Lactulose Challenge Determines Visceral Sensitivity and Severity of Symptoms in Patients With Irritable Bowel Syndrome

Common questions and rationale answers about the intestinal bacterial overgrowth syndrome (SIBO)

The recognition and treatment of intestinal bacterial overgrowth syndrome are matters of controversy. The symptoms that have guided the search for the disorder suffer from lack of specificity, especially in the absence of well-defined predisposing factors. The accuracy of diagnostic procedures has been questioned and the proposed therapies achieve generally low effectiveness figures, with large differences between available studies. It is also unknown whether the normalization of tests is really a guarantee of cure. Within this framework of uncertainty, and in order to contribute to the guidance and homogenization of medical practice, a group of experts from the AEG and ASENEM have formulated the key questions on the management of this pathology and have provided answers to them, in accordance with the available scientific evidence. In addition, they have drawn up statements based on the conclusions of the review and have voted on them individually to reflect the degree of consensus for each statement.

Dietary Intake and Quality in Irritable Bowel Syndrome: A Comparative Study With Controls and the Association With Symptom Severity

INTRODUCTION

Patients with irritable bowel syndrome (IBS) often attribute the onset or worsening of gastrointestinal symptoms to intake of food. Hence, to alleviate symptoms, patients with IBS may avoid triggering foods, potentially impacting their dietary intake and diet quality. This study aimed to compare the habitual diet intake and quality of patients with IBS with controls and to explore the association between dietary habits and symptoms in patients with IBS.

METHODS

Patients with IBS were included in 4 clinical studies reporting habitual dietary intakes at baseline. Age- and sex-matched controls representing the general population were derived from the Swedish population-based Riksmaten study. Dietary intakes were assessed using 4-day food diaries. Diet quality was measured using the diet quality index-Swedish national dietary guidelines (DQI-SNR), and diet diversity was scored based on the variety of food groups consumed.

RESULTS

The study included 646 patients with IBS and 646 controls (38 ± 14 years, 77% female). Both groups adhered to Nordic nutrition recommendations for macronutrients, except patients consumed fewer carbohydrates. Patients reported eating less carbohydrates, coffee, and dairy products and more fats, lactose-free dairy products, and nuts and seeds compared with controls. Fewer patients had a good diet quality according to the DQI-SNR. In patients, symptom severity and gastrointestinal-specific anxiety were associated with reduced energy and carbohydrate intake, lower diet diversity, and worse diet quality. Poor diet quality was associated with younger age, more severe IBS symptoms, anxiety, and depression.

DISCUSSION

Patients with IBS exhibit different dietary patterns compared with controls, with poorer dietary habits linked to more severe symptoms. Understanding food-symptom associations may enhance the optimization and personalization of dietary management for patients with IBS.

Altered Gut Microbic Flora and Haemorrhoids: Could They Have a Possible Relationship?

To date, the exact pathophysiology of haemorrhoids is poorly understood. The different philosophies on haemorrhoids aetiology may lead to different approaches of treatment. A pathogenic theory involving a correlation between altered anal canal microflora, local inflammation, and muscular dyssynergia is proposed through an extensive review of the literature. Since the middle of the twentieth century, three main theories exist: (1) the varicose vein theory, (2) the vascular hyperplasia theory, and (3) the concept of a sliding anal lining. These phenomena determine changes in the connective tissue (linked to inflammation), including loss of organization, muscular hypertrophy, fragmentation of the anal subepithelial muscle and the elastin component, and vascular changes, including abnormal venous dilatation and vascular thrombosis. Recent studies have reported a possible involvement of gut microbiota in gut motility alteration. Furthermore, dysbiosis seems to represent the leading cause of bowel mucosa inflammation in any intestinal district. The alteration of the gut microbioma in the anorectal district could be responsible for haemorrhoids and other anorectal disorders. A deeper knowledge of the gut microbiota in anorectal disorders lays the basis for unveiling the roles of these various gut microbiota components in anorectal disorder pathogenesis and being conductive to instructing future therapeutics. The therapeutic strategy of antibiotics, prebiotics, probiotics, and fecal microbiota transplantation will benefit the effective application of precision microbiome manipulation in anorectal disorders.

Low FODMAP diet reduces gastrointestinal symptoms in irritable bowel syndrome and clinical response could be predicted by symptom severity: A randomized crossover trial

BACKGROUND & AIMS

Fermentable oligo-, di-, monosaccharides and polyols (FODMAPs) can provoke symptoms in patients with irritable bowel syndrome (IBS). We aimed to compare the effects of diets with low vs. moderate FODMAP content on gastrointestinal (GI) symptoms and bowel habits, and to identify possible predictors of clinical response to a low FODMAP diet and FODMAP sensitivity in IBS.

