The Global Phenomenon of Self-Reported Wheat Sensitivity

Self-Reported Nonceliac Gluten Sensitivity in Italian Young Adults: A Cross-Sectional Study. A Dietary Fad?

INTRODUCTION

In different countries, the exact prevalence of people that refer symptoms after gluten ingestion is increasing and the unavailability of reliable laboratory tests to diagnose the condition known as nonceliac gluten sensitivity (NCGS) has opened the door to the spread of survey-based studies to hypothesize a prevalence of this condition with highly discordant results. We aim to describe the attitude toward gluten consumption in a large population of young adults in Italy.

METHODS

A questionnaire-based cross-sectional study was conducted in 13 Italian cities to investigate the dietary attitudes of more than 9,400 people distributed throughout the country about gluten consumption. Only those referring to gluten-related symptoms with a frequency equal to "always" or "most of the time" were considered self-reported NCGS (SR-NCGS) patients.

RESULTS

Five thousand two hundred thirty-four of 9,432 eligible participants (55.5%) fully completed the questionnaire. Excluding those with previous gastrointestinal diagnoses of celiac disease and wheat allergy, we have finally analyzed 4,987 questionnaires. Four hundred eighty-seven participants indicated gluten-related symptoms always or most of the time (SR-NCGS subjects), while 121 already had a medical diagnosis of NCGS. The minimum prevalence figure of SR-NCGS is 6.4% (95% confidence interval 6.0-6.9), with a higher prevalence in women (79.9%). The most frequent gluten-related symptoms were bloating, abdominal pain, and tiredness.

DISCUSSION

The high prevalence of people reporting symptoms after gluten ingestion requires that the diagnosis of NCGS should be ascertained with a double-blind controlled study to limit the number of people who improperly approach a gluten-free diet.

Effects of Gluten on Gut Microbiota in Patients with Gastrointestinal Disorders, Migraine, and Dermatitis

As gluten may trigger gastrointestinal disorders (GIDs), its presence or absence in the diet can change the diversity and proportion of gut microbiota. The effects of gluten after six weeks of a double-blind, placebo-controlled intervention with a gluten-free diet (GFD) were studied in participants with GIDs suffering from migraines and atopic dermatitis (n = 46). Clinical biomarkers, digestive symptoms, stool, the Migraine Disability Assessment questionnaire, and zonulin levels were analyzed. Next-generation sequencing was used to amplify the 16S rRNA gene of bacteria and the internal transcribed spacer (ITS) regions of fungi. The GFD increased Chao1 fungal diversity after the intervention, while the fungal composition showed no changes. Bacterial diversity and composition remained stable, but a positive association between bacterial and fungal Chao1 diversity and a negative association between Dothideomycetes and Akkermansia were observed. GIDs decreased in both groups and migraines improved in the placebo group. Our findings may aid the development of GID treatment strategies.

Home-Based Double-Blind, Placebo-Controlled Challenges for Diagnosis of Delayed Gluten/Milk Hypersensitivity in Children

BACKGROUND

Delayed hypersensitivity to gluten and milk protein is frequently reported but may be difficult to diagnose.

OBJECTIVE

We aimed to explore if a method of home-based double-blind placebo-controlled food challenges (H-FC) can identify and reduce unnecessary elimination diets in children.

METHODS

We included 73 of 92 children aged 1 to 17 years referred to a tertiary allergy clinic from 2011 to 2021 due to self-reported, delayed symptoms to gluten or milk. The children were randomized to H-FC, receiving gluten/milk protein or placebo for 5 to 7 days in a double-blind crossover manner, separated by 3 washout weeks. Patients/parents recorded symptoms using standardized forms. Two crossover periods were used from 2011 to 2016 and 3 periods from 2017 to 2021. A positive challenge required significantly more symptoms during the active period versus the placebo period. After the challenge, reintroduction of milk/gluten was assessed by a follow-up interview. The primary outcome was the proportion of children with a positive challenge.

RESULTS

The children, with a mean age of 11 years, had followed a strict gluten-free or milk-protein-free diet for a median duration of 24 months (range: 3-180 months). A positive challenge was observed in 18 of 73 children (25%), more often using 2 (35%) compared with 3 challenge periods (12%). At follow-up, 44 of 55 (80%) children with a negative challenge had successfully reintroduced milk/gluten.

