Irritable bowel syndrome (IBS) is a common disorder that affects the large intestine (colon). Irritable bowel syndrome commonly causes cramping, abdominal pain, bloating, gas, diarrhea and constipation. IBS is a chronic condition that you will need to manage long term. Even though signs and symptoms are uncomfortable, IBS — unlike ulcerative colitis and Crohn’s disease, which are forms of inflammatory bowel disease — doesn’t cause changes in bowel tissue or increase your risk of colorectal cancer. Only a small number of people with irritable bowel syndrome have severe signs and symptoms. Some people can control their symptoms by managing diet, lifestyle and stress. Others will need medication and counseling.
Types of Irritable Bowel Syndrome (IBS)
There are three types of irritable bowel syndrome, or IBS. They include:
• IBS with constipation: This comes with stomach pain and discomfort, bloating, abnormally delayed or infrequent bowel movement, or lumpy/hard stool.
• IBS with diarrhea: This comes with stomach pain and discomfort, an urgent need to move your bowels, abnormally frequent bowel movements, or loose/watery stool.
• IBS with alternating constipation and diarrhea.
Symptoms of IBS
Some of the more common signs of irritable bowel syndrome include:
• abdominal pain or cramping that is often relieved by passing wind or faeces
• alternating diarrhoea and constipation
• a sensation that the bowels are not fully emptied after passing a motion
• abdominal bloating
• mucus present in the stools
Cause of IBS
The underlying cause of irritable bowel syndrome is still unknown, but certain factors have been found to ‘trigger’ attacks in susceptible individuals. These include:
• Infection – an episode of gastroenteritis will often result in persistent bowel symptoms, long after the offending bacteria or virus has been eliminated. The cause of this is unknown, but may involve changes to nerve function in the bowel or changes in the normal bacterial population of the bowel. Up to 25 per cent of IBS may be due to this problem.
• Food intolerance – impaired absorption of the sugar lactose (found in dairy and many processed foods) is the most common dietary trigger for IBS. Other sugars believed to trigger IBS are fructose (present in many syrups) and sorbitol.
• General diet – low-fibre diets can exacerbate the constipation of constipation-predominant IBS. Some people find spicy or sugary foods cause problems. However, many experts are sceptical about the role of general diet, once specific food intolerances have been eliminated.
• Emotional stress – strong emotions, such as anxiety or stress, can affect the nerves of the bowel in susceptible people.
• Medication – certain types (such as antibiotics, antacids and painkillers) can lead to constipation or diarrhoea.
Eating, Diet, and Nutrition for Irritable Bowel Syndrome
Eating smaller meals more often, or eating smaller portions, may help your irritable bowel syndrome (IBS) symptoms. Large meals can cause cramping and diarrhea if you have IBS. Eating foods that are low in fat and high in carbohydrates, such as pasta, rice, whole-grain breads and cereals, fruits, and vegetables, may help. Fiber may improve constipation symptoms caused by IBS because it makes stool soft and easier to pass. Fiber is a part of foods such as whole-grain breads and cereals, beans, fruits, and vegetables. While fiber may help constipation, it may not reduce the abdominal discomfort or pain of IBS. In fact, some people with IBS may feel a bit more abdominal discomfort after adding more fiber to their diet. Add foods with fiber to your diet a little at a time to let your body get used to them. Too much fiber at once can cause gas, which can trigger symptoms in people with IBS. Adding fiber to your diet slowly, by 2 to 3 grams a day, may help prevent gas and bloating.
What should one avoid eating to ease IBS symptoms? Certain foods or drinks may make symptoms worse, such as
• foods high in fat
• some milk products
• drinks with alcohol or caffeine
• drinks with large amounts of artificial sweeteners
• beans, cabbage, and other foods that may cause gas
To find out if certain foods trigger your symptoms, keep a diary and track
• what you eat during the day
• what symptoms you have
• when symptoms occur
Tests and diagnosis
A diagnosis of irritable bowel syndrome depends largely on a complete medical history and physical exam.
Criteria for making a diagnosis
Because there are usually no physical signs to definitively diagnose IBS, diagnosis is often a process of ruling out other conditions. To help this process, researchers have developed two sets of diagnostic criteria for IBS and other functional gastrointestinal disorders — conditions in which the bowel appears normal but doesn’t work (function) normally. Both criteria are based on symptoms after other conditions have been ruled out.
