Results of the study are published in the May 25 issue of the American Heart Association journal Circulation.
Several components of green tea leaves are known to have natural properties that counteract the harmful effects of oxidation in the blood. In fact, the principal and most powerful of these catechins or flavonoids, EGCG (epigallocatechin-3-gallate), has been shown to provide some protection against the development of inflammation, tumors and the new blood vessels that support tumor growth.
Because of the antioxidant properties of the catechins in its leaves, tea also has been seen as a potential dietary intervention for cardiovascular diseases. Oxidation, which damages the inner surfaces of arteries and encourages the formation of plaque deposits, is believed to be one factor in the development of atherosclerosis.
In fact, antioxidants have been shown to protect against plaque formation in animal studies, but results in human trials have been disappointing. This has led researchers to wonder if failure in clinical trials might be due to the short duration of treatment, the use of the "wrong" antioxidant, or other factors such as the timing of the introduction of antioxidants. Theoretically, antioxidant therapy might be effective in human trials if it is started before atherosclerosis is established.
"Most animal experiments evaluating the effects of antioxidants are started when the animals are young, while randomized clinical trials typically enroll adult patients with varying stages of plaques," said Kuang-Yuh Chyu, MD, PhD, cardiologist, first author of the article. "This discrepancy supports s
Contact: Sandra Van
Cedars-Sinai Medical Center