The exact cause of inflammatory bowel disease (IBD), is not yet known exactly, but it is believed that abnormal action of the immune system may trigger the disease. People suffering from IBS have immune systems that seem to overreact to normal bacteria living in the digestive tract. The immune system fails to shut off when detecting these bacteria, and causes damage through prolonged inflammation of tissue.
Inflammatory bowel disease can be present in several members of the same family, suggesting that heredity and certain genes may be a cause of inflammatory bowl disease. And stress or consumption of certain foods does not cause inflammatory bowel disease, it can make symptoms worse.