Inactivated Probiotic Effective Against Irritable Bowel Syndrome

A heat-inactivated, morphologically intact strain of Bifidobacterium bifidum can help alleviate symptoms of irritable bowel syndrome (IBS), a new randomized placebo-controlled trial shows.

The B. bifidum MIMBb75 strain is one of only a few probiotics with proven efficacy in IBS, according to Dr. Peter Layer of the Israelitic Hospital, in Hamburg, Germany, and colleagues. The new findings suggest "some beneficial bacterial effects are mediated independent of cell viability and can be preserved in non-viable bacterial preparations," the researchers write in The Lancet Gastroenterology and Hepatology.

An advantage of the heat-inactivated product, called SYN-HI-001, is the "far greater, temperature-independent product stability compared with viable bacteria," which should ensure better standardization regardless of local weather and climate.

To the researchers' knowledge, "this is the first time that the efficacy and safety of a non-viable bacterial strain has been investigated in a placebo-controlled study for the treatment of IBS."

With funding from Synformulas GmbH, which has patented B. bifidum MIMBb75, the researchers randomly assigned 443 adult patients meeting Rome III criteria for IBS to active treatment or placebo.

Once every day for 8 weeks, participants took two capsules containing either placebo or a total of 1 billion non-viable B. bifidum MIMBb75 cells. In all, 377 patients completed the study, with a median follow-up of 71 days.

The primary outcome was a composite response of improvement in IBS-related pain and global symptom relief, measured on a seven-point Likert scale, in at least 4 of the 8 weeks.

This endpoint was met in 74 (34%) of 221 patients in MIMBb75 group and in 43 (19%) of 222 patients in the placebo group (P=0.0007). Similarly, patients who received the inactivated probiotic were significantly more likely than those in the placebo group to report adequate symptom relief, with treatment reducing the entire symptom spectrum of all IBS subtypes.

B. bifidum MIMBb75 has "marked mucosal adhesive properties," the authors note, and this could help explain the findings since an impaired intestinal barrier is thought to be at the root of IBS.

The team concludes that the adhesive properties may "have been preserved (and even increased)" in the inactivated probiotic, and that the "non-viable form appears to reach or even to surpass the effects observed in response to the corresponding viable form."

Dr. Clifford A. Adams, managing director and part owner of Anozene, a nutrition consulting firm in Antwerp, Belgium, told Reuters Health by email, "The great advantage of using non-viable cells is that they will be much easier to store, transport and deliver to subjects."

He said the new study "could herald a major shift in the application of micro-organisms in human and animal health."

Dr. Alexander C. Ford, a professor of gastroenterology at the University of Leeds, UK, called the study "interesting" in an email to Reuters Health, adding that it was "more rigorous methodologically than many trials of probiotics to date."

He cautioned, however, that the trial was relatively short, given that IBS is a lifelong condition.

Dr. Layer did not respond to a request for comment.

—Scott Baltic

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