CONCLUSIONS

H-FC may be an effective method in avoiding unnecessary elimination diets in children. Only 25% of the challenges were positive, and 80% of the children with negative challenges succeeded in reintroducing the food. Three challenge periods may be necessary to reduce false-positive outcomes.

Does sourdough bread provide clinically relevant health benefits?

During the last decade, scientific interest in and consumer attention to sourdough fermentation in bread making has increased. On the one hand, this technology may favorably impact product quality, including flavor and shelf-life of bakery products; on the other hand, some cereal components, especially in wheat and rye, which are known to cause adverse reactions in a small subset of the population, can be partially modified or degraded. The latter potentially reduces their harmful effects, but depends strongly on the composition of sourdough microbiota, processing conditions and the resulting acidification. Tolerability, nutritional composition, potential health effects and consumer acceptance of sourdough bread are often suggested to be superior compared to yeast-leavened bread. However, the advantages of sourdough fermentation claimed in many publications rely mostly on data from chemical and in vitro analyzes, which raises questions about the actual impact on human nutrition. This review focuses on grain components, which may cause adverse effects in humans and the effect of sourdough microbiota on their structure, quantity and biological properties. Furthermore, presumed benefits of secondary metabolites and reduction of contaminants are discussed. The benefits claimed deriving from in vitro and in vivo experiments will be evaluated across a broader spectrum in terms of clinically relevant effects on human health. Accordingly, this critical review aims to contribute to a better understanding of the extent to which sourdough bread may result in measurable health benefits in humans.

Diagnostic delay in adult coeliac disease: An Italian multicentre study

BACKGROUND

There are few data regarding the diagnostic delay and its predisposing factors in coeliac disease (CD).

AIMS

To investigate the overall, the patient-dependant, and the physician-dependant diagnostic delays in CD.

METHODS

CD adult patients were retrospectively enroled at 19 Italian CD outpatient clinics (2011-2021). Overall, patient-dependant, and physician-dependant diagnostic delays were assessed. Extreme diagnostic, i.e., lying above the third quartile of our population, was also analysed. Multivariable regression models for factors affecting the delay were fitted.

RESULTS

Overall, 2362 CD patients (median age at diagnosis 38 years, IQR 27-46; M:F ratio=1:3) were included. The median overall diagnostic delay was 8 months (IQR 5-14), while patient- and physician-dependant delays were 3 (IQR 2-6) and 4 (IQR 2-6) months, respectively. Previous misdiagnosis was associated with greater physician-dependant (1.076, p = 0.005) and overall (0.659, p = 0.001) diagnostic delays. Neurological symptoms (odds ratio 2.311, p = 0.005) and a previous misdiagnosis (coefficient 9.807, p = 0.000) were associated with a greater extreme physician-dependant delay. Gastrointestinal symptoms (OR 1.880, p = 0.004), neurological symptoms (OR 2.313, p = 0.042), and previous misdiagnosis (OR 4.265, p = 0.000) were associated with increased extreme overall diagnostic delay.

CONCLUSION

We identified some factors that hamper CD diagnosis. A proper screening strategy for CD should be implemented.

Efficacy and Acceptability of Dietary Therapies in Non-Constipated Irritable Bowel Syndrome: A Randomized Trial of Traditional Dietary Advice, the Low FODMAP Diet, and the Gluten-Free Diet

BACKGROUND & AIMS

Various diets are proposed as first-line therapies for non-constipated irritable bowel syndrome (IBS) despite insufficient or low-quality evidence. We performed a randomized trial comparing traditional dietary advice (TDA) against the low FODMAP diet (LFD) and gluten-free diet (GFD).

METHODS

Patients with Rome IV-defined non-constipated IBS were randomized to TDA, LFD, or GFD (the latter allowing for minute gluten cross-contamination). The primary end point was clinical response after 4 weeks of dietary intervention, as defined by ≥50-point reduction in IBS symptom severity score (IBS-SSS). Secondary end points included (1) changes in individual IBS-SSS items within clinical responders, (2) acceptability and food-related quality of life with dietary therapy, (3) changes in nutritional intake, (4) alterations in stool dysbiosis index, and (5) baseline factors associated with clinical response.

