Department of Nutrition and Food Science-Nutritional Physiology, University of Bonn, D-53115 Bonn, Germany.
Phytomedicine. 2011 Aug 15;18(11):903-15. doi: 10.1016/j.phymed.2011.06.006. Epub 2011 Jul 30.
Epidemiological data suggest that green tea (GT) consumption may protect against cardiovascular diseases (CVDs) and different types of cancer. This effect is attributed primarily to the antioxidant properties of flavanols from GT. This review provides an overview of controlled intervention studies investigating the effect of GT consumption on antioxidant effects ex vivo and in vivo.
The Medline and Cochrane databases were searched independently by two investigators for controlled intervention studies (English) on GT consumption and antioxidant effects published up to June 2010. Thirty-one studies investigating antioxidant effects ex vivo [plasma antioxidant capacity (AC), DNA's resistance against oxidative induced damage) or in vivo (lipid and protein oxidation, DNA damage] met the criteria. Results were compared by considering the participants, the dose of GT, the amount of ingested flavanols, the duration of supplementation and the investigated biomarkers.
The comparison between the studies was difficult as relevant data, e.g., on flavanol concentration in plasma (10 of 31 studies) or on major antioxidants contributing to AC, were often missing. Lipid peroxidation and DNA damage were commonly investigated. Data on protein oxidation are scarce. An antioxidant effect of at least one parameter (increase in AC or reduction of oxidative stress marker) was observed in 15 out of 22 studies by daily consumption of GT, primarily in participants exposed to oxidative stress (smokers or mixed collectives of smokers and non-smokers and physical activity) and in 6 out of 9 studies investigating the bolus consumption of GT.
There is limited evidence that regular consumption of GT in amounts of at least 0.6-1.5 l/day may increase AC and reduce lipid peroxidation (especially oxidation of LDL). This may contribute to the protection against CVDs and different types of cancer. Beneficial effects seem to be more likely in participants exposed to oxidative challenge.
流行病学数据表明，绿茶（GT）的消费可能有助于预防心血管疾病（CVD）和不同类型的癌症。这种效果主要归因于 GT 中黄烷醇的抗氧化特性。这篇综述提供了一个关于对照干预研究的概述，这些研究调查了 GT 消费对体外和体内抗氧化作用的影响。
两位研究者独立地在 Medline 和 Cochrane 数据库中搜索了截至 2010 年 6 月发表的关于 GT 消费和抗氧化作用的对照干预研究（英文）。有 31 项研究调查了体外[血浆抗氧化能力（AC）、DNA 对氧化诱导损伤的抵抗力]或体内[脂质和蛋白质氧化、DNA 损伤]的抗氧化作用符合标准。通过考虑参与者、GT 的剂量、摄入的黄烷醇量、补充的持续时间和研究的生物标志物来比较结果。
由于缺乏相关数据，例如血浆中黄烷醇浓度（31 项研究中有 10 项）或对 AC 有贡献的主要抗氧化剂，因此很难对研究进行比较。脂质过氧化和 DNA 损伤通常是研究的对象。关于蛋白质氧化的数据很少。每天消费 GT 时，至少有 15 项研究中的一个或多个参数（AC 增加或氧化应激标志物减少）观察到抗氧化作用，主要在暴露于氧化应激的参与者（吸烟者或吸烟者和不吸烟者以及体力活动的混合人群）和 9 项研究中的 6 项中观察到 GT 的脉冲式消费。
有有限的证据表明，每天至少消费 0.6-1.5 升 GT 可以增加 AC 和减少脂质过氧化（特别是 LDL 氧化）。这可能有助于预防 CVD 和不同类型的癌症。在暴露于氧化挑战的参与者中，有益效果似乎更有可能。
