How to Implement the 3-Phase FODMAP Diet Into Gastroenterological Practice

An evidence-based update on the diagnosis and management of irritable bowel syndrome

INTRODUCTION

Irritable bowel syndrome (IBS) is a disorder of gut-brain interaction affecting 5% of the population. The cardinal symptoms are abdominal pain and altered stool form or frequency.

AREAS COVERED

Diagnosis and management of IBS. We searched the literature for diagnostic accuracy studies, randomized controlled trials, and meta-analyses. A positive diagnosis of IBS, alongside testing to exclude celiac disease, is recommended. Exhaustive investigation has a low yield. Patients should be offered traditional dietary advice. If response is incomplete, specialist dietetic guidance should be considered. Probiotics may be beneficial, but quality of evidence is poor. First-line treatment of constipation is with laxatives, with secretagogues used where these are ineffective. Anti-diarrheal drugs should be used first-line for diarrhea, with second-line drugs including 5-hydroxytryptamine-3 antagonists, eluxadoline, or rifaximin, where available. First-line treatment of abdominal pain should be with antispasmodics, with gut-brain neuromodulators prescribed second-line. Low-dose tricyclic antidepressants, such as amitriptyline, are preferred. Brain-gut behavioral therapies are effective and have evidence for efficacy in patients refractory to standard therapies.

EXPERT OPINION

Despite substantial advances, there remains scope for improvement in terms of both the diagnosis and management of IBS. Reinforcement of positive diagnostic strategies for the condition and novel treatment paradigms are required.

Is orthorexia nervosa a hidden threat impacting quality of life in IBS patients?

BACKGROUNDS

The potential link between functional gastrointestinal disorders and eating disorders has been reported recently.

AIMS

The present study aimed to explore the relationship between orthorexic tendencies and irritable bowel syndrome (IBS)-related quality of life in IBS patients.

METHOD

This cross-sectional study was conducted with 121 IBS patients. The data were collected using Orthorexia Nervosa-11 (ORTO-11) to assess orthorexic tendencies, Irritable Bowel Syndrome Quality of Life Scale (IBS-QoL) to measure quality of life, and Irritable Bowel Syndrome Symptom Severity Score (IBS-SSS) to measure IBS symptoms. Food consumption record was taken to assess diet quality with the Healthy Eating Index 2015 (HEI-2015). The relationship between measured variables was assessed.

RESULTS

The mean ORTO-11 score of the patients was 24.76 ± 3.99. Most patients had poor diet quality (52.00%). A moderate positive correlation was found between ORTO-11 and IBS-QoL (model 0, p < 0.005 and model 1, p < 0.001) and a strong negative correlation between IBS-SSS and IBS-QoL (p < 0.001).

CONCLUSIONS

In conclusion, we can conclude that both altered IBS symptoms and orthorexic tendencies affect the quality of life of irritable bowel patients independently of each other. These findings provide valuable insights into the treatment of IBS and inform clinicians and researchers in the fields of gastroenterology, nutrition, psychiatry,and psychology.

Review article: Evidence-based dietary management of inflammatory bowel disease

BACKGROUND

Dietary management of patients with inflammatory bowel disease (IBD) involves more than defining a therapeutic diet. The profusion of 'expert advice' is not necessarily built on evidence.

AIMS

To provide evidence-based guidance on all clinically relevant aspects of nutritional and dietary management of patients with IBD.

METHODS

A comprehensive review of the published literature was made.

RESULTS

Four pillars of management should be considered in all patients. First, nutritional status should be optimised, since myopenia and visceral obesity are associated with poorer outcomes, which can be improved with attention to their correction. Accurate point-of-care measurement of body composition is advocated to identify problems, guide interventions and monitor outcomes. Second, exclusive enteral nutrition and the Crohn's Disease Exclusion Diet with partial enteral nutrition in reducing intestinal inflammation in patients with Crohn's disease have sufficient evidence to be advocated. Multiple other dietary approaches, while promising, have insufficient evidence to be recommended. Third, dietary approaches are important in symptomatic control in many non-inflammatory scenarios. Finally, guidance on following a healthy diet is fundamental to the general health of patients. Multiple approaches are advocated, but the optimal strategy is unclear. The precarious nutritional status of patients with IBD together with the risks of nutritional inadequacy and maladaptive eating behaviours associated with restrictive diets dictate involvement of expert dietitians in assessment and personalised delivery of dietary interventions.

