Irritable bowel syndrome (IBS) is one of the most common conditions seen in primary care settings. Despite this, there is no consensus as to the pathogenesis of this disorder or a consistently effective therapeutic regimen for many patients. This has encouraged the use of various alternative therapies from behavioral or complementary medicine. This review will address the evidence for alternative therapies, including the following: cognitive behavior therapy, hypnosis, elimination diets based on food antibody testing, nutrition supplements (such as fiber, probiotics, and prebiotics), and, finally, peppermint, L-glutamine, zinc, and cromolyn sodium. The review also explores the evidence for and the therapeutic ramifications of the hypothesis that increased intestinal permeability underlies the symptoms of IBS in many patients, and how a therapeutic plan that addresses nutrition, elimination diets, and nutrition supplements may be useful in restoring the integrity of the gut immune barrier.