Colonic fermentation influences lower esophageal sphincter function in gastroesophageal reflux disease

Microbiota profiling in esophageal diseases: Novel insights into molecular staining and clinical outcomes

Gut microbiota is recognized nowadays as one of the key players in the development of several gastro-intestinal diseases. The first studies focused mainly on healthy subjects with staining of main bacterial species via culture-based techniques. Subsequently, lots of studies tried to focus on principal esophageal disease enlarged the knowledge on esophageal microbial environment and its role in pathogenesis. Gastro Esophageal Reflux Disease (GERD), the most widespread esophageal condition, seems related to a certain degree of mucosal inflammation, via interleukin (IL) 8 potentially enhanced by bacterial components, lipopolysaccharide (LPS) above all. Gram- bacteria, producing LPS), such as Campylobacter genus, have been found associated with GERD. Barrett esophagus (BE) seems characterized by a Gram- and microaerophils-shaped microbiota. Esophageal cancer (EC) development leads to an overturn in the esophageal environment with the shift from an oral-like microbiome to a prevalently low-abundant and low-diverse Gram--shaped microbiome. Although underinvestigated, also changes in the esophageal microbiome are associated with rare chronic inflammatory or neuropathic disease pathogenesis. The paucity of knowledge about the microbiota-driven mechanisms in esophageal disease pathogenesis is mainly due to the scarce sensitivity of sequencing technology and culture methods applied so far to study commensals in the esophagus. However, the recent advances in molecular techniques, especially with the advent of non-culture-based genomic sequencing tools and the implementation of multi-omics approaches, have revolutionized the microbiome field, with promises of implementing the current knowledge, discovering more mechanisms underneath, and giving insights into the development of novel therapies aimed to re-establish the microbial equilibrium for ameliorating esophageal diseases..

Coeliac disease is a strong risk factor for Gastro-oesophageal reflux disease while a gluten free diet is protective: a systematic review and meta-analysis

Background

Gastro-oesophageal reflux disease (GORD) mechanisms are well described, but the aetiology is uncertain. Coeliac disease (CD), a gluten enteropathy with increased duodenal eosinophils overlaps with GORD. Functional dyspepsia is a condition where duodenal eosinophilia is featured, and a 6-fold increased risk of incident GORD has been observed. Perturbations of the duodenum can alter proximal gastric and oesophageal motor function. We performed a systematic review and meta-analysis assessing the association between CD and GORD.

Methods

A systematic search of studies reporting the association of GORD and CD was conducted. CD was defined by combined serological and histological parameters. GORD was defined based on classical symptoms, oesophagitis (endoscopic or histologic) or abnormal 24-h pH monitoring; studies reporting oesophageal motility abnormalities linked with GORD were also included. Pooled odds ratios (OR) and 95% confidence intervals (CI) were calculated using a random-effects model.

Findings

31 papers were included. Individuals with CD on a gluten containing diet were 3 times more likely to have GORD than controls (OR: 3.37, 95% CI: 2.09-5.44), and over 10 times more likely when compared to those on a gluten free diet (GFD) (OR: 10.20, 95% CI: 6.49-16.04). Endoscopic oesophagitis was significantly associated with CD (OR: 4.96; 95% CI: 2.22-11.06). One year of a GFD in CD and GORD was more efficacious in preventing GORD symptom relapse than treatment with 8 weeks of PPI in non-CD GORD patients (OR: 0.18, 95% CI: 0.08-0.36). Paediatric CD patients were more likely to develop GORD (OR: 3.29, 95% CI: 1.46-7.43), compared to adult CD patients (OR: 2.55, 95% CI: 1.65-3.93).

Interpretation

CD is strongly associated with GORD but there was high heterogeneity. More convincingly, a GFD substantially improves GORD symptoms, suggesting a role for duodenal inflammation and dietary antigens in the aetiology of a subset with GORD. Ruling out CD in patients with GORD may be beneficial.

Funding

The study was supported by an Investigator Grant from the NHMRC to Dr. Talley.

Incretin hormones, obesity and gut microbiota

Over the past 40 years, the prevalence of obesity has risen dramatically, reaching epidemic proportions. By 2030 the number of people affected by obesity will reach 1.12 billion worldwide. Gastrointestinal hormones, namely incretins, play a vital role in the pathogenesis of obesity and its comorbidities. GIP (glucose-dependent insulinotropic polypeptide) and GLP-1 (glucagon-like peptide-1), which are secreted from the intestine after nutrient intake and stimulate insulin secretion from pancreatic β cells, influence lipid metabolism, gastric empting, appetite and body weight. The gut microbiota plays an important role in various metabolic conditions, including obesity and type 2 diabetes and influences host metabolism through the interaction with enteroendocrine cells that modulate incretins secretion. Gut microbiota metabolites, such as short-chain fatty acids (SCFAs) and indole, directly stimulate the release of incretins from colonic enteroendocrine cells influencing host satiety and food intake. Moreover, bariatric surgery and incretin-based therapies are associated with increase gut bacterial richness and diversity. Understanding the role of incretins, gut microbiota, and their metabolites in regulating metabolic processes is crucial to develop effective strategies for the management of obesity and its associated comorbidities.

Intraintestinal fermentation of fructo- and galacto-oligosaccharides and the fate of short-chain fatty acids in humans

Consumption of fructo- (FOS) and galacto-oligosaccharides (GOS) has health benefits which have been linked in part to short-chain fatty acids (SCFA) production by the gut microbiota. However, detailed knowledge of this process in the human intestine is lacking. We aimed to determine the acute fermentation kinetics of a FOS:GOS mixture in healthy males using a naso-intestinal catheter for sampling directly in the ileum or colon. We studied the fate of SCFA as substrates for glucose and lipid metabolism by the host after infusion of 13C-SCFA. In the human distal ileum, no fermentation of FOS:GOS, nor SCFA production, or bacterial cross-feeding was observed. The relative composition of intestinal microbiota changed rapidly during the test day, which demonstrates the relevance of postprandial intestinal sampling to track acute responses of the microbial community toward interventions. SCFA were vividly taken up and metabolized by the host as shown by incorporation of 13C in various host metabolites.

Dietary impact on fasting and stimulated GLP-1 secretion in different metabolic conditions - a narrative review

Glucagon-like peptide 1 (GLP-1), a gastrointestinal peptide and central mediator of glucose metabolism, is secreted by L cells in the intestine in response to food intake. Postprandial secretion of GLP-1 is triggered by nutrient-sensing via transporters and G-protein-coupled receptors (GPCRs). GLP-1 secretion may be lower in adults with obesity/overweight (OW) or type 2 diabetes mellitus (T2DM) than in those with normal glucose tolerance (NGT), but these findings are inconsistent. Because of the actions of GLP-1 on stimulating insulin secretion and promoting weight loss, GLP-1 and its analogs are used in pharmacologic preparations for the treatment of T2DM. However, physiologically stimulated GLP-1 secretion through the diet might be a preventive or synergistic method for improving glucose metabolism in individuals who are OW, or have impaired glucose tolerance (IGT) or T2DM. This narrative review focuses on fasting and postprandial GLP-1 secretion in individuals with different metabolic conditions and degrees of glucose intolerance. Further, the influence of relevant diet-related factors (e.g., specific diets, meal composition, and size, phytochemical content, and gut microbiome) that could affect fasting and postprandial GLP-1 secretion are discussed. Some studies showed diminished glucose- or meal-stimulated GLP-1 response in participants with T2DM, IGT, or OW compared with those with NGT, whereas other studies have reported an elevated or unchanged GLP-1 response in T2DM or IGT. Meal composition, especially the relationship between macronutrients and interventions targeting the microbiome can impact postprandial GLP-1 secretion, although it is not clear which macronutrients are strong stimulants of GLP-1. Moreover, glucose tolerance, antidiabetic treatment, grade of overweight/obesity, and sex were important factors influencing GLP-1 secretion. The results presented in this review highlight the potential of nutritional and physiologic stimulation of GLP-1 secretion. Further research on fasting and postprandial GLP-1 concentrations and the resulting metabolic consequences under different metabolic conditions is needed.

