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Heyndrickxia coagulans (formerly Bacillus coagulans / Weizmannia coagulans)
A spore-forming probiotic that survives stomach acid and needs no refrigeration. Its real evidence is in irritable bowel syndrome, where a network meta-analysis of 81 trials ranked the MTCC 5856 strain at the top for abdominal pain and stool form in IBS-D. The immune, protein-absorption and muscle-recovery claims on the label are much weaker than they look, and a meta-analysis was negative for constipation.
What the evidence says
Most B. coagulans studies are mechanism or observational rather than RCTs that measure a clinical effect — keep findings provisional.
Most evidence is from medium-quality meta-analyses and randomised trials published 2009–2026 with a typical study size of 44 participants.
Based on 30 studies · 2 meta-analyses · 20 RCTs · 3,990 total participants
Confidence
High confidenceBy outcome
A top ranking for IBS symptoms in a 81-trial network meta-analysis, backed by two decent manufacturer-run trials — but the most-cited supporting study has a failed randomisation, the immune and protein-absorption claims do not survive scrutiny, and pooled evidence is negative for constipation.
4 trials ongoing or recruiting · 13 completed on ClinicalTrials.gov
Registered trials show research momentum for B. coagulans, not proof of effect — a registration is a plan, and posted results are sponsor-reported, not peer-reviewed. They are never counted toward the evidence rating above.
Browse these trials on ClinicalTrials.govClinicalTrials.gov · as of Sep 2026
This organism has been renamed twice: NCBI now lists taxid 1398 as Heyndrickxia coagulans, with Bacillus coagulans and Weizmannia coagulans as synonyms, so all three names refer to the same bug and products may use any of them.
Unlike most probiotics it forms spores, which is why it survives gastric transit — in a dynamic in vitro stomach/small-intestine model 70% survived passage, though under those conditions fewer than 10% of the spores actually germinated, which matters because the strain only becomes metabolically active after germination.
The best-supported use is irritable bowel syndrome. A network meta-analysis of 81 randomised trials and 9,253 participants ranked B. coagulans MTCC 5856 first for abdominal pain (SUCRA 96.9%) and among the most effective for Bristol stool form in diarrhoea-predominant IBS (SUCRA 99.6%).
Two manufacturer-affiliated trials underpin that: a self-described 36-patient pilot in IBS-D at 2 x 10^9 CFU/day for 90 days (P<0.01 versus placebo for bloating, vomiting, diarrhoea, abdominal pain and stool frequency), and a 70-adult trial in functional gas and bloating where the GSRS indigestion score fell 8.91 to 3.06 against 9.42 to 8.43 on placebo (between-group P<0.001).
A separate GBI-30 6086 trial reduced daily bowel movements in IBS-D (P=0.042), though severity and quality-of-life endpoints could not be analysed because of baseline variability.
The most-cited paper of all — Hun 2009, whose title declares the probiotic 'significantly improved abdominal pain and bloating' — is the weakest: randomisation failed, baseline values differed significantly between groups, and the authors were forced into a within-group-only analysis, so it supports no valid between-group inference at all.
Beyond the gut the claims thin out fast. In older adults the strain raised Faecalibacterium prausnitzii by 0.1 log10 (P=0.03), but the IL-10 comparison BETWEEN treatments was null and there was no effect on natural killer cell activity or C-reactive protein — that is not evidence of immune support.
The amino-acid absorption work has no placebo arm, was retrospectively registered, ran roughly twenty uncorrected comparisons, and the second study's significant amino acids differ from the first's, which argues against a specific absorption effect.
The exercise-recovery paper's title overstates its own result: the muscle-damage difference was P=0.08, not significant. In children with acute diarrhoea, duration was shorter (51.3 vs 62.7 hours, P=0.011) but diarrhoea frequency was not significantly different.
And for chronic constipation, a meta-analysis found the Unique IS2 strain did NOT increase stool frequency.
In a validated dynamic in vitro model of the stomach and small intestine, 70% of the organism survived transit — the basis for its shelf-stability and its ability to reach the intestine. The same experiment found germination under 10%, and it is only after germination that the organism is metabolically active.
