Müller-Lissner SA et al. (2005) Myths and misconceptions about chronic constipation. Am J Gastroenterol 100: 232–242

The problem of chronic constipation is complicated by 'myths and misconceptions', according to Müller-Lissner and colleagues. In their recent review, they have examined the quality of evidence supporting common beliefs about the condition.

Data from several studies suggest that a lack of dietary fiber is unlikely to be the cause of constipation in most patients. Although some individuals may benefit from increasing their fiber intake, this approach may make symptoms worse in patients with severe constipation. It is commonly believed that increasing fluid intake can alleviate the problem, but no evidence was found to support this, except in dehydrated patients. Regarding the chronic use of laxatives, the authors found that recommended doses are unlikely to cause harm and that patients rarely develop tolerance to these agents. The concept of 'rebound constipation' after stopping laxatives was not supported by the literature and this therapy did not appear to be addictive.

Dolichocolon—an elongated but not dilated colon—should not be considered a cause of constipation, say the authors, and there is no evidence that shortening the colon or straightening colonic 'kinks' can alleviate symptoms. Despite the lack of evidence supporting the concept of 'autointoxication', whereby various diseases are caused by the absorption of toxins from the bowel, the practice of colonic cleansing is not uncommon.

In summary, the review demonstrates that several commonly held beliefs about chronic constipation—some of which affect treatment strategies—are not supported by scientific evidence.