Dietary Fiber Intake Modifies the Positive Association between n-3 PUFA Intake and Colorectal Cancer Risk in a Caucasian Population

Background: The association between dietary fat intake and the risk of colorectal cancer (CRC) is still unclear. Objectives: We analyzed whether intakes of dietary polyunsaturated fatty acids (PUFAs) and saturated fatty acids (SFAs) were associated with CRC risk and whether these associations were modified by dietary fiber (DF) intake. Methods: This study was embedded in the Rotterdam Study, a prospective cohort study among subjects aged y In = 4967). At baseline, diet was measured by a food-frequency questionnaire. CRC events were diagnosed on the basis of pathology data and medical records. Multivariable adjusted HRs were calculated using Cox regression models. Results: During a mean follow-up period of 14.6 y, we identified 222 incident cases of CRC. There was no association between total PUFA, n-6 (omega-6) PUFA, or SFA intake and CRC risk. n-3 PUFA intake was associated with an increased risk of CRC Itertile 3 vs. tertile 1: HR = 1.44(95% Cl: 1.02, 2.04), P-trend = 0.04). When data were analyzed by food sources, only n-3 PUFAs from nonmarine sources were associated with an increased risk of CRC. A significant interaction between n-3 PUFA and DF intakes was found (P-interaction = 0.02). After stratification by median DF intake, an increased risk of CRC caused by n-3 PUFA intake was observed in participants with a DF intake less than the median [tertile 3 vs. tertile 1: HR = 1.96 195% Cl: 1.20, 3.19), P-trend = 0.01]. No association was observed in subjects with DF intake equal to or higher than the median. Conclusions: This study suggests that intake of n-3 PUFAs by adults is associated with an increased risk of CRC, which may be driven mainly by sources other than fish. Moreover, a complex interaction with DF intake may be present.