yet in others, acupuncture was no better than a “sham” version of acupuncture used for comparison.

“It’s difficult to interpret the results of the review,” said lead researcher Eric Manheimer, of the Center for Integrative Medicine at the University of Maryland School of Medicine.

for now, he told Reuters Health, “I think the evidence is equivocal.”

IBS is a digestive disorder that causes repeated bouts of abdominal cramps, bloating, and either diarrhea or constipation. It’s different from the similar-sounding inflammatory bowel disease — an umbrella term for ulcerative colitis and Crohn’s disease, two more-serious digestive disorders that damage the lining of the colon.

In many cases, IBS can be managed with diet changes, along with anti-diarrheal medication or, for constipation, laxatives or fiber supplements.

but people with tougher-to-treat IBS may need more. There are a few drugs for the condition — including alosetron (Lotronex), which works on nerves to relax the colon, and lubiprostone (Amitiza), which helps with constipation.

Doctors sometimes also prescribe low-dose antidepressants, anti-anxiety medications or drugs called antispasmodics, which may help with abdominal pain.

but those drugs are often limited in their effectiveness, and can have side effects.

So researchers are looking at different non-drug options. Two — namely, cognitive behavioral therapy and hypnosis — have proven effective for some people in clinical trials.

a fairly small number of studies have begun looking at acupuncture. and so far, Manheimer’s team found, those trials have yielded mixed results.

In their review, the researchers found five clinical trials that tested “true” acupuncture against a sham version of the procedure.

some studies use sham procedures to try to account for the “placebo effect” — where people feel better simply because they expect a treatment to work.

overall, Manheimer’s team found, none of the five trials showed that real acupuncture was any better than the fake version when it came to improving patients’ ratings of their symptoms or quality of life.

on the other hand, five trials done in China did find that patients reported bigger gains from acupuncture when it was tested against certain medications — which included certain anti-diarrheal, antispasmodic and anti-inflammatory drugs.

but there are limitations to both types of studies, Manheimer said.

with the trials that pitted acupuncture against drugs, the patients were recruited at hospitals for traditional Chinese medicine.

“So it’s possible that patients’ expectations played a role” in acupuncture’s higher success odds, Manheimer explained. That is, many may have believed acupuncture to be effective, or had a preference for it over medication.

with the sham-acupuncture trials, the study groups tended to be small, which may have limited their ability to pick up small benefits of true acupuncture, the researchers say.

There’s also debate over what makes for a good sham version of acupuncture. In some studies, it may involve inserting needles in the skin at sites that are not considered acupuncture points according to traditional Chinese medicine.

In others, it means using a dull needle that doesn’t penetrate the skin.

“It’s not clear that they (shams) are all inert,” Manheimer said.

That means some sham acupuncture tactics may have biological effects that are close to the real thing. no one is sure how acupuncture works, but some research suggests the needle stimulation triggers the release of pain- and inflammation-fighting chemicals in the body — even if the acupuncture doesn’t strictly follow traditional principles.

Of the five trials in this review, two were judged as having sham acupuncture that might have had real biological effects. but that doesn’t explain why the other three studies showed no benefit, the researchers say.

NOT a ‘GO-TO’ TREATMENT

In the future, Manheimer said it might be helpful to do trials that compare acupuncture against other treatments, but do it with a more general population of IBS sufferers than the Chinese studies used.

it would also be a good idea, he said, to measure patients’ expectations going into the study. That way, researchers can look at whether people who expected to improve were more likely to report benefits from acupuncture.

“This is an interesting study,” said Jeffrey M. Lackner, an associate professor at the University at Buffalo School of Medicine in New York, who was not involved in the work.

In the U.S., he noted, acupuncture would not be considered a “go-to” IBS treatment right now anyway.