Tea contains several polyphenols called cathechins which are thought to have anti-cancer activity. They are destroyed in the brewing of black tea, but are present in green tea.

In this week's Scientific Correspondence, Jerzy Jankun of the Department of Urology, Medical College of Ohio, Toledo, Ohio, and colleagues describe how a particular cathechin found in green tea, epigallocathechin-3 gallate (EGCG), may prevent cancer or reduce tumor size by binding to and inhibiting urokinase. This proteolytic enzyme is one of the most frequently over expressed enzymes in human cancers.

Binding by EGCG prevents it from invading cells and forming metastases. An added bonus is that the amount found in a single cup of green tea is many times higher than the maximum safe doses of other known urokinase inhibitors.