Irritable bowel syndrome (IBS) is a common digestive condition, affecting 10 to 15 percent of the population in the United States. In fact, it is one of the most common gastrointestinal (GI) disorders seen in primary care and one of the most common diseases diagnosed by gastroenterologists. (1)

What is IBS?

IBS is a GI condition characterized by bowel disturbances and pain that cannot be attributed to any other structural or biochemical pathology. (12) It’s important not to confuse IBS with inflammatory bowel disease (IBD), which is an inflammatory autoimmune disease that also affects the GI system.

IBS is considered a functional GI disorder that features recurrent abdominal pain or discomfort, associated with changes in bowel habits or disordered bowel movements, including constipation, diarrhea, or alternating constipation and diarrhea, as well as other possible symptoms such as gas or bloating. (5)

Woman holding abdomen

IBS patients typically experience recurrent abdominal pain.

There may also be a psychophysiological factor involved in IBS as comorbid psychiatric conditions, such as mood and anxiety disorders, may occur among these patients. (11)

The role of the gut-brain connection in IBS

The brain-gut axis is the bidirectional connection between the enteric nervous system in the GI tract and the central nervous system of the brain. (10) As a result of this connection, intestinal microbes and their interaction with the host may be an important element in the pathogenesis of IBS. Some patients may benefit from one or both of the following therapeutic approaches:

  • Modulation of the gut microbiome with prebiotics and probiotics
  • Psychological interventions, such as psychotherapy or gut-directed hypnosis (7)

In addition, identifying potential underlying IBS causes can help determine the proper course of treatment.

IBS causes

IBS is considered a complex illness and the exact etiology is not fully understood; however, the following factors have been implicated in the pathogenesis of IBS: (9)

  • Altered fecal microflora
  • Altered GI motility
  • Bacterial overgrowth
  • Brain-gut interactions
  • Chronic psychological stress
  • Carbohydrate malabsorption
  • Food sensitivities
  • Intestinal inflammation
  • Postinfectious reactivity
  • Visceral hypersensitivity

An infection in the gut, such as a Clostridium difficile (C. difficile) infection, can also cause IBS. This is known as post-infectious IBS and is commonly treated with antibiotics and other drugs that address specific symptoms, such as pain or diarrhea. (3) Research also suggests that fecal microbiota transplantation be effective in the treatment for patients with IBS, specifically those with post-infectious IBS. (13)

Examining an individual’s symptoms can provide some insight as to etiology and the best course of treatment.

IBS symptoms

IBS pain is considered a hallmark symptom of this condition. According to a 2017 review, when pain is combined with altered bowel habits, the severity of symptoms can range from inconvenient to significantly and negatively impacting day-to-day quality of life. (6)

Gas, bloating, mucus in the stool, and the feeling that a bowel movement is incomplete are also symptoms of IBS. (8) Diet can significantly impact IBS symptoms.

IBS trigger foods

More than 50% of people with IBS have self-reported food intolerances or food triggers that aggravate symptoms of bloating and abdominal pain. The following foods are the most commonly reported dietary triggers for IBS:

  • Chocolate
  • Coffee
  • Dairy products including yogurt, milk, cheese, eggs, and butter
  • Fried foods
  • Fruits, especially citrus and banana
  • Grains including wheat, barley, rye, oats, and corn
  • Legumes such as beans and lentils
  • Tea
  • Vegetables, especially onions, peas, potatoes
  • Wine

Avoiding triggering foods will help with symptom management. (2)

Pea pods

Some vegetables, such as onions, peas, potatoes, can trigger IBS symptoms.

