ARTIGO ESTUDO - BOM - Nutrição, atividade física e suplementação na síndrome do intestino irritável - Artes Visuais (2024)

Prévia do material em texto

Citation: Radziszewska, M.;Smarkusz-Zarzecka, J.; Ostrowska, L.Nutrition, Physical Activity andSupplementation in Irritable BowelSyndrome. Nutrients 2023, 15, 3662.https://doi.org/10.3390/nu15163662Academic Editor: Rosa CasasReceived: 10 July 2023Revised: 16 August 2023Accepted: 17 August 2023Published: 21 August 2023Copyright: © 2023 by the authors.Licensee MDPI, Basel, Switzerland.This article is an open access articledistributed under the terms andconditions of the Creative CommonsAttribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).nutrientsReviewNutrition, Physical Activity and Supplementation in IrritableBowel SyndromeMarcelina Radziszewska *, Joanna Smarkusz-Zarzecka and Lucyna OstrowskaDepartment of Dietetics and Clinical Nutrition, Medical University of Bialystok, ul. Mieszka I 4B,15-054 Bialystok, Poland; joanna.smarkusz-zarzecka@umb.edu.pl (J.S.-Z.); lucyna.ostrowska@umb.edu.pl (L.O.)* Correspondence: mradziszewska3@student.umb.edu.plAbstract: Irritable Bowel Syndrome (IBS) is a chronic, recurrent functional disorder of the intestinediagnosed based on the Rome IV criteria. Individuals suffering from IBS often associate the severityof their symptoms with the food they consume, leading them to limit the variety of foods they eatand seek information that could help them determine the appropriate selection of dietary items.Clear nutritional recommendations have not been established thus far. NICE recommends a rationalapproach to nutrition and, if necessary, the short-term implementation of a low FODMAP diet.Currently, the FODMAP diet holds the greatest significance among IBS patients, although it doesnot yield positive results for everyone affected. Other unconventional diets adopted by individualswith IBS lack supporting research on their effectiveness and may additionally lead to a deteriorationin nutritional status, as they often eliminate foods with high nutritional value. The role of physicalactivity also raises questions, as previous studies have shown its beneficial effects on the physicaland mental well-being of every individual, and it can further help alleviate symptoms among peoplewith IBS. Supplementation can be a supportive element in therapy. Attention is drawn to the useof probiotics, vitamin D, and psyllium husk/ispaghula. This review aims to analyze the existingscientific research to determine the impact of various food items, physical activity, and dietarysupplementation with specific components through dietary supplements on the course of IBS.Keywords: IBS; irritable bowel syndrome; FODMAP; diet; nutrition; supplements; physical activity1. IntroductionIrritable Bowel Syndrome (IBS) is one of the most commonly diagnosed chronic andrecurrent functional gastrointestinal disorders. However, a definitive diagnostic standardfor IBS has not been established [1]. Most commonly, the diagnosis is made according tothe Rome IV criteria [2–4]. The primary diagnostic criteria for IBS include the presenceof abdominal pain, bloating, constipation, and/or diarrhea without any morphologicalor biochemical changes [1,4]. According to the Rome IV criteria, in order to diagnoseIBS, symptoms must persist for at least six months before making the diagnosis, and thediagnostic criteria must be met for the last three months [2]. Abdominal pain must occurat least one day per week in the past three months, be recurrent in nature, and meet atleast two additional criteria, such as abdominal pain correlated with bowel movements,abdominal pain correlated with changes in bowel frequency, or abdominal pain correlatedwith changes in stool consistency [2,5]. If all these criteria are met and there are no additionalalarming symptoms, there is no need for further diagnostic tests and the diagnoses of IBScan be set [1], with further characterization according to the Bristol Stool Form Scale thatclassifies IBS into four subtypes: Irritable Bowel Syndrome with Constipation (IBS-C),Irritable Bowel Syndrome with Diarrhea (IBS-D), Mixed Irritable Bowel Syndrome (IBS-M),and Unsubtyped Irritable Bowel Syndrome (IBS-U) [1,2,4,6].Typical symptoms of IBS include abdominal pain and a change in bowel habits(diarrhea or constipation, often occurring alternately) [4,7]. Additional accompanyingNutrients 2023, 15, 3662. https://doi.org/10.3390/nu15163662 https://www.mdpi.com/journal/nutrientshttps://doi.org/10.3390/nu15163662https://doi.org/10.3390/nu15163662https://creativecommons.org/https://creativecommons.org/licenses/by/4.0/https://creativecommons.org/licenses/by/4.0/https://www.mdpi.com/journal/nutrientshttps://www.mdpi.comhttps://orcid.org/0000-0003-3504-951Xhttps://orcid.org/0000-0002-0543-1817https://doi.org/10.3390/nu15163662https://www.mdpi.com/journal/nutrientshttps://www.mdpi.com/article/10.3390/nu15163662?type=check_update&version=1Nutrients 2023, 15, 3662 2 of 22symptoms may include heartburn, indigestion, chest pain, bloating, urgency to have abowel movement, feeling of incomplete evacuation, chronic pelvic pain, fibromyalgia,and migraines [1,4]. Due to the adverse impact of these symptoms on mental well-being,individuals with IBS are more likely to experience anxiety and depression [1,4,7]. Thepresenting symptoms vary in intensity and exhibit significant variability throughout thecourse of the disease [7,8].The occurrence of IBS is characterized by significant variability both between countriesand within a single country [8], affecting about 7–21% of the general population, mostcommonly reported in South American countries [3,4,8,9]. IBS is diagnosed twice as oftenin women compared to men [9], and although the condition can be diagnosed at any age, itis most commonly diagnosed in women before the age of 50 [4,8].The etiopathogenesis of IBS is multifactorial and currently not fully understood [4].According to existing analyses, it is possible that IBS results from interactions betweengenetic factors, psychiatric disorders, dysregulation of the hypothalamic-pituitary-adrenalaxis, visceral hypersensitivity, and inflammatory states within the gastrointestinal tract aswell as other parts of the body [1,3,5].Treating patients with IBS is quite challenging due to the lack of a well-understoodpathophysiology of the disease and the variability of symptom occurrence throughout itscourse. Pharmacological treatment focuses on symptom relief. Commonly used medica-tions include those that regulate bowel movements (increasing the frequency of bowelmovements for IBS-C or reducing frequency for IBS-D), analgesics, and antispasmodics [10].Pharmacological treatment should be tailored individually based on the type and severityof the predominant symptoms of IBS [11].However, the greatest value in the treatment process is attributed to appropriatenutrition and lifestyle changes. Making changes in these areas can have significant effectson improving the quality of life for individuals with IBS. Even up to 70% of individualswith IBS correlate the occurrence of their symptoms with their dietary habits [4,7,9]. Theassociation between nutrition and the course of IBS leads to a reduction in the variety offoods consumed by patients. These dietary restrictions often result in inadequate intake ofenergy and nutrients, which can exacerbate symptoms and worsen IBS patients’ quality oflife [12].In addition to dietary changes, important modifiable factors for individuals with thecondition that can influence the course of IBS are supplementation and physical activity.Dietary supplements, although their effects on the human body are not precisely proven,may have beneficial effects on human health [13]. Individuals with IBS can benefit fromadditional supplementation in terms of reducing symptoms, improving well-being, andenhancing their quality of life [13].Due to the accompanying symptoms of the disease, patients often limit their engage-ment in physical activity. Ithas been shown that physical activity is essential for maintaininggood physical and mental health and can also prevent gastrointestinal symptoms amonghealthy individuals [14]. Based on existing research, it is suspected that appropriatelytailored exercise regimens may have positive effects on the course of the disease amongindividuals with IBS [14–16].Due to the limited evidence regarding the impact of different food products, physicalactivity, and selected dietary supplementation on the course of IBS, inconclusive guidelinesare available, and both patients and professional medical personnel lack reliable infor-mation regarding interventions that encompass rational dietary modifications, physicalactivity, and the inclusion of appropriate dietary supplements. Therefore, the aim of thisstudy is to review the existing literature that describes the interventions effective for IBS.2. Materials and MethodsA systematic literature search was conducted using the PubMed database to identifystudies relevant to the current review. The following search string was used: (“irritablebowel syndrome” OR “IBS” OR “microbiome” OR “intestinal diseases” OR “colorectalNutrients 2023, 15, 3662 3 of 22cancer”) AND (“treatment” OR “diet” OR “low FODMAP diet” OR “FODMAP” OR “fiber”OR “vegetables” OR “fruits” OR “legumes” OR “grain products” OR “gluten-free diet”OR “gluten” OR “dairy products” OR “fermented dairy products” OR “lactose-free diet”OR “lactose” OR “fish” OR “omega-3 fatty acids” OR “eggs” OR “meat” OR “protein”OR “processed meat” OR “processed food” OR “supplementation” OR “probiotics” OR“psyllium” OR “vitamin D”). We attempted to limit the search to articles published withinthe last 5 years; however, if no data were available within this range, studies from earlieryears were also included. Among the 2000 literature items found, 87 practical guidelines,reviews, and