• Rome criteria. According to these criteria, you must have certain signs and symptoms before a doctor diagnoses irritable bowel syndrome. The most important are abdominal pain and discomfort lasting at least three days a month in the last three months, associated with two or more of following: improvement with defecation, altered frequency of stool or altered consistency of stool.
• Manning criteria. These criteria focus on pain relieved by defecation, having incomplete bowel movements, mucus in the stool and changes in stool consistency. The more symptoms present, the greater the likelihood of IBS.
Your doctor will likely assess how you fit these criteria, as well as whether you have any other signs or symptoms that might suggest another, more serious, condition. Some red flag signs and symptoms that suggest a need for additional testing include:
• New onset after age 50
• Weight loss
• Rectal bleeding
• Nausea or recurrent vomiting
• Abdominal pain, especially if it’s not completely relieved by a bowel movement, or occurs at night
• Diarrhea that is persistent or awakens you from sleep
• Anemia related to low iron
If you fit the IBS criteria and don’t have any red flag signs or symptoms, your doctor may suggest a course of treatment without doing additional testing. But if you don’t respond to that treatment, you’ll likely require more tests.
Your doctor may recommend several tests, including stool studies to check for infection or problems with your intestine’s ability to take in the nutrients from food (malabsorption). You may undergo a number of tests to rule out other causes for your symptoms.
• Flexible sigmoidoscopy. This test examines the lower part of the colon (sigmoid) with a flexible, lighted tube (sigmoidoscope).
• Colonoscopy. In some cases, especially if you are age 50 or older or have other signs of a potentially more serious condition, your doctor may perform this diagnostic test in which a small, flexible tube is used to examine the entire length of the colon.
• X-ray (radiography). Sometimes doctors will use X-rays to obtain an image of your colon.
• Computerized tomography (CT) scan. CT scans produce cross-sectional X-ray images of internal organs. CT scans of your abdomen and pelvis may help your doctor rule out other causes of your symptoms, especially if you have abdominal pain.
• Lower GI series. In this test, doctors fill your large intestine with a liquid (barium) to make it easier to see any problems on the X-ray.
• Lactose intolerance tests. Lactase is an enzyme you need to digest the sugar found in dairy products. If you don’t produce this enzyme, you may have problems similar to those caused by irritable bowel syndrome, including abdominal pain, gas and diarrhea. To find out if this is the cause of your symptoms, your doctor may order a breath test or ask you to remove milk and milk products from your diet for several weeks.
• Breath tests. Your doctor may perform a breath test to look for a condition called bacterial overgrowth, in which bacteria from the colon grow up into the small intestine, leading to bloating, abdominal discomfort and diarrhea. This is more common among people who have had bowel surgery or who have diabetes or some other disease that slows down digestion.
• Blood tests. Celiac disease is sensitivity to wheat, barley and rye protein that may cause signs and symptoms like those of irritable bowel syndrome. Blood tests can help rule out this disorder. Children with IBS have a far greater risk of celiac disease than do children who don’t have IBS. If your doctor suspects that you have celiac disease, he or she may perform an upper endoscopy to obtain a biopsy of your small intestine.
• Stool tests. If you have chronic diarrhea, doctors may want to examine your stool for bacteria or parasites.
Treatments and drugs
Because it’s not clear what causes irritable bowel syndrome, treatment focuses on the relief of symptoms so that you can live as normally as possible. In most cases, you can successfully control mild signs and symptoms of irritable bowel syndrome by learning to manage stress and making changes in your diet and lifestyle. Try to avoid foods that trigger your symptoms. Also try to get enough exercise, drink plenty of fluids and get enough sleep. If your problems are moderate or severe, you may need more than lifestyle changes. Your doctor may suggest and medications.
• Eliminating high-gas foods. If you have bothersome bloating or are passing considerable amounts of gas, your doctor may suggest that you cut out such items as carbonated beverages, vegetables — especially cabbage, broccoli and cauliflower — and raw fruits.
• Eliminating gluten. Research shows that some people with IBS report improvement in diarrhea symptoms if they stop eating gluten (wheat, barley and rye). This recommendation remains controversial, and the evidence is not clear.
• Eliminating FODMAPs. Some people are sensitive to types of carbohydrates such as fructose, fructans, lactose and others, called FODMAPs (fermentable oligo-, di-, and monosaccharides and polyols). FODMAPs are found in certain grains, vegetables, fruits and dairy products. However, often people are not bothered by every FODMAP food. You may be able to get relief from your IBS symptoms on a strict low FODMAP diet and then reintroduce foods one at time.
