Messina M J, Persky V, Setchell K D, Barnes S
National Cancer Institute, National Institutes of Health, Bethesda, MD.
Nutr Cancer. 1994;21(2):113-31. doi: 10.1080/01635589409514310.
International variations in cancer rates have been attributed, at least in part, to differences in dietary intake. Recently, it has been suggested that consumption of soyfoods may contribute to the relatively low rates of breast, colon, and prostate cancers in countries such as China and Japan. Soybeans contain a number of anticarcinogens, and a recent National Cancer Institute workshop recommended that the role of soyfoods in cancer prevention be investigated. In this review, the hypothesis that soy intake reduces cancer risk is considered by examining relevant in vitro, animal, and epidemiological data. Soybeans are a unique dietary source of the isoflavone genistein, which possesses weak estrogenic activity and has been shown to act in animal models as an antiestrogen. Genistein is also a specific inhibitor of protein tyrosine kinases; it also inhibits DNA topoisomerases and other critical enzymes involved in signal transduction. In vitro, genistein suppresses the growth of a wide range of cancer cells, with IC50 values ranging from 5 to 40 microM (1-10 micrograms/ml). Of the 26 animal studies of experimental carcinogenesis in which diets containing soy or soybean isoflavones were employed, 17 (65%) reported protective effects. No studies reported soy intake increased tumor development. The epidemiological data are also inconsistent, although consumption of nonfermented soy products, such as soymilk and tofu, tended to be either protective or not associated with cancer risk; however, no consistent pattern was evident with the fermented soy products, such as miso. Protective effects were observed for both hormone- and nonhormone-related cancers. While a definitive statement that soy reduces cancer risk cannot be made at this time, there is sufficient evidence of a protective effect to warrant continued investigation.
癌症发病率的国际差异至少部分归因于饮食摄入的不同。最近，有人提出食用大豆制品可能是中国和日本等国乳腺癌、结肠癌和前列腺癌发病率相对较低的原因。大豆含有多种抗癌物质，美国国立癌症研究所最近的一次研讨会建议对大豆制品在癌症预防中的作用进行研究。在这篇综述中，通过研究相关的体外、动物和流行病学数据，探讨了大豆摄入可降低癌症风险这一假说。大豆是异黄酮染料木黄酮的独特膳食来源，异黄酮具有微弱的雌激素活性，在动物模型中已显示出抗雌激素作用。染料木黄酮还是蛋白酪氨酸激酶的特异性抑制剂；它还能抑制DNA拓扑异构酶和其他参与信号转导的关键酶。在体外，染料木黄酮能抑制多种癌细胞的生长，半数抑制浓度（IC50）值在5至40微摩尔/升（1至10微克/毫升）之间。在26项使用含大豆或大豆异黄酮饮食的实验性致癌动物研究中，17项（65%）报告了保护作用。没有研究报告大豆摄入会增加肿瘤发展。流行病学数据也不一致，尽管食用豆浆和豆腐等非发酵大豆制品往往具有保护作用或与癌症风险无关；然而，味噌等发酵大豆制品却没有明显的一致模式。对激素相关和非激素相关癌症均观察到了保护作用。虽然目前还不能确定地说大豆能降低癌症风险，但有足够的证据表明其具有保护作用，值得继续研究。
