Is there a fibre-depleted aetiology for colorectal cancer? Experimental evidence.

In 1971, Denis Burkitt put forward his now famous hypothesis of a fibre-depleted aetiology for colorectal cancer. This was based on his careful clinical observations of the difference in patterns of diseases between Western and traditional African societies. He noted the rarity of colorectal cancer in African countries compared to the West and found that African diets were generally higher in dietary fibre and lower in refined carbohydrates. Since these pioneering observations there have been numerous epidemiological studies but many have failed to support Burkitt's attractive hypothesis. The purpose of this review is to examine the role of dietary fibre in the animal model of colon cancer and to assess critically the findings in the light of current knowledge of the theory of carcinogenesis. The findings from the studies of the experimental model of colon cancer did not support the theory of a fibre-depleted diet as a causative factor in the aetiology of colorectal cancer in man. However, the experimental evidence did suggest that an increase in dietary fibre does have a role in protection from this disease. It was concluded that in colorectal cancer, the effect of a fibre-depleted diet was through a mechanism of promotion (co-carcinogenesis) and that the protective effect of a high fibre diet was by an anticarcinogenic mechanism.