Davis S R, Dalais F S, Simpson E R, Murkies A L
Jean Hailes Foundation Research Unit, Clayton, Victoria, Australia.
Recent Prog Horm Res. 1999;54:185-210; discussion 210-1.
Phytoestrogens are compounds found in a wide variety of plant foods that historically are said to exhibit estrogen-like activity and, more recently, have been reported to display both estrogenic and anti-estrogenic effects. Population-based studies have been interpreted to suggest that consumption of a phytoestrogen-rich diet is protective against breast, prostate, and bowel cancer and cardiovascular disease and ameliorates estrogen-deficiency symptoms in postmenopausal women. Consequently, there is a global movement towards increased consumption of phytoestrogen-rich foods and tabletized concentrated isoflavone extracts are being heavily promoted. Evaluating the effects and hence the potential benefits and risks of phytoestrogens is a complex task. The interindividual diversity and complexity in dietary phytoestrogen absorption and metabolism make the bioactivity of these compounds unpredictable. Epidemiological studies of relationships between phytoestrogens and cancer and cardiovascular disease that take into account confounding factors are scarce. Results of many of the in vitro and in vivo studies are conflicting and confusing. These compounds do not simply mimic the effects of human steroidal estrogen but rather demonstrate both similar and divergent actions. The ultimate actions of these compounds in specific cells are determined by many factors, including the relative levels of estrogen receptor (ER) alpha and ER beta and the diverse cocktail of co-activators and co-repressors present in any given cell type. Therefore, effects vary according to the phytoestrogen studied, cell line, tissue, species, and response being evaluated. Overall, it is naive to assume that exposure to these compounds is always good; inappropriate or excessive exposure may be detrimental. Extensive documentation of the specific intracellular effects of the various phytoestrogens in different tissues, the relationships between timing and duration of exposure and disease, and results from prospective randomized studies in humans of their clinical effects and potential side effects are essential. Only then can widespread recommendations regarding the dietary and pharmacological intake of these compounds be made.
植物雌激素是在多种植物性食物中发现的化合物，据说从历史上看它们具有类似雌激素的活性，最近又有报道称它们具有雌激素和抗雌激素作用。基于人群的研究表明，食用富含植物雌激素的饮食可预防乳腺癌、前列腺癌、肠癌和心血管疾病，并改善绝经后女性的雌激素缺乏症状。因此，全球范围内都在倡导增加富含植物雌激素食物的摄入量，并且大力推广片状浓缩异黄酮提取物。评估植物雌激素的作用以及潜在的益处和风险是一项复杂的任务。饮食中植物雌激素吸收和代谢的个体差异和复杂性使得这些化合物的生物活性难以预测。考虑到混杂因素的关于植物雌激素与癌症和心血管疾病之间关系的流行病学研究很少。许多体外和体内研究的结果相互矛盾且令人困惑。这些化合物并非简单地模仿人类甾体雌激素的作用，而是表现出相似和不同的作用。这些化合物在特定细胞中的最终作用取决于许多因素，包括雌激素受体（ER）α和ERβ的相对水平以及任何给定细胞类型中存在的多种共激活剂和共抑制剂混合物。因此，根据所研究的植物雌激素、细胞系、组织、物种和所评估的反应不同，其作用也会有所不同。总体而言，认为接触这些化合物总是有益的想法是幼稚的；不适当或过度接触可能有害。详细记录各种植物雌激素在不同组织中的具体细胞内作用、接触时间和持续时间与疾病之间的关系，以及关于其临床效果和潜在副作用的人体前瞻性随机研究结果至关重要。只有这样，才能就这些化合物的饮食和药物摄入量提出广泛的建议。
