Introduction In the WCRF/AICR 2^nd expert report, it was concluded that foods containing dietary fibre probably decreases colorectal cancer risk. As part of the WCRF Continuous Update Project, we updated the associations between dietary intake of total fibre and by dietary sources, and colorectal cancer incidence.

Methods Relevant prospective studies were identified in PubMed until May 2010. Random effect dose-response meta-analyses were performed on total dietary fibre, and specifically fruit, vegetable, legume, and cereal fibres and colorectal cancer risk. Heterogeneity between studies was assessed by I² statistic.

Results Total dietary fibre intake was inversely and statistically significantly associated with colorectal cancer. The summary RR for 10 g/day increase was 0.90 (95% CI 0.86 to 0.94, 15 studies). Similar association was observed in cereal fibre (RR_10g/day=0.90, 95% CI 0.83 to 0.97, 8 studies) but not in fruit fibre (RR_10g/day=0.93, 95% CI 0.82 to 1.05, 9 studies), vegetable fibre (RR_10g/day=0.98, 95% CI 0.91 to 1.06, 9 studies), and legume fibre (RR_10g/day=0.62, 95% CI 0.27 to 1.42, 4 studies). There was no evidence of heterogeneity between studies.

Conclusion The overall results of cohort studies indicate that high intake of dietary fibre is inversely associated with decreased colorectal cancer risk. The protective effect is more evident for fibre from cereal sources. More studies in different populations are needed to confirm this observation.