RESULTS

The primary end point of ≥50-point reduction in IBS-SSS was met by 42% (n = 14/33) undertaking TDA, 55% (n = 18/33) for LFD, and 58% (n = 19/33) for GFD (P = .43). Responders had similar improvements in IBS-SSS items regardless of their allocated diet. Individuals found TDA cheaper (P < .01), less time-consuming to shop (P < .01), and easier to follow when eating out (P = .03) than the GFD and LFD. TDA was also easier to incorporate into daily life than the LFD (P = .02). Overall reductions in micronutrient and macronutrient intake did not significantly differ across the diets. However, the LFD group had the greatest reduction in total FODMAP content (27.7 g/day before intervention to 7.6 g/day at week 4) compared with the GFD (27.4 g/day to 22.4 g/day) and TDA (24.9 g/day to 15.2 g/day) (P < .01). Alterations in stool dysbiosis index were similar across the diets, with 22%-29% showing reduced dysbiosis, 35%-39% no change, and 35%-40% increased dysbiosis (P = .99). Baseline clinical characteristics and stool dysbiosis index did not predict response to dietary therapy.

CONCLUSIONS

TDA, LFD, and GFD are effective approaches in non-constipated IBS, but TDA is the most patient-friendly in terms of cost and convenience. We recommend TDA as the first-choice dietary therapy in non-constipated IBS, with LFD and GFD reserved according to specific patient preferences and specialist dietetic input.

CLINICALTRIALS

gov: NCT04072991.

The low-FODMAP diet and the gluten-free diet in the management of functional abdominal bloating and distension

This review summarizes current knowledge on the role of low-FODMAP diet and gluten-free diet in functional abdominal bloating and distension, an emerging disorder of gut-brain interaction characterized by remarkable costs for healthcare systems and a significant impact on the patient's quality of life. Ingested food plays a key role in the pathophysiology of disorders of gut-brain interaction as up to 84% of patients with irritable bowel syndrome (IBS) report food-triggered symptoms. Potential pathogenetic mechanisms of food-related symptoms in these patients are discussed, focusing on bloating and abdominal distension. These mechanisms provide the rationale for dietary treatment in patients with functional abdominal bloating and distension. The role of fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAPs) and gluten in functional abdominal bloating and distension is examined. Current literature evaluating the efficacy of the low-FODMAP diet and the gluten-free diet in abdominal bloating and distension is analyzed. Available evidence originates mainly from studies on patients with IBS, since clinical studies on selected cohorts of patients with only functional abdominal bloating and distension have been missing to date. Promising evidence on the potential efficacy of the low-FODMAP diet in functional abdominal bloating and distension is provided by the reduction of the bloating observed in patients with IBS. Regarding the gluten-free diet, there is insufficient evidence to recommend it to reduce bloating and abdominal distension. In conclusion, this review asserts the need for a close collaboration with experts in nutrition to optimize the management of these patients and reduce the risks associated with elimination diets.

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.

Interaction of Pyrogallol-Containing Polyphenols with Mucin Reinforces Intestinal Mucus Barrier Properties

High consumption of polyphenol-rich green tea, coffee, fruits, and vegetables is associated with a low risk of human chronic diseases. Recent studies highlight the relevance of polyphenol-mediated gut microbiota modulation and its impact on mucus barrier. Herein, we study the direct interaction of epicatechin (EC), epigallocatechin gallate (EGCG), and tannic acid (TA) with intestinal mucin by isothermal titration calorimetry and multiple particle tracking and the impact on mucus barrier using ex vivo mucus and Caco-2/HT29-MTX cocultures. Results show that pyrogallol-containing polyphenols EGCG and TA exhibit strong binding to intestinal mucin and reinforce mucus barrier, whereas EC does not. ECGG and TA also mitigate gliadin-mediated cytotoxicity and inflammation. The chemical binding of EGCG and TA to the nucleophilic thiol groups of mucins shows their roles as cross-linkers of mucin networks. These results bring a novel understanding of the health benefits of polyphenols and provide support for the consumption of pyrogallol-containing beverages like green tea as a potential dietary therapy for gluten-related disorders.

