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

描述（由申请人提供）：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，但这种效果的流行病学证据并不一致。异黄酮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素（一种主要的大豆异黄酮）代谢为马酚。在体外观察到，雌马酚比其前体或其他主要大豆异黄酮染料木素表现出更强的雌激素和抗氧化特性。由于乳腺密度与乳腺癌有很强的相关性，因此它是乳腺癌风险的一个有用的标志。拟议的项目将检查雌马酚产生状态与乳腺密度的关系，并评估异黄酮摄入量与乳腺密度之间的关系是否因雌马酚产生状态的不同而不同。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物，o -去甲基安古霉素（O-DMA），与乳腺密度的关系。这项工作将包括280名最近移民到美国的华裔妇女，她们将参加一项单独资助的关于饮食和乳房密度的纵向研究。研究参与者为绝经前/围绝经期，乳房x光检查年龄，在美国居住<=20年。该研究收集的数据包括调查问卷、饮食访谈、血液样本和乳房密度筛查x光片。拟议的工作将增加夜间尿液样本的收集，实验室分析以确定雌马酚和O-DMA的产生状态，以及统计分析以检查雌马酚和O-DMA产生状态和饮食异黄酮与乳腺密度测量的横断关联，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.