MONDAY, July 9, 2001 (HealthDayNews) -- Need to keep those arteries unplugged? Try black tea.
Doctors at the Boston University School of Medicine found in a new study that heart patients who drank four cups of black tea a day for a month had greatly improved blood circulation.
Healthy people's arteries open 13 percent more when their blood flow is stimulated. But people with heart disease whose blood flow is stimulated only get a 6 percent increase in their artery opening, says study author Dr. Joseph A. Vita.
But after drinking the tea, the heart patients' arteries opened by 10 percent.
"You couldn't say the [heart patients' circulation] was normalized, but they were substantially better," Vita says.
The effects of the black tea were comparable to blood circulations improvements achieved by cholesterol-lowering drugs, exercise and, according to the results from another of Vita's recent studies, vitamin C. Black tea contains flavonoids, antioxidants that are linked with the reduction of low-density lipoproteins (LDL), the so-called bad cholesterol, in the blood.
"It's not a miracle drug, but [it] is comparable to other interventions," he adds.
Vita notes that you probably have to keep drinking the tea to enjoy its benefits.
"Flavonoids have a short life," Vita says. "You need to continuously ingest these kinds of foods for effect."
The results of the study appear in the most recent Circulation: Journal of the American Heart Association.
Howard Sesso, a Harvard Medical School medical instructor, calls the finding "interesting." But, he says, "the real question becomes whether it has an application for primary [those who have never had heart disease] prevention."
The aim of the study, Vita says, was to test the effects of the tea on the inner lining of the blood vessels, which is called the vascular endothelium. This inner lining is what produces substances that regulate the dilation and contraction of the vessels, ensuring appropriate blood flow, preventing clots and inflammation in the vessel wall. It is this lining that is often impaired in those with heart disease.
In the study, Vita and his colleagues chose 50 men and women who had heart disease; their average age was 55. All had undergone surgery to have a heart artery unblocked or had an artery that was at least 70 percent blocked. All were on heart drugs and were stable at the time of the study.
Half of the study participants were asked to drink four, 8-ounce cups of black tea a day for four weeks, while the other 25 people drank the same amount of water. Then the two groups switched, so that over an eight-week period, all 50 were tested for the effects of consuming black tea compared to water.
Their blood flow was measured through an ultrasound of an artery in their arm. Both immediate and long-term measurements showed that the patients' dilation was about 10 percent when they drank tea, and there was no change after water consumption.
Vita is continuing his study of the vascular endothelium in hopes that it will provide clues to predicting heart disease risk.
The study was partially funded by grants from the National Institutes of Health and the American Heart Association.
Sesso says that while the study is valid, it's still unclear what impact black tea will have on reducing your risk of heart disease.
"At this stage of the game ... moderation is the key," he says, suggesting that you drink only a small amount of black tea if you'd like to try to cut that risk.
What To Do: Black tea offers some of the same benefits as other drinks, like purple grape juice and red wine, that contain the antioxidants called flavonoids. For an interesting article on the health benefits of flavonoids, you can visit University of California at Davis. Information about the health benefits of different kinds of tea can be found at the Colorado State University Cooperative Extension.