CONCLUSIONS

Four pillars of nutritional management require specific assessment and interventional strategies that should be chosen by evidence. Optimal delivery requires the skills of a specialised dietitian.

Practices and Barriers in Implementing the Low FODMAP Diet for Irritable Bowel Syndrome Among Malaysian Dietitians: A Qualitative Study

The low fermentable oligo-, di-, mono-saccharides and polyols (FODMAP) diet (LFD) is a second-line dietary intervention for irritable bowel syndrome (IBS) patients, involving FODMAP restriction, reintroduction, and personalization, and it needs to be delivered by dietitians. However, the application of this diet among Malaysian IBS patients is not well understood. This study aimed to explore the practices and barriers in delivering the LFD among Malaysia dietitians. Semi-structured qualitative interviews were conducted online with practicing dietitians until the data reached saturation. All the interview sessions were audio recorded and transcribed verbatim. Thematic analysis was used to analyze the data. Eleven dietitians were interviewed, with 36.4% (n = 4) having more than 10 years of experience. The following four themes regarding their practices emerged: 1. dietary advice on FODMAP restriction; 2. duration of FODMAP restriction phase; 3. references used to get information about FODMAPs, and 4. strategies on reintroduction. Meanwhile, the following seven barriers were identified: 1. lack of culturally relevant educational materials; 2. limited knowledge about the LFD; 3. inadequate formal training among dietitians; 4. lack of integration in multi-disciplinary care; 5. low health literacy of patients; 6. low compliance rate among patients, and 7. restrictions for certain populations. LFD implementation in Malaysia is not standardized as only experienced dietitians can provide dietary evidence-based advice. Lack of training and culturally specific resources are some of the main barriers that were identified to be limiting the implementation of the diet. Therefore, there is a need for training programs and resource development to support Malaysian dietitians in managing IBS patients.

Exploring Dietitians' Perspectives Toward Current Practices and Services in Relation to Irritable Bowel Syndrome Management in Clinical Settings Across the United Kingdom: A Qualitative Study

BACKGROUND

Irritable bowel syndrome (IBS) is a chronic and relapsing gastrointestinal condition that negatively impacts quality of life. Dietary triggers are common and dietary management is central to the IBS treatment pathway, and dietitians are the main education providers for patients.

OBJECTIVE

The aim of this study was to explore dietitians' perspectives on current practices and services in relation to IBS management in clinical settings across the United Kingdom.

DESIGN

Qualitative semi-structured interviews were undertaken from May to October 2021 via videoconferencing software. Eligible participants were dietitians specializing in gastroenterology and working in National Health Service (NHS) Trusts in the United Kingdom. Interviews were audio recorded and transcribed following intelligent transcription. Template analysis guided by naïve realism and its underlying epistemological assumptions was used.

PARTICIPANTS/SETTING

Dietitians (N = 13) working in various NHS Trusts across the United Kingdom with at least 1 year of clinical experience in IBS management were included.

QUALITATIVE DATA ANALYSIS

Template analysis, a form of thematic analysis with hierarchical coding, was used to explore dietitians' perspectives of IBS practices.

RESULTS

Participating dietitians were mostly female (92.3%), of White race (84.6%), working in various NHS Trusts across the United Kingdom, and had more than 5 years of clinical experience (69.2%). The following 3 main themes emerged: 1) dietetics services as part of IBS referral pathways; 2) practices in relation to dietetics services; and 3) patients' expectations and feelings. Each main theme had subthemes to facilitate the description and interpretation of data. The increasing number of IBS referrals to dietitians and the need for accurate and timely IBS diagnosis and specialist dietitians were reported, along with the use of digital innovation to facilitate practice and access to dietetic care. The use of internet as a source of (mis)information by patients and the limited time available for educating patients were identified as potential barriers to dietetic practice. Dietitians follow a patient-centered approach to dietary counseling and recognize the negative implications of perceived IBS-related stigma by patients on their feelings and treatment expectations.

