Drinking a cup of tea makes blood vessels work better within two hours, dilating the arteries and improving blood flow, according to Boston researchers. This may ultimately have a beneficial effect on the heart.
In the study, researchers had 50 men and women with known heart disease drink four cups of black tea a day for 4 weeks. The participants also drank four glasses of water each day, and avoided other kinds of tea and red wine. The study participants were then monitored for another four weeks in which they drank water instead of tea.
Using ultrasound to measure blood flow in the forearm, the investigators found that the tea helped blood vessel function. While blood vessels normally dilate 11%, those with heart disease only dilated 6%. Tea drinking--but not water--restored blood vessel response to near-normal levels.
The researchers said the effects were not due to the caffeine in the tea. Antioxidants are known to improve blood vessel function, and black tea contains significant amounts of flavonoids, which are antioxidants.
Further studies will be required before tea drinking can be recommended to patients as a way to protect against coronary artery disease and stroke.
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