Epidemiological and experimental studies on the antitumor activity by green tea extracts.

Vital statistics for Japanese people showed that the death rate from cancer, especially stomach cancer in both males and females in Shizuoka Prefecture is much lower than the average of Japanese people. We further investigated this phenomenon epidemiologically and experimentally. The results were as follows:1) The standardized mortality ratio (SMR) for cancer of all sites and stomach cancer in the midwest areas of Shizuoka Pref. where green tea is the staple product was much lower compared with the national avarage in both sexes.2) Significant differences in habitual green tea drinking of the inhabitants between “3K Town” with low SMR and “O Town” with high SMR due to stomach cancer were observed in both sexes.3) The extracts from fresh green tea leaves were effective on growth inhibitory activity against mouse sarcoma 180.These data suggest the possibility that the green tea may be capable of diminishing cancer risk.