Dietary fibre, whole grains, and risk of colorectal cancer: systematic review and dose-response meta-analysis of prospective studiesBMJ 2011; 343 doi: https://doi.org/10.1136/bmj.d6617 (Published 10 November 2011) Cite this as: BMJ 2011;343:d6617
- Dagfinn Aune, research associate1,
- Doris S M Chan, research associate1,
- Rosa Lau, research associate1,
- Rui Vieira, data manager1,
- Darren C Greenwood, senior lecturer in biostatistics2,
- Ellen Kampman, professor of diet and cancer3,
- Teresa Norat, principal investigator1
- 1Department of Epidemiology and Biostatistics, School of Public Health, Imperial College London, St Mary’s Campus, London W2 1PG, UK
- 2Biostatistics Unit, Centre for Epidemiology and Biostatistics, University of Leeds, Leeds, UK
- 3Division of Human Nutrition, Wageningen University and Research Centre, Wageningen, Netherlands
- Correspondence to: D Aune
- Accepted 21 September 2011
Objective To investigate the association between intake of dietary fibre and whole grains and risk of colorectal cancer.
Design Systematic review and meta-analysis of prospective observational studies.
Data sources PubMed and several other databases up to December 2010 and the reference lists of studies included in the analysis as well as those listed in published meta-analyses.
Study selection Prospective cohort and nested case-control studies of dietary fibre or whole grain intake and incidence of colorectal cancer.
Results 25 prospective studies were included in the analysis. The summary relative risk of developing colorectal cancer for 10 g daily of total dietary fibre (16 studies) was 0.90 (95% confidence interval 0.86 to 0.94, I2=0%), for fruit fibre (n=9) was 0.93 (0.82 to 1.05, I2=23%), for vegetable fibre (n=9) was 0.98 (0.91 to 1.06, I2=0%), for legume fibre (n=4) was 0.62 (0.27 to 1.42, I2=58%), and for cereal fibre (n=8) was 0.90 (0.83 to 0.97, I2=0%). The summary relative risk for an increment of three servings daily of whole grains (n=6) was 0.83 (0.78 to 0.89, I2=18%).
Conclusion A high intake of dietary fibre, in particular cereal fibre and whole grains, was associated with a reduced risk of colorectal cancer. Further studies should report more detailed results, including those for subtypes of fibre and be stratified by other risk factors to rule out residual confounding. Further assessment of the impact of measurement errors on the risk estimates is also warranted.
We thank the systematic literature review team at Wageningen University for their contributions to the colorectal cancer database.
Contributors: The systematic literature review team at Wageningen University carried out the search, and selected and extracted data up to the end of December 2005. RV developed and managed the database for the Continuous Update Project. RL and DSMC did the updated literature search. RL, DSMC, and DA did the updated data extraction. DA and DSMC selected the studies and carried out the statistical analyses. DCG was statistical adviser and contributed to the statistical analyses. All authors revised the manuscript. EK was principal investigator of the Systematic Literature Reviews at Wageningen University. TN is principal investigator of the Continuous Update Project and wrote the protocol and implemented the study. DA wrote the first draft of the original manuscript. All authors had full access to all of the data in the study and prepared the manuscript. DA is guarantor. The sponsor of this study had no role in the decisions about the design and conduct of the study; collection, management, analysis, or interpretation of the data; or the preparation, review, or approval of the manuscript. The views expressed in this review are the opinions of the authors. They may not represent the views of the World Cancer Research Fund International/American Institute for Cancer Research and may differ from those in future updates of the evidence related to food, nutrition, physical activity, and cancer risk.
Funding: This work was funded by the World Cancer Research Fund (grant No 2007/SP01) as part of the Continuous Update Project.
Competing interests: All authors have completed the ICMJE uniform disclosure form at www.icmje.org/coi_disclosure.pdf (available on request from the corresponding author) and declare: no support from any organisation for the submitted work; no financial relationships with any organisations that might have an interest in the submitted work in the previous three years; and no other relationships or activities that could appear to have influenced the submitted work.
Ethical approval: Not required.
Data sharing: No additional data available.
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