CONCLUSIONS

The study identified areas and practices that can facilitate access to dietetic services and patient-centered care in IBS management, as outlined in UK-based guidelines.

Presence and characteristics of disordered eating and orthorexia in irritable bowel syndrome

INTRODUCTION

Orthorexia, a harmful obsession with eating healthily, may develop from illnesses characterized by dietary restriction, including irritable bowel syndrome (IBS) and eating disorders (ED). Evidence of disordered eating in IBS exists, but orthorexia has not been assessed. This cross-sectional study in adults (≥18 years) assessed presence and characteristics of disordered eating and orthorexia in IBS, compared to control subjects (CS) and ED.

METHODS

IBS participants met Rome IV, and ED participants met DSM-5 criteria. Disordered eating was assessed using "sick, control, one-stone, fat, food" (SCOFF, ≥2 indicating disordered eating), and orthorexia by the eating habits questionnaire (EHQ). Secondary measures included stress (PSS); anxiety (HADS-A); food-related quality of life (Fr-QoL), and dietary intake (CNAQ).

KEY RESULTS

In 202 IBS (192 female), 34 ED (34 female), and 109 CS (90 female), more IBS (33%) and ED (47%) scored SCOFF≥2 compared to CS (16%, p < 0.001, chi-square). IBS and ED had higher orthorexia symptom severity compared to CS (EHQ IBS 82.9 ± 18.1, ED 90.1 ± 19.6, and CS 73.5 ± 16.9, p < 0.001, one-way ANOVA). IBS and ED did not differ for SCOFF or EHQ (p > 0.05). Those with IBS and disordered eating had higher orthorexia symptom severity (EHQ 78.2 ± 16.6 vs. 92.4 ± 17.5, p < 0.001, independent t-test), worse symptoms (IBS-SSS 211.0 ± 78.4 vs. 244.4 ± 62.5, p = 0.008, Mann-Whitney U test), higher stress (p < 0.001, independent t-test), higher anxiety (p = 0.002, independent t-test), and worse FR-QoL (p < 0.001, independent t-test).

CONCLUSIONS AND INFERENCES

Disordered eating and orthorexia symptoms occur frequently in IBS, particularly in those with worse gastrointestinal symptoms, higher stress, and anxiety. Clinicians could consider these characteristics when prescribing dietary therapies.

Innovative concepts in diet therapies in disorders of gut-brain interaction

Diet therapy in disorders of gut-brain interaction (DGBI) is rapidly advancing, with accumulating evidence to support two innovative therapies-manipulation of dietary fibers and enzyme supplementation-that target specific DGBI pathophysiology and modulate digestion. Dietary fibers escape digestion in the upper gastrointestinal tract and can influence gut function by impacting digestion, improving laxation, and interacting with the microbiota. A more nuanced understanding of different fiber types and their ability to impact gut function in highly specific ways has shown that fibers can impact distinct gut symptoms and pathophysiology. By considering their functional characteristics of bulking, gel-forming, and fermentability, restriction or supplementation of specific fibers can offer clinical value in DGBI. Similarly to fiber specificity, emerging evidence suggests that supplemental digestive enzymes may be targeted to known food triggers with consideration that enzymes are substrate specific. Limited evidence supports use of lactase to target lactose, and α-galactosidase to target galacto-oligosaccharides. Application of enzymes during manufacturing of food products may prove to be an additional strategy, although evidence is scant. Both innovative therapies may be utilized in isolation or in combination with other diet and nondiet therapies. Implementation can be guided by the principles that fiber modulation can be targeted to specific symptomology or requirement for alterations to gut function, and digestive enzymes can be targeted to known food triggers. This review aims to summarize recent literature of these two innovative concepts and provide practical suggestions for their implementation in clinical practice.

Is the Mediterranean Low Fodmap Diet Effective in Managing Irritable Bowel Syndrome Symptoms and Gut Microbiota? An Innovative Research Protocol

INTRODUCTION

Irritable bowel syndrome (IBS) symptoms can be effectively managed with the low FODMAP diet. However, its efficacy in reducing inflammation is not yet proven. On the contrary, the Mediterranean diet has anti-inflammatory properties with proven efficacy in treating chronic low-grade inflammation-related diseases.

