A controlled trial of gluten-free diet in patients with irritable bowel syndrome-diarrhea: effects on bowel frequency and intestinal function

Probiotics, Prebiotics, Fecal Microbiota Transplantation, and Dietary Patterns in Inflammatory Bowel Disease

SCOPE

Inflammatory bowel disease (IBD) is one of the most common chronic and debilitating functional bowel disorders affecting around 11% of the population across the world. IBD is associated with 3.6 million physician visits per year, being the most common reason visiting a gastroenterologist and the second most common reason to be absent from work, sharply increasing the health care costs.

METHODS AND RESULTS

Several treatments seem to be effective in IBD symptoms relief, such as probiotics, prebiotics, fecal microbiota transplantation (FMT), and dietary patterns. Probiotics (living microorganisms that can be supplemented) can protect against pathogenic bacteria due to their antimicrobial qualities. Prebiotics (nondigestible food ingredients) promote the growth of beneficial microbial strains in the gut, giving a health benefit to the host. FMT is supposed to directly change the recipient's microbial composition when a transfer of gastrointestinal microbiota from a healthy donor is carried out. And finally, dietary patterns are in the spotlight, due to the presence of certain nutrients in the gastrointestinal tract affecting gastrointestinal motility, sensitivity, barrier function, and gut microbiota.

CONCLUSION

It is particularly important to know what treatment options are available and which are the most efficient in relieving IBD symptoms and improving IBD patient's quality of life.

The role of Killer immunoglobulin-like receptors (KIRs) in the genetic susceptibility to non-celiac wheat sensitivity (NCWS)

OBJECTIVES

Non-celiac wheat sensitivity (NCWS) is an emerging clinical condition characterized by gastrointestinal and extraintestinal symptoms following the ingestion of gluten-containing foods in patients without celiac disease (CD) or wheat allergy. Despite the great interest for NCWS, the genetic risk factors still need to be fully clarified. In this study, we first assessed the possible contribution of KIR genes and KIR haplotypes on the genetic predisposition to NCWS.

METHODS

Fifty patients with NCWS, 50 patients with CD, and 50 healthy controls (HC) were included in this study. KIR genes and KIR genotyping were investigated in all subjects by polymerase chain reaction with the sequence oligonucleotide probe (PCR-SSOP) method using Luminex technology.

RESULTS

We found a statistically different distribution of some KIR genes among NCWS, CD, and HC. Specifically, NCWS showed a decreased frequency of KIR2DL1, -2DL3, -2DL5, -2DS2, -2DS3, -2DS4, -2DS5, and -3DS1 genes, and an increased frequency of -3DL1 gene respect to both CD and HC. No difference was detected in the KIR haplotype expression. At the multivariate analysis, KIR2DL5, -2DS4, and -2DS5 were independent predictors of NCWS.

CONCLUSIONS

Our findings suggest a role of KIR genes in NCWS susceptibility, with KIR2DL5, -2DS4, and -2DS5 having a protective effect. Further large-scale multicentric studies are required to validate these preliminary findings.

Biophysics of claudin proteins in tight junction architecture: Three decades of progress

Tight junctions are cell-cell adhesion complexes that act as gatekeepers of the paracellular space. Formed by several transmembrane proteins, the claudin family performs the primary gate-keeping function. The claudin proteins form charge and size-selective diffusion barriers to maintain homeostasis across endothelial and epithelial tissue. Of the 27 known claudins in mammals, some are known to seal the paracellular space, while others provide selective permeability. The differences in permeability arise due to the varying expression levels of claudins in each tissue. The tight junctions are observed as strands in freeze-fracture electron monographs; however, at the molecular level, tight junction strands form when multiple claudin proteins assemble laterally (cis assembly) within a cell and head-on (trans assembly) with claudins of the adjacent cell in a zipper-like architecture, closing the gap between the neighboring cells. The disruption of tight junctions caused by changing claudin expression levels or mutations can lead to diseases. Therefore, knowledge of the molecular architecture of the tight junctions and how that is tied to tissue-specific function is critical for fighting diseases. Here, we review the current understanding of the tight junctions accrued over the last three decades from experimental and computational biophysics perspectives.

Leaky Gut Syndrome: Myths and Management

Leaky gut syndrome is a condition widely popularized in the lay literature, although it is not currently accepted as a formal medical diagnosis. Multiple gastrointestinal symptoms are ascribed to leaky gut syndrome, including diarrhea, bloating, distension, abdominal pain, and dyspeptic symptoms of early satiety, nausea, and postprandial fullness. The etiology and pathophysiology of leaky gut syndrome are multifactorial; a preceding gastrointestinal infection, inflammatory bowel disease, and certain medications may be relevant factors in some patients. The diagnosis of leaky gut syndrome is problematic. Although patients are frequently informed that the diagnosis can be readily made using results from blood work or stool studies, no validated test currently exists to make this diagnosis. Patients report a variety of myths about the etiology, diagnosis, and treatment of leaky gut syndrome, which can cause alarm and can frequently lead to expensive, unnecessary tests and unproven, sometimes dangerous treatments. This article reviews some of the most common myths about leaky gut syndrome and provides data from the scientific literature to correct these statements. Management strategies, based on data, are provided when available.

Body constitutions of traditional Chinese medicine caused a significant effect on irritable bowel syndrome

BACKGROUND

According to the theory of traditional Chinese medicine (TCM), all types of body constitutions, except for the Gentleness (ie, the control group in our study), have disease susceptibility and affect the disease development process. This study attempted to investigate the relationship between TCM body constitutions and irritable bowel syndrome (IBS).

METHODS

This cross-sectional study was based on Taiwan Biobank (TWB) and collected clinical data from 13 941 subjects aged 30 to 70. The results of the study showed that subjects with Yang-deficiency (N = 3161 subjects, odds ratio [OR] = 2.654, 95% CI = 1.740-3.910), Ying-deficiency (N = 3331 subjects, OR = 1.096, 95% CI = 0.627-1.782) or Stasis (N = 2335 subjects, OR = 1.680, 95% CI = 0.654-3.520) were more likely to have IBS.

RESULTS

If the subjects with two or more TCM body constitutions: Yang-deficiency + Ying-deficiency (OR = 3.948, 95% CI = 2.742-5.560), Yang-deficiency + Stasis (OR = 2.312, 95% CI = 1.170-4.112), Ying-deficiency + Stasis (OR = 1.851, 95% CI = 0.828-3.567), or Yang-deficiency + Ying-deficiency + Stasis (OR = 3.826, 95% CI = 2.954-4.932) were also prone to IBS.

CONCLUSION

These results confirmed the high correlation between TCM body constitutions and IBS. Because the current treatment for IBS is not entirely satisfactory, integrated traditional Chinese and Western medicine might provide patients with an alternative treatment option to alleviate IBS.

Sieving out non-celiac gluten sensitivity amongst patients with irritable bowel syndrome

OBJECTIVES

It is challenging to make diagnosis of non-celiac gluten sensitivity/non-celiac wheat sensitivity (NCGS/NCWS) in clinical practice, since there is no biomarker and diagnosis is based on response to gluten-free-diet (GFD). We used anti-gliadin antibody (AGA) for screening patients with IBS for gluten-sensitivity.

METHODS

492 Adult-patients with IBS underwent screening for celiac disease and gluten-sensitivity using IgA anti-tissue transglutaminase antibody and IgA-AGA and IgG-AGA, respectively. Patients with positive AGA (IgA and/or IgG) were invited to follow GFD, those willing were put on GFD for 6-weeks. Responsive patients were given gluten re-challenge. Diagnosis of NCGS was confirmed if they had recurrence of symptoms.

RESULTS

Of 492 patients with IBS, AGA was positive in 61(12.4 %), hence suspected to have gluten-sensitivity. Of 31 who agreed to participate and followed GFD for 6-weeks, 17 (54.8 %) had complete (>30 % improvement) and 10(32.2 %) had partial (>20 % improvement) response. All 17 complete-responders were given gluten re-challenge for 6-weeks, symptoms recurred in all and hence were confirmed to have NCGS/NCWS. Significant decrease in AGA levels occurred almost in all GFD-responders.

CONCLUSIONS

12.4 % IBS patients have biological evidence of gluten/wheat-sensitivity. Almost 87 % patients with IBS having AGA responded to GFD. The value of AGA may further be explored as a biomarker for screening for the presence of NCGS, before recommending this test for the clinical practice.