clinical studies were selected for article preparation. We only included studiesin English to which we had full access. The inclusion criteria also included studies involvinggroups of more than 20 people, lasting longer than one day, including study and controlgroups, and conducted only with adults. Included studies used questionnaires, fooddiaries, and stool or blood screening. Exclusion criteria included lack of access to fulltexts, imprecise results and study designs, studies involving groups of less than 20 subjects,shorter than one day, not including a study and control group and involving children, orinadequate relevance to the topic. The conditions for inclusion and exclusion of articles areshown in Figure 1.Nutrients 2023, 15, x FOR PEER REVIEW 3 of 23 2. Materials and Methods A systematic literature search was conducted using the PubMed database to identify studies relevant to the current review. The following search string was used: (“irritable bowel syndrome” OR “IBS” OR “microbiome” OR “intestinal diseases” OR “colorectal cancer”) AND (“treatment” OR “diet” OR “low FODMAP diet” OR “FODMAP” OR “fiber” OR “vegetables” OR “fruits” OR “legumes” OR “grain products” OR “gluten-free diet” OR “gluten” OR “dairy products” OR “fermented dairy products” OR “lactose-free diet” OR “lactose” OR “fish” OR “omega-3 fatty acids” OR “eggs” OR “meat” OR “protein” OR “processed meat” OR “processed food” OR “supplementation” OR “probiotics” OR “psyllium” OR “vitamin D”). We attempted to limit the search to articles published within the last 5 years; however, if no data were available within this range, studies from earlier years were also included. Among the 2000 literature items found, 87 practical guidelines, reviews, and clinical studies were selected for article preparation. We only included studies in English to which we had full access. The inclusion criteria also included studies involving groups of more than 20 people, lasting longer than one day, including study and control groups, and conducted only with adults. Included studies used questionnaires, food diaries, and stool or blood screening. Exclusion criteria included lack of access to full texts, imprecise results and study designs, studies involving groups of less than 20 subjects, shorter than one day, not including a study and control group and involving children, or inadequate relevance to the topic. The conditions for inclusion and exclusion of articles are shown in Figure 1. Figure 1. The conditions for inclusion and exclusion of articles. 3. Food Choices Studies have been conducted to investigate the impact of different diets on the course of IBS, including gluten-free, lactose-free, and high-fiber diets. However, these studies are not sufficient to confirm the effectiveness of any dietary intervention for all individuals with IBS [17]. The British Society of Gastroenterology (BSG) recommends that nutritional consultations should be a first-line therapeutic strategy [18]. According to the National Figure 1. The conditions for inclusion and exclusion of articles.3. Food ChoicesStudies have been conducted to investigate the impact of different diets on the courseof IBS, including gluten-free, lactose-free, and high-fiber diets. However, these studies arenot sufficient to confirm the effectiveness of any dietary intervention for all individualswith IBS [17]. The British Society of Gastroenterology (BSG) recommends that nutritionalconsultations should be a first-line therapeutic strategy [18]. According to the NationalInstitute for Health and Care Excellence (NICE), basic dietary recommendations for patientswith IBS should include regular meal consumption, avoiding meal skipping and largemeals, drinking about 2 L (8 cups) of fluids per day (mainly water and herbal teas), limitingconsumption of carbonated and alcoholic beverages, as well as reducing intake of caffeine,fats, insoluble dietary fiber (found in whole grains, cereal flakes, bran), resistant starch(present in processed and reheated foods), and gas-producing foods (including certainfruits) [19,20]. If these recommendations do not produce therapeutic effects, the nextstep is to implement a low FODMAP diet (Fermentable Oligosaccharides, Disaccharides,Nutrients 2023, 15, 3662 4 of 22Monosaccharides, And Polyols), which involves eliminating foods rich in fermentableoligosaccharides, disaccharides, monosaccharides, and polyols [18]. Table 1 presents foodsrich in specific types of FODMAPs [21].Table 1. Products rich in specific types of FODMAP [21].Types FODMAP The Main Products Rich in FODMAPFructans (fructooligosaccharides, inulin, oligofructose) Wheat, vegetables (including artichokes, onion-la, garlic,cauliflower, asparagus, broccoli, mushrooms)Galactooligosaccharides Legumes, lentils, chickpeas (hummus)Disaccharides (lactose) Milk and milk productsMonosaccharides (fructose and high fructose/high glucose)Honey, corn syrup, fruit juices in large quantities (pineapple,watermelon, pear, apple), fruit (including apples, mangoes, figs,watermelon, grapes)Polyols (sorbitol, mannitol, xylitol, isomalt)Dried prunes, apples, mushrooms, avocados, cauliflower,sweeteners for sugar-free products, including puddings,gelatine, chewing gum, mints, sweetsAlthough the low-FODMAP diet currently has the highest number of studies due toits popularity among patients with IBS, it can contribute to nutritional deficiencies anda reduction in gut microbiota diversity due to its significant restrictions. Additionally,the evidence for its effectiveness is of very low quality, and further research on dietarytreatment for individuals with IBS is necessary [17,22].Few studies are also examining the feasibility of other diets in the course of IBS. Todate, gluten-free, lactose-free and high-fiber diets are of most interest, in addition to theNICE indications and the low FODMAP diet. Clinical studies conducted to date showinconclusive results regarding the effectiveness of the aforementioned diets. It is worthnoting that the improvementof symptoms accompanying IBS depends on the group ofpeople studied and additional factors that may affect nutrient tolerance. It can be notedthat a low-FODMAP diet and additional consumption of psyllium may be beneficial in thecourse of IBS. However, attention should be paid to the timing of the diets and dosages. Onthe other hand, gluten-free and lactose-free diets have positive effects only on a case-by-casebasis depending on additional factors that interfere with nutrient tolerance [23–30]. Theresults of selected clinical trials are shown in Table 2.Table 2. Clinical studies evaluating the effectiveness of dietary interventions in the course of IBS.Country, Study, Year Design, Population Interventions Main FindingsAustralia, Biesiekierski et al., 2013 [24]1 stage: randomized, double-blind,placebo-controlled, cross-over trial,patients with IBS and non-celiacgluten sensitivity (n = 37)2 stage: rechallenge, patients with IBSand non-celiac gluten sensitivity(n = 22)1 stage: High gluten (16 g/day) vs.Low gluten (2 g/day) vs. Whey (16g/day), 1 week per intervention.2 stage: Gluten (16 g/day) vs. Whey(16 g/day) vs. Placebo (no additionalprotein), 3 days. Run-in period of2 weeks, gluten-free diet and lowFODMAP dietDuring reduction of FODMAP intake:improvement of gastrointestinalcomplaints in all subjectsDiet containing gluten and wheyprotein: significant worseningof symptomsNo evidence of a specific anddose-dependent response to glutenNorway, Skodje et al., 2018 [23]randomized, double-blind,placebo-controlled, cross-over trial,self-reported patients with non-celiacgluten sensitivity on gluten-free diet>6 months (n = 59)Gluten-free diet (placebo-concealedmuesli bars) vs. gluten-containing diet(5.7 g/day) vs. fructans containingdiet (2.1 g/day), 7 days perintervention, 7 days washoutSignificant differences ingastrointestinal symptoms betweendifferent dietary interventionsGreatest symptoms among thoseconsuming fructansNo significant differences insymptoms between the placebo groupand those consuming glutenNutrients 2023, 15, 3662 5 of 22Table 2. Cont.Country, Study, Year Design, Population Interventions Main FindingsUK, Parker et al., 2001 [25]No randomized controlled trial,observational interventional study1 stage: patients with IBS were givenlactose hydrogen breath tests (n = 122)2 stage: patients with IBS and positivelactose hydrogen breath tests (n = 23)3 stage: double-blind,placebo-controlled challenges,patients with IBS and positive lactosehydrogen breath tests and improvingon the diet to confirm lactoseintolerance (n = 9)4 stage: patients who did not respondto the low lactose diet (n = 9)5 stage: patients with IBS and negativelactose hydrogen breath tests (n = 35)Assessment of symptoms: beforelactose hydrogen breath tests, 8 h afterlactose hydrogen breath tests, everyday during each dietary change2 stage: low lactose diet for 3 weeks3 stage: diet containing 5 g vs. 10 g vs.15 g of lactose vs. placebo4 stage: followed either an exclusionor low fibre diet5 stage: other dietary interventionsBefore lactose hydrogen breath tests:no significant differences in symptomsAfter lactose hydrogen breath tests:symptoms in the positive groupsignificantly worseLow lactose diet: improvement in 39%of people among those followingthe dietExclusion diet: improvement in 50%of people among those followingthe dietLow fibre diet: improvement in 2/3 ofthose following the dietLactose-free diet has no benefit amongpeople with IBS regardless oftest resultNetherlands, Bohmer et al., 2001 [26]No randomized controlled trial,prospective observational study,patients with IBS and lactosemalabsorption (n = 17) vs. patientswith IBS and lactose tolerance (n = 53)Low lactose diet and assessment ofsymptoms before, during, 6 weeksafter and 5 years after starting the dietBefore lactose hydrogen breath tests:no significant differences in