Saccharomyces boulardii is a probiotic yeast that has been studied extensively for its benefits in supporting the health of the large intestine (colon). Clinical trials and meta-analyses support its use in several gastrointestinal conditions that affect the colon, particularly antibiotic-associated diarrhea, Clostridioides difficile infection, and some forms of inflammatory bowel disease. S. boulardii works by modulating the gut microbiota, strengthening the intestinal barrier, and exerting anti-inflammatory effects. It also inhibits the adhesion and growth of pathogenic bacteria, and can neutralize bacterial toxins. Multiple randomized controlled trials have demonstrated that S. boulardii reduces the risk of antibiotic-associated and recurrent C. difficile diarrhea, both of which typically manifest in the colon. Evidence also suggests it may be helpful in managing symptoms of irritable bowel syndrome and ulcerative colitis, though these effects are less well established. Overall, the scientific literature provides moderate to strong support for the use of S. boulardii as a supplement for maintaining or restoring colon health, particularly in relation to diarrhea and certain infections. However, while its use is well-validated for specific large intestine conditions, it should not be considered a universal remedy for all colon-related issues.