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Saccharomyces boulardii

What does the research say about Saccharomyces boulardii?

3 health outcomes synthesised

Saccharomyces boulardii has been studied across 3 health outcomes related to diarrhea, with the strongest evidence supporting its use for reducing the duration of diarrhea in children with acute gastroenteritis (3 studies, moderate evidence). A meta-analysis of 1,125 children reported a reduction of 1.63 days, though no consistent dose was identified. Other outcomes, such as reducing diarrhea rate, show moderate but preliminary evidence, while effects on general diarrhea reduction are less consistent.

Strongest evidence

Two outcomes have moderate evidence strength. For Reduced Duration of Diarrhea, all 3 studies reported beneficial effects with a large effect size; a meta-analysis (n=1,125) showed a reduction of 1.63 days (SMD -1.63, 95% CI -2.08 to -1.18) in children with acute gastroenteritis. For Reduced Diarrhea Rate, all 3 studies were also beneficial but with predominantly small effect sizes; evidence includes two RCTs (one in children with acute diarrhea, one in adults with SIBO associated with long-term PPI use) and one narrative review. The only reported dose across these studies was 500 mg twice daily.

Mixed or weaker evidence

For Reduced Diarrhea (low evidence strength), 3 RCTs showed mixed results: 1 reported a small beneficial effect (statistically significant in patients with SIBO) while 2 found neutral small effects. No consistent benefit was observed in other populations.

Effective dose patterns

The only cross-cutting dose reported across multiple syntheses is 500 mg twice daily, which appeared in studies on both reduced diarrhea rate and reduced diarrhea. However, studies on reduced duration of diarrhea did not report a consistent dose, so generalizability of this dose is limited.

Population insights

The strongest evidence is in children with acute gastroenteritis (for reduced duration of diarrhea). Studies on diarrhea rate also included children with acute diarrhea and adults with small intestinal bacterial overgrowth (SIBO) associated with long-term PPI use. The mixed evidence for reduced diarrhea was driven by a specific SIBO population, suggesting benefits may not generalize to other groups.

Notable caveats

  • All three syntheses note a small evidence base (only 3 studies each) and consider conclusions preliminary.
  • Publication bias is a concern: null-result studies are less likely to be published or indexed.
  • Two of the three studies in the strongest evidence area are narrative reviews (not primary data), which limits the strength of conclusions.
  • Many studies in the low-evidence outcome did not reach statistical significance, indicating the true effect may be smaller than the predominant direction suggests.

Frequently asked

  • What is Saccharomyces boulardii good for according to research?
    Based on 3 research syntheses covering 3 outcomes, Saccharomyces boulardii has been studied primarily for different forms of diarrhea. The strongest evidence (moderate strength) shows it can reduce the duration of diarrhea in children with acute gastroenteritis by about 1.63 days, and may reduce diarrhea rate in children and adults with certain conditions. Evidence for general diarrhea reduction is less consistent.
  • What dose of Saccharomyces boulardii is typically used in studies?
    The only dose consistently reported across studies is 500 mg twice daily, used in research on reduced diarrhea rate and reduced diarrhea. However, studies on reduced duration of diarrhea did not report a standard dose, so the optimal dose remains unclear.
  • Who benefits most from Saccharomyces boulardii?
    The strongest evidence points to children with acute gastroenteritis, where a large effect on reducing diarrhea duration was seen. Some evidence also supports benefit in adults with small intestinal bacterial overgrowth (SIBO) associated with long-term PPI use. Generalizability to other populations is uncertain.
  • Are there caveats or limitations in the research on Saccharomyces boulardii?
    Yes. All three syntheses are based on only 3 studies each, making conclusions preliminary. There is a risk of publication bias (null results less likely to be published). Two of the three studies in the strongest evidence area are narrative reviews, not primary clinical trials. Additionally, many studies in the low-evidence outcome did not reach statistical significance, suggesting the effect may be smaller than reported.
  • Does Saccharomyces boulardii help with reducing diarrhea duration?
    Research with moderate evidence strength shows a beneficial effect on reducing diarrhea duration, particularly in children with acute gastroenteritis. All 3 studies reported a large effect, with a meta-analysis of 1,125 children showing a reduction of 1.63 days. However, the evidence base is small and includes narrative reviews.
  • Is Saccharomyces boulardii effective for reducing diarrhea rate?
    All 3 studies on reduced diarrhea rate reported beneficial effects, but with predominantly small effect sizes. Evidence includes two randomized controlled trials (in children with acute diarrhea and adults with SIBO) and one narrative review. The dose used was 500 mg twice daily. Evidence strength is moderate, but caveats include small sample sizes and potential publication bias.

Safety profile

8 studies reporting safety data

Across 8 clinical studies reporting safety data on Saccharomyces boulardii, no specific adverse events were found to be increased relative to control. Two studies found no significant difference for overall adverse events and diarrhea after adjustment for multiple comparisons. The probiotic was described as well tolerated in 7 studies, with one study additionally reporting a significantly lower incidence of antibiotic-associated diarrhea (2.0% vs. 46.4%) and overall adverse events (17.0% vs. 55.7%) in the treatment group.

Caveats: Most studies were short-term and focused on efficacy rather than safety, limiting the ability to detect rare adverse events. The evidence base is also heterogeneous in terms of populations and dosing regimens, and findings may not generalize to other strains or formulations.

Most-studied combinations with Saccharomyces boulardii

most supplement research is combination research
Also studied with:Lactobacillus rhamnosus GG (2)

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