AGA Clinical Practice Update on the Role of Diet in Irritable Bowel Syndrome: Expert Review

DescriptionIrritable bowel syndrome (IBS) is a commonly diagnosed gastrointestinal disorder that can have a substantial impact on quality of life. Most patients with IBS associate their gastrointestinal symptoms with eating food. Mounting evidence supports dietary modifications, such as the low–fermentable oligo-, di-, and monosaccharides and polyols (FODMAP) diet, as a primary treatment for IBS symptoms. The aim of this American Gastroenterological Association (AGA) Clinical Practice Update (CPU) is to provide best practice advice statements, primarily to clinical gastroenterologists, covering the role of diet in IBS treatment.MethodsThis expert review was commissioned and approved by the AGA CPU Committee and the AGA Governing Board to provide timely guidance on a topic of high clinical importance to the AGA membership, and underwent internal peer review by the CPU Committee and external peer review through standard procedures of Gastroenterology. The best practice advice statements were drawn from reviewing existing literature combined with expert opinion to provide practical advice on the role of diet in treating patients with IBS. Because this was not a systematic review, formal rating of the quality of evidence or strength of the presented considerations was not performed.Best Practice Advice StatementsBest Practice Advice 1Dietary advice is ideally prescribed to patients with IBS who have insight into their meal-related gastrointestinal symptoms and are motivated to make the necessary changes. To optimize the quality of teaching and clinical response, referral to a registered dietitian nutritionist (RDN) should be made to patients who are willing to collaborate with a RDN and patients who are not able to implement beneficial dietary changes on their own. If a gastrointestinal RDN is not available, other resources can assist with implementation of diet interventions.Best Practice Advice 2Patients with IBS who are poor candidates for restrictive diet interventions include those consuming few culprit foods, those at risk for malnutrition, those who are food insecure, and those with an eating disorder or uncontrolled psychiatric disorder. Routine screening for disordered eating or eating disorders by careful dietary history is critical because they are common and often overlooked in gastrointestinal conditions.Best Practice Advice 3Specific diet interventions should be attempted for a predetermined length of time. If there is no clinical response, the diet intervention should be abandoned for another treatment alternative, for example, a different diet, medication, or other form of therapy.Best Practice Advice 4In preparation for a visit with a RDN, patients should provide dietary information that will assist in developing an individualized nutrition care plan.Best Practice Advice 5Soluble fiber is efficacious in treating global symptoms of IBS.Best Practice Advice 6The low-FODMAP diet is currently the most evidence-based diet intervention for IBS. Healthy eating advice as described by the National Institute of Health and Care Excellence Guidelines, among others, also offers benefit to a subset of patients with IBS.Best Practice Advice 7The low-FODMAP diet consists of the following 3 phases: 1) restriction (lasting no more than 4–6 weeks), 2) reintroduction of FODMAP foods, and 3) personalization based on results from reintroduction.Best Practice Advice 8Although observational studies found that most patients with IBS improve with a gluten-free diet, randomized controlled trials have yielded mixed results.Best Practice Advice 9There are limited data showing that selected biomarkers can predict response to diet interventions in patients with IBS, but there is insufficient evidence to support their routine use in clinical practice. Irritable bowel syndrome (IBS) is a commonly diagnosed gastrointestinal disorder that can have a substantial impact on quality of life. Most patients with IBS associate their gastrointestinal symptoms with eating food. Mounting evidence supports dietary modifications, such as the low–fermentable oligo-, di-, and monosaccharides and polyols (FODMAP) diet, as a primary treatment for IBS