Irritable Bowel Syndrome

Irritable bowel syndrome causes a great deal of discomfort and distress, but it does not permanently harm the intestines and does not lead to a serious disease. Most people can control their symptoms with diet, stress management, and prescribed medications. For some people, however, IBS can be disabling. They may be unable to work, attend social events, or even travel short distances.

As many as 20 percent of the adult population, or one in five Americans, have symptoms of irritable bowel syndrome, making it one of the most common disorders diagnosed by doctors. It occurs more often in women than in men, and it begins before the age of 35 in about 50 percent of people.

Signs and Symptoms

Abdominal pain, bloating, and discomfort are the main symptoms of irritable bowel syndrome. However, symptoms can vary from person to person. Some people have constipation, which means hard, difficult-to-pass, or infrequent bowel movements. Often these people report straining and cramping when trying to have a bowel movement but cannot eliminate any stool, or they are able to eliminate only a small amount.

If they are able to have a bowel movement, there may be mucus in it, which is a fluid that moistens and protect passages in the digestive system. Some people with irritable bowel syndrome experience diarrhea, which is frequent, loose, watery stools. People with diarrhea frequently feel an urgent and uncontrollable need to have a bowel movement.

Other people with irritable bowel syndrome alternate between constipation and diarrhea. Sometimes people find that their symptoms subside for a few months and then return, while others report a constant worsening of symptoms over time.

Causes

Researchers have yet to discover any specific cause for irritable bowel syndrome. One theory is that people who suffer from irritable bowel syndrome have a colon, or large intestine, that is particularly sensitive and reactive to certain foods and stress. The immune system, which fights infection, may also be involved.

• Normal motility, or movement, may not be present in the colon of a person who has irritable bowel syndrome. It can be spasmodic or can even stop working temporarily. Spasms are sudden strong muscle contractions that come and go.
• The lining of the colon called the epithelium, which is affected by the immune and nervous systems, regulates the flow of fluids in and out of the colon. In irritable bowel syndrome, the epithelium appears to work properly. However, when the contents inside the colon move too quickly, the colon loses its ability to absorb fluids. The result is too much fluid in the stool. In other people, the movement inside the colon is too slow, which causes extra fluid to be absorbed. As a result, a person develops constipation.
• A person’s colon may respond strongly to stimuli such as certain foods or stress that would not bother most people.
• Recent research has reported that serotonin is linked with normal gastrointestinal (GI) functioning. Serotonin is a neurotransmitter that delivers messages from one part of your body to another. 95 percent of the serotonin in your body is located in the GI tract, and the other 5 percent is found in the brain. Cells that line the inside of the bowel work as transporters and carry the serotonin out of the GI tract. People with irritable bowel syndrome, however, have diminished receptor activity, causing abnormal levels of serotonin in the GI tract. As a result, they experience problems with bowel movement, motility, and sensation—having more sensitive pain receptors in their GI tract.
• Researchers have reported that IBS may be caused by a bacterial infection in the gastrointestinal tract. Studies show that people who have had gastroenteritis sometimes develop irritable bowel syndrome, otherwise called post-infectious IBS.
• Researchers have found very mild celiac disease in some people with symptoms similar to irritable bowel syndrome. People with celiac disease cannot digest gluten, a substance found in wheat, rye, and barley, and cannot eat these foods without becoming very sick. This is because their immune system responds by damaging the small intestine. A blood test can determine whether celiac disease may be present.