Irritable Bowel Syndrome

Irritable bowel syndrome (IBS) has a variety of symptoms, most commonly cramping, abdominal pain, bloating, constipation, and diarrhea. Symptoms can vary from person to person, and may alternate between diarrhea and constipation. IBS causes discomfort and often is upsetting, but it does not harm the intestines or lead to diseases such as cancer.

Causes of IBS

Experts do not know what causes IBS. Stress, diet, drugs, or hormones may aggravate gastrointestinal (GI) problems. The body’s immune system, which helps fight infection, also may contribute to IBS. Some researchers think that increased levels of serotonin, a normal chemical that is found in the GI tract, is involved. Other researchers believe that individuals with IBS have a large intestine that is more sensitive to certain foods or stress, which causes more of a reaction to stressors or certain foods than others. In these people, stress may trigger colon spasms.

Tests to diagnose IBS

Irritable bowel syndrome is diagnosed using the Rome III criteria—symptoms of recurrent abdominal pain or discomfort and a marked change in bowel habits present for at least 6 months, with symptoms experienced on at least 3 days during at least three of these months, with two or more of the following findings applying:

  • Pain is relieved by a bowel movement
  • Onset of pain is related to a change in frequency of stool
  • Onset of pain is related to a change in the appearance of stool

Other tests can help rule out other problems, with diagnosis usually based on these results and a careful review of the type and frequency of symptoms.

Foods to avoid with IBS

Changing your diet might help improve your IBS symptoms. Having a well-balanced diet, eating regular meals, and drinking plenty of fluids are important in order to keep your digestive system moving. Foods that might cause problems vary from person to person, but some foods might make your IBS worse.

You might find it helpful to avoid foods that cause gas or flatulence, including:

  • Fatty meats
  • Whole milk
  • Whole-milk cheeses
  • Fatty desserts
  • Broccoli
  • Brussels sprouts
  • Cabbage
  • Cauliflower
  • Corn
  • Onions

In some people, sweeteners, such as fructose or sorbitol, or use of alcohol or caffeine can make IBS symptoms worse.

Tolerance to specific foods is very individualized. Keeping a food diary can help you decide if any specific foods are causing symptoms. You do not need to completely avoid certain foods or groups of foods, unless you are able to link them with your IBS symptoms. A registered dietitian can review your food diary and help you identify foods that might make your symptoms worse.

Foods that can help IBS

Certain foods can possibly help those suffering from IBS. A diet high in fiber seems to help with IBS symptoms. Experts recommend 25–35 grams of fiber/day.

Good sources of fiber include:

  • Most fruits and vegetables (remember you might need to avoid the vegetables listed under Foods to avoid)
  • Dried beans, such as pinto beans and black-eyed peas
  • Whole-grain breads and cereals


Some experts think probiotics (live microorganisms found in certain foods) can help with symptoms. Probiotics are available for sale in the form of dietary supplements and foods. Examples of foods containing probiotics include yogurt, miso, tempeh, and some juices and soy drinks. Many different types of probiotics exist, and as a result, it is difficult to determine which ones, if any, are beneficial to digestive health. Not enough evidence is available to say for sure that probiotics help, but they probably will not hurt, especially when you eat foods such as yogurt.


In recent years, patients with IBS have followed the low FODMAP™ Diet.

FODMAP is an abbreviation for:

  • Fermentable
  • Oligosaccharides (fructans and galactans)
  • Disaccharides (lactose)
  • Monosaccharides (excess fructose in a food) 
  • Polyols (sugar alcohols, such as sorbitol, maltitol, mannitol, xylitol and isomalt)

FODMAPs are sugars (carbohydrates) in the foods that we eat that are poorly absorbed by the gut. The intestinal bacteria in the gut can react to these foods and cause abdominal pain, gas, bloating, diarrhea, and/or constipation. When foods rich in FODMAPs are removed from the diet of patients with functional gastrointestinal disorders (IBS), often symptoms of IBS are reduced.

The FODMAP Diet sometimes is complicated, requiring elimination of many foods. You should consult with a registered dietitian skilled in FODMAPS and/or elimination to learn more about this diet.

Medicines for IBS

Medicines often are used to help with IBS symptoms. Your doctor may suggest fiber supplements for constipation or antidiarrheal medicines for diarrhea. Sometimes an antispasmodic medicine will help reduce pain in the abdomen. Tricyclic antidepressants and selective serotonin reuptake inhibitors in low doses may help reduce abdominal pain.

Other treatments

If you feel stressed frequently and have IBS, stress management may help your symptoms.

Examples of stress management include:

  • Relaxation training and therapy
  • Counseling and support
  • Regular exercise
  • Adequate sleep
  • Removing stressful situations from your life, if possible.


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