Colorectal (bowel) cancer is common worldwide but is especially prevalent in industrialised countries. Genes, diet and lifestyle all seem to be important in the development of bowel cancer. Several communities with low bowel cancer rates have diets that are rich in fibre. Increasing the levels of fibre in the diet in industrialised countries might therefore help to reduce the rate of bowel cancer. However, the review found that increasing fibre in a western diet for two to four years did not lower the risk of bowel cancer. Studies using both longer-term trials and higher dietary fibre levels may be needed.