Two-probiotic blend shown to ease non-constipated IBS symptoms in adults, study finds

A two-probiotic blend may ease symptoms of irritable bowel syndrome (IBS) in adults who do not have constipation, according to a randomized trial. Researchers tested Lactobacillus acidophilus LA-5 and Bifidobacterium animalis ssp lactis BB-12 in a 200-person study and found that those who received the probiotic combination reported greater improvement in IBS symptoms than those given a placebo, beginning within a month and continuing through the study period.

In the trial, 200 adults aged 18 to 65 with IBS without constipation were assigned to receive either the probiotic blend or a placebo for 84 days. Participants took two pills daily and kept daily symptom diaries, with regular follow-ups to monitor progress. Of the participants, 99 were in the probiotic group and 101 received placebo. About two-thirds of participants in both groups had IBS-D, where diarrhea is the dominant symptom, while the remainder had IBS-M, a mixed presentation. The average participant was about 39 years old, and roughly two-thirds were men. Up to 40 participants underwent stool tests to measure changes in the gut microbiome before and after the intervention.

By day 28, 19 percent of probiotic participants showed symptom improvement compared with 9 percent on placebo, a difference of about 75 percent in relative terms. At day 56, improvement rose to 37 percent in the probiotic group versus 24 percent in the placebo group, a 43 percent relative difference. At the end of the study, 41 percent of those taking the probiotic blend reported improvement, compared with 37 percent receiving placebo. Researchers also found that participants in the probiotic group had higher levels of nine groups of beneficial gut bacteria by the study’s end, a change the team says may underlie the symptom relief observed. The study’s authors described the results as the first evidence for the efficacy and safety of Lactobacillus acidophilus LA-5 and Bifidobacterium animalis ssp lactis BB-12 as a probiotic blend for non-constipated IBS in adults.

The study, published last month in the Journal of Gastroenterology and Hepatology, comes amid rising concern about IBS in both the United States and United Kingdom. Recent research indicates IBS has become roughly 28 percent more common over the past decade, a trend some experts attribute to greater awareness and evolving evidence that the gut microbiome can be affected by viral infections, including Covid-19. Probiotics have become a popular option; surveys estimate that about one in 20 Americans use probiotic supplements regularly. LA-5 and BB-12 are sold as dietary supplements, with monthly costs ranging roughly from $15 to $60 depending on the brand.

While the results are encouraging, the researchers noted several caveats. The trial’s duration was relatively short, and findings relied on self-reported symptoms rather than independent clinical measures. Further research is needed to determine which patients are most likely to benefit and to confirm long-term safety and efficacy across diverse populations.