Departments of Medicine and Pharmacology and Pharmacy, The University of Hong Kong, Hong Kong, China.
Clin Exp Pharmacol Physiol. 2012 Mar;39(3):265-73. doi: 10.1111/j.1440-1681.2012.05673.x.
Green tea (from the plant Camellia sinensis), a beverage whose consumption started 5000 years ago in China, has important biological and pharmacological properties. The beneficial effects of green tea have been attributed to the presence of phenolic compounds that are powerful anti-oxidants and free iron scavengers. Of all the catechins found in green tea, namely (-)-epicatechin-3-gallate, (-)-epigallocatechin, (-)-epicatechin and (-)-epigallocatechin-3-gallate (EGCG), EGCG is the most abundant and powerful. It is widely believed that green tea may protect against death from all causes, especially cardiovascular diseases (coronary heart disease and stroke) owing to the presence of catechins associated with green tea consumption. Other health benefits include various types of cancer chemoprevention, weight loss and protective effects against neurodegenerative diseases (Alzheimer's disease and Parkinson's disease). Thus far, numerous pharmacological activities regulating disease-specific molecular targets have been reported in vitro for EGCG concentrations in the micromolar range, which are physiologically irrelevant. Although most of the studies have shown benefits with two to three cups of green tea per day, the optimal dose has not yet been established to enable any solid conclusions to be drawn regarding the various health benefits of green tea or its constituents in humans. With Phase I trials providing information on the safety profile and pharmacokinetics of EGCG, the window of opportunity is wider to undertake well-controlled long-term human studies to enable a full understanding of the protective effects of green tea catechins on various parameters in different settings.
绿茶（来自茶树 Camellia sinensis），一种 5000 年前在中国开始饮用的饮料，具有重要的生物学和药理学特性。绿茶的有益作用归因于酚类化合物的存在，这些化合物是强大的抗氧化剂和游离铁清除剂。在绿茶中发现的所有儿茶素中，(-)-表儿茶素-3-没食子酸酯、(-)-表没食子儿茶素、(-)-表儿茶素和(-)-表没食子儿茶素-3-没食子酸酯（EGCG）含量最丰富、功效最强。人们普遍认为，绿茶可能具有预防各种原因导致的死亡的作用，特别是由于与绿茶消费相关的儿茶素的存在，绿茶可预防心血管疾病（冠心病和中风）。其他健康益处包括各种类型的癌症化学预防、减肥和对神经退行性疾病（阿尔茨海默病和帕金森病）的保护作用。到目前为止，已有大量的药理学研究报道了 EGCG 在体外对特定疾病分子靶点的调控作用，其浓度处于微摩尔范围，与生理无关。尽管大多数研究表明，每天饮用两到三杯绿茶有益，但尚未确定最佳剂量，因此无法对绿茶或其成分对人体各种健康益处得出任何确凿的结论。由于 I 期试验提供了有关 EGCG 安全性概况和药代动力学的信息，因此有机会进行更好控制的长期人体研究，以充分了解绿茶儿茶素对不同环境下各种参数的保护作用。
