Saccharomyces Boulardii for Diarrhea: Does it Work?

Key Findings

This 2010 meta-analysis concluded that Saccharomyces boulardii (S. boulardii) is significantly effective in preventing antibiotic-associated diarrhea (AAD) (relative risk [RR] = 0.47, 95% confidence interval [CI]: 0.35–0.63, P < 0.001) and traveler’s diarrhea in adults. Among 31 randomized, placebo-controlled treatment arms (27 trials, 5,029 patients), 84% reported statistically significant efficacy. The yeast probiotic also showed promise for reducing Helicobacter pylori treatment symptoms, preventing enteral nutrition-related diarrhea, and managing recurrent C. difficile infections, irritable bowel syndrome (IBS), and acute diarrhea, though further research is needed for these indications.

Study Design

The study was a systematic review and meta-analysis of peer-reviewed randomized clinical trials (RCTs) and pre-clinical studies published between 1976 and 2009. Meta-analysis included only randomized, blinded, placebo-controlled trials (27 studies total, 5,029 patients). Pre-clinical studies, volunteer trials, and uncontrolled studies were excluded from efficacy analysis but included in the broader systematic review. Study durations varied across trials, with follow-up periods ranging from 1 week to 3 months.

Dosage & Administration

Doses of S. boulardii ranged from 500 mg to 1,000 mg daily, administered primarily as capsules or powder. The supplement was typically given concurrently with antibiotics for AAD prevention or prior to travel for traveler’s diarrhea. Administration durations varied: AAD prevention lasted 1–2 weeks, while traveler’s diarrhea protocols spanned 1–3 weeks.

Results & Efficacy

• Antibiotic-associated diarrhea (AAD): S. boulardii reduced risk by 53% (RR = 0.47, 95% CI: 0.35–0.63, P < 0.001).
• Traveler’s diarrhea: 84% efficacy in treatment arms, with significant reductions in incidence and duration.
• Enteral nutrition-related diarrhea: 70% of trials showed reduced diarrhea frequency.
• H. pylori treatment symptoms: Adjunct use decreased diarrhea and nausea.
• Recurrent C. difficile infections: Limited evidence suggested a potential 30–50% risk reduction.
• IBS, acute diarrhea, Crohn’s disease, giardiasis, HIV-related diarrhea: Mixed results with insufficient evidence for definitive conclusions.

Limitations

• Outdated scope: Literature search ended in 2009, excluding recent trials.
• Heterogeneity: Variability in study populations (e.g., age, health status), dosing protocols, and outcome measures.
• Publication bias: Potential exclusion of negative or non-English studies.
• Mechanistic gaps: Limited exploration of S. boulardii’s mechanisms (e.g., microbiome interactions).
• Safety data gaps: No long-term safety follow-up beyond trial durations (typically <3 months).

Clinical Relevance

Adults using antibiotics may benefit from 500–1,000 mg/day of S. boulardii to reduce AAD risk by over 50%. Travelers to high-risk regions could consider prophylactic use. For H. pylori treatment or enteral nutrition support, adjunctive S. boulardii may alleviate gastrointestinal symptoms. However, evidence for recurrent C. difficile, IBS, or HIV-related diarrhea remains inconclusive. Users should prioritize blinded, placebo-controlled formulations and consult healthcare providers if immunocompromised, as safety in vulnerable populations was not fully assessed.

Sample demographics: Studies focused on adults (18+ years), but specific age ranges, comorbidities, or geographic regions were not uniformly reported.

Safety: No major adverse events were documented in immunocompetent adults, though rare fungemia cases in critically ill patients were noted in post-marketing reports (not quantified in this analysis).