Bacillus indicus is a spore-forming probiotic bacterium that has gained some attention for potential gut health benefits, including for conditions like Irritable Bowel Syndrome (IBS). The justification for its use is based on emerging scientific studies, particularly those focusing on multi-strain spore-based probiotics that include Bacillus indicus alongside other Bacillus species (such as B. subtilis and B. coagulans).

The most frequently cited rationale is that Bacillus indicus produces a variety of bioactive compounds, including carotenoids (notably, a red pigment), and can modulate the gut environment by surviving gastric acidity and colonizing the intestine transiently. Some animal and in vitro studies suggest it may have anti-inflammatory effects and contribute to a balanced gut microbiota.

However, high-quality human clinical trials directly investigating Bacillus indicus alone for IBS are lacking. The available evidence mainly comes from studies of multi-strain Bacillus formulations (such as the product “MegaSporeBiotic”), where some preliminary human trials and case reports have shown improvements in IBS symptoms, but the contribution of B. indicus specifically is unclear. Mechanistic studies suggest possible benefit, but direct clinical validation is limited.

In summary, while there is some emerging scientific rationale and preliminary evidence for the use of Bacillus indicus–containing probiotics in IBS, the overall evidence remains limited and is not yet robust, meriting a moderate-low score.