Does Green Tea Help the Heart? - TIME

Does Green Tea Help the Heart?
By ALICE PARK

The next time you're offered a choice between Earl Grey and green tea, you might want to go green.
A new study shows that the beverage, which is more popular in Eastern cultures, can protect heart arteries by keeping them flexible and relaxed, and therefore better able to withstand the ups and downs of constant changes in blood pressure. Led by Dr. Nikolaos Alexopoulos of Athens Medical School in Greece, the researchers found that among 14 subjects, those who drank green tea showed greater dilation of their heart arteries on ultrasound 30 min. later than those drinking either diluted caffeine or hot water. That's because, the scientists speculate, green tea works on the lining of blood vessels, helping cells there to secrete the substances needed to relax the vessels and allow blood to flow more freely. It's the flavonoids in the tea, which work as antioxidants and help prevent inflammation in body tissue, that keep the vessels pliable. These substances may also protect against the formation of clots, which are the primary cause of heart attacks. "We found very promptly [that] after drinking green tea, there was a protective effect on the endothelium," says Dr. Charalambos Vlachopoulos, a cardiologist and one of the authors of the study.

All it took, says Vlachopoulos, was 6 g of green tea, which amounts to 3 to 4 cups. To make sure the dilation effect was not due to the small amounts of caffeine found in green tea, the group compared the arterial sizes in the green-tea drinkers with those consuming a diluted caffeine beverage and found no change in arterial size in the caffeine drinkers. Even more intriguing, the beneficial effect seems to be long-lasting and cumulative. When the doctors measured the green-tea drinkers' arteries two weeks after daily consumption of the beverage, they found that their vessels were more dilated than they had been at the beginning of the study. "It's something that needs to be investigated, but we think that if someone takes green tea for one or two months, the beneficial effect will be even greater," says Vlachopoulos.

But experts caution that one study isn't enough to catapult green tea to wonder-drink status. Dr. Robert Eckel, a professor at the University of Colorado, Denver, and past president of the American Heart Association, notes that endothelial function is affected by a number of factors, including large doses of vitamins E and C. "Green-tea consumption may have beneficial effects on the arteries, but we should stop short of translating that into a recommendation that everybody should be drinking green tea because it's been proven to reduce heart attacks and strokes," he says. He acknowledges, however, that early studies hint that green tea may be a good addition to a heart-healthy diet. The American Heart Association does not yet include the beverage in its dietary recommendations, but more studies like this one may change that. In the meantime, if you're drinking tea, it might not be such a bad idea to go green.

绿茶有助心脏健康吗？—《时代》

　　当你下回被问及想要点格雷伯爵茶还是绿茶的时候，推荐你选绿茶。

　　最新一项研究表明，在东方较受欢迎的绿茶，可以软化血管，缓解心脏疲劳，进而增强心脏承受血压的不断变化的能力。由希腊医学院的尼古拉斯.埃里克斯普洛斯医生领导的研究小组，通过对14位试验对象进行超声波辐射然后观察其血管扩张的时间发现，爱喝绿茶的样本比喝含咖啡因的饮料或者温吞水的样本要晚30分钟才发生血管扩张。科学家们推测，这是因为绿茶作用于血管内壁细胞，帮助其分泌软化血管和加速血液流动的物质。茶中的类黄酮属于有消炎作用的抗氧化剂，并使血管有弹性。这些化学物质还可以防止心脏病头号成因——血栓的形成。“我们发现，绿茶在被饮用后不久就会在血管及淋巴管壁上起到保护作用。”卡拉蓝波斯.弗拉克波罗斯医生说。他是心脏病专家和该研究的牵头者之一。

　　要达到这个疗效，弗拉克波罗斯医生说，只需6g绿茶，可冲泡3-4杯。为了确认软化血管的疗效不是由绿茶中的少量咖啡因所达成，研究者比照了“绿茶组”和“咖啡因组”的动脉管径，发现咖啡因并无疗效。更加令人兴奋的是，绿茶的功效貌似持久且可累积。当医生在观察两周后测量嗜饮绿茶者的动脉时，他们发现其血管比两周前还要扩张。“这一事实还有待进一步研究确认，但我们认为若能连续饮用1-2个月的绿茶，将获得更加明显的功效。”

　　但也有专家警告，仅此一项研究尚不足以让绿茶一下子挂上“神奇饮料”的头衔。科罗拉多大学教授与美国心脏学会前任主席，罗伯特.埃克尔表示，血管内壁上的变化会受到一系列因素的影响，包括大剂量的维他命E和维他命C。“饮用绿茶可能有些益处，但我们不应把这片面地表达为‘因为绿茶可以减少心脏病和中风，因此建议所有人均应饮用绿茶。’”同时他也承认，早先的研究已经在暗示“绿茶应成为健心饮食的一部分”。美国心脏学会尚未将绿茶假如它的推荐饮食中，但将来更多的研究会证明绿茶的功效。

     若您常品香茗，绿茶不妨一试。