symptoms6 weeks after starting diet: significantimprovement in people with lactosemalabsorption5 years after starting the diet:significant improvement in peoplewith lactose malabsorptionAmong people with IBS, it is veryimportant to perform a lactosetolerance test and to include alactose-free diet among those with apositive test resultNetherlands, Bijkerk et al., 2009 [27]Randomized Controlled Trial, patientswith IBS (n = 275)Observation of an increase in dietaryfiber of the soluble (psyllium) orinsoluble (bran) fraction in the diet12 weeks diet containing 10 gpsyllium (n = 85) vs. 10 g bran (n = 97)vs. 10 g placebo (rice flour) (n = 93)After 4 weeks and 2 months, asignificant improvement in symptomswas noted among the psyllium groupcompared to the placebo groupNo significant effect of bran onsymptoms compared to placeboAfter 12 weeks, a significantimprovement in symptoms was notedamong the psyllium group comparedto placebo and the bran groupSweden, Bohn et al., 2015 [28]Multicenter Randomized ControlledTrial, patients with IBS (n = 75)Evaluation before and afterintervention4 weeks traditional IBS diet (NICEguidelines) vs. Low FODMAP dietDuring dietary intervention: relief ofdiscomfort in both groups, with nosignificant difference between groupsAfter 4 weeks of dietary intervention:50% of those following the lowFODMAP diet reported symptomrelief vs. 46% of those following NICErecommendations reportedsymptom reliefAustralia, Halmos et al., 2014 [29]Single-centre, Randomized ControlledTrial, cross-over, patients with IBS(n = 30) vs. healthy control (n = 8)Evaluation before, during and afterintervention21 days low FODMAP diet vs. typicalAustralian diet with a washout periodof at least 21 daysDuring the diet: overallgastrointestinal symptoms weresignificantly reduced in the group onthe low FODMAP diet compared tothe control group. Flatulence,abdominal pain and gas also eased inthe low FODMAP group. Reportedstool consistency significantly betteron the low FODMAP dietAustralia, Halmos et al., 2015 [30]Single-blinded, randomised,cross-over trial, patients with IBS (n =27) vs. healthy control (n = 6),Evaluation before, during and afterintervention21 days low FODMAP diet vs. typicalAustralian diet with a washout periodof at least 21 daysThe low FODMAP diet group hadhigher stool pH, similarconcentrations of short-chain fattyacids, and higher microbial diversityand reduced total bacteria comparedto the control group.Low FODMAP diet significantlyaffects gut microbiota composition inthe short term, long-termstudies neededIngredients in elimonated and included products during these diets can affect thecourse of IBS. In a gluten-free diet, grain products that contain gluten are eliminated, butalso other ingredients that affect the fermentation processes in the intestines and thusNutrients 2023, 15, 3662 6 of 22gastrointestinal symptoms [17,23,31]. Lactose, a milk sugar eliminated during a lactose-free diet, can also affect gastrointestinal processes [17,32]. On the other hand, the intakeof dietary fiber, particularly water-soluble fiber, which influences the density, volume,consistency of stools and the composition and functioning of the intestinal microbiota,is increased in a high-fiber diet [17]. However, the results of the studies conducted sofar are inconclusive and insufficient to recommend a single diet for every person withIBS [23–29,31,32]. The effectiveness of diets and their impact on the course of IBS ispresented in Table 3.Table 3. Types of diets used in IBS and their effectiveness.Type of Diet Dietary Assumptions Effects on IBS Based on ResearchGluten-free dietElimination of gluten, i.e., products containingwheat, barley, rye, oats and related grains.It is recommended to eat, among other things,fruit, vegetables, fish, meat and gluten-freeproducts [30].Research has shown that components of wheatmay be responsible for causing some of thesymptoms of IBS.However, there is no evidencethat gluten is a factor. Therefore, a gluten-freediet should not be recommended as standard forpeople with IBS and more research is needed toassess the effect of gluten on IBS [17,23,31].Lactose-free dietLimit consumption of lactose to 12 g/day.Eliminate the consumption of milk (cow, goat,sheep) and dairy products [33].Tests for lactose intolerance should be performedamong patients with IBS. However, this dietshould not be recommended to all people withIBS [17,24,32].High-fiber dietIncreasing the intake of foods rich in fibre of thewater-soluble fraction and introducingadditional amounts in the form of Psyllium seedhusks [17].Strong research. Dietary fibre supplementationof the water-soluble fraction (e.g., Psylliumhusks), may have a beneficial effect on the courseof IBS [17,25].Low FODMAP dietElimination of products rich in fructans,galatooligosaccharides, disaccharides,monosaccharides and polyols [21].Low-quality research. Short-term use of the diet,may be beneficial in relieving symptoms.However, prolonged use reduces the diversity ofthe gut microbiota. Therefore, once IBSsymptoms have abated, the diet should beexpanded according to tolerance. More studiesare needed to confirm efficacy [17,26–28].NICE guidelinesGeneral recommendations such as eatingregularly, avoiding skipping meals and largemeals, drinking approximately 2 litres offluids/day, limiting the consumption of alcoholicand carbonated beverages, reducing the intake ofcaffeine, fat, dietary fibre of the insolublefraction, resistant starch and gas-enhancingproducts [17,19].Current recommendations given to every patientwith IBS. The most effective and safe nutritionalintervention [19,29].It is worth noting that these diets may expose those following them to the eliminationof valuable nutrients and the possibility of deficiencies [17,21,30,33]. This manuscript willexplain and discuss that diets for IBS patients could come with deficiencies, and that specificiterative food choices for individual patients would be best to establish and consider moreintegrative diet and food group choices based on personal effectiveness.4. Food Groups4.1. Vegetables and FruitThe World Health Organization (WHO) recommends daily consumption of 5 serv-ings of fruits and vegetables [34]. These products provide biologically active substances(such as carotenoids, polyphenols, vitamin C, and others), are a primary source of manyminerals (including potassium and magnesium), and contain dietary fiber. Due to theirhigh nutritional value, fruits and vegetables can have a beneficial effect on human health,Nutrients 2023, 15, 3662 7 of 22and reduce the risk and progression of many diseases, overall mortality, as well as disease-related mortality [34]. Individuals with IBS may restrict their consumption of vegetablesand fruits due to the symptoms they experience. This is confirmed by a study conductedby Bohn et al., which showed that individuals with IBS reported intensified symptomsafter consuming apples and plums [35]. Additionally, Monsbakken et al. observed thatindividuals with IBS tend to avoid consuming onions [36]. NICE guidelines limit thedaily fruit intake for people with IBS to 3 servings (with each serving being approximately80 g) [19,37]. Furthermore, they recommend eliminating onions, garlic, cabbage, artichokes,beans, peas, and watermelon from the diet. The FODMAP diet expands the list of allowedfruits and vegetables to include the white part of leeks, scallions, mushrooms, Brusselssprouts, asparagus, cauliflower, beets, fennel, as well as apples, pears, cherries, apricots,nectarines, plums, mango, lychee, longan, dried fruits, fruit juices, and canned fruits [38].These recommendations are based on the composition and properties of these vegetablesand fruits. They contain a high amount of fructose, fructans, and galactans, as well aswater-insoluble dietary fiber. These compounds can cause increased production of methaneand hydrogen, as well as short-chain fatty acids in the intestines, increase the influx ofwater into the intestinal lumen, and stimulate gastrointestinal peristalsis [38]. As a result,they can exacerbate symptoms occurring in IBS, such as bloating, abdominal pain, or diar-rhea. However, it is worth noting that individuals with IBS can experience positive effectsby incorporating into their diet products, including vegetables and fruits, that containwater-soluble dietary fiber.Consuming dietary fiber can be challenging for individuals with IBS. According toNICE guidelines, these individuals should avoid consuming insoluble fiber (found, amongothers, in wheat bran). However, incorporating soluble fiber (found in plants like psylliumor oats) into their daily diet, even in the form of supplementation, may be beneficial [19,39].It is worth noting that recommendations regarding dietary fiber intake are influenced bythe type of IBS, as well as the type, amount, and source of fiber [13]. Insoluble dietaryfiber has the ability to bind water and increase stool volume, thus stimulating intestinalperistalsis. However, existing studies indicate that this type of fiber does not contribute tothe improvement of IBS symptoms and may even exacerbate symptoms in individuals withdiarrhea-predominant IBS, leading to abdominal pain, diarrhea, gas, and bloating [39,40].On the other hand, soluble fiber forms gels in the gastrointestinal tract, increasing stoolbulk and improving its transit through the intestines [39]. It can also directly or indirectlypositively influence the gut microbiota, improving its structure and function, as well asstimulating the growth of beneficial bacteria (such as Lactobacillus sp. and Bifidobacteriasp.) [37,41]. This type of fiber alleviates symptoms in individuals with IBS, reducingabdominal pain, bloating, and regulating bowel movements [13]. The positive effectsof soluble dietary fiber can be observed in both diarrhea-predominant and constipation-predominant forms of IBS [13]. However, existing