Authors' Affiliations: Kinesiology Department, California Polytechnic State University, San Luis Obispo, California; Department of Preventive Medicine and Biometrics, Uniformed Services University of the Health Sciences, Bethesda, Maryland; Department of Food Science and Nutrition, University of Minnesota, Saint Paul, Minnesota; and Cancer Prevention & Control Program, Fox Chase Cancer Center, Philadelphia, Pennsylvania.
Cancer Epidemiol Biomarkers Prev. 2013 Nov;22(11):1975-83. doi: 10.1158/1055-9965.EPI-13-0593. Epub 2013 Sep 9.
Differences in ability to metabolize daidzein to equol might help explain inconsistent findings about isoflavones and breast cancer. We examined equol-producing status in relation to breast density, a marker of breast cancer risk, and evaluated whether an association of isoflavone intake with breast density differs by equol-producing status in a sample of Chinese immigrant women.
Participants were 224 women, ages 36 to 58 years, enrolled in a study on diet and breast density. All women completed dietary recall interviews, underwent a soy challenge to assess equol-producing status, and received a mammogram assessed for breast density using a computer-assisted method.
In our sample, 30% were classified as equol producers. In adjusted linear regression models, equol producers had significantly lower mean dense tissue area (32.8 vs. 37.7 cm(2), P = 0.03) and lower mean percent breast density (32% vs. 35%, P = 0.03) than nonproducers. Significant inverse associations of isoflavone intake with dense area and percent density were apparent, but only in equol producers (interaction P = 0.05 for both).
These results support the possibility that equol-producing status affects breast density and that effects of isoflavones on breast density depend on ability to metabolize daidzein to equol.
Although these findings warrant confirmation in a larger sample, they offer a possible explanation for the inconsistent findings about soy intake and breast density and possibly breast cancer risk as well. The findings further suggest the importance of identifying factors that influence equol-producing status and exploring appropriate targeting of interventions.
代谢大豆苷原为黄豆苷元能力的差异可能有助于解释异黄酮与乳腺癌之间不一致的研究结果。我们研究了与乳腺密度（乳腺癌风险的一个标志物）相关的黄豆苷元产生状态，并评估了在一个中国移民妇女样本中，异黄酮摄入量与乳腺密度的相关性是否因黄豆苷元产生状态而异。
224 名年龄在 36 至 58 岁之间的妇女参加了一项关于饮食与乳腺密度的研究。所有妇女都完成了饮食回忆访谈，进行了大豆挑战以评估黄豆苷元产生状态，并接受了乳房 X 光检查，使用计算机辅助方法评估乳腺密度。
在我们的样本中，30%的妇女被归类为黄豆苷元产生者。在调整后的线性回归模型中，黄豆苷元产生者的平均致密组织面积（32.8 与 37.7cm²，P=0.03）和平均乳腺密度百分比（32%与 35%，P=0.03）显著低于非产生者。异黄酮摄入量与致密区和百分比密度呈显著负相关，但仅在黄豆苷元产生者中（交互作用 P=0.05）。
这些结果支持黄豆苷元产生状态影响乳腺密度的可能性，并且异黄酮对乳腺密度的影响取决于将大豆苷元代谢为黄豆苷元的能力。
尽管这些发现需要在更大的样本中得到证实，但它们为关于大豆摄入与乳腺密度以及可能的乳腺癌风险之间不一致的研究结果提供了一个可能的解释。这些发现进一步表明，确定影响黄豆苷元产生状态的因素并探索干预措施的适当目标的重要性。