The Efficacy of Dietary Interventions in Patients with Gastroesophageal Reflux Disease: A Systematic Review and Meta-Analysis of Intervention Studies

BACKGROUND

International guidelines recommend dietary interventions as one of the most important treatments for patients with gastroesophageal reflux disease (GERD). Evidence to confirm the efficacy of these treatment modalities is lacking. The present study aims to evaluate the efficacy of dietary interventions on GERD-related outcomes evaluated in intervention studies on GERD patients.

METHODS

A systematic review and meta-analysis was performed according to PRISMA. The PubMed/MEDLINE, Web of Sciences, and Scopus databases were utilized for the literature search. Two independent researchers searched for relevant publications published up until June 2023. Intervention studies evaluating the efficacy of dietary interventions in patients with GERD were included.

RESULTS

A total of 577 articles were identified during the initial literature search. After reviewing, 21 studies with 16 different types of dietary interventions were included in the analysis. The interventions were divided into low-carbohydrate diets (3 studies), high-fat diets (2 studies), speed of eating studies (3 studies), low-FODMAP diets (2 studies), and other interventions (12 studies). A meta-analysis could be performed for low-carbohydrate diets and speed of eating interventions. Low-carbohydrate diets resulted in a significant reduction in esophageal acid exposure time (mean difference = -2.834%, 95% confidence interval (CI): -4.554 to -1.114), while a slow speed of eating did not lead to a lower percentage of reflux events compared to fast eating (risk ratio = 1.044, 95% CI: 0.543-2.004). Most other interventions showed positive effects in only a single study.

CONCLUSION

Low-carbohydrate diets showed a significant improvement in GERD-related outcomes, while a slow eating speed did not result in a reduction in reflux events. The overall evidence regarding dietary interventions in GERD remains scarce. High-quality, long-term RCTs are still required to confirm the effects of dietary interventions in GERD patients.

Polysaccharides (pectin, mucilage, and fructan inulin) and their fermented products: A critical analysis of their biochemical, gut interactions, and biological functions as antidiabetic agents

Diabetes mellitus is a globally metabolic endocrine syndrome marked by a deficiency of insulin secretion (type-1 DM) or glucose intolerance arising from insulin response impairment (type-2 DM) leading to abnormal glucose metabolism. With an increasing interest in natural dietary components for diabetes management, the identification of novel agents witnessed major discoveries. Plant-derived mucilage, pectin, and inulin are important non-starch polysaccharides that exhibit effective antidiabetic properties often termed soluble dietary fiber (SDF). SDF affects sugar metabolism through multiple mechanisms affecting glucose absorption and diffusion, modulation of carbohydrate metabolizing enzymes (α-amylase and α-glucosidase), ameliorating β-pancreatic cell dysfunction, and improving insulin release or sensitivity. Certain SDFs inhibit dipeptidyl peptidase-4 and influence the expression levels of genes related to glucose metabolism. This review is designed to discuss holistically and critically the antidiabetic effects of major SDF and their underlying mechanisms of action. This review should aid drug discovery approaches in developing novel natural antidiabetic drugs from SDF.

Crosstalk between glucagon-like peptide 1 and gut microbiota in metabolic diseases

Gut microbiota exert influence on gastrointestinal mucosal permeability, bile acid metabolism, short-chain fatty acid synthesis, dietary fiber fermentation, and farnesoid X receptor/Takeda G protein-coupled receptor 5 (TGR5) signal transduction. The incretin glucagon-like peptide 1 (GLP-1) is mainly produced by L cells in the gut and regulates postprandial blood glucose. Changes in gut microbiota composition and function have been observed in obesity and type 2 diabetes (T2D). Meanwhile, the function and rhythm of GLP-1 have also been affected in subjects with obesity or T2D. Therefore, it is necessary to discuss the link between the gut microbiome and GLP-1. In this review, we describe the interaction between GLP-1 and the gut microbiota in metabolic diseases. On the one hand, gut microbiota metabolites stimulate GLP-1 secretion, and gut microbiota affect GLP-1 function and rhythm. On the other hand, the mechanism of action of GLP-1 on gut microbiota involves the inflammatory response. Additionally, we discuss the effects and mechanism of various interventions, such as prebiotics, probiotics, antidiabetic drugs, and bariatric surgery, on the crosstalk between gut microbiota and GLP-1. Finally, we stress that gut microbiota can be used as a target for metabolic diseases, and the clinical application of GLP-1 receptor agonists should be individualized.

Current complementary and alternative therapy forgastroesophageal reflux disease

Gastroesophageal reflux disease (GERD) is a widely prevalent gastrointestinal disorder, affecting ∼13.3% of the global population. There are shortages and limitations of current GERD treatment modalities, and complementary and alternative therapy (CAT) is a promising option to fill in the gap. Dietary and lifestyle modifications might play an important and complementary role in alleviating GERD symptoms. Traditional Chinese medicine and brain-gut behavior therapy, particularly transcutaneous electrical acustimulation and diaphragmatic breathing therapy were shown to be useful adjuncts or alternatives in treating GERD. CAT may help to relieve GERD symptoms, minimize medication dosage, and slow the demand for surgery. The aim of this review was to summarize the existing evidence of some common CATs in treating symptomatic GERD, including dietary modification, lifestyle change, traditional Chinese medicine, and brain-gut behavior therapy.

Oligofructose improves small intestinal lipid-sensing mechanisms via alterations to the small intestinal microbiota

BACKGROUND

Upper small intestinal dietary lipids activate a gut-brain axis regulating energy homeostasis. The prebiotic, oligofructose (OFS) improves body weight and adiposity during metabolic dysregulation but the exact mechanisms remain unknown. This study examines whether alterations to the small intestinal microbiota following OFS treatment improve small intestinal lipid-sensing to regulate food intake in high fat (HF)-fed rats.

RESULTS

In rats fed a HF diet for 4 weeks, OFS supplementation decreased food intake and meal size within 2 days, and reduced body weight and adiposity after 6 weeks. Acute (3 day) OFS treatment restored small intestinal lipid-induced satiation during HF-feeding, and was associated with increased small intestinal CD36 expression, portal GLP-1 levels and hindbrain neuronal activation following a small intestinal lipid infusion. Transplant of the small intestinal microbiota from acute OFS treated donors into HF-fed rats also restored lipid-sensing mechanisms to lower food intake. 16S rRNA gene sequencing revealed that both long and short-term OFS altered the small intestinal microbiota, increasing Bifidobacterium relative abundance. Small intestinal administration of Bifidobacterium pseudolongum to HF-fed rats improved small intestinal lipid-sensing to decrease food intake.

