There's good news for tea drinkers: a new study suggests that drinking the beverage slows the time it takes for LDL (bad cholseterol) to become oxidized, a process that is thought to be important in the formation of fatty plaques in coronary arteries. Slowing the oxidation of LDL could, in theory, reduce heart disease risk.
The oxidized LDL cholesterol is a reactive chemical that damages the arterial wall. Eventually, ordinary cholesterol and calcium and other things sit on that to form a block, which leads to thickening and obstruction of the vascular system. Tea contains flavonoids. Flavonoids are a group of polyphenolic antioxidants that are contained in vegetables, fruit, and beverages such as tea or wine. Most tea studies conducted in China or Japan focus on green tea, the type of tea most often consumed in those countries. However, in the new study the participants drank black tea, which is most often consumed in Western nations. Both teas are derived from the same plant, Camellia sinensis, but are the results of different processing methods. Green tea and black tea appear to be reasonably equivalent in terms of antioxidant properties.
American Journal of Clinical Nutrition (1997;66:261-266)