物谷报道：根据Arizona癌症中心的研究结果，绿茶中富含的化学物质能大大促进一类关键解毒酶的产生，特别是对于那些缺少这类有益蛋白的人而言。
以上结果发表在8月的Cancer Epidemiology, Biomarkers & Prevention上，它表明绿茶中的物质可以强化人们对抗造成癌症毒素的能力。在针对42人的研究中，小组发现富含物——相当于8-16杯绿茶中含有的绿茶酚——提高了酶产量达80%，这一酶属于谷胱甘肽S转移酶（GST）。
项目负责人，Arizona大学副教授H. H. Sherry Chow发现，GST对于身体对抗造成癌症的化学物质等很重要。科学家长期以来对绿茶很感兴趣，因为他们发现经常饮用绿茶的人群，例如中国人和日本人患癌症的几率更低。为了确认绿茶能对抗癌症，NCI支持了一系列科学研究。
而此项研究则主要用来分析绿茶酚是否对健康人的GST酶水平有影响，从而解释其抗癌作用。首先志愿者被要求戒茶4周，以确定每人的GST基线。然后志愿者被要求每天清晨空腹服用4个含Polyphenon E的胶囊，一共含有800毫克EGCG，4周后再检测血液，其间不能喝茶以及食用其它十字花科蔬菜。
结果发现，Polyphenon E能提高所有参与实验的志愿者的GST活跃性，但是其中作用最明显的是对于那些在血液基线的测量中表现出较低GST活性的志愿者——相比GST基准它们提高了80%。Chow说：“这是首次通过临床实验证实绿茶物质能增加人体的解毒酶，或许还有其它绿茶抗癌的机制，但无论如何这是一个好的开始。” （教育部科技发展中心）
原文链接：http://www.physorg.com/news105966521.html
原始出处:
Cancer Epidemiology Biomarkers & Prevention 16, 1662-1666, August 1, 2007. doi: 10.1158/1055-9965.EPI-06-0830
Modulation of Human Glutathione S-Transferases by Polyphenon E Intervention
H.-H. Sherry Chow1, Iman A. Hakim1, Donna R. Vining1, James A. Crowell3, Margaret E. Tome2, James Ranger-Moore1, Catherine A. Cordova1, Dalia M. Mikhael1, Margaret M. Briehl2 and David S. Alberts1
1 Arizona Cancer Center and 2 Department of Pathology, The University of Arizona, Tucson, Arizona and 3 Division of Cancer Prevention, National Cancer Institute, Bethesda, Maryland
Requests for reprints: H.-H. Sherry Chow, Arizona Cancer Center, The University of Arizona, Tucson, AZ 85724. Phone: 520-626-3358; Fax: 520-626-5348. E-mail: schow@azcc.arizona.edu
Purpose: Green tea consumption has been associated with decreased risk of certain types of cancers in humans. Induction of detoxification enzymes has been suggested as one of the biochemical mechanisms responsible for the cancer-preventive effect of green tea. We conducted this clinical study to determine the effect of repeated green tea polyphenol administration on a major group of detoxification enzymes, glutathione S-transferases (GST).
Methods: A total of 42 healthy volunteers underwent a 4-week washout period by refraining from tea or tea-related products. At the end of the washout period, a fasting blood sample was collected, and plasma and lymphocytes were isolated for assessment of GST activity and level. Following the baseline evaluation, study participants underwent 4 weeks of green tea polyphenol intervention in the form of a standardized Polyphenon E preparation at a dose that contains 800 mg epigallocatechin gallate (EGCG) once a day. Polyphenon E was taken on an empty stomach to optimize the oral bioavailability of EGCG. Upon completion of the intervention, samples were collected for postintervention GST assessment.
