Diet and colorectal adenoma in Japanese males and females

PURPOSE: The purpose of this study was to assess the relationship between risk of colorectal adenoma and dietary intake of nutrients and foods. METHODS: In 1992, diet was assessed by a semiquantitative food-frequency questionnaire in a cohort of the Takayama Study in Japan. Patients were 181 male and 98 female cohort members who were newly histologically proved to have colorectal adenoma at colonoscopic examination between January 1, 1993, and December 31, 1995. Controls were 12,607 males and 15,754 females who had no history of colorectal polyp, adenoma, and cancer at baseline (1992) and were not diagnosed to have these diseases during the follow-up period. RESULTS: In males, the risk of adenoma was significantly associated with intake of animal protein and vitamin A (relative risk, 1.42; 95 percent confidence interval, 1.00-2.04; and relative risk, 1.51; 95 percent confidence interval, 1.04-2.20, for the highest vs. lowest tertiles, respectively; P for trend = 0.048 and 0.03, respectively) after controlling for age, years of smoking, and alcohol intake. A significantly inverse association was observed for carbohydrate intake after controlling for the covariates (relative risk, 0.52; 95 percent confidence interval, 0.32-0.82, for the highest vs. Lowest tertiles; P for trend = 0.02). Intakes of animal fat and cholesterol were marginally associated with risk of adenoma. CONCLUSION: Some dietary components such as animal protein and carbohydrate, which have been associated with risk of colorectal adenoma or cancer in western populations, were also associated with risk of colorectal adenoma in the Japanese population.