Nutrition and Disorders of Gut-Brain Interaction

BACKGROUND

Disorders of gut-brain interaction (DGBIs) have a complex pathophysiology that is often characterized by a relationship between food ingestion and triggering of symptoms. Understanding of the underlying mechanisms and the role of nutrients as a therapeutic target are rapidly evolving.

AIMS AND METHODS

We performed a narrative review of the literature using the following keywords, their acronyms, and their associations: nutrients, disorders of gut-brain interaction; functional dyspepsia; malabsorption; irritable bowel syndrome; diarrhea; constipation.

RESULTS

Functional dyspepsia displayed a significant correlation between volume, fat and/or wheat abundance, chemical composition of ingested food and symptoms of early satiety, fullness and weight loss. Carbohydrate malabsorption is related to enzyme deficiency throughout the GI tract. Food composition and richness in soluble vs. non-soluble fibers is related to constipation and diarrhea. The elimination of fermentable oligo-, di-, monosaccharides and polyols (FODMAPs) has a significant and non-unidirectional impact on irritable bowel syndrome (IBS) symptoms.

CONCLUSIONS

Food volume, nutritive and chemical composition, and its malabsorption are associated with symptom generation in DGBIs. Further multicenter, randomized-controlled clinical trials are needed to clarify the underlying pathophysiology.

Low-level inflammation, immunity, and brain-gut axis in IBS: unraveling the complex relationships

Irritable bowel syndrome is a common functional gastrointestinal disorder, and it has been shown that the etiology of irritable bowel syndrome is a multifactorial complex of neurological, inflammatory, and immunological changes. There is growing evidence of low-grade chronic inflammation in irritable bowel patients. The peripheral action response of their intestinal immune factors is integrated into the central nervous system, while the microbiota interacts with the brain-gut axis contributing to the development of low-grade chronic inflammation. The objective of this review is to present a discussion about the impact of immune-brain-gut axis-inflammation interactions on irritable bowel syndrome, its clinical relevance in the course of irritable bowel syndrome disease, and possible therapeutic modalities.

TRAV26-2 T-Cell Receptor Expression Is Associated With Mucosal Lymphocyte Response to Wheat Proteins in Patients With Functional Dyspepsia

INTRODUCTION

An association between functional dyspepsia (FD) and wheat-containing foods has been reported in observational studies; however, an adaptive response has not been demonstrated. We examined whether antigens present in wheat could provoke a response from FD duodenal lymphocytes.

METHODS

Lamina propria mononuclear cells (LPMCs) were isolated from duodenal biopsies from 50 patients with FD and 23 controls. LPMCs were exposed to gluten (0.2 mg/mL) or gliadin (0.2 mg/mL) for 24 hours. Flow cytometry was performed to phenotype lymphocytes. Quantitative PCR was used to measure the expression of gliadin-associated T-cell receptor alpha variant ( TRAV ) 26-2.

RESULTS

In response to gliadin (but not gluten) stimulation, the effector Th2-like population was increased in FD LPMCs compared with that in controls and unstimulated FD LPMCs. Duodenal gene expression of TRAV26- 2 was decreased in patients with FD compared with that in controls. We identified a positive association between gene expression of this T-cell receptor variant and LPMC effector Th17-like cell populations in patients with FD, but not controls after exposure to gluten, but not gliadin.

DISCUSSION

Our findings suggest that gliadin exposure provokes a duodenal effector Th2-like response in patients with FD, supporting the notion that food antigens drive responses in some patients. Furthermore, these findings suggest that altered lymphocyte responses to wheat proteins play a role in FD pathogenesis.

Efficacy and safety of fecal microbiota transplantation for the treatment of irritable bowel syndrome: an overview of overlapping systematic reviews

Aim: Evidence from overlapping systematic reviews (SRs) and meta-analyses (MAs) has yielded conflicting results on the treatment of irritable bowel syndrome (IBS) with fecal microbiota transplantation (FMT). To thoroughly gather, assess, and synthesize evidence on FMT for IBS, we carried out the present study. Methods: A comprehensive search was conducted in Cochrane Library, Web of Science, PubMed, and Embase from inception to May 2023. Tools for assessing the methodological quality, reporting quality, and confidence in outcomes, including A Measurement Tool to Assess Systematic Reviews 2 (AMSTAR-2), Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA), and the Grading of Recommendations Assessment, Development and Evaluation (GRADE). Results: Seven eligible SRs/MAs were finally included in this overview. By AMSTAR-2, the methodological quality of SRs/MAs included five that were very low quality, one that was low quality, and one that was high quality. According to PRISMA, limitations were associated with items 5 (Method: Protocol and Registration), 8 (Method: Search), and 27 (Funding). In GRADE, a total of 19 outcomes were included in the seven reviews, of which 12 outcomes were low quality and seven outcomes were moderate quality. Imprecision due to small sample size was the primary factor leading to evidence downgrading. Conclusion: We conclude that there is insufficient evidence to determine whether FMT has a more beneficial effect on patient with IBS than placebo treatment. Well-designed, larger trails are needed to provide evidence in this field. In addition, selection of donor, route of administration, dosage, and frequency still need to be determined.

Mapping the knowledge structure of a gluten-free diet: a global perspective

Background

A gluten-free diet (GFD) has become one of the most popular eating plans and is essential for managing gluten-related medical conditions, signs, and symptoms. Therefore, we performed a bibliometric analysis of the scientific literature on the GFD to describe the research landscape.

Methods

The Scopus database was searched for publications on the GFD from 1952 to 2021. A bibliometric analysis of the data was performed. VOSviewer software was used to perform visualization analysis, co-occurrence analysis, and publication trends in GFD.

Results

A total of 3,258 publications were retrieved. In terms of publications, Italy (n = 468, 14.36%) led in the number of publications, followed by the USA (n = 398, 12.22%) and Spain (n = 274, 8.41%). The retrieved documents earned an average of 22.89 citations per document, for a total of 74,560 citations. Since 2001, there has been a gradual growth in the number of articles published, going from 23 to more than 370 in 2021. Using the mapping terms in the title/abstract a minimum of 50 times, 291 terms were divided into two main clusters: ‘adherence to a gluten-free diet in celiac disease’ and ‘improvement of the nutritional and sensory quality of gluten-free products.’

Conclusions

Over the past six decades, there has been a growing need for gluten-free bakery products and a noticeable increase in related publications. This study indicates that the “improvement of the nutritional and sensory quality of gluten-free products” will remain a hotspot in this research field for upcoming years.

Current evidence for dietary therapies in irritable bowel syndrome

PURPOSE OF REVIEW

Diet appears to trigger symptoms in the majority of individuals with irritable bowel syndrome (IBS) and is associated with a reduced quality of life. There has been a recent focus on the role of dietary therapies to manage individuals with IBS. The aim of this review is to discuss the utility of traditional dietary advice (TDA), low-FODMAP diet (LFD) and gluten-free diet (GFD) in IBS.

RECENT FINDINGS

Several recent randomized controlled trials (RCTs) have been published demonstrating the efficacy of the LFD and GFD in IBS, with the evidence base for TDA being predominantly based on clinical experience, with emerging RCTs evaluating TDA. Only one RCT has been published to date comparing TDA, LFD and GFD head to head, with no difference noted between diets in terms of efficacy. However, TDA has been noted to be more patient-friendly and is commonly implemented as a first-line dietary therapy.

SUMMARY

Dietary therapies have been demonstrated to improve symptoms in patients with IBS. In view of insufficient evidence to recommend one diet over another currently, specialist dietetic input in conjunction with patient preference is required to determine implementation of dietary therapies. Novel methods of dietetic delivery are required in view of the lack of dietetic provision to deliver these therapies.

Food, gut barrier dysfunction, and related diseases: A new target for future individualized disease prevention and management

Dysfunction of gut barrier is known as "leaky gut" or increased intestinal permeability. Numerous recent scientific evidences showed the association between gut dysfunction and multiple gastrointestinal tract (GI) and non-GI diseases. Research also demonstrated that food plays a crucial role to cause or remedy gut dysfunction related to diseases. We reviewed recent articles from electronic databases, mainly PubMed. The data were based on animal models, cell models, and human research in vivo and in vitro models. In this comprehensive review, our aim focused on the relationship between dietary factors, intestinal permeability dysfunction, and related diseases. This review synthesizes currently available literature and is discussed in three parts: (a) the mechanism of gut barrier and function, (b) food and dietary supplements that may promote gut health, and food or medication that may alter gut function, and (c) a table that organizes the synthesized information by general mechanisms for diseases related to leaky gut/intestinal permeability and associated dietary influences. With future research, dietary intervention could be a new target for individualized disease prevention and management.

