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- v.16(5); Sep-Oct 2022
- PMC9442469
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Am J Lifestyle Med. 2022 Sep-Oct; 16(5): 608–621.
Published online 2021 May 10. doi:10.1177/15598276211012968
PMCID: PMC9442469
PMID: 36072680
Andrew Thomas, MBBS, Annie Thomas, PhD, and Madeline Butler-Sanchez, MS (Dietetics)
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Abstract
Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder leadingto chronic debilitating issues. A healthy diet plays an integral role inmaintaining the gut microbiota equilibrium, thus promoting digestive health. Thestructure and function of gut microbiota are affected by genetics andenvironmental factors, such as altered dietary habits, gastroenteritis, stress,increased use of alcohol and drugs, and medication use. Whereas there arevarious management approaches cited in the literature to manage symptoms of IBS,the purpose of this article is to focus on dietary options that will restore thegut microbiome and help in managing IBS symptoms. Some of the diets that arediscussed in this article include a low-FODMAP (fermentable oligosaccharides,disaccharides, monosaccharides, and polyols) diet, gluten-free/wheat-free diet,high-fiber diet, dietary and herbal supplements (psyllium, peppermint oil), andprobiotics/prebiotics/synbiotics. The clinical practice guidelines recommendedby the American College of Gastroenterology outlines evidence-based dietaryrecommendations for patients with IBS to manage symptoms. Recent advancements inthe dietary management of IBS highlighting the use of a patient-centered,personalized nutrition approach along with lifestyle changes, pharmacologicaltherapies, and psychosocial and behavioral interventions are also reviewed anddiscussed.
Keywords: dietary modification, irritable bowel syndrome, gut microbiota, symptom control
‘A microbe-rich biodiverse environment may likely promote the development ofhealthy gut microbiota and lower the risk of various diseases.’
Introduction
Irritable bowel syndrome (IBS) is a chronic digestive disorder affecting people inthe United States and worldwide.1,2 It is a significant publichealth concern. IBS carries a huge burden of care across the globe, but countrieslike the United States are hugely affected. The cost and the burden of the disorderis increasing rapidly.1,3,4 According tothe National Institute of Diabetes, Digestive and Kidney Diseases, about 12% ofpeople in the United States have IBS.2 Current evidence indicates that along with genetics, environmental factorsplay an eminent role in causing IBS.3,5 Although the etiology is notclearly understood, some of the environmental factors that cause IBS are unhealthydietary habits, acute gastroenteritis, stress, smoking, and alcoholintake.5-10 People across the world aremoving toward adopting unhealthy dietary patterns such as consumption of fried andother food items abundant in fat, protein, and sugar. This can alter the gutmicrobiota.3,11,12 There are various management approaches cited in the literatureto restore gut microbiota and manage symptoms of IBS.1,3,10,11 An evidence review conductedon the management approaches reported that dietary, lifestyle, medical, andbehavioral interventions, individualized and holistic, are very effective inmaintaining the host microbiota and in managing IBS.1
There is increasing evidence for the influence of host diet and its alteration of thegut microbiome, which may play a role in the pathogenesis of digestive disorderssuch as IBS.3,4,6,11 It is important to discussthe role of various evidence-based dietary interventions that will help in restoringand maintaining the gut microbiota, thus facilitating support in symptom control inpatients with IBS. The primary objective of this article is to address how variousdietary interventions will help restore gut microbiota to normal. Some of thecurrent research on dietary interventions in IBS lack rigor in research design andevidence and therefore present a challenge for clinicians. There are evidence-basedstudies that prove the clinical efficacy of specific diet interventions for symptommanagement in IBS. This article aims to pool, condense, and present evidence-baseddata on dietary interventions that are beneficial in IBS. Given the variations ofthe gut microbiome in each individual and unique human responses to dietaryinterventions in IBS, this article will also address the importance of utilizingprecision nutrition/personalized nutrition approaches in managing IBS.
What Is Irritable Bowel Syndrome?
IBS is a functional gastrointestinal (GI) disorder characterized by abdominal pain ordiscomfort, bloating, and changes in the bowel movements that occur in the absenceof other organic GI disease.2,5,9,10 IBS is often associated withsomatic conditions (pain syndromes, migraine, overactive bladder), psychiatricconditions (anxiety, depression), and visceral hypersensitivity.9 IBS is the most prevalent type of functional GI disorder. The common subtypesof IBS are IBS with constipation (IBS-C), IBS with diarrhea (IBS-D), IBS with mixedbowel habits (IBS-M), and unsubtyped IBS.2,9,10 IBS can affect allindividuals, although it is more common in women and in individuals <50 yearsold. However, many older adults also get affected.5,10 The disorder presentsdiagnostic and treatment challenges, and it can be debilitating for many patients,contributing to a disturbed quality of life.5,9
Gut Microbiota and Factors That Shape Gut Microbiota
Gut microbiota are the organisms that reside in the GI tract.7,11,13 Gut microbiota comprise achanging ecosystem, containing trillions of bacteria.7 The GI microbiota offer many benefits to the host. They perform a variety offunctions: maintenance of the integrity of the mucosal barrier or shaping theintestinal epithelium; protection against pathogens, intestinal and systemic immunemodulation; regulation of host immunity, host nutrient metabolism, and nutrientabsorption; drug metabolism; and synthesis of essential vitamins, enzymes, and aminoacids.11,14 In the GI tract, the energy is derived, and the health of thehost is maintained through production of metabolites from ingested food and alsofrom host carbohydrates. It then undergoes processes such as fermentation andsulfate reduction. Intestinal mucus is also a great source of carbohydrates as anenergy source for the gut microbiota.13,14
The components of the intestinal barrier play a major role in protecting the hostimmune system and in shaping the microbiota composition of the GI tract. Thesecomponents are epithelial and mucosal layers (physical), enzymes and microbialproteins (biochemical), and IgA and epithelia-associated immune cells (immunological).14 The alteration in the gut microbiota composition or dysbiosis can cause manyintestinal and extraintestinal disease conditions.11 Gut microbes must be adapted to a certain type of lifestyle to survivebecause of a limited quantity of biochemical niches in the GI tract.14 A microbe-rich biodiverse environment may likely promote the development ofhealthy gut microbiota and lower the risk of various diseases.15
