Black tea may improve blood vessel health
vessels, suggests a small study that found the drink to dilate the
vessels allowing faster blood flow.
The study offers an insight into the previously reported benefits of tea on heart health, which have suggested that tea may act rather on cholesterol-lowering or help stop blood clotting.
Research published in the October 2003 issue of the Journal of Nutrition showed that five servings of black tea per day reduced LDL cholesterol by 11.1 per cent and total cholesterol by 6.5 per cent in mildly hypercholesterolemic adult study participants.
Another study in Saudi Arabia last year found that people who drank more than six cups of black tea daily lowered their risk of coronary heart disease by more than half, compared to those who were not regular tea drinkers.
It is thought that the flavonoids in tea may lower blood pressure and also have benefits on cholesterol.
However the new study by researchers from Osaka City University in Japan, published in this month's American Journal of Cardiology, (vol 93, issue 11, pp 1384-1388), suggests that flavonoids may also directly improve the health of blood vessels.
The team measured the blood flow capacity in 10 healthy men after drinking either black tea or another caffeinated beverage. They found that coronary flow velocity reserve (CFVR), which reflects how much blood-flow can speed up when demands are put on the heart, improved two hours after the men drank black tea.
The control group did not see a similar effect. The team concluded that "acute black tea consumption improves coronary vessel function".
