Instead of protecting us from colon cancer, writes Dr Robert Goodlad of the Imperial Cancer Research Fund, some fiber and fiber supplements could actually increase our risk of developing the disease, according to recent research.
We have become wedded to the idea that fiber is protective after 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.
However, it might not be fiber itself that is so beneficial, says Dr Goodlad, but rather the range of minerals and vitamins found in high-fiber foods. In addition, a high-fiber diet suggests we are not eating fat and excess calories, for example. We need to look more closely at different types of fiber and their impact, he says.
Some fiber may actually increase the risk of developing colon cancer.
|Dr Robert Goodlad|
While the benefits of fiber have been much touted, fiber can also bind to harmful materials, and has the potential to stimulate cell division, a process involved in the development of cancer.
Boosting fiber intake to the recommended levels with dietary fiber 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 colonize the colon.
The actions of fiber 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 fiber, but only if it comes from fiber-rich foods, and would favor fruit and vegetables over cereal fiber."