Dekant Wolfgang, Fujii Kenkichi, Shibata Eiichiro, Morita Osamu, Shimotoyodome Akira
Department of Toxicology, University of Würzburg, Versbacher Strasse 9, 97078 Würzburg, Germany.
R&D, Safety Science Research, Kao Corporation, 2606 Akabane Ichikai-Machi Haga-Gun, 321-3497 Tochigi, Japan.
Toxicol Lett. 2017 Aug 5;277:104-108. doi: 10.1016/j.toxlet.2017.06.008. Epub 2017 Jun 24.
The safety of green tea infusions and green tea extract (GTE)-based products is reviewed regarding catechins. Epigallocatechin 3-gallate (EGCG), the major catechin present in green tea, is suspected of being responsible for liver toxicity reported in humans consuming food supplements. Intake of EGCG with green tea infusions and GTE-based beverages is up to about 450mg EGCG/person/day in Europe and higher in Asia. Consumption of green tea is not associated with liver damage in humans, and green tea infusion and GTE-based beverages are considered safe in the range of historical uses. In animal studies, EGCG's potency for liver effects is highly dependent on conditions of administration. Use of NOAELs from bolus administration to derive a tolerable upper intake level applying the margin of safety concept results in acceptable EGCG-doses lower than those from one cup of green tea. NOAELs from toxicity studies applying EGCG with diet/split of the daily dose are a better point of departure for risk characterization. In clinical intervention studies, liver effects were not observed after intakes below 600mg EGCG/person/day. Thus, a tolerable upper intake level of 300mg EGCG/person/day is proposed for food supplements; this gives a twofold safety margin to clinical studies that did not report liver effects and a margin of safety of 100 to the NOAELs in animal studies with dietary administration of green tea catechins.
就儿茶素而言，对绿茶冲泡液和基于绿茶提取物（GTE）的产品的安全性进行了综述。表没食子儿茶素没食子酸酯（EGCG）是绿茶中存在的主要儿茶素，人们怀疑它是食用食品补充剂的人群中报告的肝毒性的原因。在欧洲，通过饮用绿茶冲泡液和基于GTE的饮料摄入的EGCG高达约450毫克/人/天，在亚洲则更高。饮用绿茶与人类肝脏损伤无关，在历史使用范围内，绿茶冲泡液和基于GTE的饮料被认为是安全的。在动物研究中，EGCG对肝脏的影响效力高度依赖于给药条件。使用一次性给药的无观察到有害作用水平（NOAEL），应用安全系数概念得出可耐受的每日摄入量上限，得出的可接受EGCG剂量低于一杯绿茶中的剂量。将EGCG与饮食一起给药/分剂量进行毒性研究得出的NOAEL是进行风险特征描述的更好出发点。在临床干预研究中，每日摄入量低于600毫克/人/天时未观察到肝脏影响。因此，建议食品补充剂的EGCG可耐受每日摄入量上限为300毫克/人/天；这为未报告肝脏影响的临床研究提供了两倍的安全系数，并且相对于绿茶儿茶素饮食给药的动物研究中的NOAEL有100的安全系数。
