Hodgson Jonathan M, Puddey Ian B, Burke Valerie, Beilin Lawrence J, Mori Trevor A, Chan Shin-Yee
University of Western Australia Department of Medicine and HeartSearch, Royal Perth Hospital, Perth, Australia.
Br J Nutr. 2002 Feb;87(2):141-5. doi: 10.1079/BJN2001499.
Results of population studies suggest that black tea can reduce cardiovascular risk. Effects of black-tea polyphenols to reduce platelet aggregability may help to explain any benefits. Given that black tea is often consumed with and after meals, and man spends much of his life in the postprandial state, the objective of the present study was to investigate the acute effects of ingestion of black tea on postprandial platelet aggregation ex vivo. Twenty healthy participants had platelet aggregation and blood lipids assessed before and 4 h after the ingestion of 50 g dairy fat on two occasions in random order, corresponding to black tea or hot water. Black tea or hot water (one cup) was consumed immediately following the dairy fat, then after 15 and 30 h. Platelet aggregation ex vivo was assessed in platelet-rich plasma in response to three concentrations of collagen (0.2, 0.6, 20 microg/ml) and ADP (2, 4, 8 microM). Urinary concentrations of 4-O-methylgallic acid were used as an indicator that tea polyphenols were absorbed. Serum total cholesterol and triacylglycerol concentrations increased significantly 4 h after ingesting the dairy fat, but there was no significant difference between black tea and hot-water treatments on the cholesterol or triacylglycerol responses. Urinary 4-O-methylgallic acid concentrations were significantly increased following ingestion of black tea (P=0.0001) but not water. Black tea in comparison to hot water did not inhibit collagen or ADP-induced postprandial platelet aggregation. The results of this study do not support the suggestion that reduced postprandial platelet aggregability contributes to any benefits of black tea on cardiovascular risk.
人群研究结果表明，红茶可降低心血管疾病风险。红茶多酚降低血小板聚集性的作用或许有助于解释其带来的任何益处。鉴于红茶常与餐食一同饮用或在餐后饮用，且人一生中大部分时间处于餐后状态，本研究的目的是调查摄入红茶对餐后离体血小板聚集的急性影响。20名健康参与者在随机顺序下分两次在摄入50克乳脂肪前及之后4小时评估血小板聚集和血脂情况，分别对应饮用红茶或热水。在摄入乳脂肪后立即饮用一杯红茶或热水，然后在15分钟和30分钟后再次饮用。在富含血小板的血浆中，针对三种浓度的胶原蛋白（0.2、0.6、20微克/毫升）和二磷酸腺苷（2、4、8微摩尔）评估离体血小板聚集情况。尿中4 - O - 甲基没食子酸的浓度用作茶多酚被吸收的指标。摄入乳脂肪4小时后，血清总胆固醇和三酰甘油浓度显著升高，但红茶和热水处理在胆固醇或三酰甘油反应方面无显著差异。摄入红茶后尿中4 - O - 甲基没食子酸浓度显著升高（P = 0.0001），但饮用热水后未升高。与热水相比，红茶并未抑制胶原蛋白或二磷酸腺苷诱导的餐后血小板聚集。本研究结果不支持以下观点，即降低餐后血小板聚集性有助于红茶对心血管疾病风险产生任何益处。
