Lactobacillus species, often in mixed probiotic formulations, have been studied for their potential role in supporting or treating Irritable Bowel Syndrome (IBS). The rationale is based on the observation that IBS patients frequently have altered gut microbiota, and probiotics may help restore a healthier balance. Several randomized controlled trials (RCTs) and meta-analyses have investigated Lactobacillus-containing probiotics for IBS symptom relief, specifically targeting symptoms like bloating, abdominal pain, and irregular bowel habits.

The evidence is moderate. Some studies demonstrate modest improvements in global IBS symptoms and abdominal pain, while others show limited or no significant benefit compared to placebo. A 2020 systematic review and meta-analysis (Ford et al., 2020, The American Journal of Gastroenterology) found that certain probiotics, including Lactobacillus species, may reduce overall IBS symptoms, though the effect size is small and results are inconsistent due to heterogeneity among studies. Guidelines from organizations such as the American College of Gastroenterology suggest that probiotics, including Lactobacillus, may be considered for IBS, but highlight the need for more targeted, strain-specific research.

In summary, there is scientific evidence, albeit moderate, supporting the use of mixed Lactobacillus probiotics for IBS. Their use is not solely traditional, and the scientific validation, while not definitive, is sufficient to justify cautious recommendation in some clinical contexts.