Associations between dietary fiber and colorectal polyp risk differ by polyp type and smoking status.

Fu Z, Shrubsole MJ, Smalley WE, Ness RM, Zheng W
J Nutr. 2014 144 (5): 592-8

PMID: 24572038 · PMCID: PMC4084407 · DOI:10.3945/jn.113.183319

The association of dietary fiber intake with colorectal cancer risk is established. However, the association may differ between cigarette smokers and nonsmokers. We evaluated this hypothesis in a large colonoscopy-based case-control study. Dietary fiber intakes were estimated by self-administered food frequency questionnaire. Unconditional logistic regression analysis was used to estimate ORs and 95% CIs with adjustment for potential confounders. Analysis also was stratified by cigarette smoking and sex. High dietary fiber intake was associated with reduced risk of colorectal polyps (P-trend = 0.003). This association was found to be stronger among cigarette smokers (P-trend = 0.006) than nonsmokers (P-trend = 0.21), although the test for multiplicative interaction was not statistically significant (P = 0.11). This pattern of association was more evident for high-risk adenomatous polyps (ADs), defined as advanced or multiple ADs (P-interaction smoking and dietary fiber intake = 0.09). Among cigarette smokers who smoked ≥23 y, a 38% reduced risk of high-risk ADs was found to be associated with high intake of dietary fiber compared with those in the lowest quartile fiber intake group (P-trend = 0.004). No inverse association with dietary fiber intake was observed for low-risk ADs, defined as single nonadvanced ADs. Cigarette smoking may modify the association of dietary fiber intake with the risk of colorectal polyps, especially high-risk ADs, a well-established precursor of colorectal cancer.

MeSH Terms (17)

Adenomatous Polyps Adult Aged Case-Control Studies Colonic Polyps Colonoscopy Colorectal Neoplasms Dietary Fiber Female Humans Male Middle Aged Precancerous Conditions Risk Factors Risk Reduction Behavior Smoking Tennessee

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