Lee Swanson Research Update

Green Tea May Help Support Healthy Cardiovascular Function

Regular consumption of green tea may improve the function of endothelial cells—cells lining the walls of blood vessels—and boost cardiovascular health, according to new research from Greece.

The small study with 14 healthy adults found that the benefits of the beverage were not related to the caffeine, indicating the possible role of green tea polyphenols.

“These findings have important clinical implications, said study co-author Charalambos Vlachopoulos from Athens Medical School in Greece. “Tea consumption has been associated with reduced cardiovascular morbidity and mortality in several studies. Green tea is consumed less in the Western world than black tea, but it could be more beneficial because of the way it seems to improve endothelial function.”

Green tea contains between 30% and 40% of water-extractable polyphenols, while black tea (green tea that has been oxidized by fermentation) contains between 3% and 10%. The four primary polyphenols found in fresh tea leaves are epigallocatechin gallate (EGCG), epigallocatechin (EGC), epicatechin gallate (ECG) and epicatechin (EC).

The researchers randomly assigned the volunteers (average age 30) to one of three groups. The first received six grams of green tea, the second received 125 mg of caffeine (equivalent to the caffeine dose from six grams of tea) and the third group received hot water.

The volunteers consumed each of the interventions on three separate occasions and the effects on flow-mediated dilation (FMD), the measure of a blood vessel’s healthy ability to relax, was charted 30, 90 and 120 minutes after consumption.

Green tea increased FMD by 3.9 percent 30 minutes after consumption, while no changes in FMD were observed following consumption of caffeine or the hot water placebo.

“Green tea consumption has an acute beneficial effect on endothelial function, assessed with FMD of the brachial artery, in healthy individuals,” wrote the researchers. “This may be involved in the beneficial effect of tea on cardiovascular risk,” they concluded.

European Journal of Cardiovascular Prevention & Rehabilitation 15(3):300-305, 2008

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