AIM

To publicly share our protocol evaluating the efficacy of the Mediterranean low-FODMAP (MED-LFD) versus NICE recommendations (British National Institute for Health and Care Excellence) diet in managing IBS symptoms and quality of life.

MATERIALS AND METHODS

Participants meeting the Rome IV criteria will be randomly assigned to MED-LFD or NICE recommendations and they will be followed for six months. Efficacy, symptom relief, quality of life and mental health will be assessed using validated questionnaires. In addition, fecal samples will be analyzed to assess gut microbiota, and to measure branched and short-chain fatty acids, and volatile organic compounds (metabolic byproducts from bacteria). Expected results and discussion: By publicly sharing this clinical study protocol, we aim to improve research quality in the field of IBS management by allowing for peer review feedback, preventing data manipulation, reducing redundant research efforts, mitigating publication bias, and empowering patient decision-making. We expect that this protocol will show that MED-LFD can effectively alleviate IBS symptoms and it will provide pathophysiology insights on its efficacy. The new dietary pattern that combines the LFD and the MED approaches allows for the observation of the synergistic action of both diets, with the MED's anti-inflammatory and prebiotic properties enhancing the effects of the LFD while minimizing its limitations. Identifier in Clinical Trials: NCT03997708.

Evolution, adaptation, and new applications of the FODMAP diet

The FODMAP diet has been a treatment of irritable bowel syndrome (IBS) for many years. Rigorous scientific evaluation and clinical application of the FODMAP diet have generated deep understanding regarding clinical efficacy, mechanisms of action, and potential adverse effects of this dietary approach. In turn, this knowledge has allowed fine-tuning of the diet to optimize treatment benefits and minimize risks, in the form of the traditional three-phase diet; the FODMAP-gentle approach, which is a less restrictive iteration; and a proposed FODMAP-modified, Mediterranean-style diet which endeavours to optimise both gastrointestinal symptoms and other health parameters. Furthermore, recognition that IBS-like symptoms feature in other conditions has seen the FODMAP diet tested in non-IBS populations, including in older adults with diarrhea and women with endometriosis. These areas represent new frontiers for the FODMAP diet and a space to watch as future research evaluates the validity of these novel clinical applications.

The low FODMAP diet in clinical practice: where are we and what are the long-term considerations?

A diet low in fermentable oligosaccharides, disaccharides, monosaccharides and polyols (FODMAP) improves functional bowel symptoms and is a second-line dietary management strategy for the treatment of irritable bowel syndrome (IBS). The diet is complex and involves three stages: restriction, reintroduction and personalisation and clinical effectiveness is achieved with dietitian-led education; however, this is not always available. The aim of this review is to provide an update on the evidence for using the low FODMAP diet, with a focus on the impact of FODMAP restriction and reintroduction considering long-term management of IBS in a clinical setting. Randomised controlled trials have assessed symptom response, quality of life, dietary intake and changes to the gut microbiota during FODMAP restriction. Systematic reviews and meta-analyses consistently report that FODMAP restriction has a better symptom response compared with control diets and a network analysis reports the low FODMAP diet is superior to other dietary treatments for IBS. Research focused on FODMAP reintroduction and personalisation is limited and of lower quality, however common dietary triggers include wheat, onion, garlic, pulses and milk. Dietitian-led delivery of the low FODMAP diet is not always available and alternative education delivery methods, e.g. webinars, apps and leaflets, are available but remove the personalised approach and may be less acceptable to patients and may introduce safety concerns in terms of nutritional adequacy. Predicting response to the low FODMAP diet using symptom severity or a biomarker is of great interest. More evidence on less restrictive approaches and non-dietitian-led education delivery methods are needed.

