This Probiotic Nearly Doubled Weekly Bowel Movements in a New Trial

Functional constipation is one of those conditions that's miserable, common, and stubbornly hard to treat well. A new randomized, double-blind, placebo-controlled trial out of China suggests a single, well-characterized probiotic strain might do more than just get things moving, it may also be nudging the gut-brain axis in a measurable way.

Probio87 Nearly Doubles Weekly Complete Bowel Movements

Researchers running the trial at Deyang People's Hospital enrolled 104 adults with functional constipation and randomly assigned them to receive either Lactiplantibacillus plantarum Probio87 or a placebo for 12 weeks. Of the 104 randomized, 101 completed the study, 51 in the probiotic group and 50 on placebo.

The headline result: by week 8, people taking Probio87 were having 5.62 complete spontaneous bowel movements per week on average, compared with 2.94 in the placebo group, a statistically significant difference (p<0.001) that held at 5.06 versus 3.08 by week 12. Using the standard clinical benchmark of more than three complete bowel movements per week, 100 percent of the probiotic group met that threshold at week 8, compared with 64 percent on placebo. Rome IV symptom scores, a widely used constipation severity measure, and PAC-QOL, a quality-of-life scale specific to chronic constipation, both improved significantly and consistently favored the probiotic group throughout the trial.

Constipation Patients and the Case for Targeting the Gut-Brain Axis

Functional constipation affects a meaningful share of adults worldwide, and the people living with it often deal with more than physical discomfort, anxiety, low mood, and poor sleep frequently travel alongside chronic bowel symptoms. That's part of what makes this trial notable: alongside the bowel movement data, the researchers also tracked scores on the HAMD-24, a standard depression and anxiety rating scale, and found significant improvements in the probiotic group specifically in the anxiety and somatization, sleep, and psychomotor retardation domains.

To try to explain that overlap, the team measured gene expression in participants' blood at week 8. The probiotic group showed increased expression of BDNF, a protein tied to brain cell growth and mood regulation, alongside decreased expression of several genes linked to inflammation and neuroendocrine signaling, including IL-1beta, CD117, CXCR5, IDO1, DBH, and MLNR. None of that proves the probiotic is directly acting on the brain, but it's a concrete, measurable signal consistent with the idea that gut bacteria can influence the body's inflammatory and neuroendocrine state in ways that reach beyond digestion.

A Randomized, Double-Blind Design Backed by Genomic Safety Checks

This wasn't a loosely controlled supplement study. It was randomized and double-blind, meaning neither participants nor researchers knew who was getting the real probiotic during the trial, which limits the placebo effect and researcher bias that plague a lot of gut-health research. The trial is also registered (ChiCTR2300075360), which means its design was locked in publicly before the results came in.

The researchers also ran genomic safety checks on the Probio87 strain itself, and reported no clinically relevant antimicrobial resistance or virulence genes, alongside normal hematological, hepatic, and renal parameters across participants, with no serious adverse events reported. Funding came entirely from Chinese public and hospital sources, the Sichuan Provincial Department of Science and Technology, Deyang People's Hospital, the Deyang Bureau of Science and Technology, the China Medical Foundation, and the Sichuan Provincial Administration of Traditional Chinese Medicine. No commercial or industry funder was involved, and the authors explicitly declared no competing interests.

A Single-Center Trial With an Inferred, Not Proven, Brain Link

The trial has real limits worth naming. It was conducted at a single hospital, so it hasn't yet been independently replicated elsewhere, and single-center results don't always hold up when tested in different populations or clinical settings. The gene-expression findings, while intriguing, come from peripheral blood, not direct measurements of brain tissue or brain activity, so the "gut-brain axis" framing is an inference based on known biological pathways rather than something the study directly observed in the brain itself. And the follow-up window was 12 weeks, so there's no data yet on whether the bowel or mood benefits persist after people stop taking the probiotic, or whether long-term use carries any downsides.

Where This Research Goes Next

The obvious next step is replication in a larger, multi-center trial, ideally one that also tracks participants after they stop taking the probiotic to see how durable the effects are. Researchers interested in the gut-brain connection specifically will likely want direct neuroimaging or cerebrospinal fluid markers in future work, rather than relying on peripheral blood gene expression as a proxy for what's happening in the brain. For now, the trial adds a genuinely well-controlled data point to a growing body of research suggesting that specific, well-characterized probiotic strains, not probiotics as a vague category, may offer real, measurable relief for functional constipation, with a mood and gut-brain angle that's worth chasing further.

For context on how this fits into the broader probiotics-for-GI-symptoms literature, a related randomized controlled trial of Lactiplantibacillus plantarum strains published in the Journal of the American College of Nutrition similarly found strain-specific benefits for gastrointestinal function, and trade press coverage of the Probio87 trial itself has already picked up on the mental-wellbeing angle.

References

1. Fan Zheng, Yong Yang, Yu Zhan, et al. (2026). Lactiplantibacillus plantarum Probio87 supplementation improves functional constipation and is associated with peripheral gene-expression responses related to inflammation and the gut–brain axis: a randomized, double-blind, placebo-controlled trial. Frontiers in Nutrition. https://doi.org/10.3389/fnut.2026.1876944
2. Ruma G. Singh, Fumiki Aoki, Maria Rodriguez-Palmero Seuma, et al. (2025). Efficacy of Probiotic Supplementation with Lactiplantibacillus plantarum Strains on Gastrointestinal Tract Function – A Randomized Controlled Trial. Journal of Dietary Supplements. https://doi.org/10.1080/19390211.2025.2507610