NEW YORK, Mar 31 (Reuters Health) -- A compound found in green tea can inhibit angiogenesis, the process in which blood vessel growth is stimulated. The finding suggests that the compound may be useful in fighting malignant tumors, which must form new blood vessels in order to grow.
In the April 1st issue of Nature, Drs. Yihai Cao and Renhai Cao, of the Karolinska Institute in Stockholm, Sweden, report "that green tea, and one of its components, epigallocatechin-3-gallate (EGCG), significantly prevents the growth of new blood vessels in animals."
The investigators found EGCG inhibited the formation of new blood vessels in laboratory culture dishes. And in a study of mice, drinking green tea was found to inhibit the growth of new blood vessels in the cornea of the eye. Blood vessel length and the area of vascularization were reduced by 55% and 70%, respectively, in tea-drinking mice compared with controls.
The researchers conclude that drinking green tea inhibits angiogenesis, an effect that may be beneficial in the prevention of cancers as well as other angiogenesis-dependent diseases, such as diabetic retinopathy -- an eye disease that is a common cause of blindness.
The new findings may explain the observed preventive effects of green tea on a variety of tumors in humans, the researchers suggest.
In a phone interview, Cao told Reuters that two or three cups of tea per day would be the human equivalent of the amount of tea given to the mice.
"Long-term consumption is very important. It not only applies to tea, but to other angiogenesis inhibitors as well, You need long-term use to stop blood vessel growth," he said.
The researchers warn that where angiogenesis is important, as in pregnancy or in patients with healing wounds, people should not drink large amounts of tea.
SOURCE: Nature 1999;398:381-382.
