NEW YORK (Reuters Health) — An abnormally high number of bacteria in the small intestine does not appear to be a major factor affecting the symptoms of irritable bowel syndrome, Swedish researchers report in the medical journal Gut.Irritable bowel syndrome (IBS), or spastic colon, is a common disorder characterised by abdominal pain, diarrhoea, cramping, and constipation. The syndrome is thought to arise from overactivity of the nerves in the intestine that control movement.

“The data do not support an important role for small intestinal bacterial overgrowth, according to commonly used clinical definitions, in IBS,” senior investigator Dr. Magnus Simren told Reuters Health.

Simren and colleagues at Sahlgrenska University Hospital, Gothenburg, note that a high rate of bacterial overgrowth has been reported in patients with IBS, but these observations were based on tests that only indirectly measured bacteria levels.