studies are insufficient to determine therecommended amount of fiber in the diet [42,43]. It is crucial to gradually introduce andincrease the consumption of dietary fiber [41,43]. The American Academy of Nutritionand Dietetics recommends a daily intake of 25 g of dietary fiber for women and 38 g formen with IBS. Natural food sources such as vegetables, fruits, whole grains, legumes, nuts(almonds, hazelnuts), and seeds (pumpkin seeds, sunflower seeds) should be the primarysources of fiber [13,42]. However, achieving the recommended intake can be challenging,and in such cases, supplementation may be considered [42]. Ground flaxseed, consumedin an amount of up to 2 tablespoons per day, is a recommended form of dietary fiberenrichment [13].Individuals with IBS should primarily consume vegetables and fruits low in insolubledietary fiber and rich in soluble fiber fractions. When it comes to vegetables, they canchoose carrots, tomatoes, zucchini, eggplant, cucumbers, bell peppers, broccoli, asparagusbeans, spinach, pumpkin, or lettuce. Well-tolerated fruits include berries, raspberries,strawberries, honeydew melon, cantaloupe, grapes, oranges, and lemons. However, it isimportant to note that individuals with IBS should not completely eliminate vegetables andNutrients 2023, 15, 3662 8 of 22fruits that are contraindicated. Instead, they should individually assess their tolerance tospecific types of vegetables and fruits. It is also important to consider not only the type ofproduct but also the quantity and preparation methods. It is worth noting that the highestamount of fructans is found in the skin of vegetables and fruits, so patients may toleratethese products well after peeling them [44,45]. Individuals with IBS should aim to consume3–5 servings of vegetables per day and 2–3 servings of fruits per day [13].In summary, vegetables and fruits are crucial elements of every person’sdiet as theyprovide a rich source of nutrients, especially vitamins and minerals. Individuals withIBS cannot omit them from their diet but need to pay attention to the type of productschosen, their quantity, and observe their individual reactions to them. Proper preparationof vegetables and fruits is also important. If raw consumption is poorly tolerated, tryingcooked, baked, pureed, or juiced forms may be helpful. Removing skins can also bebeneficial. Not only the consumption of vegetables and fruits but also the consumption oflegume seeds can pose difficulties for patients.4.2. Legume SeedsLegume seeds are an excellent source of protein, minerals (including zinc, iron, mag-nesium, potassium), vitamins (including vitamin B group, such as vitamin B9), as wellas biologically active compounds (such as phenolic acids, flavonoids), and dietary fiber.Due to their relatively high nutritional value of protein, they serve as an ideal alternativeto animal-derived products, which is particularly important for individuals followingvegetarian and vegan diets [46,47].The recommendations for consuming legume seeds vary depending on the country.However, it is suggested that incorporating 100 g (half a cup or 125 mL) of cooked legumeseeds into the daily diet can be beneficial for health due to their nutritional value [47].However, the absorption and bioavailability of protein, minerals, and vitamins may beimpaired by anti-nutritional factors, such as tannins or trypsin inhibitors. The presenceof galactooligosaccharides may also contribute to gastrointestinal symptoms such as ab-dominal pain, bloating, and gas [47,48]. It’s worth noting that both the nutritional andanti-nutritional content varies depending on the type of legume seeds. Peas have thehighest content of α-galactosides, while lentils have the lowest [48]. Proper technologicalprocessing can help reduce the levels of these unfavorable components. One of the mosteffective methods for reducing the water-soluble components, including oligosaccharides,is soaking legume seeds [48]. Reduction of oligosaccharides can also be achieved throughextrusion, pressure cooking, or regular boiling [48,49]. Studies have shown that pressurecooking can lead to a reduction of these compounds in cooked seeds by 14–77% comparedto raw seeds. Another good alternative for consuming legume seeds is incorporatingpasta made from legume flour into the diet. It has also been observed that the combina-tion of soaking and pressure cooking significantly increases the effectiveness of removinggalactooligosaccharides [48].As shown in a study conducted by Bohn et al., as many as 37% of the individualswith IBS reported experiencing symptoms after consuming beans and lentils [35]. Similarly,in the study by Monsbakken et al., 16% of the participants completely eliminated theconsumption of legume seeds [36]. NICE guidelines recommend avoiding the consumptionof beans. Additionally, the low FODMAP diet suggests the exclusion of lentils, beans, andpeas due to their high content of glu-cans and fructans [38]. Soybeans, lentils, chickpeas,beans, peas, and fava beans can be classified within this group of food items.In summary, patients with IBS should consider incorporating legume seeds intotheir daily diet, taking into account the type and processing methods. Due to their highdigestibility and lower content of oligosaccharides, individuals with the condition can startby introducing small amounts of lentils, which may be better tolerated. However, properprocessing is necessary. If good tolerance is observed, one can attempt to increase thequantity and introduce other types of legume seeds. It’s worth noting that oligosaccharidesare not only found in legume seeds but also grains.Nutrients 2023, 15, 3662 9 of 224.3. Grain ProductsGrain products are the main source of energy and carbohydrates in the diet of everyhealthy individual [17]. Among individuals with IBS, consumption of products from thisgroup may be associated with an exacerbation of symptoms. The use of a gluten-free diethas become common to alleviate the symptoms of the disease. A study conducted byBohn et al. revealed that 24% of the surveyed individuals experienced symptom exacerba-tion after consuming flour [35]. In Monsbakken et al.’s analysis, 10% of the participantsavoided consuming wheat flour [36]. Furthermore, Reuze et al. observed in their studythat individuals with IBS more frequently than the control group partially or completelyavoided gluten-containing products, and they more commonly reported gluten sensitivityor intolerance (although not all of these individuals had a medical diagnosis) [50]. Themain reason for avoiding gluten was the perceived discomfort after its consumption, whichwas more frequently reported by individuals with IBS. After eliminating these products,individuals noted greater physical and psychological comfort [50]. NICE guidelines rec-ommend avoiding wheat flour and products based on it. Additionally, the guidelinesalso recommend avoiding whole grain products, bran, and brown rice due to their highcontent of insoluble dietary fiber [19]. When following the low FODMAP diet, not onlywheat products (bread, pasta, biscuits, cakes, etc.) should be excluded but also all barleyand rye products [38]. However, it is worth noting that symptom relief occurs not aftereliminating gluten but after eliminating wheat consumption [51]. This suggests that symp-tom exacerbation after consuming wheat products is not related to the presence of glutenas previously believed, but rather caused by other components of wheat. High levels ofgluten, fructans, amylase and trypsin inhibitors, as well as lectins, can all impact the courseof the disease [17,50,51]. All these components can contribute to bloating, abdominal pain,and diarrhea [17].Therefore, individuals with IBS should replace wheat with spelt products, as recom-mended by NICE guidelines [38]. Daily diet can also include oats, rice, quinoa, or corn [13].People with IBS can utilize gluten-free products, which are mainly made from rice and/orcorn [51]. Spelt bread contains only 0.14 g of fructans per 100 g of the product, whilegluten-free bread contains 0.19 g/100 g [51]. NICE recommends individuals experiencinggas and bloating consume oatmeal or flaxseed, which can be beneficial in alleviating symp-toms [19,37]. The beneficial effect of flaxseed is due to its content of soluble dietary fiber.In the case of IBS-C, flaxseed helps relieve constipation, abdominal pain, and bloating. Itis recommended to include up to 2 tablespoons (6–24 g/day) of ground flaxseeds in thedaily diet, consumed with fluids (150 mL of fluids/1 tablespoon of ground flaxseed) [43,52].Grain products should be consumed up to 6 servings per day [13].In summary, a gluten-free diet should not be applied to all patients with IBS. Eachindividual should observe whether symptoms occur after consuming wheat products anddetermine their own tolerance. It is also crucial to identify the quantity of these productsthat triggers discomfort. In the case of poor tolerance, it is not necessary to eliminate grainproducts altogether but rather to opt for alternative grains. Specifically, spelt is highlighteddue to its high nutritional value and good tolerance.4.4. Milk and Dairy ProductsApart from a gluten-free diet, a lactose-free diet also generates significant controversy.Lactose is a disaccharide found in milk and dairy products [43]. According to NICEguidelines and the principles of the low FODMAP diet, the consumption of milk and dairyproducts should be avoided [38]. Lactose in the human digestive system is broken downinto glucose and galactose by an enzyme called lactase, which is secreted in the initialsegment of the small intestine. After lactose is broken down, it is absorbed and does notreach the further segments of the intestines [53]. As a result, it does not contribute tothe occurrence of diarrhea,bloating, or gas. However, if an individual has a