CONCLUSION

OFS supplementation rapidly modulates the small intestinal gut microbiota, which mediates improvements in small intestinal lipid sensing mechanisms that control food intake to improve energy homeostasis. Video Abstract.

Dietary factors involved in GERD management

Gastroesophageal reflux disease (GERD) is extremely common, and even modest weight gain has been associated with higher symptom burden as well as objective evidence of reflux on endoscopy and physiological measurement. Certain trigger foods, especially citrus, coffee, chocolate, fried food, spicy food and red sauces are frequently reported to worsen reflux symptoms, although hard evidence linking these items to objective GERD is lacking. There is better evidence that large meal volume and high calorie content can increase esophageal reflux burden. Conversely, sleeping with the head end of the bed raised, avoiding lying down close to meals, sleeping on the left side and weight loss can improve reflux symptoms and objective reflux evidence, especially when the esophagogastric junction 'reflux barrier' is compromised (e.g., in the presence of a hiatus hernia). Consequently, attention to diet and weight loss are both important elements of management of GERD, and need to be incorporated into management plans.

Impact of Objective Colonic and Whole Gut Motility Data as Measured by Wireless Motility Capsule on Outcomes of Antireflux Surgery

BACKGROUND

Studies show higher rates of dissatisfaction with antireflux surgery (ARS) outcomes in patients with chronic constipation. This suggests a relationship between colonic dysmotility and suboptimal surgical outcome. However, due to limitations in technology, there is no objective data available examining this relationship. The wireless motility capsule (WMC) is a novel technology consisting of an ingestible capsule equipped with pH, temperature, and pressure sensors, which provide information regarding regional and whole gut transit times, pH and motility. The aim of this study was to assess the impact of objective regional and whole gut motility data on the outcomes of ARS.

STUDY DESIGN

This was a retrospective review of patients who underwent WMC testing before ARS. Transit times, motility, and pH data obtained from different gastrointestinal tract regions were used in analysis to determine factors that impact surgical outcome. A favorable outcome was defined as complete resolution of the predominant reflux symptom and freedom from antisecretory medications.

RESULTS

The final study population consisted of 48 patients (fundoplication [n = 29] and magnetic sphincter augmentation [n = 19]). Of those patients, 87.5% were females and the mean age ± SD was 51.8 ± 14.5 years. At follow-up (mean ± SD, 16.8 ± 13.2 months), 87.5% of all patients achieved favorable outcomes. Patients with unfavorable outcomes had longer mean whole gut transit times (92.0 hours vs 55.7 hours; p = 0.024) and colonic transit times (78.6 hours vs 47.3 hours; p = 0.028), higher mean peak colonic pH (8.8 vs 8.15; p = 0.009), and higher mean antral motility indexes (310 vs 90.1; p = 0.050).

CONCLUSIONS

This is the first study to demonstrate that objective colonic dysmotility leads to suboptimal outcomes after ARS. WMC testing can assist with preoperative risk assessment and counseling for patients seeking ARS.

Role of Low-FODMAP diet in functional dyspepsia: "Why", "When", and "to Whom"

Functional dyspepsia (FD) is a frequent disorder of gut-brain interaction, affecting 5-7% of people globally, with significant impairment in quality of life. The management of FD is challenging due to the lack of specific therapeutic approaches. Although food seems to play a role in symptom production, its pathophysiologic role in patients with FD is not fully understood. Most FD patients report that their symptoms are triggered by food, especially in the post-prandial distress syndrome (PDS) group, although evidence to support the use of dietary interventions are limited. FODMAPs can increase production of gas in the intestinal lumen, through fermentation by intestinal bacteria, can exert osmotic effects by increasing water volume and can cause an excessive production of short-chain fatty acids (propionate, butyrate, and acetate). Emerging scientific evidence, confirmed by recent clinical trials, suggest that FODMAPs could be involved in the pathogenesis of FD. Given the consolidated approach of the Low-FODMAP Diet (LFD) in irritable bowel syndrome (IBS) management and emerging scientific evidence regarding the LFD in FD, a therapeutic role of this diet may be hypothesized also in FD, either alone or in combination with other therapies.

Evidence-Based and Emerging Dietary Approaches to Upper Disorders of Gut-Brain Interaction

Food ingestion is a major symptom trigger in functional esophageal and gastroduodenal disorders and gastroparesis. This review summarizes current knowledge and identifies areas of research on the role of food factors and the opportunities for dietary intervention in these disorders. While many patients experiencing functional esophageal and gastroduodenal disorders identify specific food items as symptom triggers, available data do not allow the identification of specific nutrient groups that are more likely to induce symptoms. In functional dyspepsia (FD), recent studies have shown the potential efficacy of a diet low in fermentable oligosaccharides, disaccharides, monosaccharides, and polyols, although the underlying mechanism of action is unclear. Reports of favorable responses to gluten elimination in patients with FD are confounded by the concomitant benefit of reduced intake of fructans, fermentable oligosaccharides, disaccharides, monosaccharides, and polyols present in wheat. Emerging data based on a 6-food elimination diet and confocal laser endomicroscopic evaluation of mucosal responses to food proteins suggest a role for duodenal allergic reactions in FD symptom generation. In patients with gastroparesis, a low-residue diet has been shown to improve symptoms. Novel dietary approaches under evaluation are the Mediterranean diet and the heating/cooling diet approach.

The significance and potential of functional food ingredients for control appetite and food intake

Dramatically rising global levels of obesity have raised consumers’ commercial and public health interest in foods that may help control appetite and weight. The satiety cascade consists of sensory, cognitive, physical, and hormonal events following food intake, preventing overeating, and the desire to eat for a long time. Functional foods can be one of the most influential factors in reducing appetite as long as effective ingredients, such as fiber and protein, are used to design these products. Also, functional foods should be designed to reduce appetite at different levels of oral processing, stomach, small intestine, and large intestine by various mechanisms. Therefore, the satiety power of functional foods depends on the type of ingredients and their amount. Because each compound has a different mechanism of action, it is recommended to use different compounds to influence satiety in functional foods.

Glucagon-like peptide-1: Are its roles as endogenous hormone and therapeutic wizard congruent?

Glucagon-like peptide-1 (GLP-1) is a peptide derived from differential processing of the precursor for the hormone glucagon. It is secreted predominantly by endocrine cells in the gut epithelium in response to nutrient stimulation. Studies from the last 35 years have given us an idea about its physiological functions. On the basis of some of its many actions, it has also been developed into a pharmaceutical agent for the treatment of obesity and type 2 diabetes (T2DM). It is currently positioned as the most effective anti-obesity agent available and is recommended in both national and international guidelines as an effective second-in line treatment for T2DM, in particular in patients with increased cardiovascular risk. In this review, I first discuss whether the processing of proglucagon may also result in GLP-1 formation in the pancreas and in glucagon in the gut. Next, I discuss the relationship between the physiological actions of GLP-1 and the therapeutic effects of the GLP-1 receptor agonists, which are far from being congruent and generally poorly understood. These relationships illustrate both the difficulties and the benefits of bridging results obtained in the laboratory with those emerging from the clinic.