WHOLE-meal ancient wheat-based diet: Effect on metabolic parameters and microbiota

BACKGROUND & AIMS

Ancient wheat varieties are considered to be healthier than modern ones, but the data are not univocal. We investigated changes in hematochemical parameters and evaluated microbiota data before and after a set period on a diet containing a whole-meal ancient wheat mix.

PATIENTS AND METHODS

29 cloistered nuns were recruited. The study comprised two consecutive 30-day periods; during the first one (T1), the nuns received wheat-based foods produced with refined "modern" flour ("Simeto"); during the second one (T2) received wheat-based foods produced with an unrefined flour mix composed of "ancient" cultivars. At entry to the study (T0) and at the end of T1 and T2 hematochemical parameters and fecal microbiota and metabolome were evaluated.

RESULTS

At the end of T2, there was a significant reduction in serum iron, ferritin, creatinine, sodium, potassium, magnesium, total cholesterol, LDL- and HDL-cholesterol and folic acid. Furthermore, increased the abundance of cultivable enterococci, lactic acid bacteria and total anaerobes. The ability of the gut microbiome to metabolize carbohydrates increased after the period of diet containing ancient grain products. Several volatile organic compounds increased after the one month on the diet enriched with ancient grain products.

CONCLUSIONS

Our data showed the beneficial effects deriving from a diet including ancient whole-meal/unrefined wheat flours.

Undigestible Gliadin Peptide Nanoparticles Penetrate Mucus and Reduce Mucus Production Driven by Intestinal Epithelial Cell Damage

Wheat protein is the most consumed plant protein in our diet, and there is an increased prevalence of wheat/gluten intolerance and adherence to a gluten-free diet in many countries. Despite the known immunodominant effect of undigested gliadin peptides responsible for gluten-related intolerance, it remains unclear if and how gliadin peptides self-assemble into ordered nanostructures during gastrointestinal digestion, as well as their biological impact on the mucus barrier function. In this study, we purified undigestible gliadin peptide nanoparticles (UGPNs) by ultracentrifugation and characterized their structural and physiochemical properties. The results demonstrate that the UGPNs are self-assembled nanostructures generated by cationic amino acids (Lys and Arg)-capped surfactant-like peptides (SLPs), mainly derived from γ-gliadin and α-gliadin. SLPs trigger the concentration-dependent self-assembly driven by β-sheet conformational transitions above their critical aggregation concentration (cac, ∼0.1 mg/mL). UGPNs can easily penetrate the mucus layer in Caco-2/HT29-MTX cocultures with a high P_app value (∼5.7 × 10^-6 cm/s) and reduce the production and thickness of the mucus layer driven by intestinal epithelial cell damage. Isothermal titration calorimetry and Langmuir monolayer studies indicate that the self-assembled state of UGPNs significantly affects their binding to DPPC/DOPE lipid membrane models. These results highlight the relevance of the self-assembly of gliadin peptides as a trigger of mucosal inflammation-related wheat/gluten intolerance.

British Society of Gastroenterology guidelines on the management of irritable bowel syndrome

Irritable bowel syndrome (IBS) remains one of the most common gastrointestinal disorders seen by clinicians in both primary and secondary care. Since publication of the last British Society of Gastroenterology (BSG) guideline in 2007, substantial advances have been made in understanding its complex pathophysiology, resulting in its re-classification as a disorder of gut-brain interaction, rather than a functional gastrointestinal disorder. Moreover, there has been a considerable amount of new evidence published concerning the diagnosis, investigation and management of IBS. The primary aim of this guideline, commissioned by the BSG, is to review and summarise the current evidence to inform and guide clinical practice, by providing a practical framework for evidence-based management of patients. One of the strengths of this guideline is that the recommendations for treatment are based on evidence derived from a comprehensive search of the medical literature, which was used to inform an update of a series of trial-based and network meta-analyses assessing the efficacy of dietary, pharmacological and psychological therapies in treating IBS. Specific recommendations have been made according to the Grading of Recommendations Assessment, Development and Evaluation system, summarising both the strength of the recommendations and the overall quality of evidence. Finally, this guideline identifies novel treatments that are in development, as well as highlighting areas of unmet need for future research.

