Too much fibre harms the colon
researcher. When fibre ferments in the gut, it can increase your
risk of developing...
Too much fibre may be not be good for us, warns a British cancer researcher. When fibre ferments in the gut, it can increase your risk of developing colon cancer, says Robert Goodlad, the principal scientific officer for the Imperial Cancer Research Fund's Histopathology Unit in London. "For a long time, it's been widely accepted that high-fibre diets are good for you, especially with regards to colon cancer. However, the literature has been a bit more ambiguous," writes Goodlad in an editorial in the current issue of Gut, published by the British Medical Journal. "If you look at animal studies from papers that have come out in the past few years, the findings divide basically into three categories. There is some good effect, or there is no effect or … there is an enhancing effect on the development of cancer." The idea that a high fiber, low fat diet could reduce the risk of colon cancer was challenged last year when a US National Cancer Institute study of nearly 2,000 people failed to show any reduction in the development of precancerous polyps. In October, 2000 a team of European researchers reported in the British journal The Lancet that fibre as an additive to food did not seem to prevent the formation of potentially cancerous polyps in the colon. "There's a lot of effects from fiber, but those effects are quite complicated," says Goodlad."First there are a lot of materials that can be classified as fibre. We traditionally think of fibre as an inert bulk, something humans can't digest. In that case, the fibre goes through the small intestine into the large intestine where it is fermented by bacteria, causing a dangerous surge in the number of bacteria that colonise the colon." "There's a whole range of effects when that happens, one of them being that fermenting releases short-chain fatty acids, which are metabolised by the cells lining the colon, stimulating cell division. The more cells divide, the more the possibility of carcinogenic effects," Goodlad continued. He maintained however that fibre is still an important aspect of a diet and that the source is significant. Goodlad advocated that fibre in the diet should come from fibre-rich food such as fruits and vegetables and less so from cereals. Source: Healthscout and Gut magazine.
