IBS is one of the most common disorders of digestive system producing a spectrum of symptoms such as persistent and recurring abdominal pain associated with the passing of motion, change of bowel habit (diarrhea, constipation, or alternate diarrhea and constipation), etc. without any apparent cause. The word syndrome means a group of symptoms. IBS is a syndrome because it can cause several symptoms in addition to those mentioned, like cramping, bloating, gas, frequent urge to pass stools, the sensation of incomplete evacuation etc.
IBS is the disorder of function, which means that the bowel doesn't work, as it should. If one visualizes the bowel, it appears perfectly normal without any inflammation or other structural changes. In people with IBS, the intestines squeeze too hard or not hard enough and cause food to move too quickly or too slowly through the intestines.
Through the years, IBS has been called by many names--colitis, mucous colitis, spastic colon, spastic bowel, and functional bowel disease, irritable colon, and nervous colon. Most of these terms are inaccurate and refers to an understanding of diseases at that particular time frame. Colitis, for instance, means inflammation of the large intestine (colon). IBS, however, does not cause inflammation of the bowel and should not be confused with another disorder like ulcerative colitis.
IBS is very common condition across the globe and it is estimated that around 20% of people suffer from this condition sometime during their lifetime. Over 40 million Americans and one-third of the UK population suffer from IBS sometimes in life. It is the single most common reason for which people seek gastroenterologist's opinion. The statistics state that people miss work for IBS and related disorders more than for anything else, except colds.
IBS though affect people of all ages and both the sexes; it is more common in young people; usually in late adolescence or early adulthood. The condition is almost two to three times common in females as compared to males.