Non-Celiac Gluten Sensitivity: An Update

Non-celiac gluten sensitivity (NCGS) is a clinical entity characterized by the absence of celiac disease and wheat allergy in patients that trigger reproducible symptomatic responses to gluten-containing foods consumption. Due to the lack of sensitive and reproducible biomarkers for NCGS diagnosis, placebo-controlled gluten challenges must be carried out for its diagnosis. The gluten challenges can be either double- or single-blind, for research or clinical practice purposes, respectively. For improving our understanding about the magnitude and relevance of NCGS in different populations, epidemiological studies based on self-report have been carried out. However, the gluten challenge-based prevalence of NCGS remains to be estimated. Since NCGS was recently recognized as a clinical entity, more studies are needed to delve into NCGS pathogenesis, for instance, the molecular interactions between the suspected cereal grain components that trigger NCGS, such as fermentable oligo-, di-, monosaccharides, and polyols (FODMAPs) and amylase and trypsin inhibitors, and the immune system remains to be elucidated. Although still under debate, NCGS patients can be susceptible to only one or more than one of the NCGS triggers. The treatment of NCGS involves the dietary restriction of the suspected triggers of the disease, but there is controversial data about the effectiveness of different dietary interventions such as the gluten-free diet and low-FODMAP diet. Certainly, our understanding of NCGS is improving quickly due to the constant availability of new scientific information on this topic. Thus, the aim of the present narrative review is to present an up-to-date overview on NCGS from epidemiology to current therapy.

Non-Celiac Gluten Sensitivity in the Context of Functional Gastrointestinal Disorders

Gluten-free diets are increasingly chosen in the Western world, even in the absence of a diagnosis of celiac disease. Around 10% of people worldwide self-report gluten-related complaints, including intestinal and extra-intestinal symptoms. In most cases, these subjects would be labeled as patients suffering from irritable bowel syndrome (IBS) who place themselves on a gluten-free diet even in the absence of celiac disease. In some instances, patients report a clear benefit by avoiding gluten from their diet and/or symptom worsening upon gluten reintroduction. This clinical entity has been termed non-celiac gluten sensitivity (NCGS). The symptoms referred by these patients are both intestinal and extra-intestinal, suggesting that similarly to functional gastrointestinal disorders, NCGS is a disorder of gut-brain interaction. It remains unclear if gluten is the only wheat component involved in NCGS. The mechanisms underlying symptom generation in NCGS remain to be fully clarified, although in the past few years, the research has significantly moved forward with new data linking NCGS to changes in gut motility, permeability and innate immunity. The diagnosis is largely based on the self-reported reaction to gluten by the patient, as there are no available biomarkers, and confirmatory double-blind challenge protocols are unfeasible in daily clinical practice. Some studies suggest that a small proportion of patients with IBS have an intolerance to gluten. However, the benefits of gluten-free or low-gluten diets in non-celiac disease-related conditions are limited, and the long-term consequences of this practice may include nutritional and gut microbiota unbalance. Here, we summarize the role of gluten in the clinical features, pathophysiology, and management of NCGS and disorders of gut-brain interaction.

Coeliac disease and noncoeliac wheat or gluten sensitivity

Coeliac disease (CD) and noncoeliac wheat or gluten sensitivity (NCWS/NCGS) are common gluten-related disorders. Both conditions can present with gastrointestinal and extraintestinal manifestations, which can be a challenge for physicians to discern between. Whilst coeliac serology and histological assessment are required for the diagnosis of CD, there are no clear biomarkers for the diagnosis of NCGS. The management of both conditions is with a gluten-free diet (GFD), although the duration, as well as strictness of adherence to a GFD in NCGS, is unclear. Adherence to a GFD in CD can also be challenging, with recent developments of noninvasive assessments, although histological assessment via duodenal biopsies remains the gold standard. The management of refractory coeliac disease remains particularly challenging, often requiring specialist input. Whilst wheat is noted to be a trigger for symptom generation in NCGS, it is unclear which components of wheat are responsible for symptom generation in this group, with further research required to elucidate the pathophysiology.

