Finding a cure for irritable bowel syndrome (IBS), a gastrointestinal disorder marked by abdominal pain and altered bowel habits, has been elusive. Affecting some 45 million Americans and up to 12% of those over age 50, IBS is more common than heart disease, diabetes, depression, or asthma. For some people with IBS, symptoms are no more than an annoying but manageable nuisance. For many others, however, the misery quotient is high: IBS significantly undermines the quality of their life and their ability to participate fully in daily activities. Fortunately, most IBS patients can control their symptoms through a combination of dietary changes, appropriate medications, counseling, and various stress-reducing techniques.
What Causes IBS?
People with IBS may experience variable symptoms, including recurring, crampy abdominal pain; gassiness; bloating or distention; a sudden and urgent need to go to the bathroom; and frequent diarrhea, constipation, or both. Three variants of IBS have been identified: a constipation-predominant form, a diarrhea-predominant form, and a form characterized by an alternating pattern of these two symptoms. Theodore Bayless, M.D., a Professor of Gastroenterology at Johns Hopkins, comments: “Among older patients with IBS, constipation, often accompanied by gassiness and distention, is the more common symptom.”
The underlying problem is an abnormality in the way the intestinal muscles contract. People with IBS have an exaggerated gastrocolic reflex, the signal the stomach sends to the colon to stimulate contractions after food arrives. In studies that employed a balloon to distend the colon, researchers found that people with IBS experienced pain and bloating at much lower pressures than people without IBS. In addition, serotonin (a neurotransmitter manufactured in the gut) may also play a role in the disorder. Recent research has found that serotonin can either promote or prevent intestinal contractions depending on the type of receptor it binds to. An imbalance in the beneficial bacteria that ordinarily inhabit the gut also may be involved.
Psychological stress typically exacerbates IBS symptoms. A report by Mayo Clinic researchers in the journal Gut suggests that genetic factors may also play a role in IBS. They determined that the syndrome occurred more frequently in close relatives of IBS patients than in the relatives of people without IBS (17% vs. 7%). Whether this association results from genetic factors or shared environmental factors, however, remains to be resolved. Two thirds of those with IBS are women.
Getting the Right Diagnosis for IBS
IBS is usually diagnosed in people with typical symptoms, but only after other possible illnesses have been ruled out. According to Dr. Bayless, “red flags” that should prompt a search for other causes include late-life onset of symptoms (since symptoms of IBS usually appear initially by age 30), weight loss, anemia, rectal bleeding, and fever.
In addition, the symptoms of IBS may sometimes mimic those of other diseases. People frequently do not recognize that the source of pain in their upper abdomen may be their colon. If the sigmoid colon in the left lower abdomen contracts and gas rises into the transverse colon, people may experience pain underneath their ribs. “If the pain is on the left,” Dr. Bayless says, “they mistakenly think they’re having a heart attack; if it’s in the middle, they’re nauseated; and if it’s on the right, they think it’s their gallbladder.”
Dietary Changes That Help IBS
Certain foods can trigger or exacerbate symptoms of IBS, and people with mild to moderate symptoms often respond well to dietary modifications. Avoiding caffeine, large quantities of alcohol, and foods that are known to produce symptoms is a good idea. People with IBS should steer clear of gas-producing foods, such as cabbage, coleslaw, cauliflower, broccoli, baked beans, fructose-containing foods (grapes, dates, raisins, honey, and figs), items containing sorbitol (sugar-free gums, apple juice, and pear juice), low-fat bakery products, and carbonated beverages.
In addition, people who experience symptoms after eating dairy products should avoid milk, soft cheese, ice cream, frozen yogurt, and other dairy-based foods. Similarly, if wheat and other gluten-containing foods prompt symptoms, maintaining a gluten-free diet, at least temporarily, may help. Because eating large quantities of high-fat, greasy foods can stimulate colonic contractions, patients may do better eating smaller meals that are low in fat.
Keeping a diary of food intake and symptoms can assist in identifying foods that trigger your symptoms.
New Drug Helps Patients With IBS
It’s very important for IBS patients to keep their bowels moving regularly, notes Dr. Bayless, because if they are constipated, “it’s almost impossible to get rid of the pain.” Fiber supplements such as FiberCon (polycarbophil) and Metamucil (psyllium seed) can help relieve constipation in patients with IBS. “Some patients are told to eat tons of fiber to relieve constipation, but fiber causes gassiness. So I prefer to use something like FiberCon, which avoids this problem.” Increased intake of water and other fluids is also helpful. For patients who do not respond adequately to this approach, an osmotic laxative such as lactulose, sorbitol, or polyethylene glycol (Miralax) may be effective.
Diarrhea-predominant IBS can usually be treated with dietary measures, along with Imodium (loperamide) an antidiarrheal medication, taken before meals. Lotronex (alosetron), another serotonin-receptor medication, is once again available for women with diarrhea-predominant IBS. Withdrawn in 2000 because of adverse reactions, including ischemic colitis and several fatalities, Lotronex was reintroduced in 2002. It should be reserved for those who have not responded to conventional therapy, and treatment requires monitoring.
For IBS patients who have a great deal of abdominal discomfort, mild anticholinergic antispasmodic drugs such as Bentyl (dicyclomine) or Levsin (hyoscyamine) can be helpful. When taken before meals, they can inhibit the gastrocolic reflex and reduce urgency and cramps following meals. Older patients with glaucoma or prostate problems should not use these drugs, however.
Tricyclic antidepressants, such as amitriptyline and desipramine, also may be helpful in IBS. When given in low doses, they appear to raise the pain threshold and ease abdominal pain and discomfort. Taken at bedtime, they are also useful for their sedative effect.
The Benefit of Mind-Body Therapy for IBS
Recent studies support psychological counseling for patients with IBS, especially when combined with medical therapy. IBS patients who are anxious, depressed, or under stress appear to have a better response to psychotherapy alone than those who are not. A study that appeared in Clinical Gastroenterology and Hepatology in 2003 found that an approach that combined psychotherapy with medical therapy may relieve the symptoms of IBS in a relatively short time.
Hypnotherapy can aid in controlling physical and emotional responses when coping with stress, and several studies have shown that it can produce short-term improvements for patients with IBS. A British study published in Gut in 2003 showed that these improvements appear to persist over the long term. The researchers found that 71% of 207 patients with IBS initially responded to hypnotherapy and that 81% of these patients maintained their improvement over a period of 5 years or more.
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