Good Gut 'Bugs' Help Irritable Bowel Syndrome

Probiotics Growing into First-Line IBS Treatment

By Daniel DeNoon
WebMD Medical News

Reviewed By Brunilda  Nazario, MD
on Monday, October 31, 2005

Oct. 31, 2005 - It's not a Halloween prank. Live bugs are the hottest new treatment for irritable bowel syndrome (IBS).

The "bugs" aren't insects. They're live bacteria. When bad bacteria grow in our bodies, we call them germs. Good bacteria ingested for health effects are called probiotics.

Probiotics already are in your grocery and health food store in capsules, tablets, gel caps, liquids, and in cultured yogurt products. Not every probiotic product has proven health effects. But as a medical treatment, they're more than just the latest health fad, says University of New Mexico researcher Mohamed O. Othman, MD.

Othman is one of several researchers reporting on probiotics research at this week's 70th annual scientific meeting of the American College of Gastroenterology in Honolulu.

"Probiotics now have been used in many diseases, not only IBS but also ulcerative colitis and Crohn's disease and in both children and adults with lactose intolerance," Othman tells WebMD. "It is a new field, and there is a lot of investigation going on."

Help for Some, Harm for None?

Early studies show that some specific probiotics help some IBS patients -- but not others, says gastroenterologist Jay W. Marks, MD. Marks is medical and pharmacy editor for, a WebMD company.

"Some patients with IBS respond to treatment with probiotics. But probiotics are clearly not a panacea," Marks tells WebMD. "They are not all the same. Different probiotic bacteria have different effects on the intestine. So we expect it will be important to use the right probiotic for the right patient -- which is not clear yet. We still don't know which ones are appropriate for which patients."

Even so, doctors are recommending probiotics to some IBS patients. That's because the probiotics tested in clinical trials have done no harm, says probiotics researcher Eamon Quigley, MD, of the Alimentary Pharmabiotic Center at University Cork College, Ireland.

"If probiotics are as effective as we think, the great advantage is their safety," Quigley tells WebMD. "There is no evidence of any safety issue. They have the potential to be an effective first-line therapy for IBS and other bowel symptoms in a very safe manner."

B. infantis for IBS

Quigley's team recently reported data from a study of 77 women with IBS. The researchers gave some of the women a probiotic strain called Bifidobacterium infantis 35624 -- a Proctor & Gamble product called Bifantis, sold in capsule form as Align. The other volunteers received a probiotic called Lactobacillus salivarius UCC4331 or an inactive placebo.

Women who received the lactobacillus strain did not do significantly better than those who got the placebo. But those treated with Bifantis had significantly less abdominal pain and discomfort, bloating and distention, and bowel movement difficulty.

These findings led to a larger, multicenter study of Bifantis. Quigley presented some of this study's first results at this week's ACG meeting. He reported that Bifantis normalized bowel habits for women with IBS. The probiotic worked for women with diarrhea-predominant IBS and for those with constipation-predominant IBS.

"If you look at those who were treated with [Bifantis], whether they started with loose stools or hard stools, they had normalization of bowel habits regardless of what they started out with," Quigley says.

Probiotics: A Growing Field

In their report to the ACG meeting, Othman and colleagues reviewed major clinical studies of probiotics in the treatment of IBS. There were eight studies in their review -- but Othman says that there soon will be more.

"In 1989 we looked at probiotics research, but there was only one study and it was not well known -- even though it showed promising results," Othman says. "By 1994 people started to do more and more studies. The peak is right now. Every three months you find something in the medical literature on probiotics and its use in different diseases."

In general, the studies were promising, if inconclusive. Now that probiotics seem to work in early trials, Othman says, it's time for larger studies to show exactly what they can do -- and for whom.

"For bowel disease in general, it's hard to say what the studies really show. But for IBS, a lot of patients can improve," Othman says. "I try it with a lot of my patients. Some do not respond at all. Some have a good response. I have some IBS patients who tried everything for their diarrhea without success. And after one week of probiotics, the diarrhea stops. But for other patients, we give the probiotic and nothing happens."

Othman says he has not yet given the Bifantis product to patients. He's tried a mixture of eight different bacteria (including a strain of Bifidobacterium infantis) called VSL #3 from Sigma-Tau Pharmaceuticals. He's also tried a lactobacillus GG product.

"Both of them work for some patients, and both didn't work for some patients," he says.

Why Do Probiotics Work for IBS?

Exactly how probiotics work is a question that bedevils researchers.

The most obvious theory is that the good bacteria displace bad bacteria. That appears to be part of the answer, says Marks. One thing that may affect some IBS patients is called small intestinal bacterial overgrowth or SIBO.


What is irritable bowel syndrome or IBS? See Answer

The large intestine carries a lot of bacteria -- about a billion organisms per milliliter of fluid. But the small intestine is only supposed to have 10,000 organisms per milliliter of fluid. And the small intestine is supposed to have different bacteria than the large intestine.

There's good evidence that some people with IBS have SIBO: an overgrowth of large-intestine bacteria in their small intestines. Unfortunately, Marks says, there's no simple test to detect SIBO. But patients who do have SIBO may benefit from probiotics. The good bacteria may displace the bad bacteria in the small intestine.

That's one issue. Another issue of perhaps even greater importance comes from the Quigley team's research. They find that probiotics may make subtle but important changes in the way a person's immune system works.

The immune system has built in switches that turn inflammatory immune responses on or off. This kind of immune response can be very helpful in responding to acute infection or injury. But in some people with IBS, the switch for inflammatory immune responses seems to be stuck in the "on" position. In ways that are not yet understood, probiotics turn this switch off.

"There is quite a bit of evidence that there is a change in immune function in IBS," Quigley says. "In other words, if you look in detail, you see evidence of inflammatory immune activation in IBS. Certain probiotics have potent anti-inflammatory effects that can restore the balance."

Marks is very interested in these findings, which he calls "extremely tantalizing." But he warns IBS patients that not every product sold as a probiotic is helpful.

"People should not just go to a health food store and buy any probiotic on the shelf," he says. "You want to use one that has been medically studied and that has appropriate effects. About three or four of those available have been tested. VSL #3 is the most tested, then there is lactobacillus GG, another is Flora-Q."

SOURCES: Quigley, E.M. 70th annual scientific meeting, American College of Gastroenterology, Honolulu, Oct. 28-Nov. 2, 2005. Mohamed O. Othman, MD, University of New Mexico, Albuquerque. Eamon Quigley, MD, University Cork College, Ireland. Jay W. Marks, MD, medical and pharmacy editor,

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