# Saccharomyces boulardii: The Unique Yeast That Fights Diarrhea & Restores Balance Gut health is increasingly recognized as central to overall well-being. One well-studied probiotic agent is the yeast Saccharomyces boulardii, which differs fundamentally from bacterial probiotics in behavior and resilience. In clinical and laboratory studies it has shown benefits for reducing diarrhea and supporting microbiome balance, particularly in contexts where antibiotics have disrupted gut ecology. Learn more about [Saccharomyces boulardii](https://www.innerbuddies.com/blogs/gut-health/saccharomyces-boulardii-the-probiotic-yeast-that-fights-diarrhea-restores-microbiome-balance) and how it may fit into an evidence-based approach to digestive health. ## What Saccharomyces boulardii is and why it matters Saccharomyces boulardii is a non-pathogenic yeast first isolated in the 1920s. Unlike bacterial probiotics, it is less susceptible to many antibiotics, which allows it to persist in the gut when bacterial strains are temporarily suppressed. That resilience makes it particularly relevant for preventing or treating antibiotic-associated diarrhea and for short-term restoration of microbial balance after disruptive events. ## Mechanisms of action Research indicates S. boulardii works through multiple mechanisms: it can strengthen the intestinal barrier, modulate local immune responses, compete with pathogenic organisms, and neutralize certain bacterial toxins. These combined effects help reduce intestinal inflammation and shorten the duration and severity of various diarrheal conditions. Because it is a yeast, it does not permanently colonize the gut in the same way some bacteria can, which is one reason its safety profile has been acceptable in many studies. ## Proven benefits and clinical contexts The most consistent evidence supports S. boulardii for preventing and treating antibiotic-associated diarrhea and for some forms of acute infectious diarrhea. Clinical trials and meta-analyses suggest reduced duration of symptoms and lower incidence of diarrhea when S. boulardii is used adjunctively with standard care. Additional outcomes reported include modest improvements in digestion and supportive effects on immune-related gut function. ## Safety and practical considerations Typical study doses range from about 250 mg to 1 g per day, but formulations vary, and efficacy can be dose-dependent. Mild gastrointestinal side effects such as bloating or gas are reported occasionally. Because it is a live yeast, S. boulardii is not recommended without medical supervision for people with severe immunosuppression, central venous catheters, or certain critical illnesses due to rare cases of fungemia. ## Personalized assessment and complementary resources Understanding individual gut composition can improve selection and timing of interventions. InnerBuddies offers testing and interpretation that aim to clarify microbial composition and guide personalized choices; see their methodology on 16S rDNA sequencing for context on how personalized insights are derived. For broader lifestyle context, resources such as discussions of dietary approaches can help frame nutritional strategies that affect the microbiome. An example product resource is the InnerBuddies Microbiome Test. ## Summary Saccharomyces boulardii is a distinct probiotic yeast with specific applications—most notably in preventing and reducing antibiotic-associated diarrhea. Its multiple mechanisms, evidence base, and relative resistance to antibiotics make it a useful tool in the clinical and self-care toolbox for gut disturbances. As with any intervention, use should be informed by clinical context and, where appropriate, individualized microbiome evaluation and medical advice.