Green tea and the risk of gastric cancer in Japan.

Background: Although laboratory experiments and case-control studies have s uggested that the consumption of green tea provides protection against gast ric cancer, few prospective studies have been performed. Methods: In January 1984, a total of 26,311 residents in three municipaliti es of Miyagi Prefecture, in northern Japan (11,902 men and 14,409 women 40 years of age or older), completed a self-administered questionnaire that in cluded questions about the frequency of consumption of green tea. During 19 9,748 person-years of follow-up, through December 1992, we identified 419 c ases of gastric cancer (in 296 men and 123 women). We used Cox regression t o estimate the relative risk of gastric cancer according to the consumption of green tea. Results: Green-tea consumption was not associated with the risk of gastric cancer. After adjustment for sex, age, presence or absence of a history of peptic ulcer, smoking status, alcohol consumption, other dietary elements, and type of health insurance, the relative risks associated with drinking o ne or two, three or four, and five or more cups of green tea per day, as co mpared with less than one cup per day, were 1.1 (95 percent confidence inte rval, 0.8 to 1.6), 1.0 (95 percent confidence interval, 0.7 to 1.4), and 1. 2 (95 percent confidence interval, 0.9 to 1.6), respectively (P for trend = 0.13). The results were similar after the 117 cases of gastric cancer that were diagnosed in the first three years of follow-up had been excluded, wi th respective relative risks of 1.2 (95 percent confidence interval, 0.8 to 1.8), 1.0 (95 percent confidence interval, 0.7 to 1.5), and 1.4 (95 percen t confidence interval, 1.0 to 1.9) (P for trend = 0.07). Conclusions: In a population-based, prospective cohort study in Japan, we f ound no association between green-tea consumption and the risk of gastric c ancer. (N Engl J Med 2001;344:632-6.) Copyright (C) 2001 Massachusetts Medi cal Society.