Chemopreventive effect of green tea (Camellia sinensis) against cigarette smoke-induced mutations (SCE) in humans

Abstract

Green tea (Camellia sinensis) is consumed daily between the meals or after meals in Japan and other Asian countries. In recent years, green tea and its major polyphenolics have been demonstrated to prevent chemically induced tumors in a variety of experimental animal models system. The exact mechanism(s) of its anticarcinogenic activity remains to be elucidated, but green tea polyphenolics have demonstrated antimutagenic, anticarcinogenic, antioxidant, and antipromotional effects, including inhibition of Phase I and inducing Phase II enzymes. Enzyme activities of glutathione peroxidase, catalase, and quinone reductase, and glutathione S-transferase are also induced. However, a paucity of green tea effects in humans prompted us to investigate antimutagenic effects of green tea against smoke-induced mutation in humans. Chemopreventive effects of green tea and coffee among cigarette smokers were examined in 52 clinically healthy male subjects between 20-51 years of age. Blood specimens were obtained from non-smokers (Group I), smokers (II), smokers consuming green tea (III), and smoker/coffee drinkers (IV). The mean years of cigarette smoking (> 10 cigarettes/day) of Groups II, III, and IV ranged from 13.4-14.7 years. Daily intake of green tea and coffee was 3 cups/day/6 months (III and IV). The frequencies of sister-chromatid exchange (SCE) in mitogen-stimulated peripheral lymphocytes from each experimental group were determined and statistically analyzed. SCE rates were significantly elevated in smokers (9.46 +/- 0.46) vs. non-smokers (7.03 +/- 0.33); however, the frequency of SCE in smokers who consumed green tea (7.94 +/- 0.31) was comparable to that of non-smokers, implying that green tea can block the cigarette-induced increase in SCE frequency. Coffee, by contrast, did not exhibit a significant inhibitory effect on smoking-induced SCE.