Irritable Bowel Syndrome: Searching for Underlying Causes

By: Magnus Simrén, M.D., ph.D., Associate Professor, Consultant, Section of Gastroenterology & Hepatology Department of Internal Medicine, Sahlgrenska University Hospital, Göthenburg, Sweden

Dr. Simrén is the recipient of the 2007 IFFGD Research Award for Junior Investigator – Clinical Science. His main research areas are the causes and development of functional GI disorders.

Summary

The changes in normal function that we see in irritable bowel syndrome (IBS) are not completely understood. A number of factors are considered to be of importance for the symptom generation in patients with IBS. In our research during the last couple of years we have tried to further evaluate why IBS develops. We specifically have focused on the role of food and nutrients for gut function in IBS, and the link between different alterations of function and the symptom pattern of the patient.

Food Sensitivity in IBS

The majority of patients with IBS describe a link between what they eat and their symptom severity. We have looked at potential mechanisms behind this food sensitivity in IBS.

We have for instance evaluated the effects of nutrients in upper small intestine. We also compared the effect of two different kinds of meals – one rich in carbohydrates, the other one rich in fat – on the sensitivity of the rectum in IBS patients. In other investigations we have looked at alterations found in the periods between meals of IBS patients. Worsening of symptoms following meals in IBS patients is probably due to several factors.

Link Between Symptoms and Contributing factors in IBS

One explanation behind the lack of really effective treatment options in IBS is that we do not understand the link between the presence or absence of different contributing factors and the symptom pattern of the patient. We have ongoing projects where we try to understand this link better.

Having alterations in several interacting systems increases the risk of having more severe symptoms. In the future increased knowledge about the relevance of the different alterations in symptom patterns among IBS patients will likely increase the chances of finding effective treatment alternatives for these patients.

Inflammation and Bacteria in IBS

We have also looked at the importance of mild inflammation in the gastrointestinal tract in IBS patients. Another hot area of research is the relevance of the bacterial flora in the gut for the symptoms of IBS in patients.