[Frequent Gastro-Intestinal Disorders: Management of Functional Dyspepsia and Irritable Bowel Syndrome in Clinical Practice]

Frequent Gastro-Intestinal Disorders: Management of Functional Dyspepsia and Irritable Bowel Syndrome in Clinical Practice Abstract: Functional dyspepsia (FD) and irritable bowel syndrome (IBS), two common gastrointestinal entities with overlapping symptoms, should be diagnosed according to Rome IV criteria. This includes one or more of the following symptoms: in FD, postprandial fullness, early satiation, epigastric pain or burning; in IBS, recurrent abdominal pain associated with defecation, change in frequency of stool or form of stool. To exclude structural diseases, attention should be paid to alarm symptoms. As far as treatment is concerned, a stepwise scheme proves to be effective for both diseases. Step 1: doctor-patient discussion with explanation of diagnosis and prognosis as well as clarification of therapy goals; lifestyle adaptations; use of phytotherapeutics; step 2: symptom-oriented medication: for FD, PPIs or prokinetics; for IBS, antispasmodics, secretagogues, laxatives, bile acid sequestrants, antidiarrheals, antibiotics, probiotics; step 3: visceral analgesics (antidepressants).

The Role of Gluten in Gastrointestinal Disorders: A Review

Gluten is only partially digested by intestinal enzymes and can generate peptides that can alter intestinal permeability, facilitating bacterial translocation, thus affecting the immune system. Few studies addressed the role of diet with gluten in the development of intestinal inflammation and in other gastrointestinal disorders. The aim of this narrative review was to analyse the role of gluten in several gastrointestinal diseases so as to give a useful overview of its effectiveness in the prevention and management of these disorders.

Dietary gluten worsens hepatic steatosis by increasing inflammation and oxidative stress in ApoE-/- mice fed a high-fat diet

Non-alcoholic fatty liver disease (NAFLD) is the most prevalent chronic liver disorder in the world. We have seen that gluten intake exacerbated obesity and atherosclerosis in apolipoprotein E knockout (ApoE-/-) mice. In this study, we investigated the effect of gluten consumption on inflammation and oxidative stress in the liver of mice with NAFLD. Male ApoE-/- mice were fed a gluten-free (GF-HFD) or gluten-containing (G-HFD) high-fat diet for 10 weeks. Blood, liver, and spleen were collected to perform the analyses. The animals of the gluten group had increased hepatic steatosis, followed by increased serum AST and ALT. Gluten intake increased hepatic infiltration of neutrophils, macrophages, and eosinophils, as well as the levels of chemotaxis-related factors CCL2, Cxcl2, and Cxcr3. The production of the TNF, IL-1β, IFNγ, and IL-4 cytokines in the liver was also increased by gluten intake. Furthermore, gluten exacerbated the hepatic lipid peroxidation and nitrotyrosine deposition, which were associated with increased production of ROS and nitric oxide. These effects were related to increased expression of NADPH oxidase and iNOS, as well as decreased activity of superoxide dismutase and catalase enzymes. There was an increased hepatic expression of the NF-κB and AP1 transcription factors, corroborating the worsening effect of gluten on inflammation and oxidative stress. Finally, we found an increased frequency of CD4+FOXP3+ lymphocytes in the spleen and increased gene expression of Foxp3 in the livers of the G-HFD group. In conclusion, dietary gluten aggravates NAFLD, exacerbating hepatic inflammation and oxidative stress in obese ApoE-deficient mice.

Approach to Disorders of Gut-Brain Interaction

Disorders of gut-brain interaction, previously known as functional gastrointestinal disorders (eg, functional dyspepsia and irritable bowel syndrome), are commonly encountered in both the primary care and gastroenterology clinics. These disorders are often associated with high morbidity and poor patient quality of life and often lead to increased health care use. The management of these disorders can be challenging, as patients often present after having undergone an extensive workup without a definite etiology. In this review, we provide a practical five-step approach to the clinical assessment and management of disorders of gut-brain interaction. The five-step approach includes (1) excluding organic etiologies of the patient's symptoms and using Rome IV criteria for diagnosis, (2) empathizing with the patient to develop trust and a therapeutic relationship, (3) educating the patient about the pathophysiology of these gastrointestinal disorders, (4) expectation setting with a focus on improving function and quality of life, and (5) establishing a treatment plan with central and peripherally acting medications and nonpharmacological modalities. We discuss the pathophysiology of disorders of gut-brain interaction (eg, visceral hypersensitivity), initial assessment and risk stratification, as well as treatment for a variety of diseases with a focus on irritable bowel syndrome and functional dyspepsia.

Irritable bowel syndrome: treatment based on pathophysiology and biomarkers

OBJECTIVE

To appraise the evidence that pathophysiological mechanisms and individualised treatment directed at those mechanisms provide an alternative approach to the treatment of patients with irritable bowel syndrome (IBS).

DESIGN

A PubMED-based literature review of mechanisms and treatment of IBS was conducted independently by the two authors, and any differences of perspective or interpretation of the literature were resolved following discussion.

RESULTS

The availability of several noninvasive clinical tests can appraise the mechanisms responsible for symptom generation in IBS, including rectal evacuation disorders, abnormal transit, visceral hypersensitivity or hypervigilance, bile acid diarrhoea, sugar intolerances, barrier dysfunction, the microbiome, immune activation and chemicals released by the latter mechanism. The basic molecular mechanisms contributing to these pathophysiologies are increasingly recognised, offering opportunities to intervene with medications directed specifically to food components, receptors and potentially the microbiome. Although the evidence supporting interventions for each mechanism is not at the same level of proof, the current state-of-the-art provides the opportunity to advance the practice from treatment based on symptoms to individualisation of treatment guided by pathophysiology and clinically identified biomarkers.

CONCLUSION

These advances augur well for the implementation of evidence-based individualised treatment for patients with IBS based on actionable biomarkers or psychological disturbances.

Strategies for Producing Low FODMAPs Foodstuffs: Challenges and Perspectives

In recent years, there has been a growing interest in a diet low in fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAPs) as a promising therapeutic approach to reduce the symptoms associated with irritable bowel syndrome (IBS). Hence, the development of low FODMAPs products is an important challenge for the food industry, and among the various foodstuffs associated with the intake of FODMAPs, cereal-based products represent an issue. In fact, even if their content in FODMAPs is limited, their large use in diet can be an important factor in developing IBS symptoms. Several useful approaches have been developed to reduce the FODMAPs content in processed food products. Accurate ingredient selection, the use of enzymes or selected yeasts, and the use of fermentation steps carried out by specific lactic bacteria associated with the use of sourdough represent the technical approaches that have been investigated, alone or in combination, to reduce the FODMAPs content in cereal-based products. This review aims to give an overview of the technological and biotechnological strategies applicable to the formulation of low-FODMAPs products, specifically formulated for consumers affected by IBS. In particular, bread has been the foodstuff mainly investigated throughout the years, but information on other raw or processed products has also been reported. Furthermore, taking into account the required holistic approach for IBS symptoms management, in this review, the use of bioactive compounds that have a positive impact on reducing IBS symptoms as added ingredients in low-FODMAPs products is also discussed.

Is it time to rethink the burden of non-coeliac gluten sensitivity? A systematic review

INTRODUCTION

Non-coeliac gluten sensitivity (NCGS) is still a poorly defined clinical condition. This review aims to describe the clinical features of subjects with a symptomatic response to gluten intake, and to estimate the prevalence of NCGS.

EVIDENCE ACQUISITION

Literature search was conducted in accordance with PRISMA recommendations. The PubMed database was searched for original articles until 1^st June 2020.

EVIDENCE SYNTHESIS

We identified 30 relevant articles, including 14 studies that investigated NCGS through a double-blind, placebo-controlled crossover trial (DBPCC), and 16 that examined the role of gluten in causing symptoms without a DBPCC. We found that regardless of the diagnostic work up, gluten-sensitive patients were predominately middle-aged females complaining of abdominal pain, bloating and diarrhea. The pooled prevalence of NCGS after DBPCC was 24% (5-34%). Subjects with irritable bowel syndrome or self-reporting gluten intolerance accounted for the vast majority of the patients who did not start a DBPCC. A symptomatic response to a gluten-free diet (GFD) occurred in between 7% and 93% of patients. No data on long-term outcomes of NCGS individuals were reported.