symptoms. The aim of this American Gastroenterological Association (AGA) Clinical Practice Update (CPU) is to provide best practice advice statements, primarily to clinical gastroenterologists, covering the role of diet in IBS treatment. This expert review was commissioned and approved by the AGA CPU Committee and the AGA Governing Board to provide timely guidance on a topic of high clinical importance to the AGA membership, and underwent internal peer review by the CPU Committee and external peer review through standard procedures of Gastroenterology. The best practice advice statements were drawn from reviewing existing literature combined with expert opinion to provide practical advice on the role of diet in treating patients with IBS. Because this was not a systematic review, formal rating of the quality of evidence or strength of the presented considerations was not performed. Best Practice Advice Statements Dietary advice is ideally prescribed to patients with IBS who have insight into their meal-related gastrointestinal symptoms and are motivated to make the necessary changes. To optimize the quality of teaching and clinical response, referral to a registered dietitian nutritionist (RDN) should be made to patients who are willing to collaborate with a RDN and patients who are not able to implement beneficial dietary changes on their own. If a gastrointestinal RDN is not available, other resources can assist with implementation of diet interventions. Patients with IBS who are poor candidates for restrictive diet interventions include those consuming few culprit foods, those at risk for malnutrition, those who are food insecure, and those with an eating disorder or uncontrolled psychiatric disorder. Routine screening for disordered eating or eating disorders by careful dietary history is critical because they are common and often overlooked in gastrointestinal conditions. Specific diet interventions should be attempted for a predetermined length of time. If there is no clinical response, the diet intervention should be abandoned for another treatment alternative, for example, a different diet, medication, or other form of therapy. In preparation for a visit with a RDN, patients should provide dietary information that will assist in developing an individualized nutrition care plan. Soluble fiber is efficacious in treating global symptoms of IBS. The low-FODMAP diet is currently the most evidence-based diet intervention for IBS. Healthy eating advice as described by the National Institute of Health and Care Excellence Guidelines, among others, also offers benefit to a subset of patients with IBS. The low-FODMAP diet consists of the following 3 phases: 1) restriction (lasting no more than 4–6 weeks), 2) reintroduction of FODMAP foods, and 3) personalization based on results from reintroduction. Although observational studies found that most patients with IBS improve with a gluten-free diet, randomized controlled trials have yielded mixed results. There are limited data showing that selected biomarkers can predict response to diet interventions in patients with IBS, but there is insufficient evidence to support their routine use in clinical practice. Irritable bowel syndrome (IBS) is a commonly diagnosed disorder of gut–brain interaction that can substantially impact quality of life (QOL). The multifactorial pathogenesis of IBS is characterized by altered motility, visceral sensation, brain–gut interactions, gut microbiome, intestinal permeability, and mucosal immune activation. Most medical therapies for IBS improve global symptoms in fewer than one-half of patients, with a therapeutic gain of 7%–15% over placebo.1Ford A.C. Moayyedi P. Chey W.D. et al.American College of Gastroenterology Monograph on Management of Irritable Bowel Syndrome.Am J Gastroenterol. 