Warning: Green Tea Blocks Effect Of Anti-Cancer Drug
Green tea supplements have been found to block the anti-cancer activity of the drug Velcade, used as a chemotherapy agent for multiple myeloma and mantle cell lymphoma. The study, conducted by University of Southern California (USC) researchers found that EGCG in green tea completely renders the anti-cancer effect of the lymphoma drug useless.
The study, available online from the journal Blood, came as a complete surprise to the researchers. Green tea is popular among cancer patients, and is widely used to combat the effects of chemotherapy.
Lead author Axel H. Schönthal, PhD, associate professor in the Department of Microbiology and Immunology at the Keck School of Medicine of USC, says, "Our hypothesis was that GTE or EGCG would enhance the anti-tumor effects of Velcade, and that a combination of GTE with Velcade (or EGCG with Velcade) would turn out to be a superior cancer treatment as compared to treatment with Velcade alone. Our finding that GTE [green tea extract] or EGCG blocked the therapeutic action of Velcade was completely unexpected."
The scientists used mice to study how Velcade and green tea extract interact. They found that the EGCG molecule and the Velcade molecule bind together, disallowing Velcade to target cancer cells.
The study cannot be replicated in humans because of the potential for harm. However, the researchers say their findings that green tea extract blocks the therapeutic effect of Velcade is important for cancer patients.
"The most immediate conclusion from our study is the strong advice that patients undergoing cancer therapy with Velcade must avoid green tea, and in particular all of its concentrated products that are freely available from health food stores," says Dr. Schönthal.
The authors warn that green tea extract may make patients being treated for lymphoma feel better, "while in reality, Velcade simply wasn't active in the first place."
Cancer patients being treated for lymphoma with Velcade should be warned about the potentially detrimental effects of green tea and green tea supplements.