CONCLUSIONS

Clinical features of NCGS patients did not differ among all the included studies, whereas prevalence figures are rather heterogeneous. Long-term benefit of a GFD on these patients still needs to be ascertained.

Diet and irritable bowel syndrome: an update from a UK consensus meeting

There has been a renewed interest in the role of dietary therapies to manage irritable bowel syndrome (IBS), with diet high on the agenda for patients. Currently, interest has focussed on the use of traditional dietary advice (TDA), a gluten-free diet (GFD) and the low FODMAP diet (LFD). A consensus meeting was held to assess the role of these dietary therapies in IBS, in Sheffield, United Kingdom.Evidence for TDA is from case control studies and clinical experience. Randomised controlled trials (RCT) have demonstrated the benefit of soluble fibre in IBS. No studies have assessed TDA in comparison to a habitual or sham diet. There have been a number of RCTs demonstrating the efficacy of a GFD at short-term follow-up, with a lack of long-term outcomes. Whilst gluten may lead to symptom generation in IBS, other components of wheat may also play an important role, with recent interest in the role of fructans, wheat germ agglutinins, as well as alpha amylase trypsin inhibitors. There is good evidence for the use of a LFD at short-term follow-up, with emerging evidence demonstrating its efficacy at long-term follow-up. There is overlap between the LFD and GFD with IBS patients self-initiating gluten or wheat reduction as part of their LFD. Currently, there is a lack of evidence to suggest superiority of one diet over another, although TDA is more acceptable to patients.In view of this evidence, our consensus group recommends that dietary therapies for IBS should be offered by dietitians who first assess dietary triggers and then tailor the intervention according to patient choice. Given the lack of dietetic services, novel approaches such as employing group clinics and online webinars may maximise capacity and accessibility for patients. Further research is also required to assess the comparative efficacy of dietary therapies to other management strategies available to manage IBS.

Gluten-free grains: Importance, processing and its effect on quality of gluten-free products

Gluten-enteropathy affects a significant number of people, making gluten a major concern in the food industry. With medical advancements, the diagnosis of allergies is becoming easier, and people who are allergic to gluten are recommended a complete gluten-free diet. Since wheat provides a major part of the energy and nutrition in the diet, its elimination affects nutrition intake of allergic population. Food scientists are working to formulate products using protein-rich gluten-free grains with quality attributes at par with gluten-containing products. Focused research has been done to provide nutrition and a variety of food to people suffering from gluten-related disorders. Efforts are being made to remove the gluten from the wheat and other gluten-containing grains, while applying different processing/treatments to enhance the properties of gluten-free grains. Hence, the present review summarizes the importance, processing, and products of different gluten-free grains. It also highlights the digestibility of gluten-free grains with clinical trials and gluten elimination strategies for gluten-containing grains.

Diet for Functional Gastrointestinal Disorders/Disorders of Gut-Brain Interaction

Dietary interventions may alleviate symptoms related to functional gastrointestinal disorders, now termed disorders of gut-brain interaction. We reviewed which interventions have high-quality data to support their use in gastroesophageal reflux disease (GERD), functional dyspepsia (FD), irritable bowel syndrome, and chronic idiopathic constipation.

Efficacy and safety of fecal microbiota transplant in irritable bowel syndrome: An update based on meta‐analysis of randomized control trials

Background and Aims

Fecal microbiota transfer (FMT) is a potential treatment for irritable bowel syndrome (IBS). Several randomized trials have tested FMT effects using different routes of administration, doses, and sample sizes. We aim to assess the overall efficacy of FMT for IBS patients and the safety of the intervention.

Methods

We systematically searched four databases for randomized control trials that studied the efficacy and safety of FMT in IBS patients.

Results

We included 8 randomized trials (472 patients) that compared FMT with placebo in IBS patients. Pooled results showed no statistically significant difference between FMT and control groups in the overall change in IBS symptom severity (IBS‐SSS) at 1 month (p = 0.94), 3/4 months (p = 0.82), and at the end of trials (p = 0.67). No significant difference in the total number of respondents between the FMT and control groups (risk ratios = 1.84, [95% confidence interval (CI) = 0.82–2.65], p = 0.19). Although the oral route of administration showed a significant difference in the number of respondents (p = 0.004), there was no statistically significant difference in the IBS‐SSS when subgrouping the oral route of administration (mean difference = 47.57, [95% CI = −8.74–103.87], p = 0.10).

Conclusion

FMT is not an effective treatment to relieve all the symptoms of IBS. Even in the groups that showed relatively significant improvement after FMT, the effect was proven to wear off over time and the re‐administration carries a low success rate. Future research should consider different bacterial‐based interventions such as probiotics or specific antibiotics.

Diploid Wheats: Are They Less Immunogenic for Non-Celiac Wheat Sensitive Consumers?

Non-celiac wheat sensitivity (NCWS) is a clinical entity induced by the ingestion of gluten that leads to intestinal and/or extraintestinal symptoms, and is diagnosed when celiac disease and wheat allergy have been ruled out. In addition to gluten, other grains’ components, including amylase trypsin inhibitors (ATIs) and fermentable short-chain carbohydrates (FODMAPs), may trigger symptoms in NCWS subjects. Several studies suggest that, compared with tetraploid and hexaploid modern wheats, ancient diploid wheats species could possess a lower immunogenicity for subjects suffering from NCWS. This review aims to discuss available evidence related to the immunological features of diploid wheats compared to common wheats, and at outlining new dietary opportunities for NCWS subjects.

Functional bowel disorders with diarrhoea: Clinical guidelines of the United European Gastroenterology and European Society for Neurogastroenterology and Motility

Irritable bowel syndrome with diarrhoea (IBS‐D) and functional diarrhoea (FDr) are the two major functional bowel disorders characterized by diarrhoea. In spite of their high prevalence, IBS‐D and FDr are associated with major uncertainties, especially regarding their optimal diagnostic work‐up and management. A Delphi consensus was performed with experts from 10 European countries who conducted a literature summary and voting process on 31 statements. Quality of evidence was evaluated using the grading of recommendations, assessment, development, and evaluation criteria. Consensus (defined as >80% agreement) was reached for all the statements. The panel agreed with the potential overlapping of IBS‐D and FDr. In terms of diagnosis, the consensus supports a symptom‐based approach also with the exclusion of alarm symptoms, recommending the evaluation of full blood count, C‐reactive protein, serology for coeliac disease, and faecal calprotectin, and consideration of diagnosing bile acid diarrhoea. Colonoscopy with random biopsies in both the right and left colon is recommended in patients older than 50 years and in presence of alarm features. Regarding treatment, a strong consensus was achieved for the use of a diet low fermentable oligo‐, di‐, monosaccharides and polyols, gut‐directed psychological therapies, rifaximin, loperamide, and eluxadoline. A weak or conditional recommendation was achieved for antispasmodics, probiotics, tryciclic antidepressants, bile acid sequestrants, 5‐hydroxytryptamine‐3 antagonists (i.e. alosetron, ondansetron, or ramosetron). A multinational group of European experts summarized the current state of consensus on the definition, diagnosis, and management of IBS‐D and FDr.

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

DESCRIPTION

Irritable bowel syndrome (IBS) is a commonly diagnosed gastrointestinal disorder that can have a substantial impact on quality of life. Most patients with IBS associate their gastrointestinal symptoms with eating food. Mounting evidence supports dietary modifications, such as the low-fermentable oligo-, di-, and monosaccharides and polyols (FODMAP) diet, as a primary treatment for IBS symptoms. The aim of this American Gastroenterological Association (AGA) Clinical Practice Update (CPU) is to provide best practice advice statements, primarily to clinical gastroenterologists, covering the role of diet in IBS treatment.

