Dietary fiber intake and risk of colorectal cancer: A pooled analysis of prospective cohort studies

Yikyung Park, David J. Hunter, Donna Spiegelman, Leif Bergkvist, Franco Berrino, Piet A. Van Den Brandt, Julie E. Buring, Graham A. Colditz, Jo L. Freudenheim, Charles S. Fuchs, Edward Giovannucci, R. Alexandra Goldbohm, Saxon Graham, Lisa Harnack, Anne M. Hartman, David R. Jacobs, Ikuko Kato, Vittorio Krogh, Michael F. Leitzmann, Marjorie L. McCulloughAnthony B. Miller, Pirjo Pietinen, Thomas E. Rohan, Arthur Schatzkin, Walter C. Willett, Alicja Wolk, Anne Zeleniuch-Jacquotte, Shumin M. Zhang, Stephanie A. Smith-Warner

Research output: Contribution to journalArticlepeer-review

392 Scopus citations


Context: Inconsistent findings from observational studies have continued the controversy over the effects of dietary fiber on colorectal cancer. Objective: To evaluate the association between dietary fiber intake and risk of colorectal cancer. Design, Setting, and Participants: From 13 prospective cohort studies included in the Pooling Project of Prospective Studies of Diet and Cancer, 725 628 men and women were followed up for 6 to 20 years across studies. Study- and sex-specific relative risks (RRs) were estimated with the Cox proportional hazards model and were subsequently pooled using a random-effects model. Main Outcome Measure: Incident colorectal cancer. Results: During 6 to 20 years of follow-up across studies, 8081 colorectal cancer cases were identified. For comparison of the highest vs lowest study- and sex-specific quintile of dietary fiber intake, a significant inverse association was found in the age-adjusted model (pooled RR=0.84; 95% confidence interval [CI], 0.77-0.92). However, the association was attenuated and no longer statistically significant after adjusting for other risk factors (pooled multivariate RR=0.94; 95% CI, 0.86-1.03). In categorical analyses compared with dietary fiber intake of 10 to <15 g/d, the pooled multivariate RR was 1.18 (95% CI, 1.05-1.31) for less than 10 g/d (11% of the overall study population); and RR, 1.00 (95% CI, 0.85-1.17) for 30 or more g/d. Fiber intake from cereals, fruits, and vegetables was not associated with risk of colorectal cancer. The pooled multivariate RRs comparing the highest vs lowest study- and sex-specific quintile of dietary fiber intake were 1.00 (95% CI, 0.90-1.11) for colon cancer and 0.85 (95% CI, 0.72-1.01) for rectal cancer (P for common effects by tumor site=.07). Conclusions: In this large pooled analysis, dietary fiber intake was inversely associated with risk of colorectal cancer in age-adjusted analyses. However, after accounting for other dietary risk factors, high dietary fiber intake was not associated with a reduced risk of colorectal cancer.

Original languageEnglish (US)
Pages (from-to)2849-2857
Number of pages9
JournalJAMA - Journal of the American Medical Association
Issue number22
StatePublished - Dec 14 2005

ASJC Scopus subject areas

  • Medicine(all)


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