IBS Research

Researchers are studying the underlying mechanics of the digestive system to improve diagnosis and treatment of Irritable Bowel Syndrome.

Research suggests that many patients with Irritable Bowel Syndrome have disorganized and appreciably more intense colonic contractions than normal controls. Researchers have also found that pain is frequently associated with irregular motor activity of the small intestine when compared with either normal controls. Patients with IBS appear to have a defect of visceral pain processing—although whether or not this is a true hypersensitivity or hyper-vigilance remains unknown. Rectosigmoid balloon-distention studies have demonstrated that patients with IBS experience pain and bloating at balloon pressures and volumes that are significantly lower than those which cause symptoms in normal controls. Other theories suggest that micro-inflammation of the inner lining of the gut may contribute to the symptoms of IBS, dfferent than that is seen in Inflammatory Bowel Disease (IBD).

Recent studies of IBS have been investigating biological markers that show up in blood tests or brain imaging studies and may reveal which patients will benefit from specific treatments. One such biological marker is a new blood test for diarrhea predominant IBS (IBS-D), IBSchek, tests for the presence of CdtB (cytolethal distending toxin B), a toxin caused from gastroenteritis and Vinculin, a human protein commonly found in the nerves and lining of the gut. It is known that acute gastroenteritis can lead to IBS, known as post-infectious IBS or PI-IBS. The presence of CdtB and vinculin appear to be highly predictive of a diagnosis of IBS-D.

Research Highlights:

  • Disturbances in the bacteria that live in the gut may play a role in some cases of IBS.
  • Broad spectrum antibiotics may be the cause of IBS for some; however, a specific antibiotic (rifaximin) may improve IBS symptoms.
  • Small intestinal bacterial overgrowth (SIBO) may be a cause for IBS symptoms.
  • There is emerging evidence that diet alters the diverse population of bacteria that lives in the gut.
  • Researchers have investigated probiotics and a variety of dietary supplements and diet modification, namely a low FODMAP diet, for IBS. Some may improve IBS symptoms. The quality of many of the studies has improved in the years since diet was first proposed as a treatment for IBS.
  • Fecal matter transplantation (FMT) has not shown to be completely effective for treating IBS, although the procedure is seen as safe.
  • Chinese herbs and herb combinations, have been investigated for IBS, but research can’t draw any conclusions about them.
  • Some studies suggest that mind and body practices, including cognitive behavioural theory (CBT) and hypnotherapy, may help.
  • High placebo effects are often seen in IBS treatment studies; however, this phenomenon is unexplained.

Unproven products or practices should not be used to replace conventional treatments for IBS or as a reason to postpone seeing a physician about IBS symptoms or any other health problem.


National Center for Complementary and Integrative Health (NCCIH)
John Hopkins Health Medicine
Pimentel, M., Annals of Internal Medicine vol. 145 no. 8 557-563

Last updated on Feb 1, 2022