More Fiber May Not Mean Fewer Colon Cancers – (11-09-00)

More Fiber May Not Mean Fewer Colon Cancers

Some evidence has surfaced suggesting that fiber may not be as protective as previously thought. However, there is an important fact that the researchers seemed to have missed. Fiber is not digested by humans, but rather is digested by friendly bacteria into several short chain fatty acids. One of these SCFAs is butyrate, which has been shown to help coloncytes thrive. It could very well be possible that, in order for fiber to be protective, a healthy balance of bacteria is also needed.

Lancet 2000;356:1300-1306,1286-1287 Fiber supplementation may increase the risk of colorectal adenoma recurrence, whereas calcium supplementation may reduce the risk of recurrence of these lesions. Epidemiologic studies of the value of dietary fiber, vegetables, whole-grain cereals, and calcium in preventing colorectal adenomas and cancer have yielded inconsistent results, the authors explain. Animal studies, though, suggest potent antitumor activity of such soluble, mucilaginous fibers as ispaghula husk. Dr. Bonithon-Kopp told Reuters Health that these results do not signal a need to change recommendations about prudent diets. “The increase in risk of adenoma recurrence was found after a supplementation with a soluble fibre which is not found in usual diet,” she emphasized. “Furthermore, this deleterious effect was observed only on the early stages of the adenoma-cancer sequence. We don’t know if such an effect would be observed on later stages [such as] on malignant transformation. Thus, usual recommendations regarding dietary fibre intake remain valid.”