deficiencyor absence of lactase enzyme secretion, lactose passes into the large intestine, where it isfermented by the intestinal microbiota. This fermentation produces hydrogen and short-Nutrients 2023, 15, 3662 10 of 22chain fatty acids, which can lead to gastrointestinal symptoms [17,43]. In Monsbakken’sstudy, as many as 35% of individuals declared avoiding the consumption of milk, and inBohn’s analysis, nearly 50% of people reported experiencing symptoms after consumingmilk and its products [35,36]. Studies show that individuals with IBS often report milkproduct intolerance, but this is not reflected in lactose absorption assessments (hydrogenbreath test) [13,43]. Therefore, lactose intolerance is rather rare among affected individuals,and eliminating milk and dairy products may be unwarranted. According to the BritishDietetic Association, which summarized previous studies on the link between lactoseintolerance and IBS, it is important to conduct assessments evaluating lactose tolerance.However, there is no indication to recommend a low-lactose or lactose-free diet to everypatient [52].Milk and dairy products are an important part of everyone’s diet as they providea source of protein, essential minerals (particularly calcium), and vitamins. Followinga dairy-free diet can result in calcium deficiencies in the diet [43,54]. Individuals withIBS should consume 2–3 servings of milk and dairy products per day (1 serving being200–250 mL of milk or 200–250 g of yogurt or 80–100 g of fresh cheese or 30–50 g of hardcheese) [13,43]. It’s important to note that even in the presence of lactose intolerance, itis not necessary to completely eliminate it from the diet [54]. It has been observed that asignificant portion of individuals with documented lactose intolerance can tolerate dailylactose consumption of up to 12–15 g [54]. Therefore, these individuals should ratherreduce their intake of lactose-containing products rather than eliminate them. Includingat least a small amount of dairy products has benefits as it allows for better digestion,bioavailability, and replenishment of the nutrients they contain. Patients can graduallyincorporate milk, starting with small amounts (about 30–60 mL/day), preferably consumedwith other foods and not on an empty stomach. Mature cheeses are usually well-tolerated asthey have significantly lower amounts of lactose (0.1–0.9 g of lactose per 30 g of cheese) [54].Additionally, individuals with lactose intolerance can replace milk and dairy products withlactose-free or plant-based alternatives. In this case, they can consume lactose-free milk,yogurts, plant-based beverages, and other products (such as rice and almond milk) [13].However, it’s important to read labels and choose products that are fortified with calciumand vitamins (including B2, B12, D, A) [54].To date, there is an insufficient number of studies assessing the impact of fermenteddairy products on the course of IBS. Fermented dairy products contain lactic acid bac-teria, including Streptococcus thermophilus and Lactobacillus delbrueckii subsp. Bulgaricus.Additional bacteria from the Lactobacillus and Bifidobacterium genera are often added tofermented products, enabling them to fulfill additional probiotic functions. The microor-ganisms present in these products must be live, and their quantity should be greater than107 CFU/g [55]. A review conducted by Savaiano et al. in 2021 analyzed seven randomizedclinical trials and demonstrated that the consumption of yogurt and kefir had a beneficialeffect on lactose digestion and contributed to increased lactose tolerance in individuals withdiagnosed lactose malabsorption [55]. This review also included five studies evaluatingthe impact of fermented dairy products on gastrointestinal symptoms accompanying IBS.The included studies showed that the consumption of fermented dairy products alleviatedsymptoms occurring in the course of the disease, and the effects were more favorablecompared to the consumption of non-fermented dairy products [55]. Additionally, it wasobserved that the consumption of fermented dairy products reduced the risk of colorectalcancer [55]. Based on the conducted review, it can be concluded that individuals with IBSshould not refrain from consuming fermented dairy products. Often, individuals withlactose intolerance eliminate their consumption, which is unjustified as these products areoften well-tolerated even in the presence of impaired disaccharide digestion. Fermenteddairy products, due to their composition, not only do not induce discomfort but may alsocontribute to reducing the experienced symptoms.In summary, individuals with IBS are not recommended to follow a lactose-free diet.Each patient should assess their own tolerance to milk and dairy products, both in termsNutrients 2023, 15, 3662 11 of 22of the type of product and quantity. In case of observing an exacerbation of symptoms,regular milk and its derivatives can be replaced with lactose-free or plant-based products.It is also important not to forget about fermented dairy products, which can have a positiveimpact on the experienced symptoms during the course of the disease. Before completelyeliminating dairy, attempts should be made to assess the tolerance to different types ofdairy products and their quantities. If a patient reduces or completely eliminates theconsumption of milk and dairy products, they may be at risk of protein deficiency in theirdiet. In such cases, the patient must remember to include other foods rich in high-qualityprotein in their meals, such as eggs, meat, or fish.4.5. Meat, Fish, EggsSo far, there is a lack of studies regarding the impact of consuming meat, fish, andeggs on the course of IBS. These products are a primary source of high-quality proteinfor every individual. Meat is a major source of vitamin B12 and heme iron [56]. Fish is aprimary source of polyunsaturated omega-3 fatty acids and contains vitamin D [57]. Eggsprovide a small amount of energy (approximately 140 kcal/100 g) but are rich in vitamins,particularly from the B group, as well as minerals such as iron, zinc, and calcium [58]. Itis recommended that individuals with IBS consume 2–3 servings of meat, fish, or eggsper day (1 serving is approximately 100–125 g of meat, 125–150 g of fish, or 60–80 g ofeggs) [43].Among meat products, it is important to pay attention to the consumption of redmeat and processed meat products. According to the International Agency for Researchon Cancer (WHO-IARC), processed meat products have been classified as “carcinogenicto humans”, while red meat is classified as “probably carcinogenic to humans”. Theseproducts contain nitrates, nitrites, as well as heterocyclic amines and polycyclic aromatichydrocarbons [59,60]. These compounds, through their influence on the mucous membraneof the colon, increase the likelihood of developing cancer. They also contain significantamounts of heme iron, which, by stimulating the formation of carcinogenic N-nitrosocompounds in the lumen of the intestine, likely promotes the development of tumors inthe gastrointestinal tract [59]. Additionally, processed meat products may stimulate tumori-genesis because they contain a much higher amount of fat compared to red meat, whichsignificantly increases the synthesis of secondary bile acids. However, this mechanism isnot precisely understood in humans [59].A review of the results of the multicenter prospective cohort study called the EuropeanProspective Investigation into Cancer and Nutrition (EPIC) was conducted [61]. The reviewincluded a total of 110 high-quality studies that examined the impact of various foodgroups on colorectal, lung, breast, and prostate cancer. It was demonstrated that higherconsumption of fish, along with a simultaneous reduction in the intake of red meat andprocessed meat products, was associated with a decreasedrisk of developing colorectalcancer [61].A meta-analysis conducted by Bolte et al. aimed to observe the influence of individualdietary components and food groups on the composition of the gut microbiota, as well asthe development of intestinal inflammation and various disease conditions [62]. The meta-analysis included studies that assessed the impact of dietary habits, specific food products,and individual dietary components on the gut microbiota composition in four groups ofindividuals: those with Irritable Bowel Syndrome, Crohn’s Disease, Ulcerative Colitis,and a population of healthy individuals. It was shown that dietary strategies involvingincreased consumption of fish, nuts, legume seeds, and bread were associated with a re-duction in the abundance of opportunistic microorganisms responsible for the synthesis ofpro-inflammatory factors and endotoxins. Additionally, such dietary patterns contributedto increased colonization of the gut by bacteria such as Roseburia, Faecalibacterium, andEubacterium spp. These microorganisms ferment dietary fiber into short-chain fatty acids,thus exhibiting anti-inflammatory effects. Furthermore, high fish consumption was associ-ated with the colonization of the gut by Roseburia hominis and Faecalibacterium prausnitzii.Nutrients 2023, 15, 3662 12 of 22The omega-3 fatty acids present in these products led to a decrease in the abundance ofpathobionts and pro-inflammatory factors, while an increase in anti-inflammatory factorswas observed. It was also demonstrated that high consumption of fast food and processedmeat correlated with an increase in the abundance of Ruminococcus gnavus, Akkermansiamuciniphila, and Proteobacteria, which influenced increased gut permeability and the devel-opment of intestinal mucosal inflammation. The study authors noted that well-designeddietary interventions characterized by increased consumption of fish, legume seeds, nuts,vegetables, and fruits, as well as low-fat fermented dairy products, while limiting theconsumption of