2018; 113: 1-18Crossref PubMed Scopus (195) Google Scholar Most patients with IBS associate their gastrointestinal (GI) symptoms with eating food. There is mounting evidence to support dietary modifications, such as the low–fermentable oligo-, di-, and monosaccharides and polyols (FODMAP) diet (LFD), as a primary treatment for symptoms of patients with IBS. Before committing patients to a restrictive diet, excluding disordered eating behaviors and eating disorders is critical. When possible, working closely with a GI registered dietitian nutritionist (RDN) can help to optimize outcomes. The aim of this American Gastroenterological Association (AGA) Clinical Practice Update (CPU) is to provide best practice advice (BPA) on the role of diet in the treatment of IBS. Best Practice Advice 1: Dietary advice is ideally prescribed to patients with IBS who have insight into their meal-related GI symptoms and are motivated to make the necessary changes. To optimize the quality of teaching and clinical response, referral to a RDN should be made to patients who are willing to collaborate with a RDN and patients who are not able to implement beneficial dietary changes on their own. If a GI RDN is not available, other resources can assist with implementation of diet interventions. Best Practice Advice 2: Patients with IBS who are poor candidates for restrictive diet interventions include those consuming few culprit foods, those at risk for malnutrition, those who are food insecure, and those who have an eating disorder or uncontrolled psychiatric disorder. Routine screening for disordered eating or eating disorders by careful dietary history is critical because they are common and often overlooked in GI conditions. Best Practice Advice 3: Specific diet interventions should be attempted for a predetermined length of time. If there is no clinical response, the diet intervention should be abandoned for another treatment alternative, for example, a different diet, medication, or other form of therapy. When evaluating a patient with IBS, it is important to ask whether GI symptoms, such as abdominal pain, bloating, and altered bowel habits, are triggered or worsened by eating food. Surveys suggest that >80% of patients with IBS associate their symptoms with eating a meal.2Bohn L. Storsrud S. Tornblom H. et al.Self-reported food-related gastrointestinal symptoms in IBS are common and associated with more severe symptoms and reduced quality of life.Am J Gastroenterol. 2013; 108: 634-641Crossref PubMed Scopus (390) Google Scholar Although unproven, it is reasonable that such patients may be more open and more likely to adhere to diet modifications. The most common macronutrients found to trigger IBS symptoms are carbohydrates. In particular, FODMAPs are short-chain, poorly digestible, poorly absorbed sugars that can trigger symptoms in some patients with IBS. Before considering a restrictive diet, it is useful to gauge a patient’s intake of culprit foods. For example, if a patient is consuming a diet with minimal FODMAP-containing foods, there is little benefit to trialing the LFD. There are several practical challenges to operationalizing restrictive diets, such as the LFD, in patients with IBS. Specialty diets require planning and preparation, which may be impractical for some patients. Decreased cognitive abilities and significant psychiatric disease can interfere with a patient’s ability to identify reproducible food triggers, adhere to a restrictive diet, or accurately report clinical response. There may be incremental costs to implementing restrictive diets. Patients with limited financial resources or food access may be unable to obtain foods allowed on a specific diet. Gastroenterologists and other health care providers caring for patients with IBS should familiarize themselves with disordered eating behaviors as well as eating disorders.3Werlang M.E. Sim L.A. Lebow J.R. et al.Assessing for eating disorders: a primer for gastroenterologists.Am J Gastroenterol. 2021; 116: 68-76Crossref PubMed Scopus (13) Google Scholar Disordered eating is common in patients with GI disorders that require extreme or prolonged dietary restrictions. Practical questions to help identify patients with a possible eating disorder are displayed in Table 1.3Werlang M.E. Sim L.A. Lebow J.R. et al.Assessing for eating disorders: a primer for gastroenterologists.Am J Gastroenterol. 2021; 116: 68-76Crossref PubMed Scopus (13) Google Scholar Eating disorders include anorexia nervosa, bulimia nervosa, binge eating disorder, and, of particular importance to gastroenterologists, avoidant/restrictive food intake disorder (ARFID). Patients with ARFID malignantly avoid selected foods or food groups to the point of developing malnutrition, weight loss, and need for nutritional supplements or enteral or parenteral feeding.4Zickgraf H.F. Ellis J.M. Initial validation of the Nine Item Avoidant/Restrictive Food Intake disorder Screen (NIAS): a measure of three restrictive eating patterns.Appetite. 