The trials lasted anywhere from three weeks to six months, with the green-tea users showing a bigger average decline in LDL and total cholesterol than their counterparts in the control groups.

The benefit seemed to be limited to people who already had High cholesterol when they entered the study.

Overall, teas appeared more effective than capsules. But Phung said there isn’t enough data to be sure that the beverage is better than the extract.

“We would really need to have some head-to-head studies comparing the different forms of green tea in order to show which ones work more effectively,” Phung said.

There are other questions, too - including what dose of green tea catechins is “ideal.”

In the trials Phung’s team studied, the daily catechin dose ranged from 145 milligrams to 3,000 milligrams. But the researchers were not able to test for a “dose-response” effect - which would have shown whether the cholesterol benefits increase as the catechin dose goes up.

As for side effects, green tea is considered safe in moderate amounts - though the drink and the extracts contain caffeine, which some people may need to avoid.

There have also been a few dozen cases of liver damage reported among people using green tea extracts, but it’s not certain that the supplements are to blame.

The current study had no industry funding, and none of the researchers reports financial conflicts of interest.

SOURCE:  Journal of the American Dietetic Association, November 2011.