Bacillus species, particularly Bacillus coagulans, have been investigated as probiotics for supporting patients with Inflammatory Bowel Disorders (IBD), such as Crohn's disease and ulcerative colitis. Scientifically, the rationale is based on Bacillus species' ability to survive gastric acidity due to their spore-forming nature, potentially delivering beneficial effects to the gut microbiome. Some small clinical studies and pilot trials have suggested that Bacillus coagulans supplementation may reduce symptoms of IBD, including abdominal pain, bloating, and stool frequency. For example, a few randomized controlled trials (RCTs) in patients with ulcerative colitis found modest improvements in clinical symptoms and some biomarkers of inflammation compared to placebo.

However, the overall quality and quantity of evidence remain low. Most studies are small, short-term, and often industry-sponsored. Meta-analyses generally conclude that while Bacillus-based probiotics may offer some benefit as adjunctive therapy, the evidence is insufficient to recommend them as a primary treatment for IBD. The mechanisms proposed include immune modulation, competition with pathogenic bacteria, and enhancement of gut barrier function, but these are not definitively proven in human IBD populations.

In summary, there is some scientific validation for the use of Bacillus species in IBD, but the evidence is preliminary and limited, warranting a rating of 2 out of 5.