Green Tea

The study, published in the November 2004 issue of Molecular Nutrition and Food Research evaluated the effect of green tea (5 cups per day) on 3 heavy smokers (>10 cigarettes a day) and 3 individuals who had never smoked. When the study subjects were drinking green tea, DNA damage caused by smoking was decreased, cell growth was inhibited, and cellular triggers for apoptosis (cell suicide) in abnormal cells increased.

Another larger four month study of heavy smokers involving 100 women and 33 men found that levels of urinary 8-hydroxydeoxyguanosine, a marker of free radical damage to DNA, dropped significantly in individuals drinking decaffeinated green but not black tea.

Decaffeinated green tea was especially effective in reducing DNA damage in individuals who lack the genetic ability to produce normal amounts of an enzyme called glutathione S-transferase, which plays a key role in the liver's ability to detoxify many of the carcinogens found in cigarette smoke. Individuals whose genetic inheritance does not include the GSTM1 and GSTT1 variants of the genes that instruct the cell to produce glutathione S-transferase are more susceptible to developing many different cancers. For these individuals, green tea may be especially beneficial.

Sazuka M, et al. Inhibitory effects of green tea infusion on in vitro invasion and in vivo metastasis of mouse lung carcinoma cells. Cancer Lett 1995;98:27-31.

Suganuma M, et al. Synergistic effects of (--)-epigallocatechin gallate with (--)-epicatechin, sulindac, or tamoxifen on cancer-preventive activity in the human lung cancer cell line PC-9. Cancer Research 1999;59:44-7.

Taniguchi S, et al. Effect of (-)-epigallocatechin gallate, the main constituent of green tea, on lung metastasis with mouse B16 melanoma cells lines. Cancer Lett 1992;65:51-4.

About 56,000 new cases of bladder cancer are diagnosed each year, making it the fifth most common cancer in the United States. About half of all bladder cancers are believed to be related to cigarette smoking. Bladder cancer can be difficult to detect in the early, most treatable stages, yet, when not found early, the tumors can be aggressive, and more than half of patients with advanced cancers experience recurrences. In the next phase of his research, Rao and his team will analyze urine from bladder patients, looking particularly for biomarkers associated with actin remodelling and the activation of the Rho pathway, to determine which subset of patients might benefit most from green tea.