The Role of the FODMAP Diet in IBS

The low FODMAP (fermentable oligosaccharide, disaccharide, monosaccharide, and polyol) diet is a beneficial therapeutic approach for patients with irritable bowel syndrome (IBS). However, how the low FODMAP diet works is still not completely understood. These mechanisms encompass not only traditionally known factors such as luminal distension induced by gas and water but also recent evidence on the role of FOMAPs in the modulation of visceral hypersensitivity, increases in intestinal permeability, the induction of microbiota changes, and the production of short-chain fatty acids (SCFAs), as well as metabolomics and alterations in motility. Although most of the supporting evidence is of low quality, recent trials have confirmed its effectiveness, even though the majority of the evidence pertains only to the restriction phase and its effectiveness in relieving abdominal bloating and pain. This review examines potential pathophysiological mechanisms and provides an overview of the existing evidence on the effectiveness of the low FODMAP diet across various IBS subtypes. Key considerations for its use include the challenges and disadvantages associated with its practical implementation, including the need for professional guidance, variations in individual responses, concerns related to microbiota, nutritional deficiencies, the development of constipation, the necessity of excluding an eating disorder before commencing the diet, and the scarcity of long-term data. Despite its recognized efficacy in symptom management, acknowledging these limitations becomes imperative for a nuanced comprehension of the role of a low FODMAP diet in managing IBS. By investigating its potential mechanisms and evidence across IBS subtypes and addressing emerging modulations alongside limitations, this review aims to serve as a valuable resource for healthcare practitioners, researchers, and patients navigating the intricate landscape of IBS.

Food Intolerances, Food Allergies and IBS: Lights and Shadows

This narrative review delves into the intricate relationship between irritable bowel syndrome (IBS) and food intolerances. IBS, a chronic functional gastrointestinal disorder, is characterized by symptoms like abdominal pain and altered bowel habits. The prevalence of IBS has increased globally, especially among young adults. Food and dietary habits play a crucial role in IBS management. About 85-90% of IBS patients report symptom exacerbation linked to specific food consumption, highlighting the strong connection between food intolerances and IBS. Food intolerances often exhibit a dose-dependent pattern, posing a challenge in identifying trigger foods. This issue is further complicated by the complex nature of gastrointestinal physiology and varying food compositions. This review discusses various dietary patterns and their impact on IBS, including the low-FODMAP diet, gluten-free diet, and Mediterranean diet. It highlights the importance of a personalized approach in dietary management, considering individual symptom variability and dietary history. In conclusion, this review emphasizes the need for accurate diagnosis and holistic management of IBS, considering the complex interplay between dietary factors and gastrointestinal pathophysiology. It underlines the importance of patient education and adherence to treatment plans, acknowledging the challenges posed by the variability in dietary triggers and the psychological impact of dietary restrictions.

Momordica balsamina improves glucose handling in a diet-induced prediabetic rat model

Prolonged exposure to high energy diets has been implicated in the development of pre-diabetes, a long-lasting condition that precedes type 2 diabetes mellitus (T2DM). A combination of pharmacological treatment and dietary interventions are recommended to prevent the progression of pre-diabetes to T2DM. However, poor patient compliance leads to negligence of the dietary intervention and thus reduced drug efficiency. Momordica balsamina (MB) has been reported to possess anti-diabetic effects in type 1 diabetic rats. However, the effects of this medicinal plant in conjunction with dietary intervention on pre-diabetes have not yet been established. Consequently, this study sought to evaluate the effects of MB on glucose homeostasis in a diet-induced pre-diabetes rat model in the presence and absence of dietary intervention. Pre-diabetes was induced on male Sprague Dawley rats by a high fat high carbohydrate (HFHC) diet for a period of 20 weeks. Pre-diabetic male Sprague Dawley rats were treated with MB (250 mg/kg p.o.) in both the presence and absence of dietary intervention once a day every third day for a period of 12 weeks. The administration of MB with and without dietary intervention resulted in significantly improved glucose homeostasis through reduced caloric intake, body weights, with reduced plasma ghrelin concentration and glycated hemoglobin by comparison to the pre-diabetic control. MB administration also improved insulin sensitivity as evidenced by the expression of glucose transporter 4 (GLUT 4) and glycogen synthase on the prediabetic treated animals. These results suggest that MB has the potential to be used to manage pre-diabetes and prevent the progression to overt type 2 diabetes as it demonstrated the ability to restore glucose homeostasis even in the absence of dietary and lifestyle intervention.