IBS diagnosis

Proper diagnosis of IBS is imperative for optimal treatment outcomes and effective symptom management. Unfortunately, diagnosing IBS can be difficult for several reasons, including: (4)

  • Symptoms can change and fluctuate over time
  • Symptoms can mimic other issues such as lactose intolerance
  • There is no precise biomarker for IBS
  • Providers may not be aware of the current guidelines to properly make the diagnosis

Fortunately, clinicians have very clear guidelines, known as the Rome Criteria, used to accurately diagnose IBS. The Rome Diagnostic Criteria outlines three different subtypes of IBS, including:

  1. Constipation (IBS-C)
  2. Diarrhea (IBS-D)
  3. Mixed constipation alternating with diarrhea (IBS-M) (12)

The IBS subtype is determined by looking at abnormal bowel activity days, the number of normal bowel activity days, and the following criteria based on symptoms:

  • Changes in stool frequency and form
  • Presence of abdominal pain
  • Symptom onset greater than six months, with symptom activity during the last three months
  • Symptom frequency at least one day per week (12)

Once an accurate diagnosis is made, a proactive treatment and symptom-management plan can be established.

The bottom line

IBS is a common GI disorder that can be challenging to diagnose and treat. By developing a comprehensive integrative treatment plan, healthcare practitioners can provide these patients with relief and an improved quality of life. This approach includes dietary modifications, addressing lifestyle factors, such as stress management and sleep, and dietary supplement interventions.

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  1. American College of Gastroenterology. (Accessed 2020, August). Irritable Bowel Syndrome.
  2. Capili, B., Anastasi, J. K., & Chang, M. (2016). Addressing the Role of Food in Irritable Bowel Syndrome Symptom Management. The journal for nurse practitioners: JNP, 12(5), 324–329.
  3. Iacob, T., Ţăţulescu, D. F., & Dumitraşcu, D. L. (2017). Therapy of the postinfectious irritable bowel syndrome: an update. Clujul medical (1957), 90(2), 133–138.
  4. Lacy, B. E., & Patel, N. K. (2017). Rome Criteria and a Diagnostic Approach to Irritable Bowel Syndrome. Journal of clinical medicine, 6(11), 99.
  5. Mearin, F., & Malfertheiner, P. (2017). Functional Gastrointestinal Disorders: Complex Treatments for Complex Pathophysiological Mechanisms. Digestive diseases (Basel, Switzerland), 35 Suppl 1(1), 1–4.
  6. Moayyedi, P., Mearin, F., Azpiroz, F., Andresen, V., Barbara, G., Corsetti, M., Emmanuel, A., Hungin, A., Layer, P., Stanghellini, V., Whorwell, P., Zerbib, F., & Tack, J. (2017). Irritable bowel syndrome diagnosis and management: A simplified algorithm for clinical practice. United European gastroenterology journal, 5(6), 773–788.
  7. Moser, G., Fournier, C., & Peter, J. (2018). Intestinal microbiome-gut-brain axis and irritable bowel syndrome. Intestinale Mikrobiom-Darm-Hirn-Achse und Reizdarmsyndrom. Wiener medizinische Wochenschrift (1946), 168(3-4), 62–66.
  8. National Institute of Diabetes and Digestive and Kidney Diseases. (2017, November). Symptoms & Causes of Irritable Bowel Syndrome.
  9. Occhipinti, K., & Smith, J. W. (2012). Irritable bowel syndrome: a review and update. Clinics in colon and rectal surgery, 25(1), 46–52.
  10. Saha L. (2014). Irritable bowel syndrome: pathogenesis, diagnosis, treatment, and evidence-based medicine. World journal of gastroenterology, 20(22), 6759–6773.
  11. Van Oudenhove, L., Vandenberghe, J., Demyttenaere, K, & Tack, J. (2010). Psychosocial factors, psychiatric illness and functional gastrointestinal disorders: a historical perspective. Digestion, 82(4), 201010.
  12. Weaver, K. R., Melkus, G. D., & Henderson, W. A. (2017). Irritable Bowel Syndrome. The American journal of nursing, 117(6), 48–55.
  13. Wen, W., Zhang, H., Shen, J., Wei, L., & Shen, S. (2018). Fecal microbiota transplantation for patients with irritable bowel syndrome: A meta-analysis protocol. Medicine, 97(40), e12661.