2018; 123: 32-42Crossref PubMed Scopus (96) Google Scholar Recent data suggest that 20% of patients seen in GI practice screen positive for ARFID, but it is important to note that ARFID screening tools have not been validated in patients with GI disorders.5Murray H.B. Bailey A.P. Keshishian A.C. et al.Prevalence and characteristics of avoidant/restrictive food intake disorder in adult neurogastroenterology patients.Clin Gastroenterol Hepatol. 2020; 18: 1995-2002.e1Abstract Full Text Full Text PDF PubMed Scopus (38) Google Scholar Restrictive diets like the LFD should be avoided in patients with an eating disorder.Table 1Practical Questions to Investigate a Possible Eating Disorder3Werlang M.E. Sim L.A. Lebow J.R. et al.Assessing for eating disorders: a primer for gastroenterologists.Am J Gastroenterol. 2021; 116: 68-76Crossref PubMed Scopus (13) Google ScholarGeneral questions:1.Have you changed your diet recently and, if so, why?2.What feelings do you have at mealtime or when you look at food? (Anxious or fearful?)3.How much time to do spend planning out your meals or thinking about food?For those who volunteer information about their weight loss or appear malnourished:4.What do you think caused you to lose this much weight?5.Are you concerned about your weight loss? Has anyone else expressed concern?6.Has your weight influenced how you feel about yourself?7.Would you like to go back to your previous weight?8.How often do you exercise and for how long? (Is it more than 60 minutes per day?)For those with suspected vomiting/purging/laxative use:9.How often do you eat to the point that it makes you feel sick?10.Is the vomiting spontaneous or do you ever force/induce it?11.Do you use laxatives even when you are not constipated?NOTE. This is not a validated questionnaire, but the health care provider should use their clinical judgment in referring a patient to a RDN or psychologist and/or psychiatrist with expertise in eating disorders. Open table in a new tab NOTE. This is not a validated questionnaire, but the health care provider should use their clinical judgment in referring a patient to a RDN or psychologist and/or psychiatrist with expertise in eating disorders. Screening for malnutrition should be considered before starting a specific diet intervention. The Malnutrition Screening Tool can be used to screen for adult malnutrition (Supplementary Figure 1).6Skipper A. Coltman A. Tomesko J. et al.Position of the Academy of Nutrition and Dietetics: malnutrition (undernutrition) screening tools for all adults.J Acad Nutr Diet. 2020; 120: 709-713Abstract Full Text Full Text PDF PubMed Scopus (14) Google Scholar It is a validated tool consisting of 2 questions about appetite and weight loss that can be administered by a nurse or medical assistant.6Skipper A. Coltman A. Tomesko J. et al.Position of the Academy of Nutrition and Dietetics: malnutrition (undernutrition) screening tools for all adults.J Acad Nutr Diet. 2020; 120: 709-713Abstract Full Text Full Text PDF PubMed Scopus (14) Google Scholar A higher score indicates the patient is not appropriate for dietary restrictions and should be referred to a RDN for a comprehensive nutritional assessment. When advising a restrictive diet for patients with IBS, it is good clinical practice to provide guidance on the expected duration of the treatment trial and not place patients on “open-ended” dietary restrictions. Supplementary Table 1 includes the prescribed diets for IBS.7Dionne J. Ford A.C. Yuan Y. et al.A systematic review and meta-analysis evaluating the efficacy of a gluten-free diet and a low FODMAPs diet in treating symptoms of irritable bowel syndrome.Am J Gastroenterol. 2018; 113: 1290-1300Crossref PubMed Scopus (173) Google Scholar, 8Eswaran S.L. Chey W.D. Han-Markey T. et al.A randomized controlled trial comparing the low FODMAP diet vs. modified NICE Guidelines in US adults with IBS-D.Am J Gastroenterol. 