Yang C S, Wang Z Y
Laboratory for Cancer Research, College of Pharmacy, Rutgers University, Piscataway, NJ 08855-0789.
J Natl Cancer Inst. 1993 Jul 7;85(13):1038-49. doi: 10.1093/jnci/85.13.1038.
Tea is one of the most popular beverages consumed worldwide. The relationship between tea consumption and human cancer incidence is an important concern. This topic has been studied in different populations by many investigators, but no clear-cut conclusion can be drawn. Whereas some studies have shown a protective effect of tea consumption against certain types of cancers, other studies have indicated an opposite effect. Our purpose is to provide a critical review of this topic, covering basic chemistry and biochemical activity of tea, epidemiologic investigations, and laboratory studies, as well as possible directions for future research. Studies have demonstrated either a lack of association between tea consumption and cancer incidence at specific organ sites or inconsistent results. On the other hand, many laboratory studies have demonstrated inhibitory effects of tea preparations and tea polyphenols against tumor formation and growth. This inhibitory activity is believed to be mainly due to the antioxidative and possible antiproliferative effects of polyphenolic compounds in green and black tea. These polyphenolics may also inhibit carcinogenesis by blocking the endogenous formation of N-nitroso compounds, suppressing the activation of carcinogens, and trapping of genotoxic agents. The effect of tea consumption on cancer is likely to depend on the causative factors of the specific cancer. Therefore, a protective effect observed on a certain cancer with a specific population may not be observable with a cancer of a different etiology. On the basis of this concept, we suggest future laboratory and epidemiologic studies to elucidate the relationship between tea consumption and human cancer risk.
茶是全球消费最广泛的饮品之一。饮茶与人类癌症发病率之间的关系是一个重要的关注点。许多研究人员在不同人群中对该主题进行了研究，但尚未得出明确的结论。虽然一些研究表明饮茶对某些类型的癌症有保护作用，但其他研究则显示出相反的效果。我们的目的是对该主题进行批判性综述，涵盖茶的基础化学和生化活性、流行病学调查、实验室研究以及未来研究的可能方向。研究表明，饮茶与特定器官部位的癌症发病率之间要么缺乏关联，要么结果不一致。另一方面，许多实验室研究表明茶制品和茶多酚对肿瘤形成和生长具有抑制作用。这种抑制活性被认为主要归因于绿茶和红茶中多酚类化合物的抗氧化和可能的抗增殖作用。这些多酚类物质还可能通过阻断内源性亚硝基化合物的形成、抑制致癌物的活化以及捕获遗传毒性剂来抑制致癌作用。饮茶对癌症的影响可能取决于特定癌症的致病因素。因此，在特定人群中观察到的对某种癌症的保护作用，在病因不同的癌症中可能无法观察到。基于这一概念，我们建议未来进行实验室和流行病学研究，以阐明饮茶与人类癌症风险之间的关系。
