牛奶及其制品与乳腺癌关系的研究进展

乳腺癌是西方女性最常见的肿瘤，我国女性乳腺癌患者也逐年上升。和所有的肿瘤一样，乳腺癌的病因复杂多样，其中包括饮食因素。众多考察乳腺癌的流行病学研究提及奶及其制品的影响，但没能得出一致的结论。著名的美国护士健康研究也没有发现奶和奶制品摄入与乳腺癌发生有明显关系。汇总观察这些流行病学资料发现，奶酪能微弱地增加患乳腺癌的危险。动物研究表明，现代牛奶中富含的雌激素和胰岛素样生长因子（IGF）-I有明显的促进二甲基苯并蒽（DMBA）诱导的大鼠乳腺肿瘤的生长。系统介绍流行病学研究和实验室研究的最新成果，同时讨论牛奶中存在的可能影响乳腺癌发生的诸多成分，其中起促进作用的有饱和脂肪、各类激素和污染物，起保护作用的有钙、维生素D和一些脂肪酸。

Effects of milk and its products on breast cancer risk: a review

Breast cancer is the most common female cancer in the world, and is increasing in China where its incidence is generally low. Differences in eating patterns and breast cancer rates across countries suggest that several dietary components, including dairy products, could affect breast cancer risk. Although some ecological epidemiological studies suggest that milk and its products are the risk factors in breast cancer, the association has been inconsistent in case-control studies and cohort studies. Meta analysis and other pooled analysis also showed that cheese increased the risk of breast cancer, which suggested a possible role of fat in breast cancer. In an animal study, the rats fed on milk promoted the development of 7,12-dimethylbenz(a)anthracene (DMBA)-induced mammary tumors. In fact, milk and dairy products contain saturated fat, estrogen, insulin-like growth factor (IGF)-I and pesticides, which have been showed to promote breast cancer risk. In contract, calcium, vitamin D, conjugated linoleic acid (CLA) and butyrate in milk and its products have been hypothesized to reduce breast cancer risk. Therefore, the evaluation of net effect is more important when observing the effects of milk and its products on breast cancer risk.