METHODS

Adult participants with IBS (Rome IV criteria, n = 29) were included and adhered to two 7-day diet periods, with either low (4 g/day) or moderate (23 g/day) amounts of FODMAPs, in this randomized, double-blind, crossover study. The periods were separated by a wash-out period (≥14 days). IBS-Severity Scoring System (IBS-SSS) and a stool diary (Bristol Stool Form) were completed before and after the diet periods. At baseline, severity of GI symptoms and gut microbial fermentation were assessed (every 15 min, 4 h) during the Lactulose Nutrient Challenge Test (LNCT). Clinical response and FODMAP sensitivity were defined by reduction after low FODMAP period, and increase after moderate FODMAP period in IBS-SSS (≥50 points), respectively.

RESULTS

Severity of GI symptoms (P = 0.04), stool consistency (P = 0.01), and stool frequency (P = 0.01) differed between the interventions, with reduced overall GI symptom severity, abdominal pain intensity and frequency, bowel habits dissatisfaction, and daily life interference (P < 0.05 for all), as well as more firm (P = 0.03) and less frequent (P < 0.01) stools after low FODMAP intervention, but not after moderate FODMAP intervention. A third (34%) responded clinically to the low FODMAP diet, and the response could be predicted by higher IBS-SSS at baseline (P = 0.02). Although modest associations between FODMAP sensitivity (22%) and GI symptoms during LNCT were observed, no independent predictors could be identified.

CONCLUSIONS

A diet low in FODMAPs reduces GI symptoms and affects bowel habits in IBS, compared with a moderate FODMAP diet. Assessment of IBS severity before the intervention may be used to predict clinical response to a low FODMAP diet. Trial registry (http://www.

CLINICALTRIALS

gov): Registered under Clinical Trial number NCT05182593.

Irritable bowel syndrome with food-related symptoms: Future directions in the clinical management

The majority of patients with irritable bowel syndrome (IBS) experiences food-related symptoms, which are associated with high symptom burden, reduced quality of life, increased healthcare consumption and reduced intake of certain nutrients. In this review we aimed to describe a clinically useful approach for physicians, by presenting the latest progress in knowledge and its translation to management in IBS patients with food-related symptoms, as well as the underlying mechanisms involved. The research tools currently available that can be used in the future for a better characterization of this subgroup of patients are also discussed. Working towards this approach could lead to a more individualised work-up and management of IBS patients with food-related symptoms.

European guideline on indications, performance, and clinical impact of hydrogen and methane breath tests in adult and pediatric patients: European Association for Gastroenterology, Endoscopy and Nutrition, European Society of Neurogastroenterology and Motility, and European Society for Paediatric Gastroenterology Hepatology and Nutrition consensus

INTRODUCTION

Measurement of breath hydrogen (H2 ) and methane (CH4 ) excretion after ingestion of test-carbohydrates is used for different diagnostic purposes. There is a lack of standardization among centers performing these tests and this, together with recent technical developments and evidence from clinical studies, highlight the need for a European guideline.

METHODS

This consensus-based clinical practice guideline defines the clinical indications, performance, and interpretation of H2 -CH4 -breath tests in adult and pediatric patients. A balance between scientific evidence and clinical experience was achieved by a Delphi consensus that involved 44 experts from 18 European countries. Eighty eight statements and recommendations were drafted based on a review of the literature. Consensus (≥80% agreement) was reached for 82. Quality of evidence was evaluated using validated criteria.

RESULTS

The guideline incorporates new insights into the role of symptom assessment to diagnose carbohydrate (e.g., lactose) intolerances and recommends that breath tests for carbohydrate malabsorption require additional validated concurrent symptom evaluation to establish carbohydrate intolerance. Regarding the use of breath tests for the evaluation of oro-cecal transit time and suspected small bowel bacterial overgrowth, this guideline highlights confounding factors associated with the interpretation of H2 -CH4 -breath tests in these indications and recommends approaches to mitigate these issues.

CONCLUSION

This clinical practice guideline should facilitate pan-European harmonization of diagnostic approaches to symptoms and disorders, which are very common in specialist and primary care gastroenterology practice, both in adult and pediatric patients. In addition, it identifies areas of future research needs to clarify diagnostic and therapeutic approaches.

GWAS of stool frequency provides insights into gastrointestinal motility and irritable bowel syndrome

Gut dysmotility is associated with constipation, diarrhea, and functional gastrointestinal disorders like irritable bowel syndrome (IBS), although its molecular underpinnings are poorly characterized. We studied stool frequency (defined by the number of bowel movements per day, based on questionnaire data) as a proxy for gut motility in a GWAS meta-analysis including 167,875 individuals from UK Biobank and four smaller population-based cohorts. We identify 14 loci associated with stool frequency (p ≤ 5.0 × 10-8). Gene set and pathway analyses detected enrichment for genes involved in neurotransmitter/neuropeptide signaling and preferentially expressed in enteric motor neurons controlling peristalsis. PheWAS identified pleiotropic associations with dysmotility syndromes and the response to their pharmacological treatment. The genetic architecture of stool frequency correlates with that of IBS, and UK Biobank participants from the top 1% of stool frequency polygenic score distribution were associated with 5× higher risk of IBS with diarrhea. These findings pave the way for the identification of actionable pathological mechanisms in IBS and the dysmotility syndromes.

