If you are suffering from Irritable Bowel Syndrome (IBS), you can thank your guts. An overgrowth of gut bacteria has been linked to causing IBS.

The new study builds upon previous studies linking bacteria with playing a role in IBS. Researchers collected samples from the small intestine and discovered that bacterial overgrowth led to IBS. This can help future treatments by directly targeting small intestinal bacteria overgrowth.

IBS affects nearly 30 million Americans who can suffer from a range of symptoms including constipation, diarrhea and painful bloating. For some IBS sufferers, these symptoms may be too embarrassing which could limit how much they go out, social activities or even spending time with friends.

Researchers collected small intestine bowel cultures using upper gastrointestinal (GI) tract endoscopy on 320 Greek individuals from the Sismanogleion General Hospital in Athens. An endoscopy can be used to diagnose and treat gastrointestinal disease. The cultures were collected and then examined for bacterial growth.

Of the 320 individuals, 62 had small intestinal bacteria overgrowth. In this group, 42 out of the 62 patients had IBS. Less than 10 percent of the individuals who did not have IBS had small intestine bacterial overgrowth. For those suffering from IBS where diarrhea was the main symptom, 60 percent had small intestine bacterial overgrowth.

The culture samples are especially important because it directly links bacterial overgrowth with IBS. Previously, bacterial overgrowth was shown to be associated or played a role in IBS based on breath tests for methane, a common byproduct of bacteria fermentation. This helped establish a connection but could not prove if bacterial overgrowth was the culprit behind IBS. According to the researchers, the cultures offered concrete proof linking IBS and bacterial overgrowth.

Identifying bacterial overgrowth as the cause of IBS can lead to better treatment of the disease. Previous treatments included ways to reduce symptoms and provide some measure of relief to IBS sufferers. By focusing on bacteria, doctors can use antibiotics to treat IBS itself and not just the symptoms.

One of the authors of the study, Dr. Mark Pimentel, director of the Cedars-Sinai GI Motility Program, had previously studied rifaximin as a treatment for IBS. Rifaximin is an antibiotic that can only be absorbed in the stomach and intestines and was shown to be effective in treating IBS. Future research could continue looking at other antibiotics as treatments for IBS.

The study was published in Digestive Diseases and Sciences.