Dietary fibre and the risk of colorectal cancer (Editorial)2001; 48: 587-9

Not all dietary fibre is as good for us as we have been led to believe, says an editorial in Gut. Instead of protecting us from colon cancer, writes Dr Robert Goodlad of the Imperial Cancer Research Fund, some fibre and fibre supplements could actually increase our risk of developing the disease, according to recent research.

We have become wedded to the idea that fibre is protective since a British missionary surgeon, Denis Burkitt, observed in the early 1970s that rural Africans had much less colon cancer than affluent Westerners, says Dr Goodlad.

But it might not be fibre itself that is so beneficial, says Dr Goolad, but rather the range of minerals and vitamins found in high fibre foods, and what a high fibre diet suggests we are not eatingfat and excess calories, for example. We need to look more closely at different types of fibre and their impact, he says.

While the benefits of fibre have been much touted, fibre can also bind to harmful materials, and has the potential to stimulate cell division, a process involved in the development of cancer.

Boosting fibre intake to recommended levels with dietary fibre supplements, which are now available as "functional foods" "gives us the potential to have the worst of both worlds," writes Dr Goodlad. This is because they tend to be fermented rapidly, leading to a massive and potentially dangerous surge in the numbers of bacteria that colonise the colon.

The actions of fibre on the gut are complex, says Dr Goodlad, and we should be wary of oversimplifying. But we should also be open minded about them, he writes. "I still advocate eating plenty of fibre, but only if it comes from fibre rich foods, and would favour fruit and vegetables over cereal fibre,"

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BMJ Specialty Journals
11-Apr-2001