The coexisting healthy host and microbiota relationship is important to the health ofindividuals and to prevent disease development.13,14 The factors that are known toshape the microbiota composition are genetics, dietary habits, lifestyle choices,use of antibiotics, smoking habits, medical illnesses and surgery, immunity status,mental well-being, living arrangements (urban or rural), and seasonalvariations.7,11,12,14-16
Current research reports that diet is one of the key modulators that shape the gutmicrobiota composition and the structure of the gut microbiome. It directlyinfluences host homeostasis and biological processes in the GI tract.7,11 Albeit the role of variousdiets in gut microbiota is still largely unknown, the excessive consumption ofeither animal-based or plant-based diets has been reported to cause alterations ofgut microbiota in humans.14 There are studies that show the influence of an unhealthy diet on gutmicrobiota alteration. However, the detrimental effects are largely associated withthe use of food additives, obesity, and metabolic diseases.3,11,12,14
Role of the Microbiota in the Etiology and Pathophysiology of IBS
The precise etiology of IBS is unknown.16,17 IBS is categorized as aheterogeneous disorder, with a multifactorial pathogenesis.16,18 Evidenceshows that an imbalance in the gut microbiota (gut dysbiosis) contributes to thepathogenesis of IBS.11,14,16 Some of the known etiological factors that predisposeindividuals to IBS are genetic and epigenetic factors, most notably an identifiedmutation of SCN5A, stress-induced nervous system and endocrine changes, immunedysregulation, altered gut-brain interactions, altered gut microbiota and gutmucosal inflammation, and dietary influences.5,17,19 Acute gastroenteritisfollowing exposure to various pathogens may trigger small-intestinal bacterialovergrowth, causing IBS.6
The pathophysiological changes can cause maladaptive shifts in the gut microbiota,leading to increased epithelial permeability, inflammation, mucosal barrierdysfunction, visceral hypersensitivity, enteric nervous system and immune systemdysfunction, imbalanced neurotransmitters and hormones, and altered gut-brainaxis.5,16,18 Altered gutmicrobial composition or dysbiosis can result in endotoxemia, insulin resistance,systemic inflammation, adiposity, irritable bowel disorder, colorectal cancer,metabolic disorders, nonalcoholic fatty liver diseases, and more.13 A review conducted by Staudacher et al20 reported that the worst symptoms in IBS are caused by the dysbiosis of theluminal and mucosal colonic microbiota precipitated by the reduction in species ofbifidobacterial count.
Role of Dietary Patterns in IBS
Diet plays an important role in shaping the composition and the structure of the gutmicrobiome. Dietary alterations can quickly affect the host-microbiota equilibrium,leading to GI disorders such as IBS.3,11,14,21 The structure and function ofgut microbiota are heavily influenced by diets rich in a complex mixture of fats andsimple sugars.12 Studies report that dietary shifts that comprise high-fat, high animalprotein, and high sugar diets contribute to microbiome dysbiosis and the severity ofIBS.8,11 Studies alsoreport a strong association between imbalanced carbohydrate intake affecting hosthealth and IBS pathogenesis.8,11 Additionally, increased consumption of fiber-rich food,especially polyphenols, indicates improved health outcomes through synergic andmediating effects.22 A healthy dietary pattern contributes to maintaining the gut microbiota-hostequilibrium. The alterations in lifestyle changes can cause gut dysbiosis, leadingto IBS and various other disease conditions.17,21,23,24
Dietary Strategies to Restore Gut Microbiota in IBS
The diet that is ingested interacts with the gut bacteria and the gut endocrinecells. Experimental trials have reported that dietary alterations can induce largeand temporary microbial shifts within 24 hours.1,17,21,25 The healthy diet we consumeacts as a prebiotic, favoring the growth of certain types of bacteria. Theprebiotics stimulate good bacteria to grow in the gut.25 It is believed that the symptoms that the patients experience in IBS are aresult of low density of gut endocrine cells and low number of stem cells.17,25,26 Whennutrients enter the lumen of the GI tract, the endocrine cells release various GIhormones and control several GI functions.26 The diet that is ingested can act as a substrate for gut bacteria metabolism,releasing several by-products. These by-products then act on the stem cells,eventually decreasing the gut stem cells and endocrine cells.17,20,25,26 A studyconducted by Mazzawi et al26 reports that the density of the endocrine cells in the large intestine areaffected by the type of diet consumed. Therefore, dietary modification can changethe gut microbiota, normalize the density of endocrine cells, and help recover themalfunctioning endocrine cells toward improvement of IBS symptoms.17,21,25,26 In additionto dietary modification, the American College of Gastroenterology (ACG) and CanadianAssociation of Gastroenterology have outlined various management approaches, such aspharmacological agents, cognitive behavioral therapy, hypnotherapy, exercise, andalternative therapies, to improve IBS symptoms.4,10,27
This review article will focus on using various diets as well as other therapies suchas the use of probiotics, prebiotics, and/or synbiotics and peppermint oilsupplements to restore gut microbiome and help in achieving symptom control inIBS.
Low-FODMAP (Fermentable Oligosaccharides, Disaccharides, Monosaccharides, andPolyols) Diet
A diet low in short-chain fermentable carbohydrates is an effective andinternationally accepted regimen and the first choice of diet for the managementof symptoms in IBS.25,28-36 FODMAP stands forfermentable oligosaccharides, disaccharides, monosaccharides, and polyols. Therestriction of various types of fermentable carbohydrates such asoligosaccharides (fructans, galacto-oligosaccharides [GOS]), disaccharides(lactose), monosaccharides (fructose when in excess of glucose), and polyols(sorbitol, mannitol) significantly improve GI symptoms in patients withIBS.36,37
A high-FODMAP diet contains more fermentable carbohydrates that are poorlyabsorbed, highly osmotic (draws water into the gut), and are rapidly fermentedby intestinal bacteria resulting in gut symptoms in patients with IBS.25,38 Severalstudies have reported that FODMAP restriction led to improvement of symptomssuch as abdominal pain, bloating, constipation, diarrhea, abdominal distension,and flatulence in 50% to 80 % of patients.29,31,32,35,36 The FODMAP categoriesthat cause symptoms, the mechanism of action each FODMAP category, and the foodtypes that might trigger symptoms in IBS are presented in Table 1.
Table 1.
