A cup of green tea. A few cups of green tea each day may help prevent heart disease, Greek researchers said on Wednesday.

A few cups of green tea each day may help prevent heart disease, Greek researchers said on Wednesday.

A study published in the European Journal of Cardiovascular Prevention and Rehabilitation showed further evidence of the potential health benefits from a brew already linked to a reduced risk of a range of cancers and other conditions.

The study showed that green tea improves blood flow and the ability of arteries to relax, said Charalambos Vlachopoulos, a cardiologist at the Athens Medical School in Greece who worked on the study.

Other studies have shown that black tea also has benefits for cardiovascular health.

The Greek team said they believed green tea might be even better because it had higher quantities of beneficial compounds called flavonoids -- some of which are lost in the oxidation process that black tea undergoes.

Flavonoids are also found in cocoa, tomatoes and grapes.

"A couple of cups a day would probably be a good dose for people," Vlachopoulos said. "This is the first study to show these effects for green tea."

The researchers gave 14 healthy volunteers either green tea, diluted caffeine or hot water and then measured the function of endothelial cells lining the circulatory system.

These cells help relax arteries and ease blood flow.

"What is important is these effects are evident fairly rapidly, within 30 minutes," Vlachopoulos said.

The measurements taken 30, 90 and 120 minutes following consumption showed an almost immediate benefit among people who had drunk green tea, he said.

While the researchers looked only at a short-term impact, Vlachopolous said the team's studies suggest the protection is long lasting.

"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 (circulatory) function," he said.