Mannanoligosaccharides (MOS) are prebiotic fibers derived primarily from yeast cell walls (Saccharomyces cerevisiae). Their use in the context of Irritable Bowel Syndrome (IBS) is based on their proposed ability to modulate gut microbiota, improve intestinal barrier function, and reduce inflammation. Prebiotics in general have been studied for IBS, with some evidence suggesting benefits in symptom management, particularly for bloating and stool regularity. However, most of the robust data pertains to other prebiotics like fructooligosaccharides (FOS) and galactooligosaccharides (GOS).

For MOS specifically, human clinical trials are limited. Most research on MOS has been conducted in animal models or in vitro, where MOS supplementation demonstrated positive effects on gut microbial balance and immune modulation. A few small-scale human studies have explored MOS in relation to gut health, but direct evidence for symptom improvement in IBS patients is scarce and not conclusive. Reviews of prebiotic interventions for IBS occasionally mention MOS as a potential option, but emphasize the lack of direct, high-quality clinical data.

In summary, while the use of MOS for IBS is grounded in scientific rationale and limited preliminary evidence, its efficacy for this specific condition remains to be firmly established. More rigorous, large-scale human studies are needed to better determine its role in IBS management.