METHODS

This expert review was commissioned and approved by the AGA CPU Committee and the AGA Governing Board to provide timely guidance on a topic of high clinical importance to the AGA membership, and underwent internal peer review by the CPU Committee and external peer review through standard procedures of Gastroenterology. The best practice advice statements were drawn from reviewing existing literature combined with expert opinion to provide practical advice on the role of diet in treating patients with IBS. Because this was not a systematic review, formal rating of the quality of evidence or strength of the presented considerations was not performed. Best Practice Advice Statements BEST PRACTICE ADVICE 1: Dietary advice is ideally prescribed to patients with IBS who have insight into their meal-related gastrointestinal symptoms and are motivated to make the necessary changes. To optimize the quality of teaching and clinical response, referral to a registered dietitian nutritionist (RDN) should be made to patients who are willing to collaborate with a RDN and patients who are not able to implement beneficial dietary changes on their own. If a gastrointestinal RDN is not available, other resources can assist with implementation of diet interventions. BEST PRACTICE ADVICE 2: Patients with IBS who are poor candidates for restrictive diet interventions include those consuming few culprit foods, those at risk for malnutrition, those who are food insecure, and those with an eating disorder or uncontrolled psychiatric disorder. Routine screening for disordered eating or eating disorders by careful dietary history is critical because they are common and often overlooked in gastrointestinal conditions. BEST PRACTICE ADVICE 3: Specific diet interventions should be attempted for a predetermined length of time. If there is no clinical response, the diet intervention should be abandoned for another treatment alternative, for example, a different diet, medication, or other form of therapy. BEST PRACTICE ADVICE 4: In preparation for a visit with a RDN, patients should provide dietary information that will assist in developing an individualized nutrition care plan. BEST PRACTICE ADVICE 5: Soluble fiber is efficacious in treating global symptoms of IBS. BEST PRACTICE ADVICE 6: The low-FODMAP diet is currently the most evidence-based diet intervention for IBS. Healthy eating advice as described by the National Institute of Health and Care Excellence Guidelines, among others, also offers benefit to a subset of patients with IBS. BEST PRACTICE ADVICE 7: The low-FODMAP diet consists of the following 3 phases: 1) restriction (lasting no more than 4-6 weeks), 2) reintroduction of FODMAP foods, and 3) personalization based on results from reintroduction. BEST PRACTICE ADVICE 8: Although observational studies found that most patients with IBS improve with a gluten-free diet, randomized controlled trials have yielded mixed results. BEST PRACTICE ADVICE 9: There are limited data showing that selected biomarkers can predict response to diet interventions in patients with IBS, but there is insufficient evidence to support their routine use in clinical practice.

Belgian consensus on irritable bowel syndrome

BACKGROUND

Irritable bowel syndrome (IBS) is characterised by recurrent abdominal pain related to defaecation or associated with altered stool frequency or consistency. Despite its prevalence, major uncertainties in the diagnostic and therapeutic management persist in clinical practice.

METHODS

A Delphi consensus was conducted by 20 experts from Belgium, and consisted of literature review and voting process on 78 statements. Grading of recommendations, assessment, development and evaluation criteria were applied to evaluate the quality of evidence. Consensus was defined as > 80 % agreement.

RESULTS

Consensus was reached for 50 statements. The Belgian consensus agreed as to the multifactorial aetiology of IBS. According to the consensus abdominal discomfort also represents a cardinal symptom, while bloating and abdominal distension often coexist. IBS needs subtyping based on stool pattern. The importance of a positive diagnosis, relying on history and clinical examination is underlined, while additional testing should remain limited, except when alarm features are present. Explanation of IBS represents a crucial part of patient management. Lifestyle modification, spasmolytics and water-solube fibres are considered first-line agents. The low FODMAP diet, selected probiotics, cognitive behavioural therapy and specific treatments targeting diarrhoea and constipation are considered appropriate. There is a consensus to restrict faecal microbiota transplantation and gluten-free diet, while other treatments are strongly discouraged.

CONCLUSIONS

A panel of Belgian gastroenterologists summarised the current evidence on the aetiology, symptoms, diagnosis and treatment of IBS with attention for the specificities of the Belgian healthcare system.

Effects of a gluten challenge in patients with irritable bowel syndrome: a randomized single-blind controlled clinical trial

Non-celiac gluten sensitivity (NCGS) and irritable bowel syndrome (IBS) frequently overlap. Although, gluten-free diet (GFD) and low fermentable oligosaccharides, disaccharides, monosaccharides and polyols (FODMAP) improve the IBS clinical picture, many aspects remain unclear. Therefore, we designed a study to evaluate gluten tolerance, anxiety and quality of life in a specific study population. Fifty IBS patients were asked to follow a low FODMAP strict GFD for 6 weeks and were then randomly allocated to the following groups for a further 6 weeks: (A) receiving 8 g/day of gluten for 2 weeks; gluten-tolerating subjects received 16 g/day for 2 weeks and then 32 g/day for a further 2 weeks; (B) continuing to follow a low FODMAP strict GFD; and (C) receiving a gluten-containing diet. After the first 6 weeks, symptom scores significantly improved. Pain severity, bloating and total score were significantly decreased in the GFD and in the high-gluten groups, while the satiety score significantly increased in group C. Between-group analysis revealed significant differences for pain severity (p = 0.02), pain frequency (p = 0.04) and impact on community function (p = 0.02) at the end of the study. Our findings suggest that low FODMAP strict GFD could be prescribed in IBS patients and would reduce anxiety and improve the quality of life.

Effect of Exclusion Diets on Symptom Severity and the Gut Microbiota in Patients With Irritable Bowel Syndrome

BACKGROUND & AIMS

Altered fecal microbiota have been reported in irritable bowel syndrome (IBS), although studies vary, which could be owing to dietary effects. Many IBS patients may eliminate certain foods because of their symptoms, which in turn may alter fecal microbiota diversity and composition. This study aimed to determine if dietary patterns were associated with IBS, symptoms, and fecal microbiota differences reported in IBS.

METHODS

A total of 346 IBS participants and 170 healthy controls (HCs) completed a Diet Checklist reflecting the diet(s) consumed most frequently. An exclusion diet was defined as a diet that eliminated food components by choice. Within this group, a gluten-free, dairy-free, or low fermentable oligosaccharides, disaccharides, monosaccharides, and polyols diet was further defined as restrictive because they often are implicated in reducing symptoms. Stool samples were obtained from 171 IBS patients and 98 HCs for 16S ribosomal RNA gene sequencing and microbial composition analysis.

RESULTS

Having IBS symptoms was associated with consuming a restrictive diet (27.17% of IBS patients vs 7.65% of HCs; odds ratio, 3.25; 95% CI, 1.66-6.75; P value = .006). IBS participants on an exclusion or restrictive diet reported more severe IBS symptoms (P = .042 and .029, respectively). The composition of the microbiota in IBS patients varied depending on the diet consumed. IBS participants on an exclusion diet had a greater abundance of Lachnospira and a lower abundance of Eubacterium (q value, <.05), and those on a restrictive diet had a lower abundance of Lactobacillus (q value, <.05).

CONCLUSIONS

Restrictive diets likely are consumed more by IBS patients than HCs to reduce GI symptom severity. Dietary patterns influence the composition of the fecal microbiota and may explain some of the differences between IBS and HCs.

Plasma IL-2 and Symptoms Response after Acute Gluten Exposure in Subjects With Celiac Disease or Nonceliac Gluten Sensitivity

INTRODUCTION

Treated patients with celiac disease (CeD) and nonceliac gluten sensitivity (NCGS) report acute, transient, incompletely understood symptoms after suspected gluten exposure. To determine whether (i) blinded gluten exposure induces symptoms, (ii) subjects accurately identify gluten exposure, and (iii) serum interleukin-2 (IL-2) levels distinguish CeD from NCGS subjects after gluten exposure.

METHODS

Sixty subjects (n = 20 treated, healed CeD; n = 20 treated NCGS; n = 20 controls) were block randomized to a single, double-blind sham (rice flour) or 3-g gluten challenge with 72-hours follow-up. Twelve serial questionnaires (100 mm visual analog scale; pain, bloating, nausea, and fatigue) and 10 serial plasma samples were collected. Mucosal permeability was assessed using both urinary lactulose-13C mannitol ratios and endoscopic mucosal impedance.

RESULTS

Thirty-five of 40 (83%) subjects with CeD and NCGS reported symptoms with gluten (8 CeD, 9 NCGS) and sham (9 CeD, 9 NCGS) compared with 9 of 20 (45%) controls after gluten (n = 6) and sham (n = 3). There was no significant difference in symptoms among groups. Only 2 of 10 subjects with CeD and 4 of 10 NCGS identified gluten, whereas 8 of 10 subjects with CeD and 5 of 10 NCGS identified sham. A significant plasma IL-2 increase occurred only in subjects with CeD after gluten, peaking at 3 hours and normalizing within 24 hours postchallenge despite no significant intestinal permeability change from baseline.