Myths and Facts about Food Intolerance: A Narrative Review

Most adverse reactions to food are patient self-reported and not based on validated tests but nevertheless lead to dietary restrictions, with patients believing that these restrictions will improve their symptoms and quality of life. We aimed to clarify the myths and reality of common food intolerances, giving clinicians a guide on diagnosing and treating these cases. We performed a narrative review of the latest evidence on the widespread food intolerances reported by our patients, giving indications on the clinical presentations, possible tests, and dietary suggestions, and underlining the myths and reality. While lactose intolerance and hereditary fructose intolerance are based on well-defined mechanisms and have validated diagnostic tests, non-coeliac gluten sensitivity and fermentable oligosaccharide, disaccharide, monosaccharide, and polyol (FODMAP) intolerance are mainly based on patients' reports. Others, like non-hereditary fructose, sorbitol, and histamine intolerance, still need more evidence and often cause unnecessary dietary restrictions. Finally, the main outcome of the present review is that the medical community should work to reduce the spread of unvalidated tests, the leading cause of the problematic management of our patients.

Self-reported food intolerances in an Indian population: Need for individualization rather than a universal low-FODMAP diet

Background and Aim

Low-fermentable oligo-, di-, and monosaccharides and polyol (FODMAP) diets have been recommended for individuals with food intolerance and irritable bowel syndrome (IBS). Individual food intolerances may, however, not correspond to the FODMAP content alone.

Methods

We conducted a survey on self-reported intolerance to articles of food commonly identified as high FODMAP in 400 healthy Indian subjects (median age 40 years; 69% men) and 204 consecutive consenting patients with IBS (median age 36 years; 58% men).

Results

One-hundred seventy-nine (44.8%) healthy subjects and 147 (72.1%) patients with IBS reported some food intolerance (P < 0.00001); the latter reported intolerance to all items (except nuts) more frequently than healthy subjects. The prevalence, however, varied from 2.5 to 32%. Milk intolerance was reported equally commonly by healthy subjects and patients (23% vs 29.9%). Twenty-three (11.3%) patients and no healthy subjects reported wheat sensitivity. The IBS diarrhea subgroup reported intolerance to milk, pulses, capsicum, cauliflower, leafy vegetables, and dry fruits more frequently than the constipation subgroup.

Conclusion

From among a list of high-FODMAP items, individuals' intolerance varied widely, suggesting that individuals should be the final judge in deciding their elimination diets rather than devise them based on the FODMAP content alone. As in the West, food intolerance was reported more commonly by patients with IBS, especially those with diarrhea, than by healthy individuals. Also noteworthy is the low prevalence of milk intolerance in a subcontinent labeled as high in lactose intolerance. Unlike in the West, wheat intolerance was not reported by any healthy individual.

Spot Hydrogen Breath Test for Predicting Response to Low Fermentable Oligo-, Di-, Mono-saccharides, and Polyols Dietary Advice in Patients With Bloating

Background/Aims

An increase in postprandial intestinal gas plays a role in bloating symptoms. We aim to study the utility of spot breath hydrogen (H2) level in predicting the response to a low fermentable oligo-, di-, mono-saccharides, and polyols (FODMAPs) diet.

Methods

Patients with functional gastrointestinal disorders diagnosed by Rome IV criteria with bothersome bloating for > 6 months were prospectively enrolled. Patients completed 7-day food diaries and collected a breath sample 2 hours after their usual lunch at baseline and 4 weeks after low FODMAPs dietary advice by a dietitian. The responder was defined as an improvement of ≥ 30% bloating scores in the fourth week.

Results

Thirty-eight patients (32 female, 52.6 ± 13.8 years; 22 irritable bowel syndrome) completed the study. Twenty-one patients (55%) were classified as responders. Baseline global gastrointestinal symptoms, bloating, abdominal pain scores, and numbers of high FODMAPs items were similar between responders and non-responders. Both groups significantly decreased high FODMAPs items intake with similar numbers at the follow-up. The area under the curve for predicting low FODMAPs responsiveness using baseline H2 levels was 0.692 (95%CI, 0.51-0.86; P < 0.05), with the best cutoff at 8 parts per million (sensitivity 66.7%, specificity 82.4%). 66% of responders had baseline H2 level > 8 parts per million vs 17% of non-responders (P < 0.05). The baseline spot hydrogen level in responders was 9.5 (3.3-17.3) vs 4.5 (3.3-6.3) in non-responders (P < 0.05).