Gluten Free Diet for the Management of Non Celiac Diseases: The Two Sides of the Coin

A lifelong adherence to a gluten-free (GF) diet is currently the only treatment for Celiac disease (CD), an autoimmune disorder that arises after gluten ingestion in individuals who are genetically predisposed. The gluten intake exerts toxic effects through several pathways involving gut barrier integrity, intestinal microbiota composition and immune system stimulation. However, despite the great benefit of GF diet for CD patients, its use has been debated. Indeed, individuals who adopt this diet regime may be at risk of nutrient deficiencies. Emerging evidence supports a beneficial effect of a GF diet also for other pathological conditions, including gluten-related disorders (GRD) often associated to CD, such as Non celiac gluten sensitivity (NCGS) and Dermatitis Herpetiforme (DH) as well as Irritable bowel syndrome (IBS) and Diabetes. This suggests a pathogenic role of gluten in these conditions. Despite the growing popularity of GF diet among consumers, to date, there are limited evidences supporting its use for the management of non-celiac diseases. Therefore, in this review, we discuss whether the GF diet could really improve the general quality of life of patients with GRD and non-GRD conditions, keeping in mind its sensorial limitations and nutritional inadequacies. In addition, we discuss the current motivations, leading to the use of a GF diet, despite the inferior quality of GF products respect to those containing gluten.

Brain Opioid Activity and Oxidative Injury: Different Molecular Scenarios Connecting Celiac Disease and Autistic Spectrum Disorder

Celiac Disease (CD) is an immune-mediated disease triggered by the ingestion of wheat gliadin and related prolamins from other cereals, such as barley and rye. Immunity against these cereal-derived proteins is mediated by pro-inflammatory cytokines produced by both innate and adaptive system response in individuals unable to adequately digest them. Peptides generated in this condition are absorbed across the gut barrier, which in these patients is characterized by the deregulation of its permeability. Here, we discuss a possible correlation between CD and Autistic Spectrum Disorder (ASD) pathogenesis. ASD can be induced by an excessive and inappropriate brain opioid activity during the neonatal period. Cereal-derived peptides produced in celiac patients cross the blood-brain barrier and bind to endogenous opioid receptors interfering with neurotransmission and generating deleterious effects on brain maturation, learning and social relations. Moreover, an increase in oxidative stress and a decrease in the antioxidant capacity, as well as an extended mitochondrial impairment in the brain, could represent a possible connection between ASD and CD. Therefore, we critically discuss the proposed relationship between ASD and CD and the possible usefulness of a gluten-free diet in ASD patients.

Mendelian randomization analysis of celiac GWAS reveals a blood expression signature with diagnostic potential in absence of gluten consumption

Celiac disease (CeD) is an immune-mediated enteropathy with a strong genetic component where the main environmental trigger is dietary gluten, and currently a correct diagnosis of the disease is impossible if gluten-free diet (GFD) has already been started. We hypothesized that merging different levels of genomic information through Mendelian randomization (MR) could help discover genetic biomarkers useful for CeD diagnosis. MR was performed using public databases of expression quantitative trait loci (QTL) and methylation QTL as exposures and the largest CeD genome-wide association study conducted to date as the outcome, in order to identify potential causal genes. As a result, we identified UBE2L3, an ubiquitin ligase located in a CeD-associated region. We interrogated the expression of UBE2L3 in an independent data set of peripheral blood mononuclear cells (PBMCs) and found that its expression is altered in CeD patients on GFD when compared to non-celiac controls. The relative expression of UBE2L3 isoforms predicts CeD with 100% specificity and sensitivity and could be used as a diagnostic marker, especially in the absence of gluten consumption. This approach could be applicable to other diseases where diagnosis of asymptomatic patients can be complicated.

Incidence and prevalence of self-reported non-coeliac wheat sensitivity and gluten avoidance in Australia

OBJECTIVES

To determine the incidence of self-reported non-coeliac wheat sensitivity (SR-NCWS) and factors associated with its onset and resolution; to describe the prevalence of factors associated with gluten avoidance.

DESIGN

Longitudinal cohort study; analysis of responses to self-administered validated questionnaires (Digestive Health and Wellbeing surveys, 2015 and 2018).

SETTING, PARTICIPANTS

Subset of an adult population sample randomly selected in 2015 from the electoral rolls for the Newcastle and Gosford regions of New South Wales.

MAIN OUTCOME MEASURES

Prevalence of SR-NCWS (2015, 2018) and incidence and resolution of SR-NCWS, each by demographic and medical factors; prevalence of gluten avoidance and reasons for gluten avoidance (2018).