alcoholic beverages, high-fat and processed meat, and sweetened bever-ages, would impact the gut microbiome, thereby preventing and alleviating the course ofintestinal mucosal inflammation [62].In summary, patients should include meat, fish, and eggs in their diet. They shouldpay attention to the type of meat products they choose. The diet should include leanpoultry (turkey, chicken), while the consumption of fatty meats (pork, goose, duck) andred meat should be limited. Processed meat products should be eliminated from thediet. The most important aspect is to increase the consumption of fish, especially fattyfish (salmon, herring), which, due to their high content of omega-3 fatty acids, may havepositive effects on the course of IBS. Additionally, the inclusion of eggs in the diet shouldnot be overlooked. Despite the lack of studies on the impact of eggs on IBS, they are avaluable source of protein, vitamins, and minerals, which can effectively supplement theinsufficient intake of these nutrients from other food groups.After analyzing all food groups and the recommended dietary guidelines by NICE(National Institute for Health and Care Excellence), it can be observed that the dietaryapproach for individuals with IBS varies depending on the specific type of the conditionand should be individually tailored based on the course of the disease and symptoms.Figure 2 presents a summary of the most relevant dietary recommendations supported byprevious research for individuals with IBS.Nutrients 2023, 15, x FOR PEER REVIEW 13 of 23 Figure 2. General dietary recommendations for patients with IBS. 5. Supplementation 5.1. Probiotics Probiotics are live microorganisms that, when taken in specific amounts, can have a positive impact on human health [20]. Probiotic preparations can be used in the treatment of IBS as they can contribute to changes in the composition of gut microbiota. Among individuals with IBS, abnormalities in the composition and functioning of gut-colonizing microorganisms are often observed, which may contribute to the onset of symptoms in the course of the disease [20]. A study was conducted that focused on comparing the composition of gut microbiota in individuals with IBS (study group: n = 24) and healthy individuals (control group: n = 23) [63]. Stool samples were collected from the study participants, and microbial genome analyses were performed. Individuals with IBS participating in the study exhibited a significantly different composition of gut microbiota compared to healthy individuals. It was observed that the microbiota of individuals in the study group was significantly depleted in the microorganisms Coprococcus eutactus, Clostridium cocleatum, and Collinsella aerofaciens. This analysis drew the researchers’ attention to the potential use of probiotic preparations for alleviating gastrointestinal symptoms occurring in the course of IBS [63]. One of the most commonly analyzed probiotic strains in IBS is Lactobacillus plantarum 299v [64]. These microorganisms are not pathogenic, they are resistant to the digestive enzymes of the gastrointestinal tract, and once they reach the intestines, they colonize the colonic mucosa. Through colonization of the large intestine and antimicrobial activity, mainly against pathogenic Gram-negative bacteria, this strain alleviates the inflammatory process taking place in the intestines. It also shows immunomodulatory effects as it influences the synthesis and secretion of pro-inflammatory and anti-inflammatory cytokines. Lactobacillus plantarum 299v also increases the production of carboxylic acid, acetic acid and propionic acid, thereby lowering the hydrogen potential in the colon, which supports the control of microbial proliferation in the colon [64]. A randomized controlled trial conducted in 2022 by Moeen-Ul-Haq et al. showed that the effect of Lactobacillus plantarum 299v administration on the course of IBS was not significantly Figure 2. General dietary recommendations for patients with IBS.5. Supplementation5.1. ProbioticsProbiotics are live microorganisms that, when taken in specific amounts, can have apositive impact on human health [20]. Probiotic preparations can be used in the treatmentof IBS as they can contribute to changes in the composition of gut microbiota. AmongNutrients 2023, 15, 3662 13 of 22individuals with IBS, abnormalities in the composition and functioning of gut-colonizingmicroorganisms are often observed, which may contribute to the onset of symptoms in thecourse of the disease [20].A study was conducted that focused on comparing the composition of gut microbiotain individuals with IBS (study group: n = 24) and healthy individuals (control group:n = 23) [63]. Stool samples were collected from the study participants, and microbialgenome analyses were performed. Individuals with IBS participating in the study exhibiteda significantly different composition of gut microbiota compared to healthy individuals.It was observed that the microbiota of individuals in the study group was significantlydepleted in the microorganisms Coprococcus eutactus, Clostridium cocleatum, and Collinsellaaerofaciens. This analysis drew the researchers’ attention to the potential use of probioticpreparations for alleviating gastrointestinal symptoms occurring in the course of IBS [63].One of the most commonly analyzed probiotic strains in IBS is Lactobacillus plantarum299v [64]. These microorganisms are not pathogenic, they are resistant to the digestiveenzymes of the gastrointestinal tract, and once they reach the intestines, they colonizethe colonic mucosa. Through colonization of the large intestine and antimicrobial activity,mainly against pathogenic Gram-negative bacteria, this strain alleviates the inflammatoryprocess taking place in the intestines. It also shows immunomodulatory effects as itinfluences the synthesis and secretionof pro-inflammatory and anti-inflammatory cytokines.Lactobacillus plantarum 299v also increases the production of carboxylic acid, acetic acidand propionic acid, thereby lowering the hydrogen potential in the colon, which supportsthe control of microbial proliferation in the colon [64]. A randomized controlled trialconducted in 2022 by Moeen-Ul-Haq et al. showed that the effect of Lactobacillus plantarum299v administration on the course of IBS was not significantly different from placebo [64].The study involved 190 individuals diagnosed with IBS. The subjects were divided intotwo equal groups, with one group receiving 5 × 1010 CFU of Lactobacillus plantarum299v (study group) and the other receiving placebo (control group). After a four-weekfollow-up, an alleviation of abdominal pain, bloating and the sensation of incompletebowel movements was noted; however, no significant differences were observed betweenthe groups. The authors, therefore, concluded that supplementation with Lactobacillusplantarum 299v did not show significant efficacy in the treatment of IBS [64]. In contrast,a randomized experimental study also conducted in 2022 by Bednarska et al. noted thatLactobacillus plantarum 299v had a more beneficial effect on the course of IBS compared toplacebo [65]. In this analysis, 30 people diagnosed with moderate IBS were assigned to oneof two groups. The first group received an enema containing the bacterial strain (studygroup), while the second group received a placebo (control group). In both groups, theformulations were administered twice a day for a period of 14 days, and a biopsy fromthe distal part of the colon was taken from each participant before the start and end ofthe study, as well as questionnaires on IBS symptoms. The study noted that there was asignificant reduction in intestinal mucosal permeability and improvement in transepithelialresistance (TER) in the study group relative to the control group. However, the authorsshow that confirmation of their findings requires further research [65].An interventional, randomized, controlled clinical trial conducted by Gupta et al.analyzed the safety and efficacy of using the Bacillus coagulans LBSC (DSM17654) strainamong individuals with IBS [66]. The study involved a total of 40 participants of bothsexes with IBS, who were divided into two groups (20 individuals in each). The first groupreceived preparations containing the bacterial strain at a dose of 6 billion CFU (colony-forming units) per day (2 billion CFU in powder form three times a day) for a duration of80 days. The second group (control group) received placebo preparations (the same form ofadministration containing maltodextrins) for the same duration of time. The study authorsdemonstrated that Bacillus coagulans LBSC (DSM17654) had a beneficial impact on reducinggastrointestinal symptoms such as bloating, abdominal pain, diarrhea, constipation, nausea,vomiting, and also alleviated headache pain. Additionally, it was proven that the use ofNutrients 2023, 15, 3662 14 of 22this probiotic strain, by alleviating the symptoms of the condition, can positively affect thewell-being and mood of patients, as well as improve their quality of life [66].The beneficial impact of probiotic use on the quality of life in individuals with IBS isalso confirmed by a review conducted by Le Morvan de Sequeira et al. [67]. The authorsanalyzed 35 studies involving a total of 4717 individuals. The studies utilized single-strainor multi-strain probiotics (consisting of two to eight different strains) in the form of sachets,capsules, tablets, or liquids. The participants in the studies consumed probiotics rangingfrom 1 × 108 to 9 × 1011 CFU (colony-forming units) per day (median = 1 × 1010 CFU/day).The intervention groups (using probiotics) were compared to placebo groups. After an-alyzing the results, the authors of the review concluded that the use of probiotics in themanagement of IBS can improve the quality of life of patients compared to