Bacillus licheniformis is a spore-forming probiotic bacterium that has been investigated for its potential role in supporting gut health, including in individuals with Irritable Bowel Syndrome (IBS). There is some scientific evidence supporting its use, but this evidence is limited and not yet robust.

Several small clinical trials and animal studies have examined the effects of B. licheniformis-containing probiotic formulations on gastrointestinal symptoms. For example, a few randomized controlled trials (RCTs) from India and China have reported that multi-strain probiotics containing B. licheniformis, sometimes in combination with Bacillus subtilis or Lactobacillus species, led to improvements in bloating, stool consistency, and abdominal pain in IBS patients. However, these studies often use mixed probiotic preparations, making it difficult to attribute observed benefits solely to B. licheniformis.

Mechanistically, B. licheniformis is thought to support gut health by producing antimicrobial compounds, modulating the immune response, and enhancing the integrity of the intestinal barrier. It is also notably heat-stable, allowing for easier formulation and delivery. However, the number and quality of IBS-specific studies remain limited, and large-scale, well-controlled trials are lacking.

In summary, there is preliminary scientific evidence suggesting potential benefit, but the overall strength of the evidence is weak (rated 2/5) and more research is needed before B. licheniformis can be recommended with confidence for IBS.