High-FODMAP Categories, Mechanism of Action, and Major Food Sources to Avoid.a
| Categories | Mechanism of action | Major food sources |
|---|---|---|
| Oligosaccharides | ||
| Fructans (oligo-fructose, inulin,fructo-oligosaccharides) | The fructans cannot hydrolyze the fructose bond food in thesmall intestine. It enters the colon causing fermentation bycolonic bacteria and causes IBS symptoms | Wheat, onion, garlic |
| Galacto-oligosaccharides | The galactose-galactose molecules in the small intestinealso cannot be hydrolyzed in the small intestine and causesimilar symptoms as fructans | Chickpeas (including hummus), lentils, pulses (red kidneybeans) |
| Inulin-type fructans and galacto-oligosaccharides | These offer prebiotic function and, therefore, providehealth benefits | |
| Disaccharides | ||
| Lactose | Lactose is a disaccharide of glucose and galactose. It isabsorbed in the brush border of the proximal smallintestine. When there is no function or reduced activity ofthe lactase enzymes, lactose is not broken down to glucoseand galactose. The lactose remains malabsorbed, causingincreased production of short-chain fatty acids, methane,and hydrogen, leading to increased gas production,flatulence, and distension of both the small and largeintestines | Milk, milk products |
| Monosaccharides | ||
| Fructose (in high concentrations or excess of glucose) | Fructose, in the presence of glucose is readily absorbedfrom the small intestine. However, more fructose content inthe diet can lead to malabsorption causing pain, abdominaldistension, and bloating in patients with visceralhypersensitivity and IBS | Large volumes of fruit juice (watermelon, pineapple, pears,apple), high-fructose corn syrup; mango, fig, honey(contains excess of glucose) |
| Polyols | ||
| Sorbitol and mannitol | Polyols are reduced-calorie carbohydrate sweeteners or sugaralcohols. These polyols are slowly absorbed from the smallintestine, but when they reach the large intestine, theyinduce an osmotic effect (drawing water content into thebowel). Can cause laxative effect in addition to gutbacteria fermentation and gas production | Prunes, mushrooms, avocado, cauliflower, and apples; thesubstance added to sugar-free foods such as pudding andgelatin |
| Xylitol, isomalt | Same action as sorbitol and mannitol | Artificial sweetener added in some sugar-free chewing gums,mints, and sweets |
Abbreviation: FODMAP, fermentable oligosaccharides, disaccharides,monosaccharides, and polyols; IBS, irritable bowel syndrome.
aMartinez et al12 and El-Salhy et al.25
The effects of high-FODMAP diet to cause exacerbation of GI symptoms in IBS havebeen researched in detail and documented in the literature.29,35,36,39,40Carbohydrates play a significant role in causing symptoms in IBS. Carbohydratesconstitute the major components of human diet. The digestion and absorption ofcarbohydrates in the small intestine is influenced by factors such as the amountof hydrolase enzymes, presence of digestive diseases, transit time, and the dose consumed.36 The absence of luminal enzymes capable of hydrolyzing the glycosidicbonds in the complex carbohydrates is reported as one of the factorscontributing to the poor absorption of high-FODMAP diet.37 Some short-chain fermentable carbohydrates are absorbed in the smallintestine. The absence or reduced activity of intestinal brush border enzymessuch as lactase and epithelial glucose transporter-2 and glucose transporter-5cause poor absorption of the FODMAP diet as well.36,37 The long-chain nonstarchpolysaccharides contribute to a major proportion of the nondigestiblecarbohydrates. Some disaccharides and monosaccharides remain unabsorbed from thesmall intestine.35,36 The undigested and unabsorbed carbohydrates enter thelarge intestine, where they are fermented. It is reported that up to 40 g/d ofundigested and or unabsorbed carbohydrate enters the colon. Short-chaincarbohydrates with fewer monomers (eg, oligofructose) are fermented faster andproduce a large volume of gas, leading to bloating and other GIissues.36,40 The unabsorbed fructose, polyols, and lactose lead toincreased small intestinal water. In the colon, the unabsorbed carbohydrates,mainly the fructans and the oligosaccharides, are fermented, leading toincreased production of hydrogen and methane, thus leading to accumulation ofgas. This can further result in luminal distension, causing functional GIsymptoms.34,35
The presence of visceral hypersensitivity causing symptoms in IBS has beenreported in the literature. The luminal distension caused by the intake of ahigh-FODMAP diet may aggravate symptoms in patients with visceralhypersensitivity.36,39 Visceralhypersensitivity, or an increased perception of stimuli originating from theviscera, is a distinctive feature in IBS.39 The mediators released during intestinal inflammation (histamine,tryptase, or Adenosine triphosphate (ATP) and the central factors such asaltered neuroendocrine responses, altered gut-brain axis, and psychiatriccomorbidities are the factors that contribute to the pathogenesis of visceralhypersensitivity in IBS.39 Visceral hypersensitivity can cause increase in the luminal water and GIdistension. This can induce severe GI symptoms, such as bloating, flatulence,abdominal pain, diarrhea, and functional GI symptoms, in patients withIBS.36,39,40
Recent studies have indicated that a diet high in FODMAPs is highly osmotic, andit will draw more water into the gut. This promotes an increase in the colonicwater volume in the distal small bowel and the proximal colon, thus intensifyingthe intestinal motility.34,36,38 Some FODMAPs affect thesmall-intestinal transit time, therefore reducing the time for the smallintestinal absorption to happen. This will increase the time and theavailability of carbohydrates for colonic fermentation, thus producing more gasin the colon and increased flatulence.36,40
Although the mechanism is not fully understood, research studies have reportedthat the low-FODMAP diet reduces the production of luminal short-chain fattyacids (SCFAs) and total stool SCFA concentration.36,40 An association betweenIBS symptomatology and higher concentrations of SCFAs in the stool has beenstudied, especially in those patients with increased visceralhypersensitivity.36,40 The normal mechanism isthat the human intestinal microbiota ferment the indigestible dietary fibercontent in the large intestine and release SCFAs as by-products, includingacetate, butyrate, or propionate. These are either absorbed by the gutepithelium to carry out various physiological processes or excreted in thefeces.41,42 The by-product, butyrate, mainly serves as the primaryenergy source for the colonocytes, the epithelial cell of the colon. Thecolonocyte metabolism basically helps shape the gut microbiota.36,41,42 Thereduced availability of fermentable substrate and shift in the abundance ofbacterial taxa involved in SCFA production and/or cross-feeding reactions arebelieved to be the reason for the reduction in stool SCFA concentration inpatients on a low-FODMAP diet regimen.36,41,42
Studies report that patients with IBS develop severe symptoms because of a lowdensity of gut endocrine cells.25,26 A diet low in fermentablecarbohydrates and insoluble fiber has been shown to increase the number ofendocrine cells in the gut and to foster greater improvement in the digestivesymptoms.25,26
