Irritable Bowel Syndrome
Irritable Bowel Syndrome Causes
There are a number of theories about how and why irritable bowel syndrome develops. Despite intensive research, the cause is not clear.
- One theory suggests that irritable bowel syndrome is caused by abnormal contractions of the colon and intestines (hence the term “spastic bowel,” which has sometimes been used to describe irritable bowel syndrome). Vigorous contractions of the intestines can cause severe cramps, providing the rationale for some of the treatments of IBS, such as antispasmodics and fiber (both of which help to regulate the contractions of the colon). However, abnormal contractions do not explain irritable bowel syndrome in all patients, and it is unclear whether the contractions are a symptom or cause of the disorder.
- People with irritable bowel syndrome who seek medical help are more likely to suffer from anxiety and stress than those who do not seek help. Stress and anxiety are known to affect the intestine; thus, it is likely that anxiety and stress worsen symptoms. However, stress or anxiety are probably not the cause. Some studies have suggested that irritable bowel syndrome is more common in people who have a history of physical, verbal, or sexual abuse.
Symptoms of Irritable Bowel Syndrome
Irritable bowel syndrome usually begins in young adulthood. Women are twice as likely as men to be diagnosed with irritable bowel syndrome in the United States and other western countries. In other countries (such as India), an equal number of men and women are diagnosed with irritable bowel syndrome. The most common symptom of irritable bowel syndrome is abdominal pain in association with changes in bowel habits (diarrhea and/or constipation).
Abdominal pain — Abdominal pain is typically crampy, varying in intensity, and located in the lower left abdomen. Some people notice that emotional stress and eating worsen the pain, and that having a bowel movement relieves the pain. Some women with irritable bowel syndrome notice an association between pain episodes and their menstrual cycle
Changes in bowel habits — Altered bowel habits are a second symptom of irritable bowel syndrome. This can include diarrhea, constipation, or alternating diarrhea and constipation.
Other symptoms — Other symptoms of irritable bowel syndrome include bloating, gas, belching, heartburn, difficulty swallowing, an early feeling of fullness with eating, and nausea.
Irritable Bowel Syndrome Diagnosis
Several intestinal disorders have symptoms that are similar to irritable bowel syndrome. Examples include malabsorption (abnormal absorption of nutrients), inflammatory bowel disease (such as ulcerative colitis and Crohn’s disease), and microscopic and eosinophilic colitis (uncommon diseases associated with intestinal inflammation).
Because there is no single diagnostic test for irritable bowel syndrome, many clinicians compare your symptoms to formal sets of diagnostic criteria. However, these criteria are not accurate in distinguishing irritable bowel syndrome from other conditions in everyone. Thus, a medical history, physical examination, and select tests can help to rule out other medical conditions.
Irritable Bowel Syndrome Treatment
There are a number of different treatments and therapies for irritable bowel syndrome. Treatments are often combined to reduce the pain and other symptoms of irritable bowel syndrome, and it may be necessary to try more than one combination to find the one that is most helpful for you.
Treatment is usually a long-term process; during this process, it is important to communicate with your healthcare provider about symptoms, concerns, and any stressors or home/work/ family problems that develop.
Diet changes — It is reasonable to try eliminating foods that may aggravate irritable bowel syndrome, although this should be done with the assistance of a healthcare provider. Eliminating foods without assistance can potentially worsen symptoms or cause new problems if important food groups are omitted.
Lactose — Many clinicians recommend temporarily eliminating milk products since lactose intolerance is common and can aggravate irritable bowel syndrome or cause symptoms similar to IBS. The greatest concentration of lactose is found in milk and ice cream, although it is present in smaller quantities in yogurt, cottage and other cheeses, and any prepared foods that contain these ingredients.
All lactose containing products should be eliminated for two weeks. If IBS symptoms improve, it is reasonable to continue avoiding lactose. If symptoms do not improve, you may resume eating lactose-containing foods.
People who avoid lactose should take a calcium supplement that contains at least 1000 mg of calcium and 800 IU of vitamin D.
Foods that cause gas — Several foods are only partially digested in the small intestines. When they reach the colon (large intestine), further digestion takes place, which may cause gas and cramps. Eliminating these foods temporarily is reasonable if gas or bloating is bothersome.
Foods that cause gas
Cruciferous vegetables (such as cabbage, Brussels sprouts, cauliflower, and broccoli)
Other foods: onions, celery, carrots, raisins, bananas, apricots, prunes, sprouts, and wheat
Foods that are easier for patients with IBS
Water, Ginger Ale, Sprite, and Gatorade
Soy milk or rice milk
Soy or rice based products
Plain pasta, plain noodles, white rice. No sauces or gravies
Potato: boiled or baked. No French Fries
Reads: French, Italian, whole white, English muffins, and white rolls
Plain fish, plain chicken, plain turkey, or plain ham
Eggs: soft-boiled, poached
Cereals: Plain Cornflakes, ice rispies, Corn or ice Chex, Cheerios; dry or with soymilk or rice milk
Salads: lettuce, hard-boiled egg slices, oil and vinegar dressing
Cooked peas, carrots (avoid raw vegetables)
Margarine, jams, jellies, peanut butter
In small amounts: applesauce, cantaloupe, watermelon, honeydew melon
In small amounts: fruit cocktail, peaches, pears (canned, non-dietetic)
Increasing dietary fiber — Increasing dietary fiber (either by adding certain foods to the diet or using fiber supplements) can relieve symptoms in some people with IBS, particularly if you have constipation.
Psychosocial therapies — Stress and anxiety can worsen irritable bowel syndrome in some people. The best approach for reducing stress and anxiety depends upon your situation and the severity of your symptoms. Have an open discussion with your clinician about the possible role that stress and anxiety could be having on your symptoms, and together decide upon the best course of action.
Irritable bowel syndrome medications — Although many drugs are available to treat the symptoms of irritable bowel syndrome, these drugs do not cure the condition. They are primarily used to relieve symptoms. The choice among these medications depends in part upon whether you have diarrhea, constipation, or pain- predominant irritable bowel syndrome.
As a general rule, medications are reserved for people whose symptoms have not adequately responded to more conservative measures such as changes in diet and fiber supplements.
Irritable Bowel Syndrome Prognosis
Although irritable bowel syndrome can produce substantial physical discomfort and emotional distress, most people with irritable bowel syndrome do not develop serious long-term health conditions. Furthermore, the vast majority of people with irritable bowel syndrome learn to control their symptoms.
It is important to work with a clinician to monitor symptoms over time. If symptoms change over time, further testing may be recommended. Over time, less than 5 percent of people diagnosed with irritable bowel syndrome will be diagnosed with another gastrointestinal condition.
Arnold Wald, MD; Nicholas J. Talley, MD, PhD; Leah K. Moynihan, RNC, MSN; Peter A. L. Bonis, MD.