The Effect of Fermentable, Oligosaccharides, Disaccharides, Monosaccharides, and Polyols (FODMAP) Meals on Transient Lower Esophageal Relaxations (TLESR) in Gastroesophageal Reflux Disease (GERD) Patients with Overlapping Irritable Bowel Syndrome (IBS)

A randomized crossover study in eight patients (6 F, age 57 ± 13) with overlapping GERD-IBS (non-constipation) was conducted to evaluate the effects of rice noodle vs. wheat noodle meals for breakfast and lunch on postprandial TLESR, intestinal gas production, and GERD/GI symptoms. Results: Wheat ingestion was significantly associated with more frequent TLESR after lunch than rice (5.0 ± 0.7 vs. 1.9 ± 0.3 times/2 h, p = 0.01). After lunch, wheat ingestion was significantly associated with higher H2 and CH4 levels compared to rice ingestion (p < 0.05), while H2 and CH4 levels before lunch were similar (p > 0.05). The area under curve of H2 concentration until 2 h after lunch significantly correlated with the TLESR number (r = 0.69, p = 0.04). Postprandial regurgitation (2.9 ± 1.2 vs. 0.4 ± 0.2), bloating (7.0 ± 0.4 vs. 3.1 ± 0.9), satiety (7.7 ± 0.4 vs. 3.5 ± 0.9), and belching (3.8 ± 1.2 vs. 1.1 ± 0.6) symptom scores were significantly greater after wheat compared to rice noodle ingestion (p < 0.05). Conclusion: Wheat noodle meals, part of a high FODMAP diet, induced a higher frequency of TLESRs, a higher GERD, and higher upper-GI symptom scores than rice noodle meals, part of a low FODMAP diet, in patients with overlapping IBS-GERD. These effects were associated with more intestinal gas production. Thus, a low FODMAP diet may relieve GERD symptoms in GERD patients with overlapping IBS.

Colonic Lactulose Fermentation Has No Impact on Glucagon-like Peptide-1 and Peptide-YY Secretion in Healthy Young Men

CONTEXT

The colon houses most of humans' gut microbiota, which ferments indigestible carbohydrates. The products of fermentation have been proposed to influence the secretion of glucagon-like peptide-1 (GLP-1) and peptide YY (PYY) from the many endocrine cells in the colonic epithelium. However, little is known about the colonic contribution to fasting or postprandial plasma levels of L-cell products.

OBJECTIVE

To determine the impact of colonic lactulose fermentation on gut peptide secretion and to evaluate whether colonic endocrine secretion contributes to gut hormone concentrations measurable in the fasting state.

METHODS

Ten healthy young men were studied on 3 occasions after an overnight fast. On 2 study days, lactulose (20 g) was given orally and compared to water intake on a third study day. For 1 of the lactulose visits, participants underwent a full colonic evacuation. Over a 6-h study protocol, lactulose fermentation was assessed by measuring exhaled hydrogen, and gut peptide secretion, paracetamol, and short-chain fatty acid levels were measured in plasma.

RESULTS

Colonic evacuation markedly reduced hydrogen exhalation after lactulose intake (P = 0.013). Our analysis suggests that the colon does not account for the measurable amounts of GLP-1 and PYY present in the circulation during fasting and that fermentation and peptide secretion are not acutely related.

CONCLUSION

Whether colonic luminal contents affect colonic L-cell secretion sufficiently to influence circulating concentrations requires further investigation. Colonic evacuation markedly reduced lactulose fermentation, but hormone releases were unchanged in the present study.

Acute and short-term effects of Lactobacillus paracasei subsp. paracasei 431 and inulin intake on appetite control and dietary intake: A two-phases randomized, double blind, placebo-controlled study

This study aims to examine the acute and short-term effects of prebiotics, probiotics, and their combination on appetite, energy intake and satiety related hormones in two phases. The first phase was a randomized, double blind, placebo controlled crossover study. Prebiotic (16 g inulin), probiotic (Lactobacillus paracasei subsp. paracasei 431 (L. casei 431) (>10⁶ cfu/ml), synbiotic (their combination) and control (16 g maltodextrin) dairy drinks were consumed by 16 healthy men with a standard breakfast on four separate test days, and the following satiety responses and ad libitum food intake at lunch and over 24 h were assessed. In the second phase, the effects of 21 days of synbiotic (n = 10) or control (n = 11) drink consumption on appetite sensation, energy intake, serum glucose, insulin, peptide YY, ghrelin, obestatin and adiponectin concentration were assessed in a randomized double-blind placebo-controlled design. In the first phase, energy intake values during ad libitum lunch were the lowest in the prebiotic drink, followed by probiotic, synbiotic and control drinks, respectively (p = 0.017); also the rest of the day and 24-h dietary energy intake was lower by prebiotic and probiotic drinks compared to the control drink (p < 0.05 for each). For short-term effects, no significant difference in anthropometric measurements, hunger-satiety scores and serum glucose, insulin, PYY, ghrelin, obestatin and adiponectin concentrations were recorded. Despite the potential of prebiotics and probiotics to reduce energy intake, further studies are required for a better understanding of their role in satiety related mechanisms.

Using Diet to Treat Diseases of Esophagus: Back to the Basics

The esophagus plays a crucial role in oral nutrition and digestive pathophysiology. In addition, diet is now considered an important primary or augmentative therapy in several esophageal disease states. This review highlights common dietary therapies used in treating diseases of the esophagus as well as the underlying data that support such practices. Specially, diet and its relationship to swallowing dysfunction, motility disorders, malignancies, and inflammatory mucosal diseases such as gastroesophageal reflux disease and eosinophilic esophagitis is explored.

Epigastric symptom response to low FODMAP dietary advice compared with standard dietetic advice in individuals with functional dyspepsia

BACKGROUND

Certain dietary constituents may provoke symptoms of functional dyspepsia (FD); however, there is an absence of dietary trials testing specific dietary interventions. Empirically derived dietary strategies and the low FODMAP diet are frequently used in practice. This study aimed to compare the effectiveness of low FODMAP dietary advice with standard dietary advice for reducing epigastric and overall gastrointestinal symptoms in individuals with FD.

METHODS

Data were collected from 59 consecutive eligible individuals with FD attending an initial and review outpatient dietetic consultation at Princess Alexandra Hospital. Of these, 40 received low FODMAP advice and 19 received standard dietary advice. As part of usual care, the Structured Assessment of Gastrointestinal Symptom Scale (SAGIS) was used to assess epigastric (maximum score = 28) and overall gastrointestinal symptoms (maximum score = 88). Dietary adherence data were collected, and change in symptom score and proportion of responders (defined as a ≥30% reduction in score) for epigastric and total symptoms was calculated.