RESULTS

1322 of 2185 eligible participants completed the 2018 survey (response rate, 60.5%). The prevalence of SR-NCWS was similar in 2015 (13.8%; 95% CI, 12.0-15.8%) and 2018 (13.9%; 95% CI, 12.1-15.9%); 69 of 1301 respondents (5.3%) reported developing new onset (incident) SR-NCWS between 2015 and 2018 (incidence, 1.8% per year). Incident SR-NCWS was significantly associated with a diagnosis of functional dyspepsia, and negatively associated with being male or older. Gluten avoidance was reported in 2018 by 24.2% of respondents (20.5% partial, 3.8% complete avoidance); general health was the most frequent reason for avoidance (168 of 316 avoiders, 53%). All 13 participants with coeliac disease, 56 of 138 with irritable bowel syndrome (41%), and 69 of 237 with functional dyspepsia (29%) avoided dietary gluten.

CONCLUSIONS

The prevalence of SR-NCWS was similar in 2015 and 2018. Baseline (2015) and incident SR-NCWS (2018) were each associated with functional gastrointestinal disorders. The number of people avoiding dietary gluten exceeds that of people with coeliac disease or SR-NCWS, and general health considerations and abdominal symptoms are the most frequently reported reasons for avoidance.

The role of diet in irritable bowel syndrome: implications for dietary advice

Irritable bowel syndrome (IBS) is a common functional gastrointestinal disorder that affects approximately 10% of the population. Diet triggers symptoms in the vast majority of individuals with IBS. In view of this, there has been a focus on the role of diet in IBS. The diets currently being headlined for IBS include (i) traditional dietary advice, (ii) the low fermentable oligo-, di-, mono- saccharides and polyols (FODMAPs) diet and (iii) the gluten-free diet (GFD). Although traditional dietary advice is considered as the first-line dietary therapy, its evidence base is variable, with a few randomized controlled trials (RCTs) exploring the efficacy of this approach, other than for fibre. There are now a growing number of RCTs demonstrating the efficacy of the low FODMAP diet in the short-term, with some emerging data on the long-term 'adapted' low FODMAP diet. There are also several RCTs showing the benefits of a GFD in IBS; however, this concept is hampered with uncertainty as to the mechanism of action. Nevertheless, all of these dietary therapies are viable options for individuals with IBS, with the dietitian and patient engagement at the forefront of achieving success. However, future pragmatic studies are needed to clarify the comparative efficacy and convenience of implementing these various diets into routine life. Moreover, it is imperative to better delineate the concern that restrictive diets - such as the low FODMAP and GFD - may promote nutritional inadequacies, disordered eating behaviours, and lead to detrimental alterations to the gut microbiota.

Gluten Vehicle and Placebo for Non-Celiac Gluten Sensitivity Assessment

Non-celiac gluten sensitivity (NCGS) is a syndrome characterized by gastrointestinal and extraintestinal manifestations triggered after gluten ingestion in the absence of celiac disease and wheat allergy. Because of the lack of biomarkers for NCGS diagnosis, the cornerstone for its assessment is a single- or double-blind placebo-controlled (DBPC) gluten challenge. However, there are some non-standardized points in the diagnostic approach proposed by the experts. This complicate comparisons among the results published by different research groups. The gluten vehicle and placebo must be indistinguishable from each other, which entails sensory and technological evaluations of the designed gluten vehicle and placebo products. At the moment, there is no standardized method for the preparation of the gluten vehicle and placebo for carrying out DBPC gluten challenges for NCGS assessment. This review focuses on the challenges that researchers have to face, either for the development of an accepted gluten vehicle and placebo or for identifying NCGS cases on the basis of DBPC gluten challenges.

Coeliac disease under a microscope: Histological diagnostic features and confounding factors

Coeliac disease (CD) and gluten-related disorders represent an important cornerstone of the daily practice of gastroenterologists, endoscopists and dedicated histopathologists. Despite the knowledge of clinical, serological and histological typical lesions, there are some conditions to consider for differential diagnosis. From the first description of histology of CD, several studies were conducted to define similar findings suggestive for microscopic enteritis. Considering the establishment of early precursor lesions, the imbalance of gut microbiota is another point still requiring a detailed definition. This review assesses the importance of a right overview in case of suspected gluten-related disorders and the several conditions mimicking a similar histology.