Review of Saccharomyces boulardii as a treatment, 34 patients have IBD 

This review published in 2018 assessed four human clinical trials and three reviews. Three quarters of studies were able to demonstrate significant benefits to probiotic supplementation. The studies that found benefit were smaller scale studies though there was not standardisations between the doses of the Saccharomyces and most studies were in patients with Crohn’s disease and only one in ulcerative colitis.

References:

Sivananthan K, Petersen AM. Review of Saccharomyces boulardii as a treatment, 34 patients jave IBD. Immunopharmacol Immunotoxicol. 2018;40(6):465-475. doi:10.1080/08923973.2018.1469143 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8064481/