2016; 111: 1824-1832Crossref PubMed Scopus (230) Google Scholar, 9Moayyedi P. Quigley E.M. Lacy B.E. et al.The effect of fiber supplementation on irritable bowel syndrome: a systematic review and meta-analysis.Am J Gastroenterol. 2014; 109: 1367-1374Crossref PubMed Scopus (171) Google Scholar, 10Paduano D. Cingolani A. Tanda E. et al.Effect of three diets (low-FODMAP, gluten-free and balanced) on irritable bowel syndrome symptoms and health-related quality of life.Nutrients. 2019; 11: 1566Crossref Scopus (41) Google Scholar, 11Garcia-Martinez I. Weiss T.R. Yousaf M.N. et al.A leukocyte activation test identifies food items which induce release of DNA by innate immune peripheral blood leucocytes.Nutr Metab (Lond). 2018; 15: 26Crossref PubMed Scopus (2) Google Scholar Numerous clinical trials have found 4–6 weeks of LFD is enough to determine whether a patient with IBS is going to respond.7Dionne J. Ford A.C. Yuan Y. et al.A systematic review and meta-analysis evaluating the efficacy of a gluten-free diet and a low FODMAPs diet in treating symptoms of irritable bowel syndrome.Am J Gastroenterol. 2018; 113: 1290-1300Crossref PubMed Scopus (173) Google Scholar If a patient fails to respond in the prescribed time, they should be instructed to abandon the diet and move on to another treatment option. Setting the duration for a diet trial reduces the risk of complications from prolonged dietary over-restriction. In addition to a risk of developing nutritional deficiencies, it is possible that over-restriction could also promote or exacerbate disordered eating behaviors.12McGowan A. Harer K.N. Irritable bowel syndrome and eating disorders: a burgeoning concern in gastrointestinal clinics.Gastroenterol Clin North Am. 2021; 50: 595-610Abstract Full Text Full Text PDF PubMed Scopus (7) Google Scholar Best Practice Advice 4: In preparation for a visit with a RDN, patients should provide dietary information that will assist in developing an individualized nutrition care plan. When preparing for an appointment with a RDN, the clinician and patient should provide previous medical and demographic information, including test and procedures results, biochemical data, and anthropometrics. In addition, patients should keep a food diary for a minimum of 3 days and a corresponding symptom chart before their appointment. Online platforms are available to make this task more user-friendly. A RDN then conducts the following 4-step process to assess the patient’s nutritional status, which contributes to dietary advice: 1) nutrition assessment information, 2) nutrition diagnosis, 3) nutrition intervention, and 4) nutrition monitoring and evaluation. Ongoing communication and collaboration between the referring physician and RDN is an important step to ensure the patient’s care plan is aligned and optimized. Referral to a RDN for medical nutrition therapy (MNT) is valuable for the patient’s care plan in the treatment of IBS (Figure 1). A RDN will help implement the prescribed diet and nutrition care plan in a medically responsible manner and can provide MNT for additional diagnoses. RDNs who use MNT have shown improved outcomes in weight management, diabetes, hypertension, lipid disorders, pregnancy, human immunodeficiency virus infection, chronic kidney disease, and unintended weight loss in adults.13Sikand G. Cole R.E. Handu D. et al.Clinical and cost benefits of medical nutrition therapy by registered dietitian nutritionists for management of dyslipidemia: a systematic review and meta-analysis.J Clin Lipidol. 2018; 12: 1113-1122Abstract Full Text Full Text PDF PubMed Scopus (40) Google Scholar GI practices may elect to have a RDN on staff or have a referral system that allows continuity of care. Payment for nutrition services can be limited, as coverage through public and private insurance varies by plan and by state; however, progress is being made to increase coverage for MNT in GI diseases and other comorbidities. Medicare currently covers nutrition visits for diabetes mellitus, end-stage renal disease (not on dialysis), and post kidney transplantation, with a specified number of visits per year. RDNs accepting private insurance have allowed more gastroenterologists to refer their patients to those participating in similar plans (in network). This can increase patient access to care that extends their medical