Teasing out tea’s heart-healthy effect

From New Orleans, at a meeting of the American Heart Association

Previous studies have suggested that people who drink several glasses of black tea each day are less likely to develop heart disease than are people who don’t drink tea. Joseph A. Vita of the Boston University School of Medicine reports that he may have found a mechanism for tea’s apparent protective effect.

In a study, Vita found that drinking black tea increases the ability of the blood vessels in a person’s arm to dilate. Blood vessel dilation is hampered in people with atherosclerosis—or stiff and clogged arteries—and this condition can trigger heart attacks and strokes.

Vita used a blood pressure cuff to constrict and then release blood flow in 50 middle-age men and women with atherosclerosis. He found that when the volunteers drank two 8-ounce cups of black tea, their blood vessels immediately improved their ability to respond to changes in blood flow.

During the next month, each person drank four 8-ounce cups of either tea or water daily. Then, they switched to the other beverage for another month. Before the switch, and at the end of the study, the researchers monitored blood vessel function. They found that blood vessels dilated more readily when a person had been drinking tea regularly than when he or she was drinking water. Tea had no effect on resting blood vessel size or a person’s blood pressure, heart rate, cholesterol, or blood sugar.

“This is a very intriguing study,” says Ronald M. Krauss of the University of California, Berkeley. However, he cautions, the study is small and the results should be confirmed, “so don’t go out and start drinking tea to save your heart.”