IRRITABLE-BOWEL-SYNDROME

Necia relieved when she finally figured out why she was so tired all of the time. “I kept wondering what was wrong with me,” she says. “I was just exhausted.”

Tests showed Necia was anemic, so much so that she was advised to take iron pills for the rest of her life. But Necia knew iron pills would do nothing to help her with depression or the bouts of irritable-bowel-syndrome she also experienced.

“We’ve always been a family that believed in taking vitamins,” she says. “When I visited my daughter and tried a different supplement, I felt a difference — something I’d never experienced in the years of taking all of those vitamins.”

Within 24 hours, Necia says she had more energy than she could remember ever having. She now enjoys a great sense of well-being, and blood tests show her iron levels are steadily improving.

“I plan to stay on this supplement or the rest of my life,” Necia says. “And now I’m sharing them with others through my new business.”

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What causes irritable-bowel-syndrome symptoms?

The primary purpose of the gastrointestinal tract is to digest (break down) and absorb (take into the blood stream) food. In order to fulfill this purpose, food must be ground, mixed, and transported through the intestines, where it is digested and absorbed. In addition, undigested and unabsorbed portions of the food must be eliminated from the body.

In functional diseases of the gastrointestinal tract, the grinding, mixing, digestion, and absorption functions are disturbed to only a minor degree. These functions are essentially maintained, perhaps because of a built-in over-capacity of the gastrointestinal tract to perform these functions.

The most commonly affected function in these diseases is transportation. In the stomach and small intestine, the symptoms of slowed transportation are nausea, vomiting, abdominal bloating (the sensation of abdominal fullness), and abdominal distention (enlargement). The symptom of rapid transportation usually is diarrhea. The interpretation of symptoms, however, may be more complicated than this. For example, let's say that a person has abnormally rapid emptying of the stomach.

The sensing of this rapid emptying by the intestinal sensory nerves normally brings about a motor nerve response to slow emptying of the stomach and transportation through the small intestine. Thus, rapid emptying of the stomach may give rise to symptoms of slowed transportation.

In the colon, abnormally slowed or rapid transportation results in constipation or diarrhea, respectively. In addition, there may be increased amounts of mucus coating the stool or a sense of incomplete evacuation after a bowel movement.

As discussed previously, normal sensations may be abnormally processed and perceived. Such an abnormality could result in abdominal bloating and pain.

Abnormally processed sensations from the gastrointestinal organs also might lead to motor responses that cause symptoms of slowed or rapid transportation. Slowed transportation of digesting food through the small intestine may be complicated, for example, by bacterial overgrowth.

In bacterial overgrowth, gas-producing bacteria that are normally restricted to the colon move up into the small intestine. There, they are exposed to greater amounts of undigested food than in the colon, which they turn into gas. This formation of gas can aggravate bloating and/or abdominal distention and result in increased amounts of flatus (passing gas, or flatulence) and diarrhea.

The gastrointestinal tract has only a few ways of responding to diseases. Therefore, the symptoms often are similar regardless of whether the diseases are functional or non-functional. Thus, the symptoms of both functional and non-functional gastrointestinal diseases are nausea, vomiting, bloating, abdominal distention, diarrhea, constipation, and pain. For this reason, when functional disease is being considered as a cause of symptoms, it is important that the presence of non-functional diseases be excluded (ruled out).

In fact, the exclusion of non-functional diseases usually is more important in evaluating patients who are suspected of having functional disease. This is so, in large part, because the tests for diagnosing functional disease are complex, not readily available, and often not very reliable. In contrast, the tests for diagnosing non-functional diseases are widely available and sensitive (able to diagnose most cases

Irritable-bowel-syndrome is believed to be due to the abnormal function (dysfunction) of the muscles of the organs of the gastrointestinal tract or the nerves controlling the 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 anus 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 irritable-bowel-syndrome. Studies have demonstrated that patients with irritable-bowel-syndrome produce larger amounts of gas than individuals without irritable-bowel- syndrome, and the gas may be retained longer in the small intestine.

Among patients with irritable-bowel-syndrome, abdominal size increases over the day, reaching a maximum in the evening and returning to baseline by the following morning. In individuals without irritable-bowel-syndrome, 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 irritable-bowel-syndrome.

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 irritable-bowel-syndrome 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 irritable-bowel-syndrome, much more work will need to be done before the role of intestinal gas in irritable-bowel-syndrome is clear. For more information about intestinal gas, please read the Intestinal Gas article.

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

What are irritable-bowel-syndrome symptoms?

The interpretation of symptoms, however, may be more complicated than this. For example, let's say that a person has abnormally rapid emptying of the stomach. The sensing of this rapid emptying by the intestinal sensory nerves normally brings about a motor nerve response to slow emptying of the stomach and transportation through the small intestine. Thus, rapid emptying of the stomach may give rise to symptoms of slowed transportation.

As discussed previously, normal sensations may be abnormally processed and perceived. Such an abnormality could result in abdominal bloating and pain.

Abnormally processed sensations from the gastrointestinal organs also might lead to motor responses that cause symptoms of slowed or rapid transportation.

Slowed transportation of digesting food through the small intestine may be complicated, for example, by bacterial overgrowth. In bacterial overgrowth, gas-producing bacteria that are normally restricted to the colon move up into the small intestine. There, they are exposed to greater amounts of digested food than in the colon, which they turn into gas. This formation of gas can aggravate bloating and/or abdominal distention and result in increased amounts of flatus (passing gas, or flatulence) and diarrhea.

For this reason, when functional disease is being considered as a cause of symptoms, it is important that the presence of non-functional diseases be excluded (ruled out). In fact, the exclusion of non-functional diseases usually is more important in evaluating patients who are suspected of having functional disease.

This is so, in large part, because the tests for diagnosing functional disease are complex, not readily available, and often not very reliable. In contrast, the tests for diagnosing non-functional diseases are widely available and sensitive (able to diagnose most cases.)

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