Green tea can expand arteries, which is linked to better cardiovascular health, a new study says.
In a small study of 14 people, Greek researchers found that drinking 6 grams of tea caused the study subjects' brachial arteries to expand by almost 4 per cent. The brachial artery is in the upper arm.
According to the researchers, expansion of the arteries leads to improved heart health.
"Green tea is consumed less in the Western world than black tea, but it could be more beneficial," said study researcher Dr. Charalambos Vlachopoulos.
The findings are published in the European Journal of Cardiovascular Prevention and Rehabilitation.
The researchers, from the Athens Medical School's department of cardiology, tested subjects after they consumed green tea, 125 mg of caffeine and 450 ml of hot water on three separate occasions. They measured the diameter of the brachial artery in each participant 30, 90 and 120 minutes after they consumed each beverage.
Dilation of the artery peaked at an increase of 3.9 per cent at the 30-minute test time.
The scientists found that the caffeine and hot water did not have the same effect on the brachial artery that the green tea did.
The benefits of consuming all teas, as well as dark chocolate and red wine, come from the antioxidant effect of flavonoids, which are chemical compounds that protect against oxidative damage to cells in the body.
The researchers said that there has been no oxidization during the manufacturing process of green tea leaves, so they actually have a more potent antioxidant benefit compared to black tea leaves.
Although the findings suggest that green tea may actually protect against heart disease or other cardiovascular illnesses, the researchers said that further study needs to be done on the potential long-term benefits of the beverage.
Abstract:
The acute effect of green tea consumption on endothelial function in healthy individuals
Nikolaos Alexopoulos, Charalambos Vlachopoulos, Konstantinos Aznaouridis, Katerina Baou, Carmen Vasiliadou, Panagiota Pietri, Panagiotis Xaplanteris, Elli Stefanadi and Christodoulos Stefanadis
Background Tea consumption is associated with decreased cardiovascular risk. Flow mediated dilatation (FMD) of the brachial artery is related to coronary endothelial function and it is an independent predictor of cardiovascular risk. Black tea has a beneficial effect on endothelial function; the effect, however, of green tea on brachial artery reactivity has not been defined yet.
Design and methods We studied 14 healthy individuals (age 30� 3 years) with no cardiovascular risk factors except from smoking (50%) on three separate occasions on which they took: (a) 6 g of green tea, (b) 125mg of caffeine (the amount contained in 6 g of tea), or (c) hot water. FMD of the brachial artery was measured before each intervention and 30, 90, and 120 min afterward. High-sensitivity C-reactive protein, interleukins 6 (Il-6) and 1b (Il-1b), total plasma antioxidative capacity, and total plasma oxidative status/stress were measured at baseline and at 120 min after each intervention.
Results Resting and hyperemic brachial artery diameter did not change either with tea or with caffeine. FMD increased significantly with tea (by 3.69%, peak at 30 min, P < 0.02), whereas it did not change significantly with caffeine (increase by 1.72%, peak at 30 min, P=NS). Neither tea nor caffeine had any effect on high-sensitivity C-reactive protein, Il-6, Il-1b, total plasma antioxidative capacity, or total plasma oxidative status/stress.
Conclusion Green tea consumption has an acute beneficial effect on endothelial function, assessed with FMD of the brachial artery, in healthy individuals. This may be involved in the beneficial effect of tea on cardiovascular risk.