DISCUSSION

Symptoms do not reliably indicate gluten exposure in either subjects with CeD or NCGS. IL-2 production indicates a rapid-onset gluten-induced T-cell activation in CeD despite long-standing treatment. The effector site is unknown, given no increased intestinal permeability after gluten.

Nutrition in Patients with Lactose Malabsorption, Celiac Disease, and Related Disorders

Lactose malabsorption (LM), celiac disease (CD), non-celiac gluten sensitivity (NCGS), and irritable bowel syndrome (IBS) are conditions associated with food triggers, improvement after withdrawal, treatment with dietary restriction, and subsequent nutritional detriments. LM occurs when there is incomplete hydrolysis of lactose due to lactase deficiency and frequently produces abdominal symptoms; therefore, it can cause lactose intolerance (LI). A lactose-restricted diet is frequently recommended, although it can potentially lead to nutrient deficiencies. Furthermore, lactose is an essential component of fermentable oligo-, di-, and monosaccharides and polyols (FODMAPs) and is subsequently associated with intolerance to these compounds, especially in IBS. LM commonly presents in CD. Nutritional deficits are common in CD and can continue even on a gluten-free diet (GFD). Conditions triggered by gluten are known as gluten-related disorders (GRDs), including CD, wheat allergy, and NCGS. IBS can also be associated with a gluten sensitivity. A GFD is the treatment for CD, GRDs, and gluten sensitive IBS, although compliance with this restricted diet can be difficult. Strict dietary therapies can have a negative effect on quality of life. This review aims to provide an overview of the difficult nutritional elements of these disorders, which are critical for medical providers to recognize when managing these patients.

Assessment of Markers of Gut Integrity and Inflammation in Non-Celiac Gluten Sensitivity After a Gluten Free-Diet

Purpose

Markers for gut integrity and inflammation have received increasing interest as intestinal permeability and innate immune system activation are suggested as possible pathophysiological mechanisms in non-celiac gluten sensitivity (NCGS). We aimed to assess relevant biomarkers in NCGS by analyzing serum levels of gut integrity and permeability markers, pro-inflammatory cytokines and antigliadin IgG in patients with suspected NCGS on a gluten-free diet (GFD), and compare them to serum levels in patients with irritable bowel syndrome (IBS) and healthy controls (HC).

Patients and Methods

Serum samples collected from patients with suspected NCGS on a GFD (n=20, 14 women, 21–62 years), IBS (n=20, 16 women, 24–67 years) and HC (n=20, 14 women, 21–54 years) were analyzed. IBS severity scoring system (IBS-SSS) was applied to evaluate gastrointestinal symptoms.

Results

The IBS-SSS score was higher in subjects with suspected NCGS and IBS patients compared to HC (p<0.0001). No significant differences were found in the serum levels of any of the gut integrity and permeability markers, cytokines or antigliadin IgG antibodies between the three groups. However, positive correlations were observed between claudin-1 and i-FABP, and between claudin-1 and antigliadin IgG antibodies.

Conclusion

No differences in serum levels of gut integrity and permeability markers, pro-inflammatory cytokines or antigliadin IgG antibodies were found among patients with suspected NCGS on a GFD, IBS and HC.

Review Article: Current and future treatment approaches for IBS with diarrhoea (IBS-D) and IBS mixed pattern (IBS-M)

BACKGROUND

Irritable bowel syndrome-diarrhoea (IBS-D) and IBS-mixed stool pattern (IBS-M) are disorders of gut-brain interaction characterised by abdominal pain associated with diarrhoea or both diarrhoea and constipation respectively. The pathophysiology of IBS-D/M is multifactorial and not completely understood; thus, treatment is aimed at multiple mechanisms such as altering gut microbiota, visceral hypersensitivity, intestinal permeability, gut-brain interaction and psychological strategies.

AIM

The goal of this article was to provide an up-to-date review of the current evidence for both non-pharmacological and pharmacological treatment options in IBS-D and IBS-M. Future treatments for IBS-D and IBS-M will also be discussed.

METHODS

Medline and Embase database searches (through April 30 2021) to identify clinical studies in subjects with IBS-D in which dietary modification, alternative treatments (probiotics, acupuncture, exercise) as well as FDA-approved medications were used.

RESULTS

Dietary modification is often the first line of therapy. Furthermore, lifestyle treatments include complementary alternative medications (CAM), probiotics and peppermint oil are useful adjuncts but have not specifically been described in IBS-D/M. Evidence strongly supports psychotherapy in the treatment of IBS. Beyond over-the counter anti-diarrhoeals, anti-spasmodics and anti-depressants, pharmacological treatment now includes treating for bile acid malabsorption and the FDA-approved medications rifaximin, eluxadoline and alosetron.

CONCLUSIONS

The treatment of IBS-D/M ideally involves a multidisciplinary approach of primary care, gastroenterologist and psychologist. Treatment often involves both non-pharmacological and pharmacological therapies. Future therapies may include faecal microbial transplant, Crofelemer and serotonin antagonists, but further studies are needed.

Association between Self-Reported Gluten Avoidance and Irritable Bowel Syndrome: Findings of the NutriNet-Santé Study

Self-management of irritable bowel syndrome (IBS) is increasingly focusing on exclusion diets. In particular; patients are showing a significant interest in the gluten-free diet for the treatment of IBS. However; the lack of scientific evidence prevents the establishment of clear dietary guidelines and attention is needed as dietary restriction can lead to potentially adverse effects. This cross-sectional study aims to explore the practice of gluten avoidance in participants identified with IBS in a large cohort of non-celiac French adults. The population included 15,103 participants of the NutriNet-Santé study who completed a functional gastrointestinal disorder questionnaire based on the Rome III criteria to identify IBS in 2013 and a food avoidance questionnaire in 2016. Data on diet and anthropometric and sociodemographic characteristics were collected. Multivariate logistic regression models were used to compare the avoidance of gluten between IBS and non-IBS participants. Participants were mainly women (73.4%) and the mean age in this population was 55.8 ± 13.2 years. Among these individuals, 804 (5.4%) participants were identified as IBS cases. Among them, the prevalence of gluten avoidance was estimated at 14.8%, of which 3.0% reported total avoidance; versus 8.8% and 1.6% in non-IBS participants. After adjustments; gluten avoidance was higher in IBS participants compared to their non-IBS counterparts: (OR = 1.86; 95%CI = 1.21, 2.85) for total and (OR = 1.71; 95%CI = 1.36, 2.14) for partial avoidance. Participants identified with IBS were more associated with gluten avoidance than non-IBS participants. Further studies are needed to explore the long-term consequences of dietary interventions and to provide consistent dietary guidance connected to patient perception.

Screening for Celiac Disease in Patients with Irritable Bowel Syndrome Fulfilling Rome III Criteria

Background Irritable bowel syndrome (IBS) is a common functional gastrointestinal disorder. Celiac disease (CD), a treatable autoimmune enteropathy, with varied presentations, may simulate clinically symptoms of IBS. The aim of the present study is to screen for CD in patients with IBS diagnosed based on the Rome III criteria.

Patients and Methods A cross-sectional study was conducted at a secondary care gastrointestinal unit in Al-Salam General Hospital in Mosul city, Iraq, from November 2015 to October 2016. All patients fulfilling the Rome III criteria for IBS were screened for CD using antitissue transglutaminase IgA antibodies (anti-tTG). Patients who tested positive were subjected to endoscopic duodenal biopsy to confirm the diagnosis of CD.

Results A total of 100 patients were included in the present study (58 female and 42 male), the mean age of the participants was 40.8 years old (standard deviation [SD] ± 11.57). Ten patients (10/100, 10%) tested positive for anti-tTG antibodies. Five of the seropositive patients (5/10, 50%) showed positive biopsy results according to the Marsh classification, 3 of whom having diarrhea, and 2 with constipation.

Conclusion Positive serology and biopsy results suggestive of CD are common among patients with IBS. Screening patients with IBS for CD is justified.

