Fibre and whole grains 'reduce bowel cancer risk'
Eating more cereals and whole grains could reduce the risk of developing colorectal cancer, a BMJ study says.
Researchers from Imperial College London found that for every 10g a day increase in fibre intake, there was a 10% drop in the risk of bowel cancer.
But their analysis of 25 previous studies found that fruit and vegetable fibre did not reduce risk.
A cancer charity called for more detailed research on the quantity and type of fibre to eat.
Eating fibre and whole grains is known to help protect against cardiovascular disease, but experts say that any link with colorectal cancer is less clear because studies have not had consistent results.
Reviewing the results of all previous observational studies in this area, researchers in London, Leeds and the Netherlands analysed data provided by almost two million people.
Their conclusion, published in the British Medical Journal, is that increasing fibre intake, particularly cereal fibre and whole grains, helps prevent colorectal cancer.
Whole grains include foods such as whole grain breads, brown rice, cereals, oatmeal and porridge.
Dagfinn Aune, lead study author and research associate in the department of epidemiology and biostatistics at Imperial College London, said their analysis found a linear association between dietary fibre and colorectal cancer.
"The more of this fibre you eat the better it is. Even moderate amounts have some effect."
Adding three servings (90g per day) of whole grains to diets was linked to a 20% reduction in the risk of colorectal cancer, researchers said.
Cancer Research UK data shows that the lifetime risk of being diagnosed with colorectal cancer in the UK is estimated to be one in 14 (6.9%) for men, and one in 19 for women (5.4%).
However, the study said there was no evidence that fibre in fruit and vegetables played a part in reducing risk.
A previous study which showed a reduction in risk with high intake of fruit and vegetables suggests that compounds other than fibre in fruit and vegetables could account for this result, said the authors.
They also said that the health benefits of increasing fibre and whole grains intake was not restricted to colorectal cancer.
"It is also likely to reduce the risk of cardiovascular disease, type 2 diabetes, overweight and obesity, and possibly overall mortality," the researchers said.
Mark Flannagan, chief executive of Beating Bowel Cancer, said the research supported the charity's current advice.
"These results support what we already know about the link between dietary fibre and a reduced risk of bowel cancer, although more work is needed to clarify the quantity and types of fibre we should be eating to reduce risk.
"We recommend that people eat a healthy balanced diet that includes plenty of dietary fibre, such as grains, cereals, fruit and vegetables to reduce the risk of developing bowel cancer.
"It is encouraging to know that simple changes to your diet and lifestyle could help protect you from the UK's second biggest cancer killer."
Yinka Ebo, senior health information officer at Cancer Research UK, said the review added weight to the evidence that fibre protects against bowel cancer.
"It shows that certain sources of fibre, such as cereal and whole grains, are particularly important.
"Eating plenty of fibre is just one of many things you can do to lower your risk of developing the disease, along with keeping a healthy weight, being physically active, cutting down on alcohol, red and processed meat, and not smoking."
In an accompanying editorial in the BMJ, Professor Anne Tjonneland from the Danish Cancer Society, said whole grain products should be made more appealing to shoppers.
"To increase the intake of these foods in Western countries, the health benefits must be actively communicated and the accessibility of whole grain products greatly improved, preferably with a simple labelling system that helps consumers to choose products with high whole grain contents."
Cancer of the large bowel, also known as colorectal cancer, is a common form of cancer in developed countries - but occurs much less frequently in the developing world.