Gomikawa Syuzou, Ishikawa Yuichi, Hayase Wakako, Haratake Yuko, Hirano Namiko, Matuura Hiromi, Mizowaki Akiyo, Murakami Akiko, Yamamoto Mao
Faculty of Health Sciences, Kobe University School of Medicine, Kobe 654-0142, Japan.
Kobe J Med Sci. 2008 May 23;54(1):E62-72.
Catechins in green tea have been shown to reduce a risk of coronary heart disease in epidemiological studies. Also, it has been reported catechins have hypolipidemic and antioxidant effects. Then, we investigated the effects of ground green tea drinking on the susceptibility of plasma and low-density lipoprotein (LDL) to the oxidation by CuSO4 ex vivo, and also evaluated daily food consumption using semiquantitative questionnaire. Five healthy female subjects consumed ground green tea (1.5 g/3 times/day) for 2 weeks after a washout period of 1 week, when they drank water instead of tea. After 2-week tea drinking, the subjects drank water again. They also filled food and drink-frequency questionnaires during 4 weeks to assess daily foods consumption to estimate the oxidizability of plasma and LDL. We measured the lag time of conjugated dienes formation of plasma and LDL to oxidation by CuSO4. The lag time of conjugated dienes formation are increased in all subjects after ground green tea consumption from 67+/-19 to 118+/-42 min in plasma and from 47+/-6 to 66+/-10 min in LDL. The cholesterol contents in plasma and LDL decreased 10 mg/dl after ground green tea consumption. The beta-carotene, alpha-tocopherol, vitamin C and uric acid contents in plasma did not change after ground green tea consumption. The superoxide dismutase (SOD) activity in plasma also remained unchanged during this study periods. These findings indicated that ground green tea consumption decreased susceptibility of plasma and LDL to oxidation and also modulated cholesterol metabolism and might prevent initiation and progression of atherosclerosis.
在流行病学研究中，绿茶中的儿茶素已被证明可降低冠心病风险。此外，据报道儿茶素有降血脂和抗氧化作用。然后，我们研究了饮用磨碎的绿茶对血浆和低密度脂蛋白（LDL）离体被硫酸铜氧化的敏感性的影响，并使用半定量问卷评估了日常食物摄入量。五名健康女性受试者在1周的洗脱期（期间饮用清水而非茶）后，饮用磨碎的绿茶（1.5克/天，分3次），持续2周。2周茶饮后，受试者再次饮用清水。他们还在4周内填写了食物和饮料频率问卷，以评估日常食物摄入量，从而估计血浆和LDL的氧化能力。我们测量了血浆和LDL被硫酸铜氧化形成共轭二烯的延迟时间。饮用磨碎的绿茶后，所有受试者血浆中共轭二烯形成的延迟时间从67±19分钟增加到118±42分钟，LDL中从47±6分钟增加到66±10分钟。饮用磨碎的绿茶后，血浆和LDL中的胆固醇含量降低了10毫克/分升。饮用磨碎的绿茶后，血浆中的β-胡萝卜素、α-生育酚、维生素C和尿酸含量没有变化。在本研究期间，血浆中的超氧化物歧化酶（SOD）活性也保持不变。这些发现表明，饮用磨碎的绿茶可降低血浆和LDL的氧化敏感性，还可调节胆固醇代谢，并可能预防动脉粥样硬化的发生和发展。
