Researchers at Mayo Clinic have found that a high-dose probiotic formulation can meaningfully alter gut chemistry in patients struggling with chronic diarrhea caused by bile acid malabsorption. In a randomized controlled trial of 24 participants, those who took an eight-strain probiotic for just three weeks showed a significant reduction in fecal primary bile acids, particularly a compound called chenodeoxycholic acid, compared to those who received a placebo.

What Is Bile Acid Malabsorption and Why Does It Matter?

Bile acid malabsorption is a condition in which the body fails to properly reabsorb bile acids in the intestines. These acids, which help digest fats, end up in the colon where they can trigger diarrhea and other digestive problems. The condition is also linked to increased intestinal permeability, faster movement of stool through the colon, and changes in the composition of gut bacteria. Because the microbiota play a key role in regulating bile acid levels, researchers hypothesized that probiotics might help restore balance.

How Did the Study Work?

The Mayo Clinic team enrolled 24 adults with biochemically confirmed bile acid malabsorption. Participants were randomly assigned to receive either the De Simone formulation eight-strain probiotic, delivered at a dose of 900 billion colony-forming units (CFUs) via two sachets taken three times daily, or an identical-looking placebo powder. The treatment lasted 21 days, and 22 participants completed the trial.

The researchers measured several outcomes, including changes in fecal bile acid levels, microbiome composition, stool consistency, and intestinal permeability. The primary focus was on whether the probiotic could reduce the percentage of primary bile acids in stool samples.

What Were the Key Findings?

The results were encouraging. Participants who received the probiotic showed a statistically significant reduction in the percentage of fecal primary bile acids, while the placebo group actually experienced an increase. The reduction was driven primarily by lower levels of chenodeoxycholic acid in stool. Additionally, the composition of the gut microbiome differed significantly between the probiotic and placebo groups after treatment, with the probiotic-specific bacterial species accounting for the difference.

However, the study did not find significant differences between groups in several other measures, including stool frequency, stool consistency, ease of passage, or intestinal permeability. Both treatments were well tolerated, with no serious adverse events reported.

What Do These Results Mean for Patients?

The findings suggest that probiotics may offer a microbiome-based approach to managing bile acid malabsorption. By introducing beneficial bacterial strains, the probiotic appears to shift the gut environment in ways that reduce problematic bile acid levels. This is important because it addresses the root cause of the problem rather than simply masking symptoms.

"The study demonstrated promising preliminary data in improving biochemical parameters among individuals with bile acid malabsorption. Future research with a larger sample size and longer duration treatment is required to further appraise the therapeutic effect of this probiotic preparation," the authors stated.

Study authors, Division of Gastroenterology and Hepatology, Mayo Clinic

What Are the Limitations?

The researchers acknowledged several important caveats. The sample size was small, with only 22 participants completing the trial. The three-week treatment period may have been too short to detect effects on symptoms like stool consistency or frequency. Additionally, while all enrolled participants had a prior diagnosis of bile acid malabsorption, only 12 of the 24 showed continued evidence of altered bile acid metabolism at the start of the study, which could have masked the true effects in some subgroups.

Steps to Understanding Probiotic Treatment for Digestive Issues

• Biochemical Testing: Before starting any probiotic treatment, patients should undergo testing to confirm bile acid malabsorption, including serum and fecal measurements that show elevated bile acid levels.
• Probiotic Formulation: Not all probiotics are the same; the study used a specific eight-strain formulation at a high dose of 900 billion CFUs, taken three times daily for three weeks.
• Microbiome Monitoring: Tracking changes in gut microbiome composition through stool analysis can help determine whether a probiotic is working as intended.
• Symptom Tracking: Keeping a detailed log of stool frequency, consistency, and other digestive symptoms helps assess whether biochemical improvements translate to clinical benefit.

What Comes Next?

The Mayo Clinic team emphasized that larger, longer studies are needed to confirm these findings and determine whether the biochemical improvements eventually lead to symptom relief. The current trial was published in Alimentary Pharmacology and Therapeutics in 2026 and represents an important early step in understanding how targeted probiotic interventions can reshape the gut microbiome to address specific digestive disorders.

For patients with chronic diarrhea due to bile acid malabsorption, these results offer hope that a microbiome-based treatment might become a viable option. However, anyone considering probiotic therapy should consult with a gastroenterologist to determine whether they are a good candidate and to ensure proper testing and monitoring.