Recent studies have revealed that a low-FODMAP diet affects the gut microbiotaand metabolome (total number of metabolites present within a cell, tissue, and organ).36 Long-term intake of a low-FODMAP diet is known to adversely affect theintestinal microbiota composition and functions.29,36 The significant reductionin the dietary intake of various categories of FODMAP may alter the naturalprebiotic effects of these categories. Despite known beneficial effects of thelow-FODMAP diet for symptom control, some FODMAP categories such asoligosaccharides, fructans (fructo-oligosaccharides and inulin), and GOS areknown to act as prebiotics. A prebiotic is defined as “a substrate that isselectively utilized by the microorganism, conferring a health benefit, (p. 1,3).”41 Prebiotics promote maintenance and restoration of beneficial gutorganisms, such as the Bifidobacterium andLactobacillus species.29,36,41 The low-FODMAP diet cancause nutritional inadequacies and imbalances as a result of a considerablereduction in the intake of prebiotics such as fructans and GOS.36 A few studies have reported a decrease in the fecalBifidobacterium species after following a 2- to 4-weeklow-FODMAP dietary regimen. Although beneficial to reduce IBS symptoms, thelow-FODMAP diet minimizes sufficient intake of prebiotics. The detrimentaleffect of a low-FODMAP diet on beneficial bacterial groups, such as theBifidobacterium and Lactobacillus speciesor overall gut bacteria, as well as on gut health needs furtherinvestigation.25,29,36,40,41
Evidence suggests that the low-FODMAP diet causes a major reduction in substrateavailable for colonic fermentation.29,43 The long-term dietaryelimination of all FODMAPs is not recommended in IBS because it can alter thecomposition and functioning of gut microbiota and cause a reduction in specificbacterial groups (eg, Bifidobacterium) or the overallmicrobiota community.24,36,43 The FODMAP restriction is therefore recommended forshort-term use only. Patients are counseled to liberalize the use after symptomimprovement.25,29,37
The ACG outlines the FODMAP diet categories the patient must avoid consuming.35 Among the food items are fruits (apples, apricots, peaches, pears,watermelon, grapes, mangoes); vegetables (artichokes, asparagus, cauliflower,lima beans, mushrooms, peas, beets, broccoli); artificial sweeteners (sorbitol,mannitol, isomaltose); high-lactose milk, dairy, whey; nondairy milkalternatives (soy milk, coconut milk); fructans (fructose and sweeteners such ashoney and agave apples); starchy foods (bread, pasta, semolina); and galactans(plant-based protein such as black-eyed peas, chick peas, kidney beans).35
Some types of polyols in the FODMAP diet promote gut health and, therefore, arerecommended in IBS. Polyols have been shown to increase theBifidobacterium bacteria and therefore support maintenanceof gut health.44 Polyols are naturally occurring sugar alcohols found in a variety offruits, vegetables, and sugar-free sweeteners. The polyols that promote good guthealth are lactitol, isomalt, xylitol, and erythritol. However, consuming largequantities of polyols such as sorbitol and mannitol can aggravate the symptoms.Polyols used as sweeteners in sugar-free diet products, therefore, must beconsumed with caution by patients with IBS.44
Despite the benefits of a low-FODMAP diet for symptom control in IBS, it cancause nutritional deficiencies and alteration in the gut microbiota. Therefore,the role of an expert dietitian is imperative during dietarymanagement.25,26,34,37,45 A personalized and culturally tailored dietary guidanceby a registered dietitian/nutritionist (RDN) is essential for identifying thespecific low-FODMAP food groups for symptom control and qualityoutcomes.25,26,45 The dietary plan must include replacing the high FODMAPcontent from the same food group with low FODMAPs. Dietary counseling must focuson integrating a balanced FODMAP diet to include adequate nutrients fromcarbohydrates, proteins, fats, vitamins, minerals, and other importantnutrients.25,26,37,38
The implementation of a low-FODMAP diet is divided into 3 phases: the FODMAPrestriction phase, the FODMAP reintroduction/rechallenge phase, and the FODMAPpersonalization and maintenance phase. For symptom control, all 3 phases must bestrictly practiced under the supervision of a nutritionist/dietitian. Inaddition to the comprehensive dietary counseling offered by the RDN, variousdietary resources incorporating an up-to-date list of alternative FODMAP fooditems must be utilized. Some of these resources that can complement theindividualized counseling are the low-FODMAP diet sheets, smartphoneapplications and cookbooks, and patient-led dietary websites.26,37 Theseresources combined with the individualized dietary counseling will enhancedietary adherence in the low-FODMAP regimen in all 3 phases.26,37,44
During the initial visit, the RDN completes a nutrition assessment and works withthe patient to establish a healthy and reasonable weight goal. A diet historytool can be used to gather information regarding the food groups that induce orrelieve symptoms, food groups already avoided, regularly consumed diet, andalternative food preferences. The RDN also must assess the psychosocial,cultural, ethnic, and religious background to plan a diet that is consistentwith the patient’s beliefs.25,38 After the assessment andthe goals for treatment have been established, the low-FODMAP dietaryimplementation will begin.25,38 The patient assessmentdetails, phases of low-FODMAP implementation, and guidelines are presented inTable 2.
Table 2.
Phases to Implement Low-FODMAP12,25 Diet in IrritableBowel Syndrome.a
| Low-FODMAP diet: implementationphases25,38,48,52 | |||
|---|---|---|---|
| Preassessment and dietary counseling | Phase 1: FODMAP restriction | Phase 2: FODMAP Rechallenge/reintroduction | Phase 3: FODMAP Maintenance/Personalization |
| Assessment | |||
| Baseline assessment Anthropometry (height, weight)and body mass index - Biochemical tests to excludeother comorbidities - Gather past medical history,family history, nutritional history Clinicalassessment - Start with confirming thediagnosis Use Rome IV criteria for diagnosing IBS andRome IV diagnostic criteria to confirm IBS subtypes25 - Perform comprehensive symptom assessment forgastrointestinal symptoms, stool output, quality oflife Some symptom assessment tools used are thefollowing: Global symptom questions (yes/no questions),Gastrointestinal Symptom Rating Scale, Visual Analogue Scalefor IBS, IBS Severity Scoring System, Bristol Stool FormScale, Short Form 36 Health Survey, IBS Quality of Life Questionnaire25 Dietary assessment Quantitative:assessment of current nutrients and FODMAP intake, fooddiary, 24-hour recall or diet history, food frequencyquestionnaire that includes FODMAPintake Qualitative: food that aggravates symptoms,food preferences, eating patterns, food access,availability, dietary restriction, use of nutritionalsupplements.12,25 Dietary counseling: aregistered dietitian/nutritionist specialized in training inFODMAPs will provide counseling During initialvisit: - Explain the effects of FODMAPrestriction - Counsel regarding the food sources ofeach FODMAP category, how to incorporate FODMAP restrictioninto daily lifestyle, adherence to FODMAP diet, food-relatedsocial activities, day-to-day shopping, etc - Tailorcounseling to specific symptoms and different IBS subgroupsto evaluate the effectiveness of low-FODMAPdiet - Counsel regarding the importance ofmaintaining quality25,48,52 | The food items that are high in FODMAP are restricted andsubstituted with small portions of moderate- or low-FODMAPalternatives This phase is