Eating at least 30 grams of dietary fibre a day reduces the risk of cancer of the bowel, according to two major studies published at the weekend.
The benefits are strongest for fibre obtained from grains, cereals and fruits.
Doctors in the United States and Europe have separately reached this conclusion after carrying out independent large-scale population studies of a possible link between a high-fibre diet and a reduced risk of colon cancer. There had been some controversy about the benefits of fibre following at least three other studies, published over the past four years, that found no protective effect of fibre against the development of colorectal cancer.
The US study, part of a large-scale cancer screening trial, compared the fibre intake of 34,000 people without colon polyps (non-malignant growths that are precursors of bowel cancer) with 3,600 patients who had at least one polyp in the large bowel. The results show that people with the top 20 per cent dietary fibre intake had one quarter the risk of developing a polyp compared with people in the bottom 20 per cent for fibre intake.
The European Protective Investigation into Cancer (EPIC) consortium, which also published results in the current issue of the Lancet, looked at the association between fibre intake and the incidence of colorectal cancer in over half a million people, aged 25 to 70 years, from 10 European countries, including Italy, Spain, Greece and several Scandinavian states. The Republic is not part of the consortium.
After following up the trial participants for 4½ years, it found that the top 20 per cent of people for fibre intake had their risk of colon cancer reduced by a quarter. The EPIC trial calculated the daily dietary fibre intake offering the greatest benefit at 35 grams per person.
In an editorial accompanying the research, nutritional experts from the University of Auckland, New Zealand, write that "eating a diet rich in plant foods - in the form of fruit, vegetables and whole grain cereals - probably remains the best option for reducing the risk of colon cancer and for more general health protection".