placebo. Theimprovement in quality of life was likely associated with the impact of probiotics in allevi-ating somatic symptoms. Additionally, it was noted that Bifidobacterium longum NCC3001could potentially be used as a psychobiotic as it reduces the reactivity of the limbic system,contributing to the alleviation of anxiety. However, this requires further confirmation infuture studies [67].A systematic review and meta-analysis of seventeen randomized controlled trialsconducted by Wen et al. demonstrated that the use of probiotics can have a beneficialeffect on intestinal peristalsis, stool frequency, and consistency [68]. The meta-analysisincluded studies conducted among adults with IBS-C (constipation-predominant IBS).In the randomized controlled trials, probiotic therapy was compared to placebo or toindividuals not using any supplements. However, the meta-analysis did not consider thespecific species, strains, doses, and regimens of probiotic use. The researchers observedthat individuals using probiotics did not report any adverse effects. Compared to placebo,the use of probiotics resulted in accelerated intestinal transit, significantly increased stoolfrequency, and notably improved stool consistency [68].The British Society of Gastroenterology also conducted a meta-analysis of 45 studiesevaluating the use of different types of probiotics in the management of IBS [18]. The teammembers indicate that a significant beneficial impact on overall symptoms and abdominalpain among patients can be achieved through a combination of different bacterial strainsin probiotic preparations. Less significant, yet positive therapeutic effects may also beobtained with the use of preparations containing individual strains of bacteria from theLactobacillus, Bifidobacterium, and Escherichia genera [18].The mechanism of action of probiotic preparations is not fully understood. It is notedthat it may inhibit the development of IBS in particular post-infectious IBS, as they exhibitanti-inflammatory, antimicrobial and antiviral effects [69]. It is likely that probiotics modifythe body’s immune system response by modifying the response of dendritic cells and stim-ulating the production of antimicrobial proteins [69,70]. Probiotics can relieve abdominalpain by increasing the expression of cannabinoid and opioid receptors [71]. Short-chainfatty acids, formed by probiotic-mediated fermentation in the gut, are a nutrient for in-testinal epithelial cells resulting in improved integrity and enhanced intestinal mucosalbarrier function. SCFAs are also responsible for lowering the pH of the gastrointestinallumen, as a result of which they inhibit the growth of pathogenic bacteria [69]. However, itis important to note that the authors of all the studies conducted so far emphasize the needfor more detailed randomized controlled trials that will further define the duration of useand dosage (CFU), as well as the species and strains of probiotics used [18,68].In summary, therapies involving probiotic preparations can yield significant therapeu-tic effects in the management of IBS. Probiotics, by modifying the gut microbiota, can havea beneficial impact on gastrointestinal symptoms and the functioning of the digestive tract,thereby improving the well-being of individuals with IBS, their quality of life, and theirexperience of anxiety. However, the current body of research is insufficient to provide clearrecommendations for IBS patients regarding the specific species and strains of probiotics tobe used, as well as the duration of use and the dosage (CFU).Nutrients 2023, 15, 3662 15 of 225.2. Psyllium HuskPsyllium husk, also known as Plantago ovata, is the seed of the Plantago ovata plant.These seeds contain arabinoxylan, a highly branched polysaccharide that forms a gel-richpolymer abundant in arabinose and xylose. It is the main component of dietary fiber andis not digested by human digestive enzymes.However, once it reaches the large intestinealong with food content, it is utilized by certain microorganisms colonizing the gastroin-testinal tract. The selective utilization of arabinoxylan by the microbiota can result inchanges in its composition, as demonstrated by Jalanka et al. in 2019 [72]. The researchersconducted two independent, randomized, controlled, placebo intervention studies. Onestudy aimed to investigate the impact of psyllium husk supplementation on the microbiotacomposition of healthy individuals, while the other evaluated the same intervention amongindividuals with constipation. Significant modifications in gut functioning were observedin both groups, including changes in stool water content, transit time, and production ofshort-chain fatty acids (SCFA). The analyses also revealed slight alterations in the gut mi-crobiota composition of the healthy group following supplementation, whereas individualswith constipation experienced significant changes in the composition of colon-residingmicroorganisms, notably a significant increase in the abundance of bacteria from the Lach-nospira genus. Some strains of Lachnospira have the ability to produce lactate and acetate,which are further transformed into butyrate and propionate. Insufficient butyrate produc-tion reduces mucin secretion, which can lead to constipation. This study demonstratedthat psyllium husk supplementation contributes to an increase in the abundance of gutmicrobiota responsible for SCFA production, indicating the positive effects of using suchpreparations [72].The mechanisms of action of psyllium are currently not well understood. However,a 2023 study by Bretin et al. showed that psyllium can alleviate colitis by affecting bileacid metabolism [73]. The study was conducted among mice that were fed diets enrichedwith dietary fiber from various sources. It was noted that individuals fed psyllium weresignificantly better protected against colitis. It is likely that this relationship was due toinduced changes in the composition of the intestinal microbiota and, most importantly, theability of psyllium to alter bile acid production. Psyllium shows the ability to modify thesynthesis of bile acids and increase their concentration in blood serum, resulting in theactivation of the farnesoid X receptor, which in turn is involved in protection against colitis.The authors of the analysis note that it is worth focusing on further investigation of themechanisms of action of psyllium [73].Psyllium husk, also known as Plantago ovata, does not irritate the colon mucosa. Ithas a high water-holding capacity and exhibits dualistic normalizing activity on bowelmovements. In cases of constipation, it softens hard stool, while in cases of diarrhea,it solidifies loose stool and stabilizes the frequency and form of bowel movements inindividuals with IBS [74]. However, in order for psyllium husk to fulfill its functions, itis important to ensure an adequate intake of water along with the preparation. It hasbeen noted that there is a lack of precise recommendations regarding the amount of waterconsumed, and additionally, the recommended dosage of psyllium husk is often too small(7–14 g/day) to fully fulfill its functions. It has been shown that the average fiber intake ofadults in the United States is below 15 g per day, while the average daily fiber requirementfor adults is around 25–38 g. Therefore, researchers suggest that at least 20 g of psylliumhusk should be consumed along with a minimum of 500 mL of water [74].The Canadian Association of Gastroenterology conducted a literature review to es-tablish guidelines for managing IBS [75]. Specialists analyzed 15 randomized controlledclinical trials and performed a meta-analysis. The existing studies have shown that supple-mentation with psyllium husk yields positive effects in alleviating IBS symptoms comparedto the use of a placebo or no treatment. It has been observed that the use of psyllium huskhas a beneficial impact on the occurrence of constipation and diarrhea, and its mechanismof action involves changes in stool consistency, modifications in the production of fer-mentation products by the gut microbiota, and alterations in the composition of intestinalNutrients 2023, 15, 3662 16 of 22microorganisms. Therefore, the association recommends the use of psyllium husk supple-mentation among individuals with IBS as it is a cost-effective, safe, and patient-acceptedform of treatment [75].In summary, considering the effects of psyllium husk and the guidelines providedby the Canadian Association of Gastroenterology, the use of preparations containing thisingredient should be recommended among patients with IBS. According to the existingresearch, its utilization is safe and yields positive effects in treating IBS symptoms. However,when recommending the use of psyllium husk, it is important to remind patients toincrease their fluid intake (at least 2 L per day) as it is crucial for the proper functioning ofpsyllium husk.5.3. Vitamin DVitamin D is a fat-soluble vitamin that is converted into 25-hydroxyvitamin D andother compounds (such as 1.25(OH)2D) in the human body. The proper level of vitamin Din the body and the occurrence of deficiencies largely depend on geographic location anddietary habits. Vitamin D can be synthesized in the skin through exposure to sunlight orobtained through food, although dietary intake is usually very low [76]. Vitamin D is crucialfor maintaining proper bone mineralization, reducing the risk of rickets in children andosteomalacia in adults, and minimizing the risk of fractures. However, vitamin D also playsmany extra-skeletal functions, reducing symptoms in psoriasis, potentially influencingthe course and alleviating symptoms of inflammatory bowel diseases, playing a role inimmune system support, impacting autoimmune diseases, and current research suggests itspotential in reducing the risk of certain cancers [76,77]. To prevent diseases