Causes of Irritable Bowel Syndrome (IBS)

Causes of Irritable Bowel Syndrome (IBS)

The exact cause is not known. One theory is that a person with IBS has a colon that is particularly reactive and sensitive to meals, drugs, gut hormones, and stress. An augmented motility of the colon occurs following meal in such a person. An exaggerated response of the small intestine (the ileum, to be specific) may explain abdominal pain. Gut sensations get abnormally perceived by affected individuals; this is termed visceral hypersensitivity.

The symptoms of IBS are neither figments nor the result of any psychiatric disorders. Convincing human data to associate psychiatric disorders with IBS are not available. A person's response to IBS is however influenced by his personality, level of social support, and childhood experiences. Pschycological factors such as stress have a role to play in making the condition worse.

Whether bacterial infection in the gastrointestinal tract can cause IBS is still being studied. Many studies reveal that 'post-infectious IBS' can occur following gastroenteritis. Biopsy specimen from some patients shows low-grade colonic inflammation.

There are evidences to suggest that an excess serotonin contributes to IBS (post-infectious IBS, to be specific). Serotonin is a compound present in blood that acts as a neurotransmitter.

True food allergy being a cause of IBS is rare. Intolerance to certain food items can make patients feel worse. No single food group has been implicated as a cause of IBS. Foods such as wheat, yeast, nuts, eggs, and dairy products may, however may have an association with IBS.

The role of genetics is yet to be confirmed. Increasing evidences do exist though.

References:

1. Cecil Medicine, 23rd Ed.
2. Harrison's Principles of Internal Medicine, 17^TH Edition
3. 5 million in the USA 1987 (Digestive diseases in the United States: Epidemiology and Impact � NIH Publication No. 94-1447, US Government Printing Office, 1994