Use of a heat-inactivated form of the probiotic Bifidobacterium bifidum (B bifidum) MIMBb75 (SYN-HI-001) was associated with significant reduction in abdominal pain as well as relief of symptoms in patients with irritable bowel syndrome (IBS) for at least 50% of the treatment period. These findings were published in Lancet Gastroenterology & Hepatology.
Enhancing the gut barrier is a useful treatment approach for patients with IBS. However, the efficacy of viable probiotics is highly strain-specific, with only a few strains having been shown to significantly alleviate IBS symptoms. In addition, safety concerns have been raised for specific patient groups who are susceptible to infection. B bifidum MIMBb75 is one of a few probiotic strains that have been shown to be effective in the treatment of IBS. In this double-blind, placebo-controlled trial study, researchers evaluated the efficacy of non-viable, heat-inactivated (HI) B bifidum MIMBb75 (SYN-HI-001).
A total of 443 participants were treated at 20 primary care and referral centers in Germany from April 2016 to February 2017. Most patients were in their early 40s, and approximately 70% were women. 1:1 randomization allocated 222 participants to receive 2 placebo capsules (placebo group) while 221 participants received 2 capsules with a combined total of 1 × 10⁹ nonviable B bifidum HI-MIMBb75 cells (B bifidum group) to be taken orally once a day for 8 weeks. Patients recorded their pain levels and other IBS parameters daily. Median follow-up was 71 days. The primary composite endpoint was at least 30% improvement of abdominal pain and adequate relief of overall IBS symptoms being fulfilled in at least 4 of 8 weeks during treatment.
Results showed that the composite primary endpoint was reached by 34% of the patients in the B bifidum group compared to 19% in the placebo group, leading to a risk ratio of 1.7 (95% CI 1.3-2.4, P=0.0007). A total of 60% of patients in the B bifidum group reported adequate symptom relief, defined as a Likert score of 3 or less, compared to the 44% in the placebo group. No serious adverse events occurred in the B bifidum group. There were 7 adverse events suspected to be tied to the study product and 8 in the placebo group. No deaths were reported in either group. The most commonly reported adverse event was abdominal pain (both representing less than 1% of the groups). Tolerability was rated very good or good by 91% of individuals in the B bifidum HI-MIMBb75 group versus 86% in the placebo group.
A limitation of the study was the considerable placebo response, with a primary endpoint response rate of 19% in the control group.
The authors concluded that their findings are the first demonstration of substantial and clinically relevant efficacy of nonviable bacteria in the treatment of IBS. They stress that more research must be performed to understand the applications of nonviable bacterial strains in IBS and potentially in other gastroenterological diseases.
Andresen V, Gschossmann J, Layer P. Heat-inactivated Bifidobacterium bifidum MIMBb75 (SYN-HI-001) in the treatment of irritable bowel syndrome: a multicentre, randomised, double-blind, placebo-controlled clinical trial (published online April 8, 2020). Lancet Gastroenterol Hepatol. doi.org/10.1016/S2468-1253(20)30056-X