maintained for 3-6 weeks.Many people will notice improvement in symptoms by week 2.If symptoms have improved by week 4, patients move toreintroduction phase The degree of symptomimprovement is variable for patients. If the symptoms havenot improved, consider other treatment options22,38 One of the goals during this phaseis to increase the variety of diet to ensure compliance andreduce nutritional deficiencies associated with prolongedrestriction There may be situations where all theFODMAP categories need not be restricted; therefore, dietarycounseling is tailored to each case25,52 Assess for clinical response. Usevarious symptom assessment tools and IBS Quality of Life Questionnaire25 | FODMAPs are slowly introduced into the patient’s diet totest tolerance and exacerbation of symptoms Thisphase is usually commenced after 2-6 weeks on therestrictive phase of the low-FODMAP diet Afterreassessing for the symptoms and diet, counsel regardingFODMAP re-introduction Patients are instructed toremain on the strict low-FODMAP diet while completing the challenges38 One challenge is completed at a time, and eachspecific food is tested every 3 days38 For each food challenge, only 1 food from anew FODMAP category is recommended52 Counsel patients to identify triggers anddoses (quantity) that induce symptoms with each dietary challenge25 The food groups that are frequently consumedare challenged first11 Instruct patients to document the symptomtypes, symptom control, and severity of symptoms with eachchallenge25,38 After all the FODMAPcategories have been trialed, patients can follow anindividualized, modified version of the low-FODMAPdiet38,52 | After identifying the trigger foods, patients continue totake other high-FODMAP foods that are tolerated. Thetriggers are eliminated altogether during thisphase The dietitian recommends a personalized dietaryplan to meet nutritional needs The personalizationwill focus on a diverse healthy diet that is enjoyable andnot restricting the psychosocial aspects (eg, dining out,other socializing events etc)25,38 Inform that a certain degreeof symptoms is normal11,52 Patients are advised toreturn to normal diet gradually to prevent abrupt worseningof symptoms If FODMAP restriction failed to resolvesymptoms, other dietary approaches such as administration ofprebiotics must be utilized25 In the long-term, counsel on personalizationwith a less restrictive and diverse diet. Exclude theFODMAPs that induce symptoms25 |
Abbreviations: FODMAP, fermentable oligosaccharides, disaccharides,monosaccharides, and polyols; IBS, irritable bowel syndrome.
aRome IV criteria: presence or recurrent abdominal pain (on average atleast 1 day per week in past 3 months associated with 2 or more of(1) pain related to defecation; (2) a change in frequency of stool;and (3) a change in the form (appearance of stool).25 IBS subtypes: IBS with diarrhea, IBS with constipation, IBSwith mixed symptoms, IBS unclassified/unsubtyped.25
Although the efficacy of the low-FODMAP diet for the successful control ofsymptoms in IBS has been studied and reported in the literature, it can posesome challenges to patients.25,46-48 Adhering to a low-FODMAPschedule may be quite challenging for patients, mainly because of the risk fornutritional deficiencies and gut microbiota alteration and issues related topsychosocial adjustments. Adhering to a low-FODMAP diet requires psychosocialadjustments, such as in social dining and dining out and limited food choiceswhile traveling.25,37,38 For better symptom control, patients must, however,adhere to dietary guidelines during each phase.25,37,38 If patients do notachieve symptom control after adhering to FODMAP restriction and reintroduction,the low-FODMAP diet may have been ineffective and, therefore, discontinuation isrecommended.25,37,38 For those patients, some therapeutic approaches arerecommended. These include the use of prebiotics and immunoglobulins,medications to manage symptoms, cognitive behavioral therapy, and gut-directedhypnotherapy. A low-FODMAP diet supplemented with a microbiota-targeted therapyhas also been used and found to be beneficial in patients with IBS.25,27,37,49
Gluten-Free and Wheat-Free Diet
Many studies report that patients with IBS experience symptom control whenfollowing a gluten-free and wheat-free diet.29,34,50-52 Gluten is an immunogenicprotein found primarily in grains such as wheat, rye, and barley. Gluten isknown to cause celiac disease—an inflammatory, autoimmune disease—in geneticallysusceptible individuals. It is found that a gluten-containing diet alsocontributes to the pathogenesis of IBS. Although the exact mechanism is unknown,it can cause altered bowel barrier function in patients with IBS-D.50,51 Somepatients with IBS report worsening of symptoms with wheat and wheatproducts.50,51 Rej and Sanders50 report that gluten may not be the only contributing factor, but thatother wheat compounds such as amylase and trypsin inhibitors (ATIs) or wheatgerm agglutinins (WGA’s) found in wheat molecules can trigger inflammation inthe intestines and inflammatory responses in immune cells, thus leading toimpaired intestinal cell permeability.31,50 Current evidenceindicates that a gluten-free and wheat-free diet offer symptom relief inpatients who may have gluten-sensitive IBS.31,50
Studies report that it is important to weigh the benefits and disadvantages whenplanning on initiating a gluten-free diet for patients with IBS.29,31,34,50-53 A prospective studycarried out on 41 individuals demonstrated improvement of symptoms when theywere put on a gluten-free diet for 6 weeks. There was a reduction in the IBSSymptom Severity Score from 286 to 131 (P < .001). However,the gluten-free diet presented some drawbacks when it was administered toindividuals without IBS.51 An expert consensus meeting and the reviews of studies conducted bygastroenterologists and dietitian specialists suggests the use of a low-FODMAPdiet, gluten-free diet, and a wheat-free diet as dietary therapies for IBS. Theconsensus team recommends a dietary approach that is individualized and directedby a registered dietitian.31 However, another study by Dieterich and Zopf29 reported that patients with IBS were found to rarely describe ingestionof gluten as a trigger in causing symptoms. Additionally, wheat products containfructans, a FODMAP food category that is recommended to be avoided by patientswith IBS.29 Therefore, the symptom improvement in IBS cannot be correctly correlatedwith the reduction of either a low-FODMAP diet or gluten-free diet.29 This raises the question of how effective a gluten-free diet is in themanagement of IBS.
A significant reduction in the gut bacterial concentrations ofBifidobacterium adolescentis and Faecalibacteriumprausnitzii are also found with a gluten-free and low-FODMAP diet.These bacterial groups help in maintaining the gut ecosystem, thus promoting GIhealth.29,31,50 A gluten-free diet is also known to cause nutritionaldeficiencies in patients with IBS.29 A systematic review and meta-analysis of randomized controlled trials(RCTs) conducted by Dionne et al52 reported that some patients with IBS may have an intolerance to gluten,despite not having celiac disease. That might prompt the clinicians to recommenda gluten-free diet in IBS. The authors in this review reported that conclusiveevidence is still lacking to recommend a gluten-free diet for symptom control in IBS.52 Therefore, high-quality RCTs are required to evaluate the effect of agluten-free diet for its safe use in IBS.