KEY RESULTS

Most individuals (48/59, 81%) had FD and coexisting irritable bowel syndrome. There was a greater reduction in epigastric score in those receiving low FODMAP dietary advice compared with those receiving standard advice (est. marginal mean [95% CI]: -3.6 [-4.9, -2.2] vs. -0.9 [-2.9, 1.1], p = 0.032) and total symptom score (-9.4 [-12.4, -6.4] vs. -3.3 [-7.7, 1.1] p = 0.026). A greater proportion receiving low FODMAP dietary advice were responders versus those receiving standard advice (50% vs. 16%, p = 0.012). Dietary adherence did not differ between groups (p = 0.497).

CONCLUSIONS & INFERENCES

The low FODMAP diet appears more effective for improving epigastric symptoms in people with FD compared with standard advice. A randomized controlled trial is required to substantiate these findings.

Effect of inulin-type fructans on appetite in patients with type 2 diabetes: a randomised controlled crossover trial

The aim of the study was to investigate the effect of prebiotic fibres on appetite-regulating hormones, subjective feeling of appetite and energy intake in subjects with type 2 diabetes. Data presented are secondary outcomes of a study investigating the effect of prebiotics on glucagon-like peptide-1 and glycaemic regulation. We conducted a randomised and placebo-controlled crossover trial to evaluate the effects of 16 g/d of inulin-type fructans or a control supplement (maltodextrin) for 6 weeks in randomised order, with a 4-week washout period in-between, on appetite in thirty-five men and women with type 2 diabetes. Data were collected at visits before and after each treatment: plasma concentration of the satiety-related peptides ghrelin and peptide YY (PYY) were assessed during a standardised mixed meal. The subjective sensation of appetite was evaluated in response to an ad libitum lunch by rating the visual analogue scale. Twenty-nine individuals (twelve women) were included in the analyses. Compared to control treatment, the prebiotics did not affect ghrelin (P =0⋅71) or the ratings of hunger (P = 0⋅62), satiety (P = 0⋅56), fullness (P = 0⋅73) or prospective food consumption (P = 0⋅98). Energy intake also did not differ between the treatments. However, the response of PYY increased significantly after the control treatment with mean (sem) 11⋅1 (4⋅3) pg/ml when compared to the prebiotics -0⋅3 (4⋅3) pg/ml (P = 0⋅013). We observed no effect of inulin-type fructans on appetite hormones, subjective feeling of appetite or energy intake in patients with type 2 diabetes.

Low FODMAPs diet or usual dietary advice for the treatment of refractory gastroesophageal reflux disease: An open-labeled randomized trial

BACKGROUND

The low FODMAPs (fermentable oligo-, di-, monosaccharides, and polyols) diet improves lower gastrointestinal symptoms. Patients suffering from proton pump inhibitor (PPI) refractory gastroesophageal reflux disease (GERD) have limited treatment options. We investigated the efficacy of a low FODMAPs diet in patients with PPI refractory GERD.

METHODS

This multicenter, randomized, open-label study compared the efficacy of a 4-week low FODMAPs diet and usual dietary advice (ie, low-fat diet and head of bed elevation) in patients with symptomatic PPI refractory GERD, defined by a Reflux Disease Questionnaire (RDQ) score >3 and abnormal pH-impedance monitoring on PPIs. The primary endpoint was the percentage of responders (RDQ ≤3) at the end of the diet.

RESULTS

Thirty-one patients (55% women, median age 45 years) were included, 16 randomized in the low FODMAPs diet group and 15 in the usual dietary advice group. Adherence to the assigned diet was good, with a significant difference in the FODMAPs intake per day between the low FODMAPs diet (2.5 g) and the usual dietary advice group (13 g) (p < 0.001). There was no difference in response rates (RDQ score ≤3) between the low FODMAPs diet (6/16, 37.5%) and usual dietary advice (3/15, 20%) groups (p = 0.43). Total RDQ score and dyspepsia subscore decreased significantly over time in both groups (p = 0.002), with no difference according to the assigned diet group (p = 0.85).

CONCLUSION

Low FODMAPs diet and usual dietary advice have similar but limited beneficial effects on symptoms in patients with PPI refractory GERD.

The Association between Free Sugars Consumption and Laryngopharyngeal Reflux: A Cross-Sectional Study among Chinese Adolescents

There is a lack of evidence to show prevalence of laryngopharyngeal reflux (LPR) and the association between LPR and dietary factors. Adolescents consume the most amount of free sugars among the Chinese population. We conducted this study to investigate the prevalence of LPR in Chinese adolescents and explore the association between free sugars consumption and LPR. A cross-sectional study was conducted on 1517 middle school students in Hunan, China. An online questionnaire was applied to collect data on the condition of LPR, consumption of free sugars and other self-reported covariates. Height, weight and waist circumference were collected by anthropometric measurements. Logistic regression was applied to assess the association between LPR and free sugars consumption. The mean and standard deviation of free sugars consumption was 53.14 ± 44.75 (g/d). The prevalence of LPR was 8.11%. A positive association was observed between LPR and higher free sugars consumption after adjusted multiple covariates, with adjusted odds ratio (95% confident interval) of 1.656 (1.125–2.438). The prevalence of LPR among Chinese adolescents was high. Further analytic studies with strict design are required to test the association between LPR and free sugar consumption. Systematic strategies and policies should to be developed to reduce the intake of free sugars in order to prevent LPR.

ASSESSMENT OF THE INTESTINAL MICROBIOTA IN ADULTS WITH EROSIVE ESOPHAGITIS

BACKGROUND

The intestinal microbiota influences the appropriate function of the gastrointestinal tract. Intestinal dysbiosis may be associated with a higher risk of esophageal lesions, mainly due to changes in gastroesophageal motility patterns, elevation of intra-abdominal pressure, and increased frequency of transient relaxation of the lower esophageal sphincter.

OBJECTIVE

The aim of this study was to evaluate the intestinal microbiota in individuals with erosive esophagitis and in healthy individuals using metagenomics.

METHODS

A total of 22 fecal samples from adults aged between 18 and 60 years were included. Eleven individuals had esophagitis (eight men and three women) and 11 were healthy controls (10 men and one woman). The individuals were instructed to collect and store fecal material into a tube containing guanidine solution. The DNA of the microbiota was extracted from each fecal samples and PCR amplification was performed using primers for the V4 region of the 16S rRNA gene. The amplicons were sequenced using the Ion Torrent PGM platform and the data were analyzed using the QIIME™ software version 1.8. Statistical analyses were performed using the Mann-Whitney non-parametric test and the ANOSIM non-parametric method based on distance matrix.

RESULTS

The alpha-diversity and beta-diversity indices were similar between the two groups, without statistically significant differences. There was no statistically significant difference in the phylum level. However, a statistically significant difference was observed in the abundance of the family Clostridiaceae (0.3% vs 2.0%, P=0.032) and in the genus Faecaliumbacterium (10.5% vs 4.5%, P=0.045) between healthy controls and esophagitis patients.

CONCLUSION

The findings suggest that reduced abundance of the genus Faecaliumbacterium and greater abundance of the family Clostridiaceae may be risk factors for the development of erosive esophagitis. Intervention in the composition of the intestinal microbiota should be considered as an adjunct to current therapeutic strategies for this clinical condition.

Effects of synbiotic supplement on body weight and fasting blood glucose levels in obesity: A randomized placebo-controlled trial

BACKGROUND

Obesity and diabetes are related. The role of gut microbiota disruption in obesity has been reported as a cause of several metabolic diseases including diabetes.

