雌二醇補充療法除了用來減緩停經後症狀，也被認為對心血管疾病有保護作用。然而，更年期或是停經後婦女使用荷爾蒙補充療法的主要顧慮是可能增加乳癌和子宮內膜相關疾病的風險。文獻上的證據顯示，飲食中的豆類所含豐富的植物性雌激素異黃酮素，可能減少心血管疾病與乳癌的罹患率。本研究對雌二醇和植物性雌激素對於ApoE基因剔除小鼠的作用作一評估。ApoE基因剔除小鼠於性腺未成熟前或成熟後進行去卵巢後，給予混有不同劑量的雌二醇、黃豆胚軸萃取物或是紅花苜蓿萃取物的含膽固醇飼料。於餵食12-16週之後，將小鼠犧牲，取血清以分析總膽固醇、三酸甘油脂、低密度脂蛋白、高密度脂蛋白的含量。並以oil red O染色分析動脈脂肪層面積。此外並利用乳腺全組織染色分析乳腺生長。結果顯示，給予十二週雌二醇後，血清中膽固醇量減少，乳腺的導管長度和分支點數目明顯增加，顯示雌二醇刺激乳腺生長。黃豆胚軸萃取物或是紅花苜蓿萃取物對血清膽固醇、動脈硬化程度則沒有顯著影響。紅花苜蓿萃取物不會刺激小鼠乳腺生長，高劑量的黃豆胚軸萃取物則稍微刺激乳腺導管長度和分支數目。總結來說，黃豆胚軸萃取物或是紅花苜蓿萃取物所含的植物性雌激素不具有雌二醇的降血脂及刺激乳腺生長作用。

　　Estrogen replacement therapy has been used to relieve postmenopausal symptoms and may have beneficial effects on cardiovascular disease. However, the fear of potential risks of breast and endometrial cancers is always a major concern. Accumulating evidences have shown that the consumption of dietary soy protein, that is rich in isoflavone phytoestrogens, is associated with a decreased incidence of cardiovascular disease and breast cancer. This study wants to compare the estrogenic actions of 17-estradiol (E2) and phytoestrogens in apoE-deficient mice. Immature or mature mice were ovariectomized and then fed cholesterol-rich diet mixed with different doses of E2 or phytoestrogen containing products prepared from soy or red clover. After 12 - 16 weeks, mice were sacrificed and sera were collected for the measurements of cholesterol, triglycerides, LDL-cholesterol and HDL-cholesterol. Aortic fat deposition was examined by oil red O staining and the growth of mammary gland was analyzed by whole-mount preparation. The results show that the treatment of E2 for 12 weeks decreased plasma cholesterol levels, and increased ductal length and numbers of branch points of mammary gland. But it did not affect the extent of atherosclerosis. Phytoestrogens from soy or red clover exhibited no significant effects on plasma cholesterol levels and atherosclerosis. Red clover product did not stimulate mammary gland growth, but soy product at high concentration slightly increased ductal length and numbers of branch points in mammary gland. In summary, phytoestrogens from soy and red clover are not as effective as E2 in affecting plasma cholesterol levels and mammary gland growth.

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