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by Dr. C. H. Weaver M.D. 3/2020

Irritable bowel syndrome (IBS) is a disorder that affects the large intestine, or colon. Its symptoms include cramping, abdominal pain, bloating, constipation, and diarrhea. IBS is common, affecting up to 20 percent—one in five—of adults in the United States. More women suffer from IBS than men.

If you suffer from IBS, it may be reassuring to know that this disorder does not permanently damage the intestines. IBS doesn’t lead to cancer or other serious diseases, (1-4) and new medications and Fecal Microbiota Transplant (FMT) are promising for the management of patients with refractory disease. (5)

Causes of Irritable Bowel Syndrome

There is currently no known cause of IBS, but research indicates that it’s the result of sensitivity of the large intestine to certain foods and stress. This sensitivity may be the result irregular (too fast or too slow) muscle movement in colon (called motility), periodic spasms in motility, or temporary halts in motility.

Other potential factors in IBS include diminished serotonin (a neurotransmitter largely located in the gastrointestinal tract) receptor activity, the immune system, bacterial infection, and mild celiac disease (an inability to digest gluten).

Certain lifestyle factors, mostly related to diet, may make symptoms of IBS worse. These include:

  • Large meals
  • Caffeinated drinks such as coffee, tea, and cola
  • Alcohol
  • Foods such as wheat, rye, barley, chocolate, and milk products
  • Some medicines
  • Stress, conflict, emotional events, and anxiety

Symptoms of Irritable Bowel Syndrome

The main symptoms that characterize IBS are:

  • Bloating
  • Abdominal pain
  • Abdominal discomfort

Symptoms of IBS tend to vary from person to person as well as in frequency. In addition to the main symptoms described above, you may experience constipation or diarrhea or alternate between the two. Bowel movements may also change in appearance. In some cases symptoms come and go, while in others they remain constant.

Symptoms of Other Problems

When symptoms of IBS are accompanied by the following complaints, there is a risk for medical problems other than IBS: bleeding, fever, weight loss, or persistent severe pain.

Diagnosis of IBS

If you think you have symptoms of IBS, see your doctor for a diagnosis. Be prepared to share your complete medical history and to describe your symptoms. There is no test for IBS, but you may be tested to rule out other conditions.

If your doctor rules out other conditions and confirms that symptoms indicating IBS are present, he or she may make a diagnosis of IBS. To diagnose IBS many doctors look for symptoms (abdominal pain and discomfort) that have been present for at least 12 weeks during the previous year and share two of these three features: 1) pain is relieved by having a bowel movement; 2) when pain is present, frequency of bowel movements change; 3) when pain is present, the form and appearance of stool changes.

What are the four types of IBS?

Doctors classify IBS into one of four types based on “usual stool consistency. These types are important because they determine the types of treatment that are most likely to improve your symptoms.

The four types of IBS are

IBS-C with constipation:

o hard or lumpy stools at least 25 percent of the time

o loose or watery stools less than 25 percent of the time

IBS-D with diarrhea:

o loose or watery stools at least 25 percent of the time

o hard or lumpy stools less than 25 percent of the time

Mixed IBS-M, experience both diarrhea and constipation:

o hard or lumpy stools at least 25 percent of the time

o loose or watery stools at least 25 percent of the time

Unsubtyped IBS-U

o hard or lumpy stools less than 25 percent of the time

o loose or watery stools less than 25 percent of the time

Treatment of IBS

There isn’t currently a cure for IBS, but with a combination of medical treatment and diet and lifestyle adjustments, symptoms can be managed.

Lifestyle - Because IBS is often made worse by stress, taking steps to manage stress in your life may help relieve symptoms. Some people find that relaxation techniques including breathing exercises, meditation, and yoga help reduce stress. As well, physical activity and adequate sleep can help control stress, as can any activity that you find calming—reading, listening to music, taking a walk with a friend, for example. Counseling and support from counselors, friends, family, and support groups can also help manage stress and help you find ways to avoid or navigate stressful situations.

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Diet - Keep track of the foods that seem to trigger symptoms of IBS. Some people find that a written record, or food journal, helps them identify problem foods. Record details such as what you eat, time of day, and how much and how you feel afterward. By avoiding foods that seem to cause discomfort, you may be able to reduce symptoms. For additional help making changes to your diet, you may wish to consult a registered dietician.

