Which probiotic strains can treat IBS? Original paper

Irritable bowel syndrome (IBS) is characterized by recurrent abdominal pain, bloating, and changes in bowel habits, which may include diarrhea- or constipation-predominant symptoms. Treatment guidelines for IBS recommend the use of probiotics,^[1] but choosing an appropriate supplement can be challenging due to the diversity of available probiotics, the unique efficacy of different strains, and the lack of randomized controlled trials for some strains.

This meta-analysis of 40 randomized controlled trials examined which probiotic strains are effective for the treatment of IBS in more than 3,000 participants. The primary outcomes were change in the global IBS-Symptom Severity Score, improvement of global IBS symptoms reported by a physician or participant interview/diaries, change in abdominal pain scores, frequency of reporting abdominal pain relief, change in bloating scores, and change in quality-of-life scores. The secondary outcome was the number and types of adverse reactions.

The dosage of the probiotic was typically 1x10⁹–1x10¹⁰ CFU/day for 4–8 weeks. There were no significant differences in the frequency or types of adverse reactions in the probiotic and placebo groups.

The following probiotics reduced the global IBS-Symptom Severity Score in at least 2 studies:

• Bifidobacterium infantis 35624
• Bacillus coagulans MTCC5260
• A 7-strain mixture of Bifidobacterium brevis 11858BP, Bifidobacterium lactis 11903BP, Bifidobacterium longum 11860BP, Lactobacillus acidophilus 11858BP, Lactobacillus rhamnosus 11868BP, Lactobacillus plantarum 11867BP, and Streptococcus thermophilus 11870BP
• A 4-strain mixture of Lactobacillus rhamnosus GG, Lactobacillus rhamnosus LC705, Bifidobacterium breve Bb99, and Propionibacterium shermanii

The following probiotics reduced abdominal pain scores in at least 2 studies:

• Bacillus coagulans MTCC5260
• Lactobacillus rhamnosus GG
• The 7-strain mixture described above
• An 8-strain mixture of Bifidobacterium breve DSM24732, Bifidobacterium longum DSM24736, Bifidobacterium infantis DSM24737, Lactobacillus acidophilus DSM24735, Lactobacillus plantarum DSM24730, Lactobacillus paracasei DSM24733, Lactobacillus delbruckii subspecies bulgaricus DSM24734, and Steptococcus thermophilus DSM24731

The following probiotics improved the reporting frequency of abdominal pain relief in at least 2 studies:

• Bacillus coagulans MTCC5260
• Lactobacillus plantarum 299v
• Saccharomyces boulardii CNCM I-745
• Saccharomyces cerevisiae CNCM I-3856

In the subgroup analysis by IBS type, the 7-strain mixture reduced abdominal pain scores in people with IBS-diarrhea. Additionally, there was no difference between adults and children in the ability of probiotics to reduce abdominal pain score.

Of the 64 different types of probiotics screened, 50 had an insufficient number of randomized controlled trials to be included in the analysis. Therefore, it can’t be concluded that these probiotics aren't effective for treating IBS, but more studies are needed to validate their efficacy.