Affecting up to one in five Americans, irritable bowel syndrome (IBS) is a common gastrointestinal ailment that may cause abdominal pain, bloating, diarrhea and constipation, particularly in women. Therefore, it’s important to get patients with IBS effective treatments. Yet, because the cause (or causes) of the disorder have never been fully understood, that has been difficult to accomplish.
Some scientists believe the malady stems from bacterial overgrowth in the stomach. Support for this theory comes from two large studies published in the New England Journal of Medicine, in which researchers assigned 1,260 participants with moderate IBS to receive either rifaximin — an antibiotic that is not rapidly absorbed and stays in the gut longer — or a placebo, three times daily for two weeks. Forty-one percent of patients who took the antibiotic experienced significant symptom improvement compared to 32 percent of patients taking placebo. More importantly, their relief was sustained for up to ten weeks.
Some health experts believe stress and certain foods may trigger IBS, among other factors (including bacteria, as noted above). Perhaps this is why some patients may not react positively to the antibiotic. Acknowledging this, ACSH’s Dr. Elizabeth Whelan observes: “It’s a very puzzling disease because the demographic suggests that anxiety and other psychological problems may contribute to the cause of IBS symptoms more than just physiological factors.”
That rifaximin did work in a certain cohort of patients, however, demonstrates that “there may be an antimicrobial basis for IBS treatment for some people after all,” says ACSH’s Dr. Josh Bloom. “The parallels to ulcers and H. pylori infection are more than obvious here. The theory that microbes in the stomach and upper intestine might contribute to ulcers was widely scorned in the 1980s — but research eventually confirmed that link, and now ulcers are treated with combinations of drugs including antibiotics. Someday, the same may be said about IBS.”
What strikes Dr. Mark Pimentel, lead study researcher from Cedars-Sinai Medical Center-Los Angeles, as most important is that the antibiotic extended relief for up to ten weeks following treatment, which means “we’ve actually touched on the cause of IBS, as opposed to just covering up symptoms.”