的大豆黄酮）代谢为雌马酚。雌马酚在体外被观察到比它的前体或其他主要的大豆黄酮染料木黄酮表现出更强的雌激素和抗氧化特性。由于其与乳腺癌的密切相关性，乳腺密度是乳腺癌风险的一个有用标志。拟议的项目将检查雌马酚产生状态与乳房密度的关系，并评估在一个独特的美国中国妇女队列中，雌马酚产生状态是否会导致摄入量和乳房密度之间的关联不同。一个次要的，更具探索性的目的是检查另一种大豆苷元代谢产物，O-去甲基安哥拉辛（O-DMA），与乳腺密度。这项工作将包括280名最近移民美国的中国妇女，她们参加了一项单独资助的关于饮食和乳房密度的纵向研究。研究受试者为绝经前/围绝经期，乳腺X线摄影筛查年龄，美国居住时间<=20年。该研究收集的数据包括问卷调查和饮食访谈，血液样本和乳房密度筛查乳房X光检查。拟议的工作将增加收集过夜尿样，实验室分析，以确定雌马酚和O-DMA生产状态，以及统计分析，以检查雌马酚和O-DMA生产状态和饮食中的雌马酮与乳腺密度测量的横截面关联，这些测量已经作为饮食乳腺密度研究的一部分收集。

DESCRIPTION (provided by applicant): Isoflavones, phytoestrogens found primarily in soy foods, are thought to protect against breast cancer, but epidemiologic evidence for such an effect is inconsistent. Inter-individual variability in isoflavone metabolism might explain some of the inconsistent results. Between 20 and 60% of individuals have intestinal bacteria capable of metabolizing daidzein, one of the primary soy isoflavones, to equol. Equol has been observed in vitro to demonstrate stronger estrogenic and antioxidant properties than either its precursor or the other primary soy isoflavone, genistein. Because of its strong association with breast cancer, breast density is a useful marker for breast cancer risk. The proposed project will examine equol producing status in relation to breast density and evaluate whether the association between isoflavone intake and breast density differs by equol producing status in a unique cohort of US Chinese women. A secondary, more exploratory aim is to examine another daidzein metabolite, O-desmethylangolensin (O-DMA), in relation to breast density. The work will include 280 recently immigrated US Chinese women participating in a separately funded, longitudinal study on diet and breast density. Study participants are pre-/peri-menopausal, of mammography screening age, with US residence <=20 years. Data being collected for that study include questionnaires and dietary interviews, blood samples, and a screening mammogram examined for breast density. The proposed work will add collection of overnight urine samples, laboratory analyses to define equol and O-DMA producing status, and statistical analyses to examine cross-sectional associations of equol and O-DMA producing status and dietary isoflavones with breast density measures already being collected as part of the diet-breast density study.