The conclusion may help to explain why green tea has been linked to a lower risk of heart disease, said Xin-Xin Zheng and colleagues from Peking Union Medical College in Beijing in their report.
Few people in the US drink green tea, encouraging people to consume more of it could have significant health benefits, the researchers write in their paper, published online in the American Journal of Clinical Nutrition.
Still, one US expert cautioned that the effect found in the Chinese study was small. The research team pooled the results of 14 randomised trials in which participants drank green tea or took an extract for periods ranging from three weeks to three months, or were assigned to a placebo group.
On average, green tea reduced total cholesterol by 7.2 mg/dL compared to placebo. LDL cholesterol dropped by a mean of 2.2 mg/dL, or slightly less than 2%.
There was no effect on high density lipoprotein levels.
The cholesterol-lowering effects of green tea may be due to catechins, which decrease the absorption of cholesterol in the gut, according to the researchers.
However, the cholesterol reduction with green tea is pretty small, cautioned Nathan Wong, who runs the heart disease prevention program at the University of California, Irvine.
He said green tea "should not be recommended in place of well-proven cholesterol-lowering medicines for people with high cholesterol".
Some researchers have raised concerns over possible side effects from heavy consumption of green tea or green tea extracts. For instance, there have been a few dozen reports of liver damage, and green tea may also reduce the effectiveness of some medications.
Still, Wong said smaller amounts "could be a useful component of a heart-healthy diet", with benefits that may go beyond its effect on cholesterol.
(Reuters Health, Eric Schultz July 2011 )