OBJECTIVES

Evaluate the effects of synbiotic supplementation (a combination of probiotic and prebiotic) on body weight (BW), Body Mass Index (BMI), and Fasting Blood Glucose (FBG) in obese subjects.

METHODS

This study was a randomized, double-blind placebo-controlled. Participants were allocated with randomization into 2 groups: the obese group with synbiotic supplementation and the obese group with placebo; each group consists of 8 participants. BW, BMI, and FBG level were measured at baseline, 8 weeks after supplementation, and 4 weeks after terminating the supplementation.

RESULTS

There were no significant change of body weight and BMI after 8 weeks synbiotics supplementation and 4 weeks after supplement discontinuation, but there were significant increases in body weight by 3.38 kg and BMI by 1.37 kg/m2 in the control group. Fasting blood glucose levels were significantly decreased by 6.125 mg/dL after synbiotic supplementation. FBG did not resume 4 weeks after terminating the supplementation. In contrast, there was a significant increase of FBG in control group on week 8 and was further increased 4 weeks after placebo was discontinued.

CONCLUSIONS

Synbiotic supplementation may prevent increase of body weight and BMI in obesity and this may be related with lower fasting blood glucose levels.

Effect of oligofructose on resistance to postoperative high-fat diet-induced damage of metabolism in diabetic rats after sleeve gastrectomy

BACKGROUND

Sleeve gastrectomy (SG) can induce prominent remission of type 2 diabetes mellitus. However, the long-term remission rate of diabetes usually decreases over time. Oligofructose has been verified to modulate host metabolism. The aim of this study was to explore the protective effect of oligofructose on high-fat diet (HFD)-induced metabolic dysfunction after SG.

AIM

To study the effect and mechanism of oligofructose on diabetic remission in diabetic rats after SG.

METHODS

SG and SHAM operation were performed on diabetes rats induced with an HFD, nicotinamide, and low-dose streptozotocin. Then the rats in the SHAM and SG groups were continuously provided with the HFD, and the rats in sleeve gastrectomy-oligofructose group were provided with a specific HFD containing 10% oligofructose. Body weight, calorie intake, oral glucose tolerance test, homeostasis model assessment of insulin resistance, lipid profile, serum insulin, glucagon-like peptide 1 (GLP-1), total bile acids, lipopolysaccharide (LPS), and colonic microbiota levels were determined and compared at the designated time points. All statistical analyses were performed using Statistic Package for Social Science version 19.0 (IBM, United States), and the statistically significant difference was considered at P < 0.05.

RESULTS

At 2 wk after surgery, rats that underwent SG exhibited improved indexes of glucose and lipid metabolism. Compared with the SG group, the rats from SG-oligofructose group exhibited better parameters of glucose and lipid metabolism, lower body weight (526.86 ± 21.51 vs 469.25 ± 21.84, P < 0.001), calorie intake (152.14 ± 9.48 vs 129.63 ± 8.99, P < 0.001), homeostasis model assessment of insulin resistance (4.32 ± 0.57 vs 3.46 ± 0.52, P < 0.05), and LPS levels (0.19 ± 0.01 vs 0.16 ± 0.01, P < 0.05), and higher levels of insulin (1.17 ± 0.17 vs 1.58 ± 0.16, P < 0.001) and GLP-1 (12.39 ± 1.67 vs 14.94 ± 1.86, P < 0.001), and relative abundances of Bifidobacterium (0.0034 ± 0.0014 vs 0.0343 ± 0.0064, P < 0.001), Lactobacillus (0.0161 ± 0.0037 vs 0.0357 ± 0.0047, P < 0.001), and Akkermansia muciniphila (0.0050 ± 0.0024 vs 0.0507 ± 0.0100, P < 0.001) at the end of the study. However, no difference in total bile acids levels was observed between the two groups.

CONCLUSION

Oligofructose partially prevents HFD-induced glucose and lipid metabolism damage after SG, which may be due to the changes of calorie intake, insulin, GLP-1, LPS, and the gut microbiota in rats.

The Natural History of Chronic Unexplained Gastrointestinal Disorders and Gastroesophageal Reflux During 20 Years: A US Population-Based Study

OBJECTIVE

To explore the natural history of chronic unexplained gastrointestinal (GI) symptoms and to determine the longitudinal trends of prevalence during a 20-year period in a single US community.

METHODS

Between January 1, 1990, and December 31, 2009, valid self-report questionnaires of GI symptoms were mailed to randomly selected cohorts of a community. The study used respondents who answered questions on 1 or more of 3 surveys (initial, 1990-1992; second, 2003-2004; and third, 2008-2009). The trends of prevalence of GI symptoms over time were analyzed in responders who completed 3 surveys, and the natural history or transition was evaluated.

RESULTS

The overall prevalence of major symptom groupings including gastroesophageal reflux disease was consistent among residents in a community on 3 survey time points (1990-1992, 2003-2004, and 2008-2009). The transitions of GI symptoms were common in 228 patients who responded to all 3 surveys; only 29% had the same symptom category in 3 surveys; otherwise, symptoms changed over time, resolving, recurring, or transitioning to another disorder. Observed proportions of symptom transitions were significantly different from expected during 20 years (P<.001). Higher non-GI somatic symptom scores were significantly associated with both symptom transitions (odds ratio, 3.9; 95% CI, 1.38 to 10.77) and having sustained symptoms (odds ratio, 12.7; 95% CI, 4.62 to 34.90).

CONCLUSION

The overall population prevalence of chronic unexplained GI symptoms is stable, but in individuals, transitions seem to be the rule. As these various GI syndromes appear to be so intimately interconnected, the common underlying pathogenesis may account for a major subgroup of chronic unexplained GI disorders.

Optimal management of severe symptomatic gastroesophageal reflux disease

Gastroesophageal reflux disease (GERD) is a common disorder, and empirical proton pump inhibitor (PPI) treatment is often the first step of management; however, up to 40% of patients remain symptomatic despite PPI treatment. Refractory reflux refers to continued symptoms despite an adequate trial of PPI, and management remains challenging. The differential diagnosis is important; other oesophageal (e.g. eosinophilic oesophagitis) and gastroduodenal disorders (e.g. functional dyspepsia) should be ruled out, as this changes management. A combination of clinical assessment, endoscopic evaluation and in selected cases oesophageal function testing can help characterize patients with refractory reflux symptoms into oesophageal phenotypes so appropriate therapy can be more optimally targeted. Medical options then may include adding a H2 receptor antagonist, alginates, baclofen or antidepressant therapy, and there is emerging evidence for bile acid sequestrants and diaphragmatic breathing. The demonstration of a temporal association of symptoms with reflux events on pH-impedance testing (reflux hypersensitivity) serves to focus the management on modulating oesophageal perception and reducing the reflux burden, or identifies those with no obvious pathophysiologic abnormalities (functional heartburn). Anti-reflux surgery based on randomized controlled trial evidence has a role in reflux hypersensitivity or continued pathological acid reflux despite PPI in carefully considered, fully worked up cases that have failed medical therapy; approximately two of three cases will respond but there is a small risk of complications. In patients with persistent volume reflux despite medical therapy, given the lack of alternatives, anti-reflux surgery is a consideration. Promising newer approaches include endoscopic techniques. This review aims to summarize current diagnostic approaches and critically evaluates the evidence for the efficacy of available treatments.

