In Canada approximately 5 million people suffer from irritable bowel syndrome (IBS). But what exactly is IBS and why does it occur? To answer these questions, we must first understand the digestive process and the changes that occur in the gut of those who are affected.

Digestion of a meal is a complex process, consisting of many steps to extract nutrients for nourishment. This process begins with the mechanical and chemical breakdown of food in the mouth and stomach before food is passed to the small intestine where it is further broken down and finally absorption of nutrients occurs.

In order to facilitate the passing of food along the digestive tract, muscles found in its walls relax and contract to slowly push food forward. The rate of propulsion of food can be influenced by several factors, including type and amount of food eaten, physical activity, mood, and certain hormones (cortisol, estrogen, etc).

In addition to its role in transport and nourishment, the digestive system also contains a large number of ‘defenses’ to fight off any potentially harmful intruders that are taken in by the mouth. These defenses include the acid found in the stomach and most importantly, immune system cells that line the entire length of the digestive tract. The immune system of the gastrointestinal tract also has the ability to distinguish between healthy bacteria that normally inhabit the tract and potentially harmful bacteria. This distinction is important as it allows us to benefit from the actions of these healthy bacteria, which include the production of certain nutrients (e.g. vitamin K) which aid in the digestion of food (e.g. fermenting fiber), prevention of the growth of harmful bacteria that influence the normal reproduction and growth of intestinal cells and prevention against certain diseases (e.g. Chron’s disease).

Digestive disorders or diseases can be caused by or be the result of an alteration or disruption of normal healthy digestive processes. One such common digestive disorder is IBS, affecting approximately 10-15% of the population. IBS is a disease that can have a great impact on the lives of those affected. It is a disease that is characterized by recurring abdominal discomfort or pain and a change in stool frequency (frequent or delayed bowel movements) and consistency (diarrhea or constipation).

While the exact cause of IBS is not known, the most commonly accepted risk factor is a history of bacterial gastroenteritis (i.e., bacterial infection of the digestive tract) or by an alteration in the normal intestinal bacteria. Specifically, healthy intestinal bacteria can be altered by several factors, including recent antibiotic use, mental/emotional stress, lack of physical activity, and by certain hormones. Other risk factors for developing IBS include food intolerance, mood disorders (anxiety, depression), or genetic predisposition.

The symptoms experienced with IBS are believed to originate from a combination of altered contractions of the muscles in the intestines and from a change in pain sensation in the intestines. With respect to the altered rate of muscular contractions of the intestines, there can be either more frequent and more forceful contractions, causing pain and diarrhea, or slowed non-progressive contractions that lead to constipation. Alterations in the frequency of the contractions may result from ingestion of a fatty meal, mood (stress, anxiety, depression, anger), or the release of certain hormones (estrogen, serotonin, or cholescystokinin, which is a digestive hormone).

People who suffer from IBS are also more likely to have increased pain sensation in their intestines. This altered sensation is triggered by the stretch of the intestinal walls by stool or by gas. This process is often made worse by changes in contraction of the muscles of the smooth intestine, which can cause pain during a contraction or with non-productive contractions which lead to a build up of gas or stool, stretching the walls of the intestine and causing pain. There are several factors that can affect this process, including ingesting certain gas forming foods (beans, cabbage, broccoli, etc.), having an alteration in normal intestinal bacteria (which ferments fiber differently, causing more gas), or mood.

As indicated above psychological factors like anxiety, stress, depression, etc., affect muscular contractions of the small intestines and altered pain sensation. Moreover, these psychological factors can affect the release of secretions that aid with digestion and can alter the function of the immune system. Alterations of immune function then go on to influence the presence of healthy bacteria and can cause an increased release of inflammation producing immune cells.

From a treatment perspective, there are several factors to address in the treatment of IBS. Specifically, one’s diet should be examined, looking to eliminate food sensitivities, and irritants, as well as avoiding gas forming foods. Furthermore, other factors such as mood, sleep, physical activity, intestinal bacteria and any possible damage done to the gut should be considered for their potential contribution to IBS.

If you have questions about IBS, digestive health or how a naturopathic doctor can help you, please call 613-290-6115 or visit Graham Beaton is a Doctor of Naturopathic Medicine in practice at Ottawa Collaborative Care Centres – 102 Lewis Street, Ottawa.