ibs 6Irritable bowel syndrome (IBS) may be due to bacterial overgrowth. Between 11% and 14% of Americans suffer from IBS. An article appearing in the Journal of the American Medical Association (August 18, 2004;292(7):852-858) looked into the possibility of bacteria overgrowth in the small intestine. The lactulose breath test (a way of testing for bacterial overgrowth) is abnormal in 84% of patients with IBS. Furthermore, there is a 75% improvement in symptoms when small intestine bacterial overgrowth is treated. In research that appeared in the American Journal of Gastroenterology (December 2000;95(12):3503-3506), the effect of killing small intestine bacteria was tested on IBS patients. The subjects were 202 people suffering from IBS. According to the results of a lactulose hydrogen breath test, 157 had small intestine bacterial overgrowth and 45 patients did not have bacterial overgrowth. Those with the bacterial overgrowth were treated with antibiotics. During a follow-up visit, 47 of those patients no longer had bacterial overgrowth and 48% of those patients no longer had IBS symptoms (according to Rome criteria). The subjects who tested for bacterial overgrowth during the follow-up visit did not experience improvement in symptoms. The researchers concluded that there is a link between small intestine bacterial overgrowth and IBS.