Some dietary tips that may help relieve symptoms include:

  • Drink plenty of water and avoid carbonated beverages, which may cause gas.
  • Don’t chew gum or eat too quickly; these behaviors can cause you to swallow air, which can cause gas.
  • Try eating smaller meals more frequently and avoid large meals.
  • Try increasing fiber in your diet gradually. Fiber can help reduce constipation, but it can also make gas and cramping worse. It’s therefore important to slowly increase the amount of fiber you consume.
  • Avoid foods and beverages that make your symptoms worse. For some people these include alcohol, drinks with caffeine, dairy products, beans, cauliflower, and broccoli.

Medication - Medication may be used to address symptoms of IBS. Even though some of these medications are available over the counter, it’s important to consult your doctor before taking them and to follow his or her directions. Medications include:

  • Fiber supplements or laxatives to relieve constipation.
  • Medicines such as Lomotil® (diphenoxylate and atropine) or Imodium® (loperamide) to decrease diarrhea.
  • Antispasmodics to reduce muscles spasms in the colon.
  • Antidepressants to relieve some symptoms

There are some medications available specifically for the treatment of IBS:

  • Lotronex® (alosetron hydrocholoride) is approved by the U.S. Food and Drug Administration for women with severe IBS who have not responded to conventional therapy and whose primary symptom is diarrhea. Lotronex, however, is associated with serious side effects and is therefore used cautiously.
  • Zelnorm (tegaserod) offers a new approach to treatment. Zelnorm is a selective serotonin-4 (5-HT4) receptor agonist and the only IBS-C medicine that activates specific serotonin neuroreceptors in the gut to help regain healthy movement and ease abdominal pain. Learn more about IBS treatment with Zelnorm
  • Lubiprostone increases the fluid your small intestine secretes which helps pass stool more easily reducing the risk of constipation.
  • Linaclotide helps ease the symptoms of IBS-C by spurring more frequent bowel movements.

Fecal Transplantation Associated With Improvements in IBS Symptoms

Fecal microbiota transplantation therapy (FMT) is associated with significant improvements in the symptoms of IBS, according to the results of a randomized clinical trial published in Gastroenterology.

Patients with refractory IBS symptoms consisting of severe bloating and either diarrhea-prominent or mixed-type IBS were then randomly assigned in a 2:1 ratio to nasojejunal administration of either autologous (placebo) or donor (treatment) stools. Donor stools were provided by 2 active, healthy men with no prior or current gastrointestinal symptoms. The primary study endpoint was relief of general IBS symptoms and bloating at 12 weeks after FMT. Secondary endpoints were overall improvements in IBS symptoms and patient-reported quality of life. IBS symptoms were re-assessed 1 year after FMT by self-report questionnaire.

At week from initiation of treatment 56% of the donor group reported improvements in IBS symptoms, compared with only 26% of the placebo group. Patients in the donor group also experienced a mean increase of 16% in self-reported quality of life scores. Overall, 21% of patients given donor stool reported that effects lasted for over 1 year. By contrast, just 5% of patients given placebo reported long-term improvements. Open-label re-transplantation improved symptoms in 67% of those who responded to the first FMT.

Results from this pilot study suggest that FMT may be a viable option for patients with IBS who present with significant bloating. However, further study is necessary to identify which patients with IBS may best benefit from FMT. The ability of certain microbial biomarkers to predict FMT response also warrants additional research. (5)

Living with Irritable Bowel Syndrome

If IBS isn’t managed, symptoms may impact your overall quality of life. The condition may impact your social life by causing you to avoid making plans when you’re experiencing symptoms. Your sex life may also be affected, as IBS may make you too physically uncomfortable to enjoy intimacy. As well, IBS may affect your professional life — people with the condition tend to miss more workdays than people who don’t have IBS.

Fortunately, with proper management, you can live a full and active life if you have IBS. By following your doctor’s recommendations and finding medications and lifestyle and diet changes to help control symptoms, IBS can be a very manageable condition.

Smart Food Tips for Living With IBS

With symptoms that include cramping, gas, bloating, and constipation in some, and diarrhea in others, IBS can certainly impact your quality of life. As a result, sufferers are generally on the lookout for relief. The good news is that treatment often starts with something you can do at home: eating a sensible diet and avoiding foods that irritate your digestive system.

