Lactobacillus acidophilus is a probiotic bacterium commonly used as a dietary supplement with the aim of supporting gastrointestinal health, including in individuals with Inflammatory Bowel Disorders (IBD) such as Crohn's disease and ulcerative colitis. The rationale for its use is based on the idea that probiotics can help restore balance to the intestinal microbiota, which is often disrupted in IBD patients.

Scientific studies investigating L. acidophilus for IBD have produced mixed results. Some small clinical trials and animal studies suggest that L. acidophilus may help reduce inflammation, improve intestinal barrier function, and modulate immune responses in the gut. However, when evaluated in larger, well-controlled human trials, the evidence remains limited and not robust enough to draw definitive conclusions. Systematic reviews and meta-analyses have generally found that probiotics as a group may have modest benefits for some symptoms, but the effect size is small, and results are inconsistent. Few studies have isolated L. acidophilus as a sole intervention, and most have used combinations of probiotic strains, making it difficult to attribute effects specifically to this species.

In summary, the use of L. acidophilus for IBD is supported by a modest body of scientific evidence, but the quality and consistency of the data are not strong. Its use is not purely traditional; rather, it is based on plausible mechanisms and preliminary scientific findings, but high-quality evidence supporting significant clinical benefits is lacking.