Green tea in chemoprevention of cancer

The concept of prevention of cancer using naturally occurring substancesthat could be included in the diet consumed by the human population isgaining increasing attention. Tea, next to water, is the most popularlyconsumed beverage in the world and it is grown in about 30 countries.Abundant data, amassed from several laboratories around the world in thelast ten years, provided convincing evidence that polyphenolic antioxidantspresent in tea afford protection against cancer risk in many animal-tumorbioassay systems. The epidemiological studies, though inconclusive, havealso suggested that the consumption of tea is associated with a loweredrisk of cancer. Much of this work has been done on green tea; less is knownabout black tea. Green tea contains many polyphenolic antioxidants, and(-)-epigallocatechin-3- gallate (EGCG) is the key polyphenolic antioxidantbelieved to be responsible for most of the cancer chemopreventiveproperties of green tea. This review will discuss these effects and themolecular mechanisms associated with the biological response to green-teapolyphenols.