Irritable Bowel Syndrome : Understanding IBS

by Food and Drug Administration (FDA)

(Page 2 of 3)

IBS is one of three major "functional intestinal disorders" — a general term for conditions that show no physical evidence of disease in the intestines upon examination, and the cause of which does not show up in a blood test or an X-ray.

According to the National Institutes of Health, people with IBS seem to have colons that are more sensitive and reactive than usual, so they respond to stimuli that would not bother most people. Eating, stress, gas, depression, and other ordinary events can cause the colon to overreact. Certain medications and foods, such as milk products in lactose-intolerant people, dietary fats, corn, and wheat, are known to trigger spasms in some people. Sometimes these spasms delay the passage of stool, leading to constipation.

IBS often is mistaken for colitis and is commonly referred to as spastic colon — terms which are "inadequate, inaccurate or both," says Marvin M. Shuster, M.D., a gastroenterologist at Johns Hopkins Bayview Medical Center in Baltimore. Colitis, for example, means that the colon is inflamed, and IBS does not cause inflammation.

"Irritable bowel syndrome is the most suitable and accurate term used by doctors," Shuster says, because it emphasizes that the condition is a "motor disorder manifesting irritability" that "involves many areas of the gut."

Jeffrey Roberts, 40, has IBS flare-ups once or twice a month. Despite the pain and diarrhea he's had for 25 years, he's always been able to get around without much restriction. Still, he keeps a "bag-of-tricks-to-go" in anticipation of an emergency. Shortly after he formed an IBS self-help group, he was amazed to learn that people's lives could be affected so dramatically by IBS. "I just kept thinking, could my IBS ever get that bad?"

Marcelo A. Barreiro, M.D., a medical officer in FDA's division of gastrointestinal and coagulation drug products, explains that most people assume that the brain alone controls all activity in the body. In fact, he says, the gut has its own independent nervous system that regulates the processes of digesting food and eliminating solid waste. "There's a network of nerve cells within the wall of the gut — the gut nervous system — that does not depend on the brain for its minute-to-minute function," Barreiro says, but rather, "responds to its inputs under various conditions."

Under stress, for example, the brain sends conflicting messages to the gut that may exaggerate the irritability of the gut nervous system. Barreiro says that with IBS, the connections between the brain that is the central nervous system, and the gastrointestinal, or gut, system, also known as the enteric nervous system, "appear to be out of sync."

Douglas A. Drossman, M.D., of the University of North Carolina in Chapel Hill, emphasizes that "stress does not cause IBS," although it may aggravate the symptoms. Therefore, minimizing stress is for many, but not necessarily all people, an important part of coping with IBS.

Another Point of View

Not all doctors agree that IBS should be labeled a syndrome — a group of symptoms that collectively indicate or characterize a disease. Some physicians traditionally have considered the symptoms to be mostly psychological because they could not find something physically wrong to explain the trouble. Others, like Howard Spiro, M.D., a retired Yale University School of Medicine professor, worry that the catch-all term "IBS" has become a marketing tool that will send thousands of basically healthy people running to their doctors demanding prescriptions. Spiro, who continues his practice as a consulting gastroenterologist, believes that irritable bowel for many people is an emotional response to the troubles and incidents of everyday life, which he says have always led to digestive problems, and probably always will. "Recognizing an irritable bowel is one thing," he adds. "Deeming it the equivalent of a disease is another."

On the other hand, Spiro recognizes that some people, like Marcus, complain of abdominal pains that are far more than a simple annoyance. Marcus is often awakened by excruciating cramps about every hour in the middle of the night, and seldom, if ever, can commit to activities outside her home. Spiro believes that research behind new drugs is certainly worth reviewing in the hope that future developments will successfully calm, for whatever the reasons, an overactive intestine.

Hope Marcus, 53, has had IBS for 12 years. The severity of her condition forced her to close down a business and work from home. Until she began taking Lotronex, she couldn't leave the house. Unexpected hemorrhoid surgery in October 2000, quelled Marcus' IBS symptoms, deceiving her into thinking she was cured. When the pain and diarrhea returned four months later, "I didn't worry because I had a month's supply of Lotronex." Now that the drug is no longer available, Marcus worries constantly about the day she will use her last pill.

Drossman says that in about 65 percent of the population with IBS, the condition isn't severe enough to prompt them to see a doctor. They may have pain in the gut from time to time that bothers them, "but it's possible they may not even recognize it as a clinical condition."

In a significant number of women with IBS who have severe constipation or other bowel disorders, doctors also uncovered a history of sexual or physical abuse. Some say that such experiences may make people unusually sensitive and vulnerable to their bodily sensations.

In a recent issue of the American Journal of Gastroenterology, a relatively small study piqued the interest of many as another possibility to understanding and treating IBS. Scientists at Cedars-Sinai Medical Center in Los Angeles looked at the possibility that there may be excess bacteria in the small intestine, causing symptoms similar to IBS. Further research is being carried out to determine the mechanism by which bacterial overgrowth occurs.

Whatever the cause, doctors agree on one thing: IBS symptoms can be controlled when people work with their doctors to find the best combination of treatments.

About the Author

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