treatment. It is advised for the gastroenterologist to provide a referral for nutrition and use a specific ICD-10 (International Classification of Diseases, Tenth Revision) diagnosis along with stating clearly that the consultation is medically necessary and/or preventative to ensure seamless processing by the RDN and/or patient. It is important to realize that it is out of the scope of practice for a RDN to determine a medical diagnosis and the RDN must use the codes assigned by the physician. Supplementary Table 2 displays the billable codes that are used most often. Best Practice Advice 5: Soluble fiber is efficacious in treating global symptoms of IBS. Dietary fiber is defined as a carbohydrate that is not absorbed or digested in the small intestine and that has a degree of polymerization of 3 or more monomeric units. The US Food and Drug Administration recommends that all people should consume 25–35 g of total fiber daily.14Reynolds A. Mann J. Cummings J. et al.Carbohydrate quality and human health: a series of systematic reviews and meta-analyses.Lancet. 2019; 393: 434-445Abstract Full Text Full Text PDF PubMed Scopus (626) Google Scholar Soluble fiber is found in psyllium, ispaghula husk, corn fiber, calcium polycarbophil, methylcellulose, oat bran, and the flesh of fruits and vegetables, and insoluble fiber is found in wheat bran, whole grains, and fruit and vegetable skins and seeds. The 2021 American College of Gastroenterology Guidelines on the management of IBS made a strong recommendation for the use of soluble (but not insoluble) fiber for the treatment and improvement of global IBS symptoms.15Lacy B.E. Pimentel M. Brenner D.M. et al.ACG Clinical Guideline: management of irritable bowel syndrome.Am J Gastroenterol. 2021; 116: 17-44Crossref PubMed Scopus (179) Google Scholar This recommendation is based on a systematic review and meta-analysis of 15 randomized controlled trials (RCTs) that showed that soluble fiber may benefit patients with IBS, while causing only minor adverse effects.9Moayyedi P. Quigley E.M. Lacy B.E. et al.The effect of fiber supplementation on irritable bowel syndrome: a systematic review and meta-analysis.Am J Gastroenterol. 2014; 109: 1367-1374Crossref PubMed Scopus (171) Google Scholar Insoluble fiber did not significantly improve IBS symptoms, but may exacerbate bloating and abdominal pain. A recent network meta-analysis evaluating 5 ispaghula husk studies did not show benefit in terms of global IBS symptoms compared with placebo16Black C.J. Yuan Y. Selinger C.P. et al.Efficacy of soluble fibre, antispasmodic drugs, and gut-brain neuromodulators in irritable bowel syndrome: a systematic review and network meta-analysis.Lancet Gastroenterol Hepatol. 2020; 5: 117-131Abstract Full Text Full Text PDF PubMed Scopus (74) Google Scholar; the 2 excluded studies were positive studies.15Lacy B.E. Pimentel M. Brenner D.M. et al.ACG Clinical Guideline: management of irritable bowel syndrome.Am J Gastroenterol. 2021; 116: 17-44Crossref PubMed Scopus (179) Google Scholar Selection of soluble fiber should be made specifically among patients with constipation-predominant IBS (IBS-C). It should be noted that there are many characteristics to fiber that impact effectiveness on symptomatology, from viscosity to rate of fermentation.17So D. Gibson P.R. Muir J.G. et al.Dietary fibres and IBS: translating functional characteristics to clinical value in the era of personalised medicine.Gut. 2021; 70: 2383-2394Crossref PubMed Scopus (16) Google Scholar Best Practice Advice 6: The LFD is currently the most evidence-based diet intervention for IBS. Healthy eating advice as described by the National Institute of Health and Care Excellence Guidelines, among others, also offers benefit to a subset of patients with IBS. Best Practice Advice 7: The LFD consists of 3 phases: 1) restriction (lasting no more than 4–6 weeks), 2) reintroduction of FODMAP foods, and 3) personalization based on results from reintroduction. The impact of different macronutrients on GI function and sensation has been the topic of considerable investigation. For example, fat content and total caloric intake can enhance the gastrocolonic response that contributes to increased sensorimotor bowel dysfunction and symptoms in patients with IBS.18Simren M. Abrahamsson H. Bjornsson E.S. An exaggerated sensory component of the gastrocolonic response in patients with irritable bowel syndrome.Gut. 2001; 48: 20-27Crossref PubMed Scopus (174) Google Scholar,19Wiley J. Tatum D. Keinath R. et al.Participation of gastric mechanoreceptors and intestinal chemoreceptors in the gastrocolonic response.Gastroenterology. 