Gluten-free Diet Reduces the Risk of Irritable Bowel Syndrome: A Mendelian Randomization Analysis

Background: Whether a gluten-free diet (GFD) is a cause of irritable bowel syndrome (IBS) remains controversial. We aim at exploring the causal relationship between gluten intake and IBS within Mendelian randomization (MR) design. Methods: We conducted a two-sample MR and selected single-nucleotide polymorphisms (SNPs) associated with GFD as instrumental variables (IVs). SNPs and genetic associations with GFD and IBS were obtained from the latest genome-wide association studies (GWAS) in Europeans (GFD: cases: 1,376; controls: 63,573; IBS: cases:1,121; controls: 360,073). We performed inverse variance weighting (IVW) as the primary method with several sensitivity analyses like MR-Egger and MR-PRESSO for quality control. The above analyses were re-run using another large dataset of IBS, as well as changing the p-value threshold when screening IVs, to verify the stability of the results. Results: The final estimate indicated significant causal association [per one copy of effect allele predicted log odds ratio (OR) change in GFD intake: OR = 0.97, 95% confidence interval (CI) 0.96 to 0.99, p < 0.01] without heterogeneity statistically (Q = 2.48, p = 0.78) nor horizontal pleiotropy biasing the causality (p = 0.92). Consistent results were found in validation analyses. Results of MR Steiger directionality test indicated the accuracy of our estimate of the causal direction (Steiger p < 0.001). Conclusion: GFD might be a protective factor of IBS. Therefore, we suggest taking a diet of lower gluten intake into account in IBS prevention and clinical practice.

Alterations in Gut Microbiome Composition and Function in Irritable Bowel Syndrome and Increased Probiotic Abundance with Daily Supplementation

Irritable bowel syndrome (IBS) is characterized by abdominal discomfort and irregular bowel movements and stool consistency. As such, the gut microbiome has been posited as being influential for the syndrome. However, identifying microbial features associated with IBS symptom heterogeneity is difficult without large cohorts. Our aim was to identify microbial features associated with IBS and IBS subtypes compared to healthy controls and to determine if a synbiotic supplementation intervention could decrease the proportion of those microbial features. Stool samples from 490 individuals with IBS (including all dominant subtypes) and 122 individuals without IBS were analyzed with metagenomic sequencing. One hundred thirty-four IBS subjects were followed over time while receiving daily synbiotic supplementation, the composition of which varied between participants. IBS participants had significantly lower alpha diversity, an enrichment in Gram-negative bacteria, and a reduction in pathways associated with short-chain fatty acid and vitamin synthesis. Shigella species were significantly associated with IBS, while Eubacterium rectale and Faecalibacterium prausnitzii were associated with healthy controls. Random forest identified unique and overlapping microbial features associated with each IBS subtype. Longitudinal assessment of 134 IBS subjects receiving synbiotic supplements demonstrated a significant difference in microbial features and an increase in probiotic abundance across time. We identified microbial features that differentiate healthy and IBS subtypes. Synbiotic supplementation in IBS subjects did not result in alpha diversity change in the microbiome but did demonstrate changes in microbial features. Future work is needed to determine if the observed microbiome changes are associated with IBS symptom improvement. IMPORTANCE An estimated 35 million people in the United States and 11.5% of the population globally are affected by IBS. Immunity, genetics, environment, diet, small intestinal bacterial overgrowth (SIBO), and the gut microbiome are all factors that contribute to the onset or triggers of IBS. With strong supporting evidence that the gut microbiome may influence symptoms associated with IBS, elucidating the important microbes that contribute to the symptoms and severity is important to make decisions for targeted treatment. As probiotics have become more common in treating IBS symptoms, identifying effective probiotics may help inform future studies and treatment.

Gluten-Free Diet Reduces Symptoms, Particularly Diarrhea, in Patients With Irritable Bowel Syndrome and Antigliadin IgG

BACKGROUND & AIMS

Many patients with irritable bowel syndrome (IBS) perceive that their symptoms are triggered by wheat-containing foods. We assessed symptoms and gastrointestinal transit before and after a gluten-free diet (GFD) in unselected patients with IBS and investigated biomarkers associated with symptoms.

METHODS

We performed a prospective study of 50 patients with IBS (ROME III, all subtypes), with and without serologic reactivity to gluten (antigliadin IgG and IgA), and 25 healthy subjects (controls) at a university hospital in Hamilton, Ontario, Canada, between 2012 and 2016. Gastrointestinal transit, gut symptoms, anxiety, depression, somatization, dietary habits, and microbiota composition were studied before and after 4 weeks of a GFD. HLA-DQ2/DQ8 status was determined. GFD compliance was assessed by a dietitian and by measuring gluten peptides in stool.

RESULTS

There was no difference in symptoms among patients at baseline, but after the GFD, patients with antigliadin IgG and IgA reported less diarrhea than patients without these antibodies (P = .03). Compared with baseline, IBS symptoms improved in 18 of 24 patients (75%) with antigliadin IgG and IgA and in 8 of 21 patients (38%) without the antibodies. Although constipation, diarrhea, and abdominal pain were reduced in patients with antigliadin IgG and IgA, only pain decreased in patients without these antibodies. Gastrointestinal transit normalized in a higher proportion of patients with antigliadin IgG and IgA. Anxiety, depression, somatization, and well-being increased in both groups. The presence of antigliadin IgG was associated with overall reductions in symptoms (adjusted odds ratio compared with patients without this antibody, 128.9; 95% CI, 1.16-1427.8; P = .04). Symptoms were reduced even in patients with antigliadin IgG and IgA who reduced gluten intake but were not strictly compliant with the GFD. In controls, a GFD had no effect on gastrointestinal symptoms or gut function.

CONCLUSIONS

Antigliadin IgG can be used as a biomarker to identify patients with IBS who might have reductions in symptoms, particularly diarrhea, on a GFD. Larger studies are needed to validate these findings. ClinicalTrials.gov: NCT03492333.

Food Allergies and Intolerances: A Clinical Approach to the Diagnosis and Management of Adverse Reactions to Food

Food allergy is an aberrant immunological response to food antigen, which can result in potentially life-threatening reactions. It is often challenging to differentiate food allergy from other adverse reactions to food because their presentations can be indistinguishable. The purpose of this article is to give an overview of the classification, evaluation, and management of adverse food reactions, key differentiating features of food allergy, roles and limitations of various food allergy testing, and promising areas of emerging research. Case studies are used to highlight some of the clinical pearls in diagnosing and managing food-related diseases.

From celiac disease to coccidia infection and vice-versa: The polyQ peptide CXCR3-interaction axis

Zonulin is a physiological modulator of intercellular tight junctions, which upregulation is involved in several diseases like celiac disease (CeD). The polyQ gliadin fragment binds to the CXCR3 chemokine receptor that activates zonulin upregulation, leading to increased intestinal permeability in humans. Here, we report a general hypothesis based on the structural connection between the polyQ sequence of the immunogenic CeD protein, gliadin, and enteric coccidian parasites proteins. Firstly, a novel interaction pathway between the parasites and the host is described based on the structural similarities between polyQ gliadin fragments and the parasite proteins. Secondly, a potential connection between coccidial infections as a novel environmental trigger of CeD is hypothesized. Therefore, this report represents a promising breakthrough for coccidian research and points out the potential role of coccidian parasites as a novel trigger of CeD that might define a preventive strategy for gluten-related disorders in general. Also see the video abstract here: https://youtu.be/oMaQasStcFI.

Fermentable oligo-, di-, monosaccharides, and polyols (FODMAPs), but not gluten, elicit modest symptoms of irritable bowel syndrome: a double-blind, placebo-controlled, randomized three-way crossover trial

BACKGROUND

Irritable bowel syndrome (IBS) has been associated with diets rich in fermentable oligo-, di-, monosaccharides, and polyols (FODMAPs), and gluten. Most previous studies have been single-blind and have focused on the elimination of FODMAPs or provocation with single FODMAPs. The effect of gluten is unclear, large trials isolating the effect of gluten from that of FODMAPs are needed.

OBJECTIVES

The aims of this study were to ensure high intakes of a wide range of FODMAPs, gluten, or placebo, and to evaluate the effects on IBS symptoms using the IBS-severity scoring system (IBS-SSS).

METHODS

The study was carried out with a double-blind, placebo-controlled, randomized 3-way crossover design in a clinical facility in Uppsala from September 2018 to June 2019. In all, 110 participants fulfilling the IBS Rome IV criteria, with moderate to severe IBS, were randomly assigned; 103 (90 female, 13 male) completed the trial. Throughout, IBS participants maintained a diet with minimal FODMAP content and no gluten. Participants were block-randomly assigned to 1-wk interventions with FODMAPs (50 g/d), gluten (17.3 g/d), or placebo, separated by 1-wk washout. All participants who completed ≥1 intervention were included in the intention-to-treat analysis.

