Eating a diet high in fibre could reduce the risk of colorectal cancer, research published in the British Medical Journal (BMJ) claims.
The study hopes to provide further support for public health recommendations to increase fibre intake, particularly cereal fibre and whole grains (including oatmeal, brown rice and porridge), to help prevent colorectal cancer.
An analysis of almost two million participants claimed to show a "clear gradient" in the level of risk associated with dietary fibre intake.
UK and Dutch researchers found each 10 g/day increase in the intake of total dietary fibre and cereal fibre was associated with a 10% reduction in risk of colorectal cancer.
Adding three servings (90 g/day) of whole grains was associated with about a 20% reduction.
Yet, overall reductions in the risks of colorectal cancer were deemed to be "small".
In addition, no "significant evidence" was found associating fruit or vegetable fibre with a lower risk of colorectal cancer.
"In summary, our meta-analysis suggests that a high intake of dietary fibre, particularly from cereal and whole grains, is associated with a reduced risk of colorectal cancer," said the researchers.
Despite this conclusion, the research team has pointed out further studies are needed to clarify the results for different types of fibre and subsites within the colorectum, and in populations with different lifestyles and dietary characteristics.
Professor Anne Tjønneland from the Danish Cancer Society agrees.
She said research is still needed to "explain the biological mechanisms responsible for the beneficial effects of these foods in detail and to study barriers to increasing the intake of wholegrain products."