Functional gastrointestinal (GI) disorders (FGIDs), in particular irritable bowel syndrome (IBS) in adults and children, are among the most common and costly health care problems in the US. IBS disproportionately affects adult women (10-15% in western nations) and adolescent girls. Yet, health care providers remain challenged to provide effective clinical management. The etiology of IBS is not well defined and likely multi-factorial.