Lactose intolerance and the irritable colon.

Symptoms of lactase deficiency include nausea, abdominal pain, distension, bloating and diarrhea after ingesting foods which contain lactose. Lactose intolerance and bowel motility disorders have similar symptoms, and people with irritable bowel syndrome and unexplained abdominal pain may have lactose intolerance. A definite diagnosis can be made by detecting hydrogen in the breath after a lactose load, by lactase assay from a small bowel biopsy specimen or by lactose intolerance testing. Lactose intolerance is more likely in blacks, Asians and South Americans. If lactose intolerance is present without concomitant bowel motility disorder, the response to a lactose free diet is excellent.