Conclusions

A higher baseline breath hydrogen level was associated with bloating improvement after low FODMAPs dietary advice. A spot breath test after lunch, a simple point-of-care test, is possibly helpful in managing patients with bloating.

Diet-microbiota interaction in irritable bowel syndrome: looking beyond the low-FODMAP approach

BACKGROUND

Diet is one of the main modulators of the gut microbiota, and dietary patterns are decisive for gut-microbiota-related diseases, including irritable bowel syndrome (IBS). The low-FODMAP diet (LFD) is commonly used to treat IBS, but its long-term effects on microbiota, symptoms and quality of life (QoL) are unclear. Alternative dietary strategies promoting beneficial gut microbiota, combined with reduced symptoms and improved QoL, are therefore of interest.

AIMS

To review current evidence on the diet-microbiota-interaction as a modulator of IBS pathophysiology, and dietary management of IBS, with particular emphasis on strategies targeting the gut microbiota, beyond the LFD.

METHODS

Literature was identified through PubMed-searches with relevant keywords.

RESULTS

Dietary patterns with a low intake of processed foods and a high intake of plants, such as the Mediterranean diet, promote gut microbiota associated with beneficial health outcomes. In contrast, Western diets with a high intake of ultra-processed foods promote a microbiota associated with disease, including IBS. Increasing evidence points towards dietary strategies consistent with the Mediterranean diet being equal to the LFD in alleviating IBS-symptoms and having a less negative impact on QoL. Timing of food intake is suggested as a gut microbiota modulator, but little is known about its effects on IBS.

CONCLUSIONS

Dietary recommendations in IBS should aim to target the gut microbiota by focusing on improved dietary quality, considering the impact on both IBS-symptoms and QoL. Increased intake of whole foods combined with a regular meal pattern and limitation of ultra-processed foods can be beneficial strategies beyond the LFD.

Microbial inulinase promotes fructan hydrolysis under simulated gastric conditions

Fermentable oligo-, di-, monosaccharides and polyols (FODMAPs) have emerged as key contributors to digestive discomfort and intolerance to certain vegetables, fruits, and plant-based foods. Although strategies exist to minimize FODMAP consumption and exposure, exogenous enzyme supplementation targeting the fructan-type FODMAPs has been underexploited. The objective of this study was to test the hydrolytic efficacy of a food-grade, non-genetically engineered microbial inulinase preparation toward inulin-type fructans in the INFOGEST in vitro static simulation of gastrointestinal (GI) digestion. Purified inulin was shown to undergo acid-mediated hydrolysis at high gastric acidity as well as predominantly inulinase-mediated hydrolysis at lower gastric acidity. Inulinase dose-response simulations of inulin, garlic, and high-fructan meal digestion in the gastric phase suggest that as little as 50 inulinase units (INU) and up to 800 INU per serving promote fructan hydrolysis better than the control simulations without inulinase. Liquid chromatography-mass spectrometry (LC-MS) profiling of fructo-oligosaccharides (FOS) in the gastric digestas following inulinase treatment confirms the fructolytic activity of inulinase under simulated digestive conditions. Altogether, these in vitro digestion data support the use of microbial inulinase as an exogenous enzyme supplement for reducing dietary fructan-type FODMAP exposure.

Effects of a Low-FODMAP Diet on Irritable Bowel Syndrome in Both Children and Adults-A Narrative Review

Irritable bowel syndrome is a typical gastrointestinal disease that causes bloating, flatulence, abdominal pain, diarrhoea, constipation, or alteration of the last two in adults and children. A diet low in fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAP) is one of the potential treatment strategies to reduce abdominal symptoms and increase the quality of life. The present narrative review aims to present a general overview of current studies that have evaluated the efficacy of a low-FODMAP diet against other diets in gastrointestinal symptoms, nutrient intake in adults and children, and lifestyle quality. The research was performed using seven searchable databases, which included the Cochrane Central Register of Controlled Trials (CENTRAL), Cochrane Database of Systematic Reviews (CDSR), Excerpta Medica Database (EMBASE), Medline, PubMed, Scopus, and Web of Science, up to March 2023. In conclusion, there is significant evidence that the follow-up of a low-FODMAP diet might be a feasible first-line therapeutic strategy to reduce stomach discomfort, pain, bloating, and quality of life for patients with irritable bowel syndrome.

