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June 23, 2003 -- It has long been suspected that tea helps lower cholesterol, and now new research offers some of the first evidence that this is true. But you probably won't see a benefit by drinking only an extra cup or two a day.
The study shows that people with moderately high cholesterol who took a supplement containing extracts of green and black tea for 12 weeks had mean reductions in low-density lipoprotein (LDL) cholesterol of 16%. (LDL cholesterol is the type of cholesterol in the blood that is responsible for plaque buildup in the arteries.) While this is not as large a reduction as that typically seen with statin drugs, it is comparable to many non-statin treatments, lead researcher David Maron, MD, tells WebMD.
Although an earlier study involving a green tea extract alone failed to lower cholesterol levels, Maron says it is not yet clear if the addition of the black tea extract made the difference in this trial.
Protective Properties
Tea is rich in polyphenols, which are believed to have antioxidant, anti-cancer, anti-bacterial, and anti-viral properties. Green tea has the polyphenol catechin. Black tea, which is fermented green tea, contains the pigment of polyphenols known as theaflavins that are produced during the fermentation process.
Each 375-mg capsule of the combined extract used in the study contained the amount of theaflavin and catechin equal to that in 35 cups of black tea or seven cups of green tea, respectively. The extract is marketed by Nashville, Tennessee-based nutraceutical company Nashai Biotech, Inc., which funded the study.
The trial included 240 men and women in China with moderately high cholesterol who were already following low-fat diets. Half the participants took the tea extract for 12 weeks and the other half took placebos. The study is published in the June 23 issue of Archives of Internal Medicine.
Maron, who is an associate professor of medicine at Nashville's Vanderbilt University Medical Center, says he was surprised by the large reduction in LDL cholesterol levels in the tea-extract group.
"These findings obviously have to be confirmed in larger studies with longer follow-up," he says. "But for centuries tea has been thought to have medicinal uses, and here is a study that shows an apparent therapeutic value."
Reading the Tea Leaves
Among the studies Maron would like to see are a similar trial evaluating green tea extract without theaflavins, one looking at more diverse populations, and a trial combining statins with the tea extract.
He says there are plenty of apparent health benefits to drinking green or black tea, but drinking a few cups a day probably won't impact cholesterol levels.
Researcher Mohsen Meydani, DVM, PhD, who is studying the anti-cancer properties of tea, says there is growing clinical evidence that drinking moderate amounts of tea can protect the heart. He cites a study from Boston University that concluded that drinking four cups of black tea a day can reverse abnormal blood vessel functioning that leads to heart attack and stroke.
"At this point, I think it is most prudent to recommend drinking tea rather than taking tea extract supplements to get the benefits, because we are still very early in these studies," says Meydani, who is a professor of nutrition at Tuft University's Friedman School of Nutrition Science and Policy.
"Drinking tea is an enjoyable thing, and just about everyone can drink a few cups a day."
SOURCES: Archives of Internal Medicine, June 23, 2003. David J. Maron, MD, Division of Cardiovascular Medicine, Vanderbilt University Medical Center, Nashville, Tenn. Mohsen Meydani, DVM, PhD, professor of nutrition; director, vascular biology laboratory, Friedman School of Nutrition Science and Policy, Tufts University, Boston.