Mike Lee asked:


Irritable bowel syndrome is caused by abnormal function (dysfunction) of the muscles and organs of the gastrointestinal tract or the nerves controlling these organs. The nervous control of the gastrointestinal tract, however, is complex. A system of nerves runs the entire length of the gastrointestinal tract from the esophagus to the **** in the muscular walls of the organs.

These nerves communicate with other nerves that travel to and from the spinal cord. Nerves within the spinal cord, in turn, travel to and from the brain. (The gastrointestinal tract is exceeded in the numbers of nerves it contains only by the spinal cord and brain.) Thus, the abnormal function of the nervous system in IBS may occur in a gastrointestinal muscular organ, the spinal cord, or the brain.

The nervous system that controls the gastrointestinal organs, as with most other organs, contains both sensory and motor nerves. The sensory nerves continuously sense what is happening within the organ and relay this information to nerves in the organ’s wall.

From there, information can be relayed to the spinal cord and brain. The information is received and processed in the organ’s wall, the spinal cord, or the brain. Then, based on this sensory input and the way the input is processed, commands (responses) are sent to the organ over the motor nerves.

Two of the most common motor responses in the intestine are contraction or relaxation of the muscle of the organ and secretion of fluid and/or mucus into the organ.

As already mentioned, abnormal function of the nerves of the gastrointestinal organs, at least theoretically, might occur in the organ, spinal cord, or brain. Moreover, the abnormalities might occur in the sensory nerves, the motor nerves, or at processing centers in the intestine, spinal cord, or brain.

Some researchers argue that the cause of functional diseases is abnormalities in the function of the sensory nerves. For example, normal activities, such as stretching of the small intestine by food, may give rise to abnormal sensory signals that are sent to the spinal cord and brain, where they are perceived as pain.

Other researchers argue that the cause of functional diseases is abnormalities in the function of the motor nerves. For example, abnormal commands through the motor nerves might produce a painful spasm (contraction) of the muscles. Still others argue that abnormally functioning processing centers are responsible for functional diseases because they misinterpret normal sensations or send abnormal commands to the organ. In fact, some functional diseases may be due to sensory dysfunction, motor dysfunction, or both sensory and motor dysfunction. Still others may be due to abnormalities within the processing centers.

One area that is receiving a great deal of scientific attention is the potential role of gas produced by intestinal bacteria in patients with IBS. Studies have demonstrated that patients with IBS produce larger amounts of gas than individuals without IBS, and the gas may be retained longer in the small intestine. Among patients with IBS, abdominal size increases over the day, reaching a maximum in the evening and returning to baseline by the following morning. In individuals without IBS, there is no increase in abdominal size during the day.

There has been a great deal of controversy over the role that poor digestion and/or absorption of dietary sugars may play in aggravating the symptoms of IBS. Poor digestion of lactose, the sugar in milk, is very common as is poor absorption of fructose, a sweetener found in many processed foods.

Poor digestion or absorption of these sugars could aggravate the symptoms of IBS since unabsorbed sugars often cause increased formation of gas.

Although these abnormalities in production and transport of gas could give rise to some of the symptoms of IBS, much more work will need to be done before the role of intestinal gas in IBS is clear.

Dietary fat in healthy individuals causes food as well as gas to move more slowly through the stomach and small intestine. Some patients with IBS may even respond to dietary fat in an exaggerated fashion with greater slowing. Thus, dietary fat could–and probably does–aggravate the symptoms of IBS.

Mike Lee asked:


There are currently many possible treatment choices for patients with IBS to try, and research is continually being done to find new effective medications. Nonetheless, many of the commonly used drugs to treat IBS have not been definitively proven to be superior to placebo.

An extensive review by Klein of randomized, double-blind, placebo-controlled trials performed between 1966 and 1988 found that none of the studies provided sound statistical evidence to suggest that any of the medications used were beneficial in treating IBS, chiefly because of poor trial design and statistical analyses in the published studies.

More recent improvements in the design of trials has yielded evidence to support the use of smooth muscle relaxants and antidepressants in pain-predominant IBS, use of the antidiarrheal loperamide for diarrhea, and the use of fiber for constipation. The emergence of combination medications, as well as the increased use of neurotransmitter regulators, will most likely enhance the efficacy of future IBS treatments.

One of the main problems, of course, is that a muscle relaxant or an anti-depressant induces severe side effects in some patients. Suddenly, the patient has to choose whether to endure the side effects of the medication, or simply allow the IBS to run their lives. This is unfortunately not an ideal way to treat a life-altering condition like IBS.

Doctors also advocate some simple remedies for patients with mild forms of the IBS condition. The initial suggestion is to try to remove stress as much as possible and eat a healthy diet. Since some foods may in fact aggravate the condition, it is up do the patient to identify and try to avoid these foods. Foods that are high in caffeine, for instance, like coffee and cola, are thought to make certain individuals feel worse. Alcohol and excessive dietary fat is also thought to induce cramping of the intestines.

Fiber can also be quite helpful to individuals that suffer from IBS. There are two main types of fiber that can be used to treat the different symptoms associated with Irritable Bowel Syndrome.

The first type of fiber is called soluble fiber. This helps with both diarrhea and constipation. Some of the foods that contain soluble fiber are apples, beans, citrus fruits, and many garden vegetables. You can also buy supplements to enhance your intake of soluble fiber. Some popular brands are Fiberall, Metamucil, and Perdiem.

The second type of fiber is called insoluble fiber. This helps with constipation by bulking up the stool and adding more material to allow for easier passage through the digestive tract. You can find soluble fiber in many whole grain and wheat based products, as well as many vegetables.

Try to increase your daily fiber intake very slowly so to make sure your system can adjust. You will notice gas and bloating gradually decrease as you make these dietary changes. Try to eat a wide variety of foods so you can sample how each affects your symptoms.