Acute postprandial effect of yacon syrup ingestion on appetite: A double blind randomized crossover clinical trial

Yacon syrup is a rich source of fructooligosaccharides (FOS); however, its diet supplementation effect on subjective sensation and appetite biomarkers in human is still unknown. This study aimed to evaluate the acute postprandial effect of yacon syrup ingestion on appetite. The double-blind crossover clinical trial was carried out with 40 adult women: 20 eutrophic and 20 obese grade I. On each day, the first blood collection was performed after a 12-h fast. Then, the volunteers ingested either intervention A (breakfast + 40 g of placebo) or intervention B (breakfast + 40 g of yacon syrup, containing 14 g of FOS). New aliquots of blood were collected at 45, 60, 90, 120, and 180 min. Appetite was assessed by estimating ghrelin and glucagon-like peptide-1 (GLP-1) levels and by assessing subjective appetite sensation. Analysis was performed using two-way ANOVA, followed by Bonferroni's multiple comparison test. No effect of yacon syrup was observed on postprandial ghrelin and GLP-1 levels at all times evaluated. Similar observations were made after stratifying the analysis by BMI (body mass index) (eutrophic and obese). The effect of yacon syrup on postprandial subjective sensations of hunger, satiety, fullness, and desire to eat was not evident in the total group of women evaluated and even after BMI stratification. We concluded that yacon syrup had no effect on postprandial ghrelin and GLP-1 levels and on the subjective appetite sensation in young adult women.

The interaction between microbiome and host central nervous system: the gut-brain axis as a potential new therapeutic target in the treatment of obesity and cardiometabolic disease

INTRODUCTION

The role of the intestinal microbiota in host cardiometabolic health and disease has gained significant attention over recent decades. Previous studies have shown effects on metabolic health through gut microbiota modulation; this suggests diverse interaction pathways that constitute the communication between gut microbiota and host central nervous system, the so-called gut-brain axis.

AREAS COVERED

This article provides an overview of the various mechanisms that may mediate the gut-brain axis. It places an emphasis on cardiometabolic health, including effects of short-chain fatty acids (SCFA), alterations in neurotransmitters and gut peptides and microbial effects on chronic inflammation and immune function. Moreover, this paper sheds light on whether these mechanisms afford therapeutic targets to promote metabolic health. To this end, a PubMed search with the terms 'gut microbiota,' 'obesity' and 'insulin sensitivity' was performed.

EXPERT OPINION

Many properties of the human gut microbiome are associated with the central regulation of appetite and metabolic status. Some of these relationships are causal and there are positive effects from certain intervention methods. Microbial manipulation may offer a means to prevent or treat obesity and associated co-morbidities. However, to establish direct causal relations between altered gut microbiota and metabolic disease, clinical intervention studies are necessary.

Bacillus coagulans (PROBACI) in treating constipation-dominant functional bowel disorders

Bacillus coagulans (PROBACI) bacteria have been examined for efficacy against infectious or inflammatory bowel diseases. The aim of this observational and cross-sectional study was to evaluate the effects of PROBACI against various functional bowel symptoms.Thirty-eight enrolled patients (36.5 ± 12.6 years) with functional bowel disorders in a gastrointestinal clinic were administered PROBACI (300-mg formulation containing 1 × 10 colony-forming units of B coagulans) twice/day over a 4-week period. Abdominal pain, abdominal distention, and global assessment were evaluated using a 5-point visual analog scale. The defecation characteristics, discomfort level, and effort required for defecation were recorded. The gut-microbiota composition in terms of the Firmicutes/Bacteroidetes ratio was analyzed by 16S-ribosomal RNA gene sequencing with stool samples at days 0, 14, and 28 post-treatment.The 38 patients achieved significant improvements in abdominal pain (2.8 ± 0.5 to 3.3 ± 0.7, P = .0009), abdominal distention (2.5 ± 0.7 to 3.2 ± 0.8, P = .0002), and global assessment (2.7 ± 0.6 to 3.6 ± 0.7, P = .0001) from days 0 to 14. Compared with the diarrhea group, the constipation group achieved greater improvements in terms of discomfort during defecation (2.5 ± 0.7 to 3.1 ± 0.7, P = .02) and normalization of defecation style (50% vs 7.1%, P = .007) by day 28. A difference was observed in the Firmicutes/Bacteroidetes ratio between the constipation-dominant group (118.0) and diarrhea-dominant group (319.2), but this difference was not significant.PROBACI provided control of abdominal pain, less discomfort during defecation, and a more normalized defecation style, especially in the constipation-dominant group.

Mechanism and Pathophysiology of Gastroesophageal Reflux Disease

Gastroesophageal reflux (GER) describes a process in which gastric contents travel retrograde into the esophagus. GER can be either a physiologic phenomenon that occurs in asymptomatic individuals or can potentially cause symptoms. When the latter occurs, this represents GER disease (GERD). The process by which GER transforms into GERD begins at the esophagogastric junction. Impaired clearance of the refluxate also contributes to GERD. Reflux causes degradation of esophageal mucosal defense. The refluxate triggers sensory afferents leading to symptom generation.

Acute administration of fructans increases the number of transient lower esophageal sphincter relaxations in healthy volunteers

INTRODUCTION

Dietary measures are often advised to patients with gastro-esophageal reflux disease (GERD). Fermentable Oligo-, Di-, Mono-saccharides and Polyols (FODMAPs) induce lower gastrointestinal (GI) symptoms. However, their effects on esophageal motility, including transient lower esophageal sphincter relaxations (TLESRs), reflux events and GERD symptoms are unknown. We investigated the effect of acute administration of two FODMAPs, fructose, and fructans, on the number of TLESRs, reflux episodes and symptom perception in healthy volunteers (HVs).

MATERIALS

After an overnight fast, 20 HVs (10 males; 32.6 ± 2.8 years) underwent a high-resolution impedance manometry. The number of TLESRs and reflux episodes was quantified during five hours after consumption of a high-caloric meal (740 kcal) enriched with 40 g of either fructose, fructans or glucose (as placebo). Results were analyzed using mixed models.

RESULTS

There was a trend for a change in the number of TLESRs between the three conditions (P = .06). Post hoc analysis revealed a trend toward a higher number of TLESRs in the fructan condition compared with placebo (P_corr  = .06). Acute administration of fructose did not influence the number of TLESRs. The total number of reflux events was not affected by either FODMAP condition. Lower esophageal sphincter (LES) pressures dropped significantly in the first postprandial hour to recover slowly back to baseline values (P < .0001), without any difference in LES pressure between the three conditions.

CONCLUSION

Ingestion of fructans increased the number of TLESRs slightly compared with placebo. The effect of FODMAPs such as fructans or a low FODMAP diet on reflux parameters in GERD patients remains to be investigated.

