April 2024 Issue

Digestive Wellness: Is It Irritable Bowel Syndrome?
By Densie Webb, PhD, RD
Today’s Dietitian
Vol. 26 No. 4 P. 10

Discover the latest science-backed interventions to improve symptoms.

When clients or patients complain of abdominal pain, it could suggest any number of conditions or diseases, from constipation to cancer. One possibility, however, is irritable bowel syndrome (IBS). IBS is the most common functional gastrointestinal disorder in the United States. Researchers estimate that IBS affects between 5% and 12% of people in North America.1,2 While the chronic condition can affect anyone at any age, it’s more prevalent among women; it’s most commonly diagnosed in people under the age of 50,1 and about 50% of patients’ symptoms start before the age of 35.3

In addition, IBS is a costly condition. In 2005, direct medical costs associated with IBS were estimated to be between $1.5 billion and $10 billion per year in the United States alone, excluding prescriptions and over-the-counter medications. There’s also the cost of lost work days due to debilitating symptoms.4 When taking inflation into account, the current costs are likely to be far greater. While IBS isn’t life threatening, symptoms have been associated with an increased incidence of depression and anxiety.

This article will discuss how IBS may present, what the current research says, and therapies and lifestyle changes that may help clients improve their symptoms. While some new research as to the causes of IBS have emerged and been recognized in the last few years, such as a possible connection between COVID-19 and gluten intolerance, most dietary recommendations have remained relatively unchanged.

IBS Diagnosis
Symptoms associated with IBS can vary greatly, making diagnosis difficult. Abdominal pain is a major symptom of IBS, and the feeling of being bloated is also common. IBS symptoms also can include altered consistency or frequency of stools, distention, straining, and urgency.5 Amy Bragagnini, MS, RD, CSO, a spokesperson for the Academy of Nutrition and Dietetics in Grand Rapids, Michigan, counsels patients with IBS and says, “Most of the time, ‘complicated’ is an appropriate description of the condition.” In fact, one recent journal article described IBS as being “astoundingly complicated.”6

However, IBS generally is divided into the following three types2:

• IBS-C: IBS with constipation;
• IBS-D: IBS with diarrhea; and
• IBS-Mixed: IBS with both constipation and diarrhea.

There’s no lab test or imaging procedure that can accurately identify IBS. Diagnosis typically is based on symptoms and their frequency. While diagnostic procedures may vary by provider, whether a physician, nurse, or dietitian, it likely would begin with a medical history, diet history, family history, a physical exam to rule out other underlying conditions, and questions about the patient’s lifestyle. “For some patients, life stressors contribute to the development of IBS,” Bragagnini explains. She also says some experts are investigating a possible connection between COVID-19 and the development of IBS.

Diet Therapy
Because of the chronic nature of IBS and the potential side effects of long-term usage of any medication, diet therapy may be the best approach for treating the condition long term. While there’s no definitive diet therapy that works for everyone with IBS, research has found that up to 84% of patients report specific food-related symptoms, and almost one-half report worsening symptoms within 90 minutes after eating.7,8 However, determining which foods are going to cause symptoms in any given patient at any given time is a matter of trial and error.

While research findings vary, fiber supplementation, particularly psyllium fiber, is considered to be safe and effective for treating IBS symptoms.9 It’s believed that the fermentation of psyllium and other soluble fibers can increase the production of short-chain fatty acids, such as butyrate, which provide energy for the colon’s mucosal cells and act as anti-inflammatories.10 Physicians often recommend patients with IBS increase their intake of dietary fiber to 20 to 35 g daily to regulate stools and reduce abdominal pain and bloating, although there isn’t specific guidance for how much of that total fiber intake should be soluble.9

“Every one of my patients is different, so it’s hard to generalize their nutrition prescription,” Bragagnini says. Because there’s no single effective therapy for all IBS sufferers, therapies tend to focus on alleviating the nature and timing of an individual’s symptoms.1 She further explains that physicians often recommend IBS patients follow a low-FODMAP (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols, which are poorly absorbed and may trigger IBS symptoms) diet, but that recommendation often comes without much guidance, which can leave IBS patients feeling overwhelmed, confused, and with little or no relief. There are many foods to avoid on a low-FODMAP diet, including dairy-based milk, yogurt, and ice cream; wheat-based products such as cereal, bread, and crackers; beans and lentils; some vegetables, such as artichokes, asparagus, onions, and garlic; and some fruits, such as apples, cherries, pears, and peaches.11 The benefits regarding symptoms appear to be higher in patients with IBS-D than in those with IBS-C.6 In addition, following a low-FODMAP diet can be challenging for vegetarians and vegans.