High-Fiber Diet
The emerging increase in chronic digestive diseases is reported to be related tothe progressive loss of microbial diversity. It is attributed to the decline inthe consumption of dietary fiber.54,55 The health benefits of ahigh-fiber diet and its role in shaping the colonic microbiota are wellinvestigated. The microbiota-accessible carbohydrates that are found in dietaryfibers are fermented and used by the colon bacteria as a source ofnourishment.14,45
Polyphenols are a vital constituent of fiber-rich foods. They have antibacterialand anti-inflammatory properties. Polyphenols can change the makeup of gutbacteria in a beneficial way by increasing the concentrations ofBifidobacteria and Lactobacillus, thusaiding in symptom control in IBS.22 The restoration of beneficial bacteria and microbiota by followinghealthy dietary patterns might prevent the progression of chronic diseases suchas IBS.55
A systematic review of 3 randomized clinical trials showed that fiber supplementswere beneficial in IBS-C.54 The authors, however, recommended a larger and increased number of RCTsfor generating stronger evidence that supports the beneficial effects offiber-rich diets in restoring gut microbiome and managing IBS-related symptoms.54
Fiber Supplements (Psyllium)
Psyllium is a form of fiber made from the husk of plant seeds—namelyPlantago ovata. It is found to be very effective in themanagement of symptoms in IBS.54,56 The fermentation ofsoluble fiber such as psyllium in the gut can have an impact on gutfunction. It is believed that the fermentation of the soluble fiber such aspsyllium can increase SCFA production, such as butyrate, which can provideenergy for colonic mucosal cells and act as an anti-inflammatory agent.These SCFAs or other fermentation products can also act as a substrate forgut bacteria.56 The prebiotic effect of psyllium can change the composition of thegut microbiome and promote gut health.54,56 The high-waterholding capacity and bulk-forming capability of psyllium can improve stoolconsistency in IBS-D.57 The same mechanism increases stool frequency in patients withIBS-C.56,57 Psyllium can be considered as one of the first-linetherapies because of its low cost and easy availability.
Probiotics, Prebiotics, and Synbiotics
Studies report that alteration of gut microbiota plays a beneficial role in reversingthe pathophysiology of IBS.17,58,59 This could be achieved by enhancing the host and gut microbiotaequilibrium with the use of probiotics, prebiotics, and synbiotics.17,32,58-62
Probiotics
Probiotics are live strains of microorganisms that when administered in adequateamounts confer a health benefit on the host.59,60,62 The mechanisms throughwhich probiotics exert their beneficial effects in IBS are not fullyknown.60,62 However, in a survey among clinicians, most believedthat probiotics are a good therapeutic option for IBS, and more than 90%recommended probiotics.62 Probiotics, mainly the Bifidobacterium andLactobacillus species, are known to induce beneficialmodulation of altered gut microbiota by reducing the number of competingpathogens. The modulation effects are accomplished through mechanisms such asthe production of antimicrobial substances and by interfering in the intestinalmucosal adhesion.59 The probiotic strains that are found to be effective in reducing IBSsymptoms, if used alone or as a multistrain formulation, areBifidobacterium species (Bifidobacteriumlactis, Bifidobacterium infantis, etc),Lactobacillus species, Streptococcusspecies, Saccharomyces boulardii (yeast), andLactobacillus rhamnosus GG.17,59,62
A randomized, placebo-controlled trial conducted by Staudacher et al32 evaluated the effect of a multistrand probiotics formulation with lowFODMAP for symptom control in patients with IBS.32 The coadministration of the multistrain probiotic with a low-FODMAP dietincreased the numbers of the Bifidobacterium species comparedwith placebo. Bifidobacteria provided immunomodulatory effectsand prevented clinical symptoms in IBS. The total IBS severity score wassignificantly lower in patients who received a low-FODMAP diet and probiotics.32 The low-FODMAP diet was found to cause a reduction inBifidobacteria. The study recommended use of multistrainBifidobacterium-containing probiotics with a low-FODMAPdiet to restore Bifidobacteria in IBS.32
There are multiple research studies and meta-analyses that evaluate the effectsof single probiotic strains and combinations of probiotic strains inIBS.17,32,59,62 A systematic review with meta-analysis of 53 RCTsperformed by Ford et al62 reported that certain combinations of probiotics or specific species andstrains have beneficial effects on global IBS symptoms and abdominal pain. Amongthe combinations, Lac Clean gold and the 7-strain combination of 3Bifidobacterium, 3 Lactobacillus, and 1Streptococcus were associated with significant improvementsin global symptoms and abdominal pain scores.62 Among individual probiotics, Lactobacillus plantarum DSM9843, Escherichia coli DSM 17252, and Streptococcusfaecium had benefits on global symptoms.62 However, it remains unclear which specific combination, species, orstrain must be used in IBS. Definitive evidence on the efficacy of probiotics inIBS is yet to be established.17,62 It is recommended that apersonalized probiotics therapy guided by individual microbiota profiling mayoffer promising benefits to patients with IBS in the future.
Prebiotics
Prebiotics are substrates that are selectively utilized by host microorganisms,conferring health benefits.62 According to the Food and Agriculture Organization of the United Nations,prebiotics are nonviable food components that confer a health benefit on thehost through the modulation of microbiota.17 Prebiotics may serve as an alternative treatment in IBS because theyprovide the metabolizable substrates for growth of specific bacteria, thusaffecting the composition and function of the gut microbiota.17,59Prebiotics are effective in modifying the individual strains and species of gut microbiota.59 Many sources of prebiotics exist. These are lactulose,fructo-oligosaccharides, GOS, trans-GOS, inulin and reflux starch, cellulose andhemicellulose, pectin, and other natural sources from foods.17,58,59,61,62 Naturalsources of prebiotics include cereals, fruits, green vegetables, andplants.17,59 The 2 most investigated prebiotics categories areinulin-type fructans and GOS.61 Currently, other novel classes of prebiotics such asarabinoxylan-oligosaccharides, manno-oligosaccharides, resistant starch, andxylo-oligosaccharides are also being investigated to test their efficacy in IBS treatment.58
Although the beneficial effects of prebiotics in IBS have been studied, there islittle evidence for their use in IBS. Therefore, researchers recommend moretrials to establish their efficacy and safe use in IBS.17,58,59,62 Asystematic review and meta-analysis of 11 randomized, placebo-controlled trialswas conducted by Wilson et al58 to evaluate the effect of prebiotics on global response, GI symptoms,quality of life, and gut microbiota in adult patients with IBS and otherfunctional bowel disorders. The review reported that patients who receivedprebiotics experienced no differences in the severity of abdominal pain,bloating, flatulence, and quality of life compared with the placebo group.58 The flatulence severity improved with non–inulin-type fructan prebioticsat doses ≤6 g/dL. The non–inulin-type fructan prebiotics in higher doses had noeffect. The inulin-type fructans worsened the flatulence. Prebiotics did notsignificantly affect anxiety or depression scores. The variations in prebiotictypes affected symptom improvement in IBS. The prebiotic supplementation ofβ-GOS and pectin powder significantly increased fecal bifidobacterial counts.The type of prebiotics, dose, and duration did not influence the overallsymptoms in IBS, but differences were seen in individual symptoms.58 In summary, robust clinical trials are needed to evaluate the efficacy ofnovel prebiotics and non–inulin-type fructans for symptom control in IBS.