Gastroesophageal Reflux Disease: Pathophysiology, Diagnosis, and Treatment

Gastroesophageal reflux disease (GERD) is a common chronic disorder in industrialized countries. Gastroesophageal reflux disease is one of the most frequent diseases encountered by primary care providers. The primary symptoms of GERD include heartburn, regurgitation, globus sensation, dysphagia, chest pain, and belching. If symptoms are left untreated, a major concern is complications and the potential risk of esophageal adenocarcinoma associated with GERD. With the increasing prevalence and incidence of GERD and the increasing cost of this disease, there is a need for advanced practice registered nurses to understand the nature of GERD including its pathophysiology, signs and symptoms, and treatment options to address the disease.

The Gluten-Free Diet: Use in Digestive Disease Management

PURPOSE OF REVIEW

Gluten is a commonly ingested polymeric protein found in wheat, barley, and rye that has gained recent notoriety because of its relationship to disease and health. Avoidance of gluten is appropriate in patients with a diagnosed gluten-related disorder and may have treatment implications in other diseases of the digestive tract. This review highlights current knowledge of gluten related disorders and the use of a gluten-free diet in gastrointestinal disease management.

RECENT FINDINGS

Gluten-free diets should be used in patients with a diagnosed gluten-related disorder including celiac disease, non-celiac gluten sensitivity, and wheat-sensitive eosinophilic esophagitis. Use of this diet in management of other digestive conditions including gastroesophageal reflux disease, irritable bowel syndrome, and inflammatory bowel disease is controversial and not currently supported by the literature. This review provides a framework for classifying gluten-related disorders in terms of pathogenesis, understanding the literature that supports dietary avoidance in modulation of gastrointestinal disease, and identifies limitations of dietary restriction in patients.

The Gut Microbiome Influences Host Endocrine Functions

The gut microbiome is considered an organ contributing to the regulation of host metabolism. Since the relationship between the gut microbiome and specific diseases was elucidated, numerous studies have deciphered molecular mechanisms explaining how gut bacteria interact with host cells and eventually shape metabolism. Both metagenomic and metabolomic analyses have contributed to the discovery of bacterial-derived metabolites acting on host cells. In this review, we examine the molecular mechanisms by which bacterial metabolites act as paracrine or endocrine factors, thereby regulating host metabolism. We highlight the impact of specific short-chain fatty acids on the secretion of gut peptides (i.e., glucagon-like peptide-1, peptide YY) and other metabolites produced from different amino acids and regulating inflammation, glucose metabolism, or energy homeostasis. We also discuss the role of gut microbes on the regulation of bioactive lipids that belong to the endocannabinoid system and specific neurotransmitters (e.g., γ-aminobutyric acid, serotonin, nitric oxide). Finally, we review the role of specific bacterial components (i.e., ClpB, Amuc_1100) also acting as endocrine factors and eventually controlling host metabolism. In conclusion, this review summarizes the recent state of the art, aiming at providing evidence that the gut microbiome influences host endocrine functions via several bacteria-derived metabolites.

The role of diet in the development and management of gastroesophageal reflux disease: why we feel the burn

Gastroesophageal reflux disease (GERD) is a common esophageal disorder that is characterized by troublesome symptoms associated with increased esophageal acid exposure. Cornerstones of therapy include acid suppressive agents like proton pump inhibitors (PPI) and lifestyle modifications including dietary therapy, although the latter is not well defined. As concerns regarding long term PPI use continue to be explored, patients and providers are becoming increasingly interested in the role of diet in disease management. The following is a review of dietary therapy for GERD with an emphasis on the effect food components have on pathophysiology and management. Although sequential dietary elimination of food groups is common, literature supports broader manipulation including reduction of overall sugar intake, increase in dietary fiber, and changes in overall eating practices.

Bile acids drive colonic secretion of glucagon-like-peptide 1 and peptide-YY in rodents

A large number of glucagon-like-peptide-1 (GLP-1)- and peptide-YY (PYY)-producing L cells are located in the colon, but little is known about their contribution to whole body metabolism. Since bile acids (BAs) increase GLP-1 and PYY release, and since BAs spill over from the ileum to the colon, we decided to investigate the ability of BAs to stimulate colonic GLP-1 and PYY secretion. Using isolated perfused rat/mouse colon as well as stimulation of the rat colon in vivo, we demonstrate that BAs significantly enhance secretion of GLP-1 and PYY from the colon with average increases of 3.5- and 2.9-fold, respectively. Furthermore, we find that responses depend on BA absorption followed by basolateral activation of the BA-receptor Takeda-G protein-coupled-receptor 5. Surprisingly, the apical sodium-dependent BA transporter, which serves to absorb conjugated BAs, was not required for colonic conjugated BA absorption or conjugated BA-induced peptide secretion. In conclusion, we demonstrate that BAs represent a major physiological stimulus for colonic L-cell secretion. NEW & NOTEWORTHY By the use of isolated perfused rodent colon preparations we show that bile acids are potent and direct promoters of colonic glucagon-like-peptide 1 and peptide-YY secretion. The study provides convincing evidence that basolateral Takeda-G protein-coupled-receptor 5 activation is mediating the effects of bile acids in the colon and thus add to the existing literature described for L cells in the ileum.

Review article: dietary fibre in the era of microbiome science

BACKGROUND

Explanations for the health benefits of dietary fibre have, in the past, been inconsistent and studies of the physiological effects of dietary fibre were, perhaps, directed at the wrong read-outs. Confounding factors included a failure to appreciate the molecular diversity and varied properties of fibre-types and the role of fibre as a substrate for microbial metabolism in the gut.

AIM

To present a modern perspective on fibre science and to encourage clinicians to re-consider the health impact of dietary fibre and how best to approach adjustments in dietary consumption.

METHODS

This perspective is drawn selectively from recent microbiome science; no attempt was made to perform an exhaustive review of all articles related to every aspect of dietary fibre.

RESULTS

Advances in microbiome science have revealed not only the functional impact of dietary fibre on the composition and function of the microbiota but have also demonstrated the physiologic responses to microbial-derived metabolites from fibre digestion. Moreover, studies have shown the personalised nature of host responses to dietary fibre intervention, with outcomes being dependent on individual pre-treatment gut ecology.

CONCLUSIONS

The physical properties of dietary fibres are important for homeostasis within the gut, but the predominant health benefits extend beyond the gut to enhanced metabolic welfare, including protection against obesity and related metabolic diseases. Fibre is a form of functional food joining a growing list of examples of diet-microbe-host interactions which link microbe-host metabolic and immune cascades.

Impact of Gut Microbiota on Host Glycemic Control

Given that obesity and associated disorder type II diabetes mellitus have reached epidemic proportions worldwide, the development of efficient prevention and therapeutic interventions is a global public health interest. There is now a large body of evidence suggesting that the micro-organisms colonizing the human gut, known as gut microbiota, play a central role in human physiology and metabolism. Understanding how gut microbiota affects and regulates key metabolic functions such as glucose regulation and insulin resistance is an important health issue. The present review summarizes recent advances in our understanding of how gut bacterial species interfere with host metabolic phenotype. We will examine key biological molecular mechanisms underlying the impact of gut microbiota on host glycemic control including: incretin secretion, short-chain fatty acid production, bile acid metabolism, and adipose tissue regulation. We will highlight how prebiotic/probiotic interventions affect these bacterial processes and are now considered as promising approaches to treat obese and diabetic patients.