Breath Test Helps Sniff Out Irritable Bowel Syndrome

From the WebMD Archives

Dec. 13, 2000 -- Up to 80% of all irritable bowel syndrome sufferers may be infected with bacteria that overgrows in the intestines. And researchers found that a special breathalyzer test can detect the condition, which is treatable with antibiotics.

"This is very dramatic, in my opinion," says lead author says Mark Pimentel, MD, whose study appears in the December issue of the American Journal of Gastroenterology. "If we get rid of the overgrowth [of bacteria], patients get dramatically better."

Approximately 20% of the adult population suffers from irritable bowel syndrome. The condition, which is characterized by bloating, abdominal pain, diarrhea, and/or constipation, affects twice as many women as men.

Pimentel and colleagues tested more than 200 people who had symptoms of irritable bowel syndrome. For the breath testing, patients first were required to swallow a special kind of syrup. The machine then took a sample of their breath every 15 minutes for three hours.

The test, which tracks the level of gases in the air you exhale, isn't new. Doctors have used it for decades to check for bacterial infections in people who have had bowel surgery or other intestinal problems.

"Nobody had actually looked at [the test] before in a person with a normal bowel," says Pimentel, assistant director of the Gastrointestinal Motility Program at Cedars-Sinai Medical Center in Los Angeles. "The thing that's striking about irritable bowel is there is always bloating, gas, and distention. The only way gas can be created in the intestine is to have bacteria present."

But he stresses that the bacteria isn't an infection. On the contrary, it's actually normal to have bacteria in your body, but it's supposed to stay in your colon. It doesn't cause problems until it overgrows and gets into an area where food is absorbed into the body.

Approximately 78% of people in the study had positive breath tests, meaning they had definite overgrowth of the bacteria in their intestines. Those who were positive were then treated with antibiotics for 10 days. When they returned, they were again tested to see if the bacteria was still present. Of people in whom the bacteria was completely gone, 48% also no longer had symptoms of irritable bowel syndrome.

Pimentel says, "We think [overgrowth of bacteria] is probably the cause of irritable bowel syndrome and therefore should become a target for more study."

But a researcher who reviewed the study for WebMD says the authors may have jumped the gun.

William E. Whitehead, PhD, says he doesn't doubt that the patients had an overgrowth of bacteria that was causing their symptoms, but he does doubt that they actually had irritable bowel syndrome.

"The majority of them were referred for the test because their doctors suspected that they had bacterial overgrowth," says Whitehead, head of the gastroenterology and physiology laboratory at the University of North Carolina-Chapel Hill School of Medicine.

He says that it may be a coincidence that so many of the patients met the criteria for irritable bowel syndrome. The only way to know for sure how many people with true irritable bowel syndrome have treatable bacterial overgrowth as the source of their problems is to conduct larger studies using the breath test.

But Whitehead says the study may help uncover a group of patients who have been until now misdiagnosed and mistreated. "While there are some questions about how best to interpret the findings, the authors have nevertheless pointed out that a significant number of patients who are currently classified as [irritable bowel syndrome] have a treatable cause of their symptoms," he says.