The American College of Gastroenterology considers IBS to be a disorder of gut-brain interaction and has suggested that probiotics may play a role in managing IBS symptoms by altering the gut microbiota. Several studies have found probiotics superior to placebo in alleviating IBS symptoms, but study methodologies vary, and there’s no clear probiotic prescription for a specific strain or dose.1 Overall, the evidence on the efficacy of probiotics is relatively weak, and more research is needed to determine whether probiotics may be an option as a complementary therapy for IBS.

Gluten-Free Diet
A gluten-free diet also has been reported to reduce symptoms in patients with IBS, and it’s been suggested that some IBS patients may be gluten intolerant, otherwise known as non-celiac gluten sensitivity. While the American College of Gastroenterology strongly recommended in 2020 that serological testing be done on IBS patients with diarrhea symptoms to rule out celiac disease, the organization also stated that the recommendation was based on “moderate quality evidence.”12 The association between gluten intolerance and IBS needs to be examined more carefully for accurate treatment.5

Additional Nonmedical Therapies
Other suggested nonmedical therapies have included exercise, peppermint oil, and psychological therapies, such as cognitive behavioral therapy or relaxation therapy. However, none of these has strong evidence of their efficacy for treating IBS symptoms.1 According to the American College of Gastroenterology Monograph on IBS, there are medications that have shown moderate-to-high quality evidence for improving IBS symptoms, including linaclotide (Linzess), plecanatide (Trulance), and lubiprostone (Amitiza).1 And there’s at least one drug, tenapanor, that the FDA has approved within the last couple of years that has been found to alleviate symptoms for IBS-C.13 While effective for treating IBS symptoms, medications don’t alter the condition long term. They’re designed merely to treat symptoms.5

Recommendations for RDs
Given the complexity of IBS diagnosis and treatment, Bragagnini says it’s essential for patients with significant digestive distress to see their health care provider and consult an RD to develop an individualized plan. Because presentation of IBS symptoms and response to treatment can vary significantly from patient to patient, it’s important for treatment to be personalized. Finding an effective approach to alleviate symptoms is likely to be a matter of trial and error.

— Densie Webb, PhD, RD, is a freelance writer, editor, and industry consultant based in Austin, Texas.

1. Ford AC, Moayyedi P, Chey WD, et al. American College of Gastroenterology monograph on management of irritable bowel syndrome. Am J Gastroenterol. 2018;113(Suppl 2):1-18.

2. About irritable bowel syndrome (IBS). American College of Gastroenterology website. https://webfiles.gi.org/images/patients/IBS-infographic.pdf. Accessed January 15, 2024.

3. Lovell RM, Ford AC. Global prevalence of and risk factors for irritable bowel syndrome: a meta-analysis. Clin Gastroenterol Hepatol. 2012;10(7):712-721.e4.

4. Cash B, Sullivan S, Barghout V. Total costs of IBS: employer and managed care perspective. Am J Manag Care. 2005;11(1 Suppl):S7-16.

5. Sarvepalli SS, Vemula SL, Aramadaka S, et al. Digesting the impact of diet on irritable bowel syndrome (IBS): exploring solutions for controlling IBS. Cureus. 2023;15(9):e45279.

6. Di Rosa C, Altomare A, Terrigno V, et al. Constipation-predominant irritable bowel syndrome (IBS-C): effects of different nutritional patterns on intestinal dysbiosis and symptoms. Nutrients. 2023;15(7):1647.

7. Simrén M, Månsson A, Langkilde AM, et al. Food-related gastrointestinal symptoms in the irritable bowel syndrome. Digestion. 2001;63(2):108-115.

8. Ragnarsson G, Bodemar G. Pain is temporally related to eating but not to defaecation in the irritable bowel syndrome (IBS). Patients' description of diarrhea, constipation and symptom variation during a prospective 6-week study. Eur J Gastroenterol Hepatol. 1998;10(5):415-421.

9. El-Salhy M, Ystad SO, Mazzawi T, Gundersen D. Dietary fiber in irritable bowel syndrome (Review). Int J Mol Med. 2017;40(3):607-613.

10. Thomas A, Thomas A, Butler-Sanchez M. Dietary modification for the restoration of gut microbiome and management of symptoms in irritable bowel syndrome. Am J Lifestyle Med. 2021;16(5):608-621.

11. FODMAP diet: what you need to know. Johns Hopkins Medicine website. https://www.hopkinsmedicine.org/health/wellness-and-prevention/fodmap-diet-what-you-need-to-know. Accessed January 22, 2024.

12. Lacy BE, Pimentel M, Brenner DM, et al. ACG clinical guideline: management of irritable bowel syndrome. Am J Gastroenterol. 2021;116(1):17-44.

13. Herekar A, Shimoga D, Jehangir A, et al. Tenapanor in the treatment of irritable bowel syndrome with constipation: discovery, efficacy, and role in management. Clin Exp Gastroenterol. 2023;16:79-85.