It is a lactic acid-producing organism. In the in vitro model, adding lactose or fructose to the meal raised cumulative lactate production slightly (+0.12-0.18 mmol), which is the proposed basis for easing symptoms in people sensitive to those sugars — but this has not been tested clinically.
In adults aged 65-80, 28 days of supplementation raised Faecalibacterium prausnitzii by 0.1 log10 cells/mL more than placebo (P=0.03) and Bacillus spp. by 0.5 log10 from baseline. The accompanying immune measures did not differ between treatments.
How B. coagulans works — from molecular targets to health outcomes. Click an edge to see supporting research.This visualization is in beta — pathways are being refined and expanded.
One 110-child trial in acute diarrhoea (ages 1-10) recorded no adverse events, using it as an adjunct to oral rehydration and zinc. That is a single study, and PubMed does not index it as a randomised controlled trial.
Tolerated in a 36-person crossover in adults aged 65-80. Expect a microbiota shift, not an immune benefit — the immune endpoints in that trial were null between treatments.
No trial has enrolled pregnant or breastfeeding women. Discuss with a clinician.
Pooled evidence is negative — a meta-analysis found the Unique IS2 strain did not increase stool frequency. Choose something else.
A general consideration for any live bacterial product. No B. coagulans trial tested concurrent antibiotic use; the pediatric diarrhoea trial co-administered oral rehydration solution and zinc, not antibiotics.
Tip: Trials up to 90 days reported laboratory parameters, anthropometrics and vital signs within the normal clinical range, and no adverse events in the bloating and pediatric trials
B. coagulans has an evidence score of 5/10 — moderate evidence based on 27 indexed studies, including 2 meta-analyses. A spore-forming probiotic that survives stomach acid and needs no refrigeration. Its real evidence is in irritable bowel syndrome, where a network meta-analysis of 81 trials ranked the MTCC 5856 strain at the top for abdominal pain and stool form in IBS-D. The immune, protein-absorption and muscle-recovery claims on the label are much weaker than they look, and a meta-analysis was negative for constipation. Representative study: PMID 36372047.
The commonly studied dose of B. coagulans is 1-2 billion CFU (spores) daily. The IBS-D and gas/bloating trials used 2 x 10^9 CFU/day of MTCC 5856 (LactoSpore); the GBI-30 6086 (BC30) studies used 1 x 10^9 CFU/day.. Individual needs vary — start at the lower end of the range and adjust based on how you respond.
Timing is flexible for B. coagulans — consistent daily use matters more than the time of day. Trials dosed once daily without specifying a time.
B. coagulans is generally well-tolerated and considered safe for most healthy adults at recommended doses. Reported side effects are uncommon and include mild gas or digestive upset. Use caution if any of these apply to you: Immunocompromise or critical illness (a general precaution for live bacterial products; no trial enrolled such patients).
Probiotics
Likely helpsLive microorganisms where strain selection determines outcome — Lactobacillus and Bifidobacterium strains best studied for gut, immune, and mood.
Saccharomyces Boulardii
Likely helpsAntibiotic-resistant probiotic yeast that supports digestive regularity and gut flora during travel and antibiotic use.
VSL#3 / Visbiome
Mostly mechanism / observationalAn 8-strain blend dosed in the hundreds of billions to trillions of CFU per day — roughly 45 to 7,000 times a typical 1-10 billion CFU consumer probiotic — with the largest effect size in the probiotic literature for one narrow use: maintaining remission in chronic pouchitis after ulcerative colitis surgery. It is null for IBS and Crohn's — and since 2016 the brand name no longer reliably identifies the formulation that was studied.
B. lactis (BB-12 / HN019)
Mostly mechanism / observationalThe most-replicated probiotic effect on gut transit — it measurably speeds things up and adds roughly one bowel movement a week in people who are already low. But it is not a constipation cure: the two largest, best-designed trials both missed their primary endpoints, and the honest effect is hours off transit time, not a fix.
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Reviewed by Dr. Baher Al Hakim · Last reviewed July 2026 · evidence from 30 studies · how we score · editorial policy
This information is for educational purposes only. It is not a substitute for professional medical advice. Always consult a qualified healthcare provider before starting, stopping, or changing any supplement or medication.
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