Synbiotics
Synbiotics are the combination of synergistically acting probiotics andprebiotics.17,59,62 Synbiotics selectively stimulate growth and survival ofbeneficial organisms or activate the metabolism of intestinal microbiota, thuscontributing to beneficial effects in IBS.59,62 Some examples ofsynbiotics used in IBS with beneficial effects are yogurt with acacia fiber plusB lactis, inulin plus B lactis, andS boulardii plus ispaghula husk.17 Although synbiotics are safe for consumption, the randomized controlledclinical trials that evaluated their effectiveness in patients with IBS haveshown mixed results.17,59,61,62 A review of RCTs conducted by Rodiño-Janeiro et al59 that focused on interventions targeting the gut microbiota reportedseveral beneficial effects of synbiotics. With various combinations ofsynbiotics, patients reported significant improvement in bowel habits,satisfaction with bowel habits, and a total IBS quality-of-life score.59
The systematic review and meta-analysis of 53 RCTs that evaluated the efficacy ofprebiotics, probiotics, and synbiotics in IBS reported that there are relativelyfew studies and there is insufficient evidence to support the use of prebioticsand synbiotics in the treatment of IBS.62 Because there are only a relatively limited number of clinical trialsconducted on synbiotics therapies in IBS patients, more data from RCTs areneeded to support the benefits of synbiotics in the management of IBS.
Peppermint Oil Supplements
Peppermint oil has been found to be effective for symptom control in patients withIBS and other GI disorders.63-66 Despite a lack of strongevidence to support its effectiveness from high-quality RCTs, it has shown greatpromise for treating IBS.63,66 Peppermint oil is derived from the peppermint plant,Mentha × piperita, which grows mostly in NorthAmerica and Europe. It has been found to affect upper- and lower-GIphysiology.63,64 The physiological effects of peppermint oil are smooth musclerelaxation via calcium channel blockade, direct enteric nervous system effects,visceral sensitivity modulation via transient receptor potential cation channels,5-hydroxy tryptamine antagonism effect and alleviating properties on functional GIdisorders, k-opioid receptor modulation causing decrease in severity of abdominalpain, antimicrobial/antifungal effects, anti-inflammatory activities, and modulationof psychosocial distress.63-66
Studies have investigated the safety and efficacy of various formulations ofpeppermint oil in IBS.63,65,66 A meta-analysis of 12 randomized clinical trials with a totalof 835 patients revealed that peppermint oil is a safe and effective therapy forpain and global symptoms in IBS.65 The US Food and Drug Administration recommends a novel peppermint oilformulation designed for sustained release in the small intestine. This formulationis reported to be a more safe and effective form for the relief of abdominalpain/discomfort and IBS severity, with very mild adverse effects.63,66 A randomized,double-blind, placebo-controlled trial evaluated the efficacy and tolerability ofthis novel formulation of peppermint oil designed for sustained release in the smallintestine in patients with IBS-M and IBS-D types.66 The trial was carried out for 4 weeks. The study revealed that the sustainedrelease formulation in the small intestine provided rapid relief of IBS symptoms.There was a decrease in the Total IBS Symptom Score from baseline by 19.6% at 24hours and a 40% decrease after 4 weeks of treatment.66 The patients in this trial had greater improvement in multiple individual GIsymptoms as well as severe or unbearable symptoms.66 The enteric-coated sustained release formulation of peppermint oil in thesmall intestine was well tolerated with fewer adverse effects.66
A randomized, double-blind trial performed on 190 patients with IBS that evaluatedthe efficacy and safety of small-intestinal-release peppermint oil andileocolonic-release peppermint oil found that neither form of peppermint oilproduced statistically significant reductions in abdominal pain response or overallsymptoms relief in 8 weeks.63 However, the small-intestinal-release peppermint oil produced greaterimprovements in abdominal pain and IBS severity compared with ileocolonic-releasepeppermint oil and placebo. The authors recommended the use ofsmall-intestinal-release peppermint oil with moderate efficacy in the treatment of IBS.63
Peppermint oil is used successfully for several GI and other disorders, and feweradverse effects have been reported in the clinical trials. It is well tolerated bymost patients with IBS, with occasional reports of heartburn, nausea, belching (withor without a minty taste), headache, altered anal sensation, sensitive urethra,peppermint oil–scented stool, and abdominal cramps.63-66 It is recommended todiscontinue if the patient continues to experience severe headache, palpitations,diarrhea, abdominal cramps, tightness of chest, bloating, or muscle cramps.63
The mechanism related to the direct effect of peppermint oil on the gut microbiome inIBS remains unclear. The immune-modulating, anti-inflammatory, anti-microbial,antiviral, antifungal, and antioxidant effects of peppermint oil have beendocumented in the literature.63-65 The antispasmodic effect ofpeppermint oil offers significant symptom relief in IBS.63,64 However, the other GI effectsof peppermint oil that contribute to the clinical benefits are not entirely known.64 Overall, the balancing effects of peppermint oil would be beneficial inmaintaining or restoring the gut-host microbiome equilibrium andpreventing/reversing the pathogenesis of IBS.
