New evidence published in the British Medical Journal (BMJ) has shown that a diet high in fibre, particularly from cereal and whole grains, is associated with a reduced risk of colorectal cancer. The study was funded as part of the WCRF/AICR Continuous Update Project (CUP).
Strengthening the evidence
The CUP aims to keep the evidence on the links between food, nutrition, physical activity, weight management and cancer current and up to date. This study adds to the findings of the WCRF/AICR Second Expert Report (2007). The updated meta-analyses of 16 prospective cohort studies showed that a 10g/day increase in intake of total dietary fibre was associated with a 10% reduction in risk of colorectal cancer. On the basis of its findings, an independent panel of leading experts – convened by WCRF/AICR – met earlier this year to review the evidence. The panel was so convinced, after taking all the information into account, that they subsequently upgraded the strength of evidence for fibre and bowel cancer from ‘probable’ to ‘convincing’ protective effect.
This provides further support to the existing WCRF/AICR Recommendations for Cancer Prevention to eat mostly foods of plant origin. Relatively unprocessed cereals (grains) and/or pulses (legumes) are a good natural source of fibre and can be found in foods such as wholegrain breads, cereals, oatmeal, brown rice and porridge.
Sources of dietary fibre
The study also looked at the source of dietary fibre and showed an association for cereal fibre and wholegrains but not for fibre from fruits and vegetables. Previous research from the CUP has shown a reduction in risk of colorectal cancer with high intake of fruit and vegetables, suggesting a potential role of other components in fruit and vegetables other than fibre.
WCRF International uses the phrase “foods containing fibre” rather than just “fibre”. This is because we are keen to emphasise that while the evidence is very strong for high fibre foods such as wholegrains, we do not recommend getting fibre from dietary supplements. There is no strong evidence that fibre in supplements has the same effect on bowel cancer risk as foods containing fibre.
Importance of this research
Colorectal cancer is the third most common cancer worldwide with 1.2 million new cases diagnosed each year. Increasing intake of dietary fibre will not only contribute to a reduced risk of colorectal cancer, but is also likely to reduce the risk of cardiovascular disease, type II diabetes, overweight and obesity.