Saccharomyces boulardii CNCM I-745
Also known as: S. boulardii, Florastor®, Yeast probiotic
Saccharomyces cerevisiae var. boulardii strain CNCM I-745 is a transient yeast that survives gastric transit, reaches steady-state colonic concentrations within 3 days, and is cleared 3–5 days after stopping. It works via secreted proteases, anti-inflammatory signalling, and pathogen binding rather than colonisation.
Last reviewed: 2025-01-15 · 3 indexed studies
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Overview
A non-pathogenic probiotic yeast (not a bacterium) with the strongest clinical evidence of any probiotic for antibiotic-associated and C. difficile-associated diarrhoea. Naturally resistant to antibiotics, making it uniquely suited to co-administration during a course.
Mechanism & Function
Mechanism of Action
Secretes a 54 kDa serine protease that hydrolyses C. difficile toxins A and B and their intestinal receptors. Binds enteric pathogens (E. coli, Salmonella) preventing adhesion. Stimulates secretory IgA and brush-border disaccharidases. Inhibits NF-κB and IL-8 inflammatory signalling in enterocytes.
Physiological Role
Restores microbial diversity disturbed by antibiotics, neutralises bacterial toxins, and modulates mucosal immunity. Unaffected by antibacterial antibiotics so can be taken concurrently with the offending drug.
Primary Pathways
Performance / Health Relevance
Limited direct ergogenic role; indirectly preserves training continuity by preventing antibiotic- and travel-associated GI disruption that would otherwise interrupt programming.
Evidence Review
Practical Use & Dosage
- Minimum Effective Dose
- 250 mg (≈5 billion CFU) daily
- Optimal Range
- 500–1000 mg (10–20 billion CFU) daily, split BID with antibiotics
- Upper / Caution Level
- Avoid in immunocompromised hosts and patients with central venous catheters (fungaemia risk)
- Timing
- Start within 48h of beginning antibiotics; continue 1 week after completion
- Best Format
- Lyophilised capsule or sachet; heat-stable, no refrigeration needed
- Bioavailability
- Resistant to gastric acid and bile; does not require enteric coating. Antibiotic-resistant — no need to space dosing.
- Absorption Considerations
- Acts locally in the GI lumen; not absorbed systemically in healthy gut.
Safety & Interactions
Side Effects
- •Mild flatulence
- •Thirst (rare)
- •Constipation (rare)
Contraindications
- Severe immunosuppression
- Critically ill ICU patients
- Indwelling central venous catheter
Drug Interactions
- •Systemic antifungals (fluconazole) inactivate the yeast
Who Should Avoid
- •Neutropenic or post-transplant patients
- •Premature neonates
Monitoring
No routine monitoring; discontinue and culture blood if unexplained fever in high-risk hosts.
Frequently Asked Questions
Auto-generated from indexed evidence — dosage, safety, interactions, and more.
When is Saccharomyces boulardii CNCM I-745 typically used or indicated?
Saccharomyces boulardii CNCM I-745 is most commonly used for: Antibiotic-associated diarrhoea, Traveller's diarrhoea, C. difficile recurrence, IBS-D. Restores microbial diversity disturbed by antibiotics, neutralises bacterial toxins, and modulates mucosal immunity. Unaffected by antibacterial antibiotics so can be taken concurrently with the offending drug.
How does Saccharomyces boulardii CNCM I-745 work?
Secretes a 54 kDa serine protease that hydrolyses C. difficile toxins A and B and their intestinal receptors. Binds enteric pathogens (E. coli, Salmonella) preventing adhesion. Stimulates secretory IgA and brush-border disaccharidases. Inhibits NF-κB and IL-8 inflammatory signalling in enterocytes.
What is the recommended dose of Saccharomyces boulardii CNCM I-745?
The optimal range is 500–1000 mg (10–20 billion CFU) daily, split BID with antibiotics. with a minimum effective dose of 250 mg (≈5 billion CFU) daily. Best taken: Start within 48h of beginning antibiotics; continue 1 week after completion. Upper / caution level: Avoid in immunocompromised hosts and patients with central venous catheters (fungaemia risk).
What are the side effects of Saccharomyces boulardii CNCM I-745?
Reported side effects include: Mild flatulence; Thirst (rare); and Constipation (rare). Monitoring: No routine monitoring; discontinue and culture blood if unexplained fever in high-risk hosts.
Does Saccharomyces boulardii CNCM I-745 interact with medications?
Known or theoretical interactions: Systemic antifungals (fluconazole) inactivate the yeast. Always check with a clinician before combining with prescription medication.
Who should avoid Saccharomyces boulardii CNCM I-745?
Saccharomyces boulardii CNCM I-745 is generally not recommended for: Neutropenic or post-transplant patients; Premature neonates; Severe immunosuppression; Critically ill ICU patients; and Indwelling central venous catheter.
How strong is the evidence for Saccharomyces boulardii CNCM I-745?
Evidence level: Strong (overall score 85/100), based on 3 indexed studies on SuppIndex.
Research & References (3)
Meta-analysis of probiotics for the prevention of antibiotic associated diarrhea and C. difficile disease
McFarland LV. Analysis of 31 RCTs (n=3164) — S. boulardii significantly reduced AAD risk (RR 0.47) and CDAD recurrence.
Saccharomyces boulardii for prevention of antibiotic-associated diarrhoea in adults: Cochrane review
Cochrane systematic review concluding moderate-quality evidence that S. boulardii reduces AAD risk in adults receiving antibiotics.
Saccharomyces boulardii in maintenance treatment of Crohn's disease
1g/day S. boulardii reduced relapse rate vs placebo over 6 months in patients with quiescent Crohn's.
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Research Overview
Strong EvidenceCite this ingredient
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Stable URL
https://thesuppindex.com/ingredients/saccharomyces-boulardii
SuppIndex. (2026). Saccharomyces boulardii CNCM I-745: Evidence summary, dosage and clinical studies. Retrieved October 16, 2026, from https://thesuppindex.com/ingredients/saccharomyces-boulardii
Based on 3 indexed studies · Evidence level: Strong.
Goal Ratings
Stack Compatibility
Can be co-administered with bacterial probiotics; complementary mechanism.