It is estimated that 20% of Americans suffer from Irritable Bowel Syndrome (IBS) which is a functional gastrointestinal disorder characterized by abdominal pain, constipation and diarrhea (National Digestive Diseases Information Clearinghouse, 2011). Many IBS sufferers have attempted to manage their symptoms through probiotic therapy, which is the ingestion of microorganisms, similar to those normally present in the gastrointestinal tract, to achieve health benefits (American Gastroenterological Association, 2011). The information about probiotics for IBS was confusing and conflicting. This paper examined the evidence for the relationship between IBS symptoms and gastrointestinal microorganisms, the species of bacteria that are identified as probiotics, and the efficacy of utilizing probiotic therapy to manage IBS symptoms. It addressed the following question; "Does the current research provide evidence for the efficacy of probiotic therapy for the treatment of IBS symptoms?" A variety of Internet sources and 20 research articles were examined and a summary of the research suggested (a) there is likely a relationship between gastrointestinal microorganisms and IBS symptonls; (b) the term "probiotics" encompasses a variety of species of bacteria; (c) although a variety of bacteria species have been studied, there is not yet conclusive evidence about the most effective species to treat IBS symptoms; (d) the genera Bifidobacterium and Lactobacillus have been the most studied and produced the most favorable data; and (e) few adverse effects are reported in the literature. Further research is necessary to establish guidelines for the use of probiotics to manage IBS symptonls
