Score another win for green tea: New research suggests that the potent leaves can rapidly improve the functioning of the endothelial cells lining blood vessels, aiding blood flow and relaxing the arteries. That may lower the risk of clots and heart disease. "We saw the effects just 30 minutes after the participants consumed the tea, and it lasted for two hours," says Charalambos Vlachopoulos, a cardiologist at Athens Medical School in Greece and lead author of the study, published in the current issue of the European Journal of Cardiovascular Prevention and Rehabilitation.
Green tea's benefits stem from its naturally high levels of flavonoids—antioxidant substances that slow down natural damage to cells. Though black tea also has been shown to promote cardiovascular health, Vlachopoulos thinks green tea may do a superior job because it isn't fermented as long and so retains more of its flavonoids. What's a proper dose? One or two cups per day is probably enough to do the trick.