Green tea polyphenols in the prevention of colon cancer

Abstract

Several plant-based nutrients and non-nutrients that can inhibit mutagenesis and proliferation have been identified. Some of the most promising nutrients identified as chemopreventive agents in colon cancer prevention include isoflavones, curcumin, calcium, vitamin D and more recently Green tea polyphenols (GTP). In addition to inhibiting mutagenesis and proliferation, these compounds are relatively non-toxic, are of low cost and can be taken orally or as a part of the daily diet. Epidemiological and laboratory studies have identified epigallocatechin gallate (EGCG) in green tea polyphenols (GTP), as the most potent chemopreventive agent that can induce apoptosis, suppress the formation and growth of human cancers including colorectal cancers (CRC). It is only logical then, that future clinical studies should focus on examining the efficacy of phytochemicals such as EGCG in cancer chemoprevention as an alternative to pharmacological agents, especially in populations where administration of COX-2 inhibitors, Aspirin and NSAIDS is contraindicated. The goal of this review is to provide the rationale, and discuss the use of EGCG in GTP as a chemopreventive agent for prevention of colon carcinogenesis and present evidence for the efficacy and safety of these agents based on epidemiological, animal, in vitro studies and Phase I clinical trials.