Chronic constipation reconsid... Health Article

Eat fiber, right? Wrong, according to experts who say that many beliefs about constipation are off base.

In the United States, constipation results in about 2.5 million doctor visits a year. It’s one of the most common — and commonly misunderstood — gastrointestinal complaints. Many people think, for example, that anything less than a daily bowel movement means you’re suffering from constipation. But the frequency of bowel movements normally varies a great deal. Some people in perfectly fine gastro-intestinal health have several movements a day, while others have that many in a week. The defining characteristic of constipation is not how frequently you have a bowel movement but the passage of hard, dry stools, often with pain and considerable effort.

Length doesn’t matter Doctors used to think that having an extra-long colon led to constipation. It doesn’t. Study results vary, but the normal length seems to range from 4 to 6 feet.

In early 2005, a group of specialists debunked myths and misconceptions about constipation in an article written for the American Journal of Gastroenterology. Here is some of what they had to say:

1. Constipation isn’t caused by an extra-long colon. People used to have their colons surgically shortened and sometimes removed entirely because doctors thought an elongated colon caused constipation. The theory was that a long colon would prolong “stool residence time.” It was wrong and doctors stopped performing the operations decades ago, but the idea that colon length is associated with constipation still lingers.

2. Increasing fiber intake may not help, and could make matters worse. A high-fiber diet makes stool softer and increases its bulk — in healthy people. So if the problem is new and seems temporary, the textbook advice to increase fiber intake makes some sense. But studies of fiber for chronic constipation have been inconsistent. It may help some, but others get worse symptoms from high fiber intake.

3. Increasing fluid intake may not help. Adding or removing even a small amount of water changes the consistency of feces, so increased fluid intake would seem to help with constipation. But researchers have found that drinking more fluids has only modest effects on the stools of volunteers, whether they are healthy or chronically constipated. But increased fluid intake does help when constipation is caused by dehydration.

4. Physical activity seems to help, but the evidence is uncertain. The message on physical activity is mixed. There’s little doubt that exercise helps keep the bowels moving, and many studies have found that active people are less likely to suffer from constipation. But we don’t know whether physical activity deserves the credit. And the authors said there is no evidence that more severe constipation is helped by physical activity.

5. There’s little evidence that long-term laxative use is harmful. Most sources recommend against long-term use of stimulant laxatives, which act directly on the intestine to increase the secretion of water and, in some cases, trigger more vigorous intestinal movement. That advice is based partly on concern about damage to intestinal nerves and muscles. But the evidence for such damage is based only on conflicting animal data and uncontrolled human studies. It’s possible that laxatives have been blamed wrongly for the nerve and muscle abnormalities that caused the constipation in the first place.

Some reservations

Especially for garden-variety problems like constipation, tradition and accepted wisdom often hold sway because good, controlled studies are rare. It’s always good to challenge assumptions and set a high standard for proof. That’s what science-based health and medical care is all about.

But some experts commenting on the article have quoted the maxim that “absence of proof is not proof of absence.” Although the authors cite studies that directly refute conventional wisdom, their main theme is the dearth of evidence either way. That’s troubling, but not as troubling as solid evidence that contradicts standard advice.

Moreover, many of the debunking statements and studies involve chronic or severe constipation. Eating more fiber, drinking fluids, and exercise may very well work for mild or temporary cases. Besides, they have plenty of other health benefits.