Vlachopoulos Charalambos, Alexopoulos Nikolaos, Dima Ioanna, Aznaouridis Konstantinos, Andreadou Ioanna, Stefanadis Christodoulos
Ist Department of Cardiology, Athens Medical School, Hippokration Hospital, Athens, Greece.
J Am Coll Nutr. 2006 Jun;25(3):216-23. doi: 10.1080/07315724.2006.10719535.
While most studies have shown an inverse relation between tea consumption and cardiovascular risk, other studies have shown opposite results. Aortic stiffness and wave reflections are markers of cardiovascular disease and prognosticators of cardiovascular risk.
The acute effect of black and green tea on aortic stiffness and wave reflections was assessed in 29 healthy volunteers in a randomized, single-blind, sham-procedure controlled, cross-over design. In the black tea sub-study, 16 subjects received 6 gm of tea, caffeine (175 mg), or hot water in 3 different sessions. In the green tea sub-study, 13 subjects received 6 gm of tea, caffeine (125 mg), or hot water. Carotid-femoral pulse wave velocity and wave reflection indices were measured at baseline and for 3 hours after consumption.
Black tea increased pulse wave velocity during the first 90 min (increase by 0.49 m/sec, P < 0.05), showing a rapid return towards baseline values thereafter (P = 0.07 for the whole study period); in contrast, green tea had no effect. Both black and green tea increased augmentation index (by 5.0% and by 6.6%, P < 0.01 and P < 0.001, respectively) throughout the study. These changes were less than the respective changes produced by caffeine. Both black and green tea had a significant pressor effect. No change in oxidant status was found with both types of tea.
Both black and green tea increases acutely wave reflections and only black tea increases aortic stiffness. Tea flavonoids may play a role in the attenuation of the effects of caffeine contained in tea.
虽然大多数研究表明饮茶与心血管风险呈负相关，但其他研究却得出了相反的结果。主动脉僵硬度和波反射是心血管疾病的标志物以及心血管风险的预测指标。
采用随机、单盲、假手术对照、交叉设计，对29名健康志愿者评估红茶和绿茶对主动脉僵硬度和波反射的急性影响。在红茶子研究中，16名受试者在3个不同时段分别饮用6克茶、咖啡因（175毫克）或热水。在绿茶子研究中，13名受试者分别饮用6克茶、咖啡因（125毫克）或热水。在基线以及饮用后3小时测量颈股脉搏波速度和波反射指数。
红茶在最初90分钟内使脉搏波速度增加（增加0.49米/秒，P<0.05），此后迅速恢复至基线值（整个研究期间P=0.07）；相比之下，绿茶无此作用。在整个研究过程中，红茶和绿茶均使增强指数增加（分别增加5.0%和6.6%，P<0.01和P<0.001）。这些变化小于咖啡因所产生的相应变化。红茶和绿茶均有显著的升压作用。两种茶均未发现氧化状态有变化。
红茶和绿茶均可急性增加波反射，且只有红茶会增加主动脉僵硬度。茶中的类黄酮可能在减轻茶中所含咖啡因的作用方面发挥作用。
