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HomeIngredientsSaccharomyces boulardii
Reviewed by the Scan Dose Research Team and Clinical Advisory Board

Saccharomyces boulardii

MODERATE EVIDENCEProbioticLast updated

SCAN DOSE SUMMARY

S. boulardii is a probiotic YEAST (not bacteria) with the strongest clinical evidence of any probiotic for diarrhea prevention and treatment. A Cochrane review found it reduces antibiotic-associated diarrhea (AAD) risk by 53%. Our research highlights its unique advantage: as a yeast, it is COMPLETELY RESISTANT to all antibiotics — making it the only probiotic that works WHILE you're taking antibiotics. It also has the most rigorous evidence for C. difficile infection prevention (reducing recurrence by 50%) and acute infectious diarrhea in children (reducing duration by 1 day).

WHAT IT DOES

S. boulardii has four distinct mechanisms: (1) it secretes proteases that directly destroy C. difficile toxins A and B and their intestinal receptors; (2) it produces anti-inflammatory signals (via NF-κB modulation) that reduce intestinal inflammation; (3) it strengthens tight junctions between intestinal epithelial cells, improving barrier function; (4) it stimulates secretory IgA production, enhancing mucosal immunity. As a yeast (not bacteria), it's unaffected by antibiotics — the antibiotics kill pathogenic bacteria while S. boulardii simultaneously restores intestinal ecology and protects against opportunistic infections like C. difficile.

OPTIMAL DOSAGE

  • Look for: Strain CNCM I-745 (Florastor — most clinical data); 250-500mg (5-10 billion CFU) per capsule; shelf-stable
  • Avoid: Products not specifying strain; combination products where S. boulardii is a minor ingredient; products requiring refrigeration (yeast should be shelf-stable)
  • Minimum effective dose: 250mg (5 billion CFU) once daily for prevention; 500mg twice daily for active diarrhea
  • Third-party tested brands: Florastor (CNCM I-745 — gold standard, >50 years of clinical data), Jarrow Formulas
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SAFETY PROFILE

Critical Interactions (Do Not Combine Without Medical Supervision)

Moderate Interactions (Monitor Closely)

Theoretical/Low-Risk Interactions

RELATED RESEARCH

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Bifidobacterium Species
Lactobacillus rhamnosus GG
Probiotics
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Reviewed by the Scan Dose Research Team and Clinical Advisory Board | Last updated:

Not medical advice. Based on published clinical research and systematic reviews.

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