• Fiber supplements. Taking fiber supplements, such as psyllium (Metamucil) or methylcellulose (Citrucel), with fluids may help control constipation. Fiber obtained from food may cause much more bloating compared with a fiber supplement. If fiber doesn’t help symptoms, your doctor may prescribe an osmotic laxative such as milk of magnesia or polyethylene glycol.
• Anti-diarrheal medications. Over-the-counter medications, such as loperamide (Imodium), can help control diarrhea. Some people will benefit from medications called bile acid binders, such as cholestyramine (Prevalite), colestipol (Colestid) or colesevelam (Welchol), but these can lead to bloating.
• Anticholinergic and antispasmodic medications. These medications, such as hyoscyamine (Levsin) and dicyclomine (Bentyl), can help relieve painful bowel spasms. They are sometimes used for people who have bouts of diarrhea, but they can worsen constipation and can lead to other symptoms, such as difficulty urinating. They should also be used with caution among people with glaucoma.
• Antidepressant medications. If your symptoms include pain or depression, your doctor may recommend a tricyclic antidepressant or a selective serotonin reuptake inhibitor (SSRI). These medications help relieve depression as well as inhibit the activity of neurons that control the intestines.
If you have diarrhea and abdominal pain without depression, your doctor may suggest a lower than normal dose of tricyclic antidepressants, such as imipramine (Tofranil) or nortriptyline (Pamelor). Side effects of these drugs include drowsiness and constipation. SSRIs, such as fluoxetine (Prozac, Sarafem) or paroxetine (Paxil), may be helpful if you’re depressed and have pain and constipation.
• Antibiotics. Some people whose symptoms are due to an overgrowth of bacteria in their intestines may benefit from antibiotic treatment. Some people with symptoms of diarrhea have benefited from rifaximin (Xifaxan), but more research is needed.
• Counseling. You may benefit from counseling if you have depression or if stress tends to worsen your symptoms.
Medication specifically for IBS
Two medications are currently approved for specific cases of IBS:
• Alosetron (Lotronex). Alosetron is designed to relax the colon and slow the movement of waste through the lower bowel. The Food and Drug Administration (FDA) removed it from the market for a time, but has since allowed alosetron to be sold again. However, alosetron can be prescribed only by doctors enrolled in a special program and is intended for severe cases of diarrhea-predominant IBS in women who haven’t responded to other treatments. Alosetron is not approved for use by men. It has been linked to rare but important side effects, so it should only be considered when other treatments are not successful.
• Lubiprostone (Amitiza). Lubiprostone works by increasing fluid secretion in your small intestine to help with the passage of stool. It is approved for women age 18 and older who have IBS with constipation. Its effectiveness in men is not proved, nor its long-term safety. Common side effects include nausea, diarrhea and abdominal pain. Lubiprostone is generally prescribed only for women with IBS and severe constipation for whom other treatments haven’t been successful.
Anyone can experience digestive upset from worry or anxiety. But if you have irritable bowel syndrome, stress-related problems such as abdominal pain and diarrhea tend to occur more often and be more severe. Finding ways to deal with stress may help prevent or ease symptoms:
• Counseling. In some cases, a psychologist or psychiatrist can help you learn to reduce stress by looking at how you respond to events and then working with you to modify or change that response.
• Biofeedback. This stress-reduction technique helps you reduce muscle tension and slow your heart rate with the feedback help of a machine. You’re then taught how to produce these changes yourself. The goal is to help you enter a relaxed state so that you can cope more easily with stress.
• Progressive relaxation exercises. These help you relax muscles in your body, one by one. Start by tightening the muscles in your feet, then concentrate on slowly letting all of the tension go. Next, tighten and relax your calves. Continue until the muscles in your body, including those in your eyes and scalp, are relaxed.
• Deep breathing. Most adults breathe from their chests. But you become calmer when you breathe from your diaphragm, the muscle that separates your chest from your abdomen. When you inhale, allow your belly to expand. When you exhale, your belly naturally contracts. Deep breathing can also help relax your abdominal muscles, which may lead to more-normal bowel activity.
• Mindfulness training. This stress-reduction technique helps you focus on being in the moment and letting go of worries and distractions.
• Other techniques. Set aside at least 20 minutes a day for any activity you find relaxing — listening to music, reading, playing computer games or just soaking in a warm bath.