The Usefulness of the Low-FODMAP Diet with Limited Tryptophan Intake in the Treatment of Diarrhea-Predominant Irritable Bowel Syndrome

(1) Background: A low-FODMAP diet is often recommended in the treatment of irritable bowel syndrome, but it does not improve abdominal symptoms in all patients, and an alternative diet is desirable. The purpose of this study was to evaluate the efficacy of a low-FODMAP diet with a concomitant reduction in tryptophan (TRP) intake in irritable bowel syndrome with diarrhea predominance (IBS-D) in relation to its metabolism via the serotonin and kynurenine pathways. (2) Methods: 40 healthy people (Group I, Controls) and 80 patients with IBS-D were included in the study. IBS-D patients were randomly divided into two groups of 40 each (Groups IIA and IIB). In Group IIA, the low-FODMAP diet was recommended, while in Group IIB, the same diet was recommended but with limited TRP intake for 8 weeks. The TRP intake was analyzed with the use of the nutritional calculator. Abdominal complaints were assessed using the Gastrointestinal Symptom Rating Scale (GSRS-IBS), and psychological status was simultaneously determined using two scales: the Hamilton Anxiety Scale (HAM-A) and the Hamilton Depression Scale (HAM-D). TRP and its metabolites: 5-hydoxyindoleacetic acid (5-HIAA), kynurenine (KYN), kynurenic acid (KYNA), and quinolinic acid (QA) were measured in urine using liquid chromatography tandem mass spectrometry (LC-MS/MS). (3) Results: The consumption of TRP per mg/kg/b.w./24 h has decreased in Group IIA from 20.9 ± 2.39 to 17.45 ± 2.41 (16.5%) and in Group IIB from 21.3 ± 2.33 to 14.32 (34.4%). Significantly greater improvement was found after nutritional treatment in patients in Group IIB as compared to Group IIA (GSRS score: 38.1% vs. 49.8%; HAM-A: 38.7% vs. 49.9%; HAM-D: 13.8% vs. 35.0%; p < 0.01). Reducing TRP intake showed a negative correlation with the degree of improvement in the GSRS score. (4) Conclusions: Lowering the TRP content in a low-FODMAP diet may be useful in treating IBS-D.

Small Intestinal Bacterial Overgrowth and Non-Alcoholic Fatty Liver Disease: What Do We Know in 2023?

Non-alcoholic fatty liver disease (NAFLD) is a chronic liver disease associated with the pathological accumulation of lipids inside hepatocytes. Untreated NAFL can progress to non-alcoholic hepatitis (NASH), followed by fibrosis, cirrhosis, and hepatocellular carcinoma (HCC). The common denominator of the above-mentioned metabolic disorders seems to be insulin resistance, which occurs in NAFLD patients. Obesity is the greatest risk factor for lipid accumulation inside hepatocytes, but a part of the NAFLD patient population has a normal body weight according to the BMI index. Obese people with or without NAFLD have a higher incidence of small intestinal bacterial overgrowth (SIBO), and those suffering from NAFLD show increased intestinal permeability, including a more frequent presence of bacterial overgrowth in the small intestine (SIBO). The health consequences of SIBO are primarily malabsorption disorders (vitamin B12, iron, choline, fats, carbohydrates and proteins) and bile salt deconjugation. Undetected and untreated SIBO may lead to nutrient and/or energy malnutrition, thus directly impairing liver function (e.g., folic acid and choline deficiency). However, whether SIBO contributes to liver dysfunction, decreased intestinal barrier integrity, increased inflammation, endotoxemia and bacterial translocation is not yet clear. In this review, we focus on gut–liver axis and discuss critical points, novel insights and the role of nutrition, lifestyle, pre- and probiotics, medication and supplements in the therapy and prevention of both SIBO and NAFLD.