and ensure theproper functioning of the skeletal system and other organs and systems in the human body,attention should be paid to vitamin D supplementation. According to current guidelines,there is no single recommended dose for vitamin D supplementation, and it should beadjusted individually for each person, but typically ranges from 800 to 2000 IU/day [78]. Itis considered that the concentration of 25(OH)D in blood serum should not be lower than50 nmol/L to prevent adverse effects of vitamin D deficiency [76]. Due to the fact that 20%of vitamin D is obtained through diet, gastrointestinal disorders have been observed as apossible cause of insufficient vitamin D levels in the blood serum. Therefore, it has beennoted that vitamin D deficiency is more common among individuals with IBS than in thegeneral population [77,79].A study conducted in 2021 by Linsalata et al. aimed to assess the relationship be-tween vitamin D serum levels, intestinal barrier structure, and symptoms among individ-uals with diarrhea-predominant Irritable Bowel Syndrome (IBS-D) [77]. The study ulti-mately involved 36 participants with IBS-D, among whom 44% had a vitamin D deficiency(<20 ng/mL), while the remaining portion of the group had low but within-normal-rangevitamin D levels (≥20 ng/mL) in their blood serum. During the study, the participantsattended three visits. The first visit involved providing basic information about the projectand conducting all required tests. One week after the first visit, the patients had theirsecond meeting, during which anthropometric analyses were performed, and individualsqualifying for intervention were identified. The final visit took place 12 weeks after im-plementing the recommendations from the first visit. During the third visit, all necessaryexaminations and analyses of dietary journals were conducted. The researchers noted thatafter 12 weeks of observation, the vitamin D serum levels significantly increased in bothgroups, particularly among individuals with a pre-existing vitamin D deficiency before theimplementation of the new dietary recommendations. It was observed that individualswith a vitamin D deficiency prior to the intervention exhibited significantly more severesymptoms compared to those with normal vitamin D levels in their blood serum. How-ever, after 12 weeks of following the recommendations, a substantial improvement in IBSsymptoms was observed in both groups, with particular attention given to the regulationof bowel movements. The study also included analyses of intestinal permeability andthe intensity of inflammation. It was demonstrated that an increase in vitamin D serumNutrients 2023, 15, 3662 17 of 22levels led to an improvement in the intestinal barrier in both groups and a reduction inpro-inflammatory factors (IL-6, IL-8). The researchers provided evidence that vitaminD serum levels play a crucial role in maintaining proper intestinal barrier function andinfluence the development of IBS. Vitamin D deficiency contributed to the heightenedseverity of disease-specific symptoms, central nervous system sensitivity, and symptoms ofdepression and anxiety [77].A review conducted in 2022 by Huang et al. assessed whether the inclusion of vitaminD supplements could impact the treatment of IBS and positively influence the qualityof life for affected individuals [80]. Among 149 studies, the researchers included fourrandomized controlled trials in their meta-analysis, involving a total of 334 participants,with 169 individuals with IBS receiving vitamin D supplementation and 166 individualsreceiving a placebo. The duration and dosage of vitamin D supplementation varied acrossthe publications [80]. The conducted review demonstrated that the use of vitamin Dsupplements can alleviate most symptoms associated with IBS (such as abdominal pain,diarrhea, constipation, and bloating) and positively impact the improvement of qualityof life (including reducing the occurrence of depression and anxiety). The mechanism ofaction of vitamin D is not fully understood, but it is suggested that it reduces inflammationof the intestinal mucosa and alleviates psychological and psychiatric conditions [80].A meta-analysis conducted in 2023 by Yan et al. indicates that vitamin D supplemen-tation can alleviate gastrointestinal discomfort associated with IBS, possibly by increasingvitamin D receptor expression and, as a result, attenuating inflammatory responses of theintestinal mucosa. However, researchers indicate that the pathophysiology of the devel-opment of IBS is highly complex, making the effects of this vitamin on gastrointestinalmotility, visceral hypersensitivity, gut-brain axis function, stress sensation and other factorsaffecting disease development likely to be much more complicated [81].In summary, vitamin D is incredibly important for every individual. Due to limitedsynthesis in the skin and very low dietary intake, considering vitamin D supplementa-tion is recommended for everyone. The recommended preventive dosage ranges from800–2000 IU per day. It is particularly important to pay attention to the occurrence of vita-min D deficiencies among patients with IBS and to recommend vitamin D supplementationin this group, as the inclusion of supplements can have positive effects on the course of thedisease. Supplementation can alleviate IBS symptoms and improve quality of life.6. Physical ActivityRegular physical activity brings health benefits to the cardiovascular system andoverall body functioning, and reduces the risk of many chronic diseases (including cardio-vascular diseases, diabetes, and cancer), as well as overall mortality. It positively affectsgrowth and development. Exercise not only influences the physical aspects of human lifebut also has mental benefits, improving well-being, enhancing cognitive processes such asthinking, learning, and judgment, and reducing symptoms of anxiety and depression [82].According to the recommendations of the World Health Organization (WHO), every adultshould engage in aerobic and moderate-intensity exercise for at least 150–300 min per weekor at least 75–150 min per week of aerobic exercise at high intensity or a proportionate mixof both types of exercise [82]. Additionally, adults should engage in muscle-strengtheningactivities of moderate or high intensity at least two times per week to gain additional healthbenefits, activating all major muscle groups [82].According to the guidelines of the National Institute for Health and Care Excellence,patient education regarding engaging in physical activity is necessary for the preventionand treatment of IBS [19]. Individuals with the condition should be provided with briefinstructions that take into account the recommended exercises and are tailored to theiraccompanying symptoms. Short advice on physical activity aims to increase the motivationof individuals with IBS to engage in it more frequently. Particularly, these brief recom-mendations regarding physical activity are significant among patients with IBS who havepreviously had a relatively low level of physical activity [19].Nutrients 2023, 15, 3662 18 of 22To date, there have been limited and relatively low-quality studies that have analyzedthe impact of physical activity on the course and treatment of IBS. In 2018, Sadeghian et al.,as part of the SEPAHAN project (The Study on the Epidemiology of Psycho-AlimentaryHealth and Nutrition), conducted a cross-sectional study among nearly 5000 adult residents(both women and men) of Iran [15]. The study authors observed that individuals leading asedentary lifestyle have a 27% higher risk of developing IBS compared to physically activeindividuals. It was also noted that physically active individuals exhibit better dietary habits.They consume more water, prioritize breakfast, maintain regular meal patterns, and chewtheir food thoroughly. However, the authors acknowledge that the mechanism by whichphysical activity influences the development of IBS remains unknown, and they emphasizethe need for further prospective studies [15].A randomized controlled trial was conducted among patients with IBS by Daleyet al. [83]. In this study, individuals were divided into two groups: one group had access tobasic medical care only, while the other group received additional advice on engaging inphysical activity. Throughout the study, the quality of life and accompanying symptoms ofIBS were analyzed, with particular emphasis on abdominal pain, diarrhea, constipation, andgeneral symptoms. After a 12-week observation period, researchers observed significantdifferences between the groups regarding the accompanying symptoms of the disease.It was demonstrated that physical activity can have a significant impact on symptomrelief, particularly in reducing the occurrence of constipation. Furthermore, no significantdifferences were observed between the groups in terms of improvements in quality oflife [83].Two controlled studies were also conducted in Sweden to investigate the impact ofphysical activity on the treatment process of IBS [84,85]. In the first study, patients weresubjected to a 12-month observation period, while the median duration in the second studywas 5.2 years. Researchers observed that engaging in physical activity of moderate tohigh intensity (such as walking, cycling, aerobics) three to five times a week, ranging from20 to 60 min, had beneficial effects on gastrointestinal symptoms and the well-being ofindividuals with IBS. It was shown that compared to the control group, individuals in theintervention group reported better quality of life and reduced experience of depression andanxiety [84,85].A study conducted in 2016 by Shahabi et al. [86] also confirmed the beneficial effectsof physical activity among individuals with IBS. The study examined the impact of regularwalking and practicing yoga on IBS symptoms and the well-being