Clinical Practice Guidelines for Dietary Management in IBS
The ACG published the first clinical practice guideline in 2021 for the management of IBS.4 The guideline focused on addressing key issues related to the diagnosis andmanagement of IBS, including dietary management and recommended evidence-basedguidelines for clinical practice. The quality of evidence for each category ofdiagnosis and management in the guideline is expressed as “high,” “moderate,” “lowor very low.” For the high evidence level, it is stated that the estimate of effectis unlikely to change with new research and data. However, for the moderate, low,and very low levels of evidence, the estimate of effect is reported to be uncertainand might change.4 The strength of recommendation for each diagnosis and management category iscategorized as either “strong” or “conditional.” If the recommendation is labeled asstrong, it is safe for most patients to opt for that recommendation. If therecommendation is labeled as conditional, patients can follow the recommended courseof action, but different choices may be appropriate for some patients. An expertdiscussion is recommended in this situation to arrive at a decision based on thepatient’s values and preferences.4
The ACG’s clinical practice guideline recommends the following dietary options forthe management of symptoms in IBS4:
Limited trial of a low-FODMAP diet in patients with IBS to improve globalsymptoms (conditional recommendation; very low quality of evidence). Therationale for this recommendation is the complexity of a low-FODMAP diet,potential for nutritional deficiencies, and time and resources needed fordietary counseling in the 3 phases, requiring the services of a traineddietitian during each phase of the FODMAP treatment. Although the use of alow-FODMAP diet is not fully recommended in the ACG’s clinical practiceguideline, the expert committee recommends future trials to evaluate itsefficacy and safe use in IBS.
Use soluble, but not insoluble, fiber to treat global IBS symptoms (strongrecommendation; moderate quality of evidence). Most experts recommend 25 to35 g of total fiber intake per day.
Use peppermint to provide relief of global IBS symptoms (conditionalrecommendation; low quality of evidence). Although the dose range,frequency, and forms of peppermint oil are not mentioned, the RCTs thatevaluated the effectiveness of peppermint used 182 mg of peppermint oil andrecommended to use the enteric-coated form that is released in the smallbowel for greater benefits.
Suggest against using probiotics for the treatment of global symptoms in IBS(conditional recommendation, very low quality of evidence). Further researchis recommended, given the importance of probiotics to restore the intestinalmicrobiome in IBS.
As mentioned above, the most recent clinical practice guideline published by theAmerican Gastroenterology Association mentioned the use of a low-FODMAP diet withindividualized dietary counseling, high-fiber (soluble-fiber) diet, peppermint oil,and probiotics as the evidence-based dietary options for symptom management in IBS.4 Albeit not integrated in the recent ACG guideline published in 2021, the useof a gluten-free diet, prebiotics, and synbiotics has also been studied by theresearchers and recommended for IBS management.4,10,52,58,62 An ACG monograph published in2018 had included these dietary options in addition to the 2021 dietary guidelinesto manage symptoms in IBS.4,10 Although not supported with stronger evidence to use thesedietary options per the 2018 monograph, the safety and efficacy of these dietaryoptions to manage symptoms in IBS have been studied and reported. The researchersrecommended more trials to validate the current findings before the clinicians canrecommend a gluten-free diet, prebiotics, and synbiotics for managing IBS.4,10,52,58,62
Personalized Nutrition Approach for Managing IBS
The gut microbiota profile of each individual is unique.67,68 It is shaped in early life.The personal and healthy environment of host and gut microbiota remains stable inadulthood. However, it differs between individuals and is influenced byenvironmental factors such as stress, dietary changes, antibiotic use, lifestylechanges, obesity, and so on.55,68 Diet is one of the majorfactors that play a significant role in determining the makeup of the gutmicrobiome, structural integrity, protection against pathogens, digestive functions,immune modulation, and so on.7,67 This realization of differenthuman responses to dietary changes contributing to the unique composition andfunction of gut microbiota led researchers to recommend personalized nutritionapproaches in IBS.68,69 The symptoms of IBS greatly affect the quality of life patients.4 Although the details provided in this review offer insight into the dietarymanagement options in IBS, the simplified algorithm for clinical practicerecommended by Moayyedi et al70 proposes to use a personalized consultation to educate and reassure patientswith IBS symptoms. The authors propose a patient-centered, step-by-step approach byconsidering the nutritional needs, cost, culture, and values of the patient.70
As more research studies are yet to be conducted on this, it will be interesting tosee if the precision nutrition approaches will prevent, reverse, or correctalteration of gut microbiota in IBS.
Conclusion and Recommendations
Dietary patterns and environmental factors help shape our gut microbiota from infancyto adulthood. This review article highlights how the restoration of gut microbiotato a healthier state can help achieve symptom control in IBS, specifically byadhering to various diets and supplements, such as a low-FODMAP diet, agluten-free/wheat-free diet, high-fiber diet, probiotics/prebiotics/synbiotics, andpeppermint oil. IBS-specific clinical practice guidelines offer insight into anevidence-based dietary regimen that is found to be effective for patients with IBS.The novel, personalized nutrition management approach may be integral for optimizingcare and for quality outcomes in patients with IBS. A strong physician-patientrelationship from diagnosis to management is the key to success in IBS management.Therefore, it is recommended to integrate personalized lifestyle changes, dietarymodifications, pharmacological and psychological interventions, and a combination oftherapies for the best clinical response in IBS.
In conclusion, healthy lifestyle choices and a healthy dietary routine from childhoodthrough adulthood, as integral components of lifestyle medicine, help maintain thestructure and functions of the gut microbiome.
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Supplemental Material
sj-pdf-1-ajl-10.1177_15598276211012968 – Supplemental material forDietary Modification for the Restoration of Gut Microbiome and Management ofSymptoms in Irritable Bowel Syndrome:
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Supplemental material, sj-pdf-1-ajl-10.1177_15598276211012968 for DietaryModification for the Restoration of Gut Microbiome and Management of Symptoms inIrritable Bowel Syndrome by Andrew Thomas, Annie Thomas and MadelineButler-Sanchez in American Journal of Lifestyle Medicine
Footnotes
Authors’ Note: All authors contributed equally to develop this manuscript. This is a reviewarticle, and the literature search was carried out by accessing the databases.Therefore, an approval from the Institutional Review Board was notnecessary.
Declaration of Conflicting Interests: The authors declared no potential conflicts of interest with respect to theresearch, authorship, and/or publication of this article.
Funding: The authors received no financial support for the research, authorship, and/orpublication of this article.
Ethical Approval: Not applicable, because this article does not contain any studies with human oranimal subjects.
Informed Consent: Not applicable, because this article does not contain any studies with human oranimal subjects.
Trial Registration: Not applicable, because this article does not contain any clinical trials.
ORCID iD: Andrew Thomas 
https://orcid.org/0000-0001-5494-9623
Supplemental Material: Supplemental material for this article is available online.
Contributor Information
Andrew Thomas, Bharati Vidyapeeth Medical College, Pune,India, and University of Illinois Health Sciences System, Chicago,Illinois.
Annie Thomas, Marcella Niehoff School of Nursing, LoyolaUniversity Chicago, Illinois.
Madeline Butler-Sanchez, Parkinson School of Health Sciences and PublicHealth, Loyola University Chicago, Illinois.
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