Currently there is no conclusive answer addressing this issue.
Probiotics are used more and more for symptoms relief of irritable bowel syndrome (IBS):
As probiotics have shown benefit and possess a favorable adverse-effect profile, their use may represent an option for symptom relief in patients with IBS. However, additional data are necessary before probiotics can become a standard of care in the treatment of IBS, a complex and chronic condition .
The results are highly variable as another paper agrees:
Clearly, some probiotics have considerable potential in the management of IBS; however, the benefits are likely to be strain-specific. Preliminary studies suggest low doses of prebiotics may improve symptoms of IBS, although further robust clinical trials are required .
Yet there are some conditions in which probiotics have shown benefits. These include :
- Antibiotic-associated diarrhea
- Clostridium difficile colitis
- Infectious diarrhea in both adults and children
- (Inflammatory bowel disease - but with variable efficacy)
The same study  questions:
- the delivery method of probiotics
- the dose
- interaction between probiotic and immune system
- treatment duration
A newer study agrees on all of the above:
Promising results have been found and in some, indications such as maintenance of remission of ulcerative colitis and pouchitis guidelines recommend therapy with probiotics already today. However, many open questions still remain and the urgent need for high-quality trials requires much more research in the future .
- Wilhelm SM, Brubaker CM, Varcak EA, Kale-Pradhan PB. Effectiveness of probiotics in the treatment of irritable bowel syndrome. Pharmacotherapy. 2008 Apr;28(4):496-505. doi: 10.1592/phco.28.4.496. PubMed PMID: 18363533.
- Whelan K. Probiotics and prebiotics in the management of irritable bowel syndrome: a review of recent clinical trials and systematic reviews. Curr Opin Clin Nutr Metab Care. 2011 Nov;14(6):581-7. doi: 10.1097/MCO.0b013e32834b8082. PubMed PMID: 21892075.
- Elizabeth C. Verna and Susan Lucak. Use of probiotics in gastrointestinal disorders: what to recommend? Therap Adv Gastroenterol. Sep 2010; 3(5): 307–319. doi: 10.1177/1756283X10373814. PMCID: PMC3002586
- Kruis W. Probiotics. Dig Dis. 2013 Nov 14;31(3-4):385-7. doi: 10.1159/000354706. PubMed PMID: 24246993.