Foods and food groups associated with the incidence of colorectal polyps: the Adventist Health Study.

Colorectal cancer (CRC) is a leading cause of cancer death in the United States. The majority of CRC arise in adenomatous polyps and 25-35% of colon adenoma risk could be avoidable by modifying diet and lifestyle habits. We assessed the association between diet and the risk of self-reported physician-diagnosed colorectal polyps among 2,818 subjects who had undergone colonoscopy. Subjects participated in 2 cohort studies: the AHS-1 in 1976 and the AHS-2 from 2002-2005. Multivariate logistic regression analysis was used to estimate the period risk of incident cases of polyps; 441 cases of colorectal polyps were identified. Multivariate analysis adjusted by age, sex, body mass index, and education showed a protective association with higher frequency of consumption of cooked green vegetables (OR 1 time/d vs. <5/wk = 0.76, 95% CI = 0.59-0.97) and dried fruit (OR 3+ times/wk vs. <1 time/wk = 0.76, 95%CI = 0.58-0.99). Consumption of legumes at least 3 times/wk reduced the risk by 33% after adjusting for meat intake. Consumption of brown rice at least 1 time/wk reduced the risk by 40%. These associations showed a dose-response effect. High frequency of consumption of cooked green vegetables, dried fruit, legumes, and brown rice was associated with a decreased risk of colorectal polyps.

Association between dietary fiber and incident cases of colon polyps: the adventist health study.

BACKGROUND: Colorectal cancer (CRC) is a leading cause of cancer death in the United States. Most cases of CRC arise in adenomatous polyps. It has been estimated that 25%-35% of colon adenoma risk could be avoidable by modification of dietary and life-style habits. METHODS: We estimated the association between total dietary fiber and fiber intake from fruits, vegetables, and grains, and the risk of physician-diagnosed colon polyps among 2818 men and women who had undergone colonoscopy. Data were drawn from 2 cohort studies-the Adventist Health Study-1 (AHS-1) of 1976 and the Adventist Health Study-2 (AHS-2) conducted from 2002 to 2005. Dietary information was obtained from the self-administered questionnaire from AHS-1, while outcome was assessed from AHS-2 data. Multivariate logistic regression analysis was used to estimate the period risk of incident cases of polyps. RESULTS: A total of 441 incident cases of colon polyps were identified. After adjusting for age, sex, body mass index, physical activity, education, and alcohol and meat consumption, total fiber intake was inversely associated with the risk of colon polyps (odds ratio [OR] for highest vs lowest quartile = 0.71, 95% confidence interval [CI] 0.51-0.99). This association showed a dose-response effect (p = .04). Analyses of various sources of fiber showed the most clear effect of fiber from vegetables including legumes (OR for highest vs lowest quartile = 0.65; 95% CI 0.47-0.90; p = .02). CONCLUSIONS: In this population comprising a high proportion of vegetarians, persons who consumed low amounts of fiber, especially fiber contained in vegetables, had a higher risk of developing colon polyps.