According to the American Gastroenterological Association, a “proper diet” can help control your IBS symptoms. “Proper” in this case includes avoiding eating large amounts at one time and avoiding or eating less of the foods that seem to cause a problem. Some people, for example, find that dairy products or high-fat foods can trigger symptoms. (1)

A common dietary guideline for people suffering from IBS is to follow a diet known as FODMAP. This stands for “fermentable oligo-di-monosaccharides and polyols,” or, more simply, certain types of carbohydrates found in foods that are hard to digest. By following FODMAP, also known as a low-FODMAP diet, you avoid or limit these particular carbohydrates. Some of the foods that contains FODAMPs include (2):

  • Fruits such as apples, apricots, blackberries, cherries, mango, nectarines, pears, plums, and watermelon, or juice containing any of these fruits.
  • Canned fruit in natural fruit juice, or large quantities of fruit juice or dried fruit.
  • Vegetables such as artichokes, asparagus, beans, cabbage, cauliflower, garlic and garlic salts, lentils, mushrooms, onions, and sugar snap or snow peas.
  • Dairy products such as milk, milk products, soft cheeses, yogurt, custard, and ice cream.
  • Wheat and rye products.
  • Honey and foods with high-fructose corn syrup.
  • Products, including candy and gum, with sweeteners ending in “–ol” (for example, sorbitol, mannitol, xylitol, and maltitol).

If you’re living with IBS, it’s of course as important to know what to eat as it is to know what not to eat. Foods that contain insoluble fiber—which is found in foods such as wheat bran, vegetables, and whole grains—can help ease IBS symptoms in some people. Insoluble fiber adds bulk to stools, helping them pass more quickly through the digestive system. More fiber, however, isn’t necessarily better: too much can cause gas and bloating, so aim to eat just enough high-fiber foods to keep bowel movements easy to pass and painless.

Researchers Identify Origin of Pain Relief in Irritable Bowel Syndrome

Defects in the immune system in individuals with irritable bowel syndrome (IBS) is the major reason why sufferers have ongoing issues with pain, and one reason why some painkillers do not provide satisfactory relief to these patients, according to a recent study by researchers in Australia.

IBS is a functional gastrointestinal (GI) disorder leading to bowel changes, pain and discomfort. It is estimated that IBS affects 3% to 20% of the adult population; however, only 5% to 7% of adults have been diagnosed, according to the U.S. National Institute of Diabetes and Digestive and Kidney Diseases. Clinicians have further classified IBS into four subtypes based on a person’s usual stool consistency: IBS with constipation (IBS-C), IBS with diarrhea (IBS-D), mixed IBS (IBS-M) and unsubtyped IBS (IBS-U). Unexplained GI pain is common to all four subtypes and often has the greatest impact on quality of life.

Scientists in the Nerve-Gut Research Laboratory at the University of Adelaide in Australia obtained blood samples from more than 100 people, half with IBS and half without the condition in order to determine if substance that mediate pain were different in the two groups. Specifically they analyzed the amount of endorphins and immune mediators that play a role in controlling pain, and found that these chemicals were deficient in subjects with IBS.

The researchers demonstrated that the mechanisms involved in GI pain, and the differences between the immune pain response in healthy people and in those with IBS are different. The gut contains immune effector cells that normally release opioid chemicals that block pain, but production and release of these opioid chemicals is defective in patients with IBS. Researchers hope that targeted treatment strategies can now be developed to specifically relieve pain associated with IBS. (6)


  1. IBS: A Patient’s Guide to Living with Irritable Bowel Syndrome. The American Gastroenterological Association. Available here. Accessed February 23, 2019.
  2. Eating, Diet, and Nutrition for Irritable Bowel Syndrome. National Institute of Diabetes and Digestive and Kidney Diseases. Available at: Accessed February 23, 2019.
  3. International Foundation for Functional Gastrointestinal Disorders
  4. National Digestive Diseases Information Clearinghouse
  5. Holvoet T, Joossens M, Vázquez-Castellanos JF, et al.[ Fecal microbiota transplantation reduces symptoms in some patients with irritable bowel syndrome with predominant abdominal bloating: short- and long-term results from a placebo-controlled randomized trial]( [published online July 15, 2020]. Gastroenterology. doi: 10.1053/j.gastro.2020.07.013
  6. Published online in Brain, Behavior, and Immunity (2014 July [Epub ahead of print]).