RESULTS

In participants with IBS (n = 103), FODMAPs caused higher IBS-SSS scores (mean 240 [95% CI: 222, 257]) than placebo (198 [180, 215]; P = 0.00056) or gluten (208 [190, 226]; P = 0.013); no differences were found between the placebo and gluten groups (P = 1.0). There were large interindividual differences in IBS-SSS scores associated with treatment. No adverse events were reported.

CONCLUSION

In participants with IBS, FODMAPs had a modest effect on typical IBS symptoms, whereas gluten had no effect. The large interindividual differences in responses to the interventions warrant further detailed studies to identify possible underlying causes and enable individual prediction of responses. This trial was registered at www.clinicaltrials.gov as NCT03653689.

"Let Food Be Thy Medicine": Diet and Supplements in Irritable Bowel Syndrome

Overview: The purpose of this review is to introduce options for dietary therapies and supplements for the treatment of irritable bowel syndrome (IBS). IBS is a common condition with heterogeneity in pathogenesis and clinical presentation. Current treatment options are targeted at symptom relief with medications. Patients naturally pursue dietary modifications when dealing with symptoms. Dietary therapy for IBS has been poorly studied in the past; however, newer evidence suggests the use of certain diets, such as the low FODMAP (fermentable oligosaccharides, disaccharides, monosaccharides and polyols) diet, as an intervention in patients with IBS for symptom improvement. Exclusion strategies are frequently tried, such as gluten restriction or lactose avoidance, but lack quality evidence behind their use. Additionally, supplements, such as fiber, probiotics, and peppermint oil, have also been used for IBS with more recent data suggesting the use of these supplements with specific caveats.

Gluten and fructan intake and their associations with gastrointestinal symptoms in irritable bowel syndrome: A food diary study

BACKGROUND & AIMS

Wheat contains several components, including gluten and fructan, that may be associated with gastrointestinal symptoms (GI) in irritable bowel syndrome (IBS). The aims of the study were to determine the average daily intake of gluten, investigate the association of gluten and GI symptoms, as well as the association between fructan and GI symptoms in IBS subjects.

METHODS

We assessed dietary intake, including total energy, and calculated average gluten and fructan intake in this 4-day food diary study. The subjects reported GI symptoms using the validated Gastrointestinal Symptom Rating Scale-IBS (GSRS-IBS).

RESULTS

In total, 147 IBS subjects (116 females) were included in this study. The median (IQR) intake of gluten was 11.0 (7.5-15.4) (range: 0.6-52.1) g/day, and this intake was significantly higher for males (16.2 (11.5-18.8), g/day) compared with females (10.3 (7.3-13.2), g/day) (P ≤ 0.001). For analyses purposes, the subjects were stratified in tertiles of gluten intake. Median (IQR) overall GI symptom severity (GSRS-IBS) was significantly worse for the subjects with the lowest (52 (45-57)) and intermediate gluten intake (51 (43-58)), compared with the highest gluten intake (45 (37-50), P ≤ 0.05, and P ≤ 0.01 respectively). In addition, caloric intake was significantly lower in subjects with the lowest (1905 ± 446, kcal/day) and intermediate gluten intake (1854 ± 432, kcal/day), compared with subjects with the highest gluten intake (2305 ± 411, kcal/day), P < 0.001 for both. Analyses of the stratified fructan tertiles resulted in no significant differences in GSRS-IBS.

CONCLUSIONS

The mean intake of gluten varies substantially among subjects with IBS, and IBS subjects with more severe GI symptoms have lower intake of gluten and calories.

TRIAL REGISTRY

(http://www.clinicaltrials.gov): Registered under Clinical Trial number NCT02970591.

Why use nutraceutical strategies for the Irritable Bowel Syndrome

Irritable bowel syndrome (IBS) is a chronic functional bowel disorder, often stress-related, identified by many abdominal symptoms, the most important of which is the chronic visceral abdominal pain. Therefore, IBS commonly impairs the quality of life of patients, moreover it is frequently linked to depressive and anxiety symptoms. The treatment of IBS primarily focuses on symptoms relief. Unfortunately, up to now, no efficacious therapies have been found. Therefore, it would be important to develop new anti-IBS interventions. The aim of this brief review is to summarize the current evidence of nutraceutical supplementation in IBS treatment, with probiotics, prebiotics, synbiotics, butyrate, palmitoylethanolamide and colostrum. Since nutraceutics are over the counter products, the review has the purpose to better inform the medicinal chemist and the practitioner about the possible benefit mechanisms and the many advantages that these therapies offer. All of these compounds present multiple mechanisms of action, such as restoring the physiological microbiota, potentiating gastrointestinal barrier's function, immunomodulatory, anti-inflammatory and antinociceptive activities. From the literature data it results that these compounds are not only capable to improve IBS symptomatology, but mainly display an optimal safety and tolerability profile. Although extensive studies must be carried out to reinforce the evidences from the so far limited clinical trials, the supplementation with these compounds may be useful considering the warnings of prescription medicines for special populations of patients, such as elders, youngsters, or patients who need a combination therapy. Finally, the nutraceutical approach may improve adherence to treatment, given its better acceptance by the patients compared to pharmacological therapy.

The Role of Intestinal Permeability in Gastrointestinal Disorders and Current Methods of Evaluation

An increased intestinal permeability has been described in various gastrointestinal and non-gastrointestinal disorders. Nevertheless, the concept and definition of intestinal permeability is relatively broad and includes not only an altered paracellular route, regulated by tight junction proteins, but also the transcellular route involving membrane transporters and channels, and endocytic mechanisms. Paracellular intestinal permeability can be assessed in vivo by using different molecules (e.g., sugars, polyethylene glycols, ⁵¹Cr-EDTA) and ex vivo in Ussing chambers combining electrophysiology and probes of different molecular sizes. The latter is still the gold standard technique for assessing the epithelial barrier function, whereas in vivo techniques, including putative blood biomarkers such as intestinal fatty acid-binding protein and zonulin, are broadly used despite limitations. In the second part of the review, the current evidence of the role of impaired barrier function in the pathophysiology of selected gastrointestinal and liver diseases is discussed. Celiac disease is one of the conditions with the best evidence for impaired barrier function playing a crucial role with zonulin as its proposed regulator. Increased permeability is clearly present in inflammatory bowel disease, but the question of whether this is a primary event or a consequence of inflammation remains unsolved. The gut-liver axis with a crucial role in impaired intestinal barrier function is increasingly recognized in chronic alcoholic and metabolic liver disease. Finally, the current evidence does not support an important role for increased permeability in bile acid diarrhea.

What is the leaky gut? Clinical considerations in humans

PURPOSE OF REVIEW

To review the components of the intestinal barrier, the practical measurements of intestinal permeability, and the clinical conditions associated with altered intestinal barrier function, and to summarize the effects of dietary substances that fortify or weaken the intestinal barrier.

RECENT FINDINGS

The intestinal barrier includes surface mucus, epithelial layer, and immune defense mechanisms. Transport across the epithelium may result from increased paracellular transport, apoptosis, or transcellular permeability. Assessment of the intestinal barrier requires measurements beyond the transport across the epithelial layer or the measurement of tight junction expression. Barrier function is most meaningfully tested in vivo using orally administered probe molecules; other approaches are performed in vitro using mucosal biopsies from humans, or exposing colonic mucosa from rats or mice or cell layers to extracts of colonic mucosa or stool from patients. Dietary factors can influence intestinal leakiness: fortifying the barrier with vitamins A and D, zinc, short-chain fatty acids, methionine, glutamine, and probiotics; weakening of the barrier has been reported with fat, bile acids, emulsifiers, and gliadin. Intestinal mucosal leakiness in 'stress' disorders such as major burns is reversed with enteral glutamine.

SUMMARY

Inflammatory or ulcerating intestinal diseases result in leakiness of the gut barrier; however, no such disease has been cured by simply normalizing intestinal barrier function. Similarly, it is still unproven that restoring barrier function (reversing 'leaky gut') can ameliorate clinical manifestations in nonulcerating gastrointestinal disease or systemic or neurological diseases. On the other hand, dietary and enteral interventions can fortify the intestinal barrier in stress-associated states.