1988; 94: 1144-1149Abstract Full Text PDF PubMed Google Scholar Patients with IBS use a wide range of diets to eliminate trigger foods, including a gluten-free diet (GFD) and elimination diets based on IgG antibody testing, leukocyte activation testing, and confocal laser endomicroscopy (CLE) after food challenges, although there are few data to support these interventions.20Chey W.D. Keefer L. Whelan K. et al.Behavioral and diet therapies in integrated care for patients with irritable bowel syndrome.Gastroenterology. 2021; 160: 47-62Abstract Full Text Full Text PDF PubMed Scopus (57) Google Scholar Of the available options, the LFD is currently the most evidence-based dietary treatment choice for patients with IBS.15Lacy B.E. Pimentel M. Brenner D.M. et al.ACG Clinical Guideline: management of irritable bowel syndrome.Am J Gastroenterol. 2021; 116: 17-44Crossref PubMed Scopus (179) Google Scholar A LFD improves symptoms and disease-specific QOL in patients with IBS, particularly diarrhea-predominant IBS (IBS-D).8Eswaran S.L. Chey W.D. Han-Markey T. et al.A randomized controlled trial comparing the low FODMAP diet vs. modified NICE Guidelines in US adults with IBS-D.Am J Gastroenterol. 2016; 111: 1824-1832Crossref PubMed Scopus (230) Google Scholar,21Eswaran S. Chey W.D. Jackson K. et al.A diet low in fermentable oligo-, di-, and monosaccharides and polyols improves quality of life and reduces activity impairment in patients with irritable bowel syndrome and diarrhea.Clin Gastroenterol Hepatol. 2017; 15: 1890-1899.e3Abstract Full Text Full Text PDF PubMed Scopus (64) Google Scholar,22Zahedi M.J. Behrouz V. Azimi M. Low fermentable oligo-di-mono-saccharides and polyols diet versus general dietary advice in patients with diarrhea-predominant irritable bowel syndrome: a randomized controlled trial.J Gastroenterol Hepatol. 2018; 33: 1192-1199Crossref PubMed Scopus (55) Google Scholar Although studies assessing the efficacy of the LFD in patients with IBS-C are currently lacking, RCTs have found that patients with IBS-C benefit from a higher intake of soluble fiber.9Moayyedi P. Quigley E.M. Lacy B.E. et al.The effect of fiber supplementation on irritable bowel syndrome: a systematic review and meta-analysis.Am J Gastroenterol. 2014; 109: 1367-1374Crossref PubMed Scopus (171) Google Scholar A previous traditional meta-analysis of 7 RCTs found that the LFD significantly reduced global symptoms relative to different control interventions in 397 patients with IBS.7Dionne J. Ford A.C. Yuan Y. et al.A systematic review and meta-analysis evaluating the efficacy of a gluten-free diet and a low FODMAPs diet in treating symptoms of irritable bowel syndrome.Am J Gastroenterol. 2018; 113: 1290-1300Crossref PubMed Scopus (173) Google Scholar A more recent network meta-analysis of 13 RCTs, which provides an indirect comparativeness effectiveness analysis between competing diet strategies, found that the LFD was the most effective diet strategy for relief of global symptoms, abdominal pain, and bloating in patients with IBS.23Black CJ, Staudacher HM, Ford AC. Efficacy of a low FODMAP diet in irritable bowel syndrome: systematic review and network meta-analysis [published online ahead of print August 10, 2021]. Gut https://doi.org/10.1136/gutjnl-2021-325214Google Scholar Recent studies reported that short-term FODMAP restriction has little impact on micronutrient intake and, when taught by a RDN, might actually improve overall diet quality relative to the habitual diets of most patients with IBS.24Eswaran S. Dolan R.D. Ball S.C. et al.The impact of a 4-week low-FODMAP and mNICE diet on nutrient intake in a sample of US adults with irritable bowel syndrome with diarrhea.J Acad Nutr Diet. 2020; 120: 641-649Abstract Full Text Full Text PDF PubMed Scopus (30) Google Scholar,25Staudacher H.M. Ralph F.S.E. Irving P.M. et al.Nutrient intake, diet quality, and diet divers