Adding a liquid test meal to a standardized lactulose hydrogen breath test significantly influences abdominal symptom generation and hydrogen values

OBJECTIVE

While single sugar tests are controversially discussed, combination tests with meals are gaining more attention. The aim of this study was to analyze the impact of adding a test meal to lactulose hydrogen breath tests (LHBT) on hydrogen values and abdominal symptoms in patients with functional gastrointestinal disorders (FGIDs).

METHODS

Data of 81 FGID patients between 2014-2018 were analyzed. Patients underwent LHBT with 30 g lactulose + 300 mL water and a nutrient challenge test (NCT) including 400 mL liquid test meal + 30 g lactulose. To statistically assess the effect of a test meal on abdominal symptoms and H2, mixed-effect models were used.

RESULTS

Adding a test meal to LHBT showed a significant increase in nausea [odds ratio (OR) 1.4; 95% confidence interval (CI), 1.1-1.7], decrease in abdominal pain (OR 0.7; 95% CI, 0.6-0.9), borborygmi (OR 0.5; 95% CI, 0.4-0.6), diarrhea (OR 0.4; 95% CI, 0.3-0.6), and H2 production (estimate -5.3, SE 0.7, P < 0.001). The effect on bloating was only significant in functional dyspepsia, irritable bowel syndrome-functional dyspepsia mixed type and functional abdominal pain/bloating (OR 0.1; 95% CI, 0.0-0.2; OR 1.7; 95% CI, 1.2-2.3 resp OR 4.4; 95% CI, 1.8-10.6).

CONCLUSIONS

Significant effects on abdominal symptoms and H2 production by adding a test meal to LHBT in FGID patients are shown. Increased occurrence of nausea may be caused by gastric/duodenal hypersensitivity; decreased H2, diarrhea and borborygmi by slower and more physiologic gastric emptying resulting in later arrival of the test substance in the bowel. We recommend NCTs instead of LHBT to more physiologically represent FGID patients' meal-induced burden.

Functional Gastrointestinal Disorders and the Microbiome-What Is the Best Strategy for Moving Microbiome-based Therapies for Functional Gastrointestinal Disorders into the Clinic?

There have been numerous human studies reporting associations between the intestinal microbiome and functional gastrointestinal disorders (FGIDs), and independently animal studies have explored microbiome-driven mechanisms underlying FGIDs. However, there is often a disconnect between human and animal studies, which hampers translation of microbiome findings to the clinic. Changes in the microbiota composition of patients with FGIDs are generally subtle, whereas changes in microbial function, reflected in the fecal metabolome, appear to be more precise indicators of disease subtype-specific mechanisms. Although we have made significant progress in characterizing the microbiome, to effectively translate microbiome science in a timely manner, we need concurrent and iterative longitudinal studies in humans and animals to determine the precise microbial functions that can be targeted to address specific pathophysiological processes in FGIDs. A systems approach integrating multiple data layers rather than evaluating individual data layers of symptoms, physiological changes, or -omics data in isolation will allow for validation of mechanistic insights from animal studies while also allowing new discovery. Patient stratification for clinical trials based on functional microbiome alterations and/or pathophysiological measurements may allow for more accurate determination of efficacy of individual microbiome-targeted interventions designed to correct an underlying abnormality. In this review, we outline current approaches and knowledge, and identify gaps, to provide a potential roadmap for accelerating translation of microbiome science toward microbiome-targeted personalized treatments for FGIDs.

Associations among neurophysiology measures in irritable bowel syndrome (IBS) and their relevance for IBS symptoms

Abnormal gut-brain interactions are common in irritable bowel syndrome (IBS), but the associations between neurophysiological measures and their relation to gastrointestinal (GI) symptoms are poorly understood. Our aim was to explore these relationships and define the most relevant neurophysiology measures for GI symptom severity in IBS. IBS patients underwent small intestinal motility (manometry; fasted and fed contraction frequency, phase III time) and secretion (transmural potential difference), rectal sensorimotor (barostat; sensory thresholds, tone response, compliance), autonomic nervous system (baroreceptor sensitivity and effectiveness), and colonic motor function (transit time) examinations. GI symptom severity (GSRS-IBS), and anxiety and depression (HAD) as a proxy measure of central nervous system (CNS) dysfunction, were assessed. In total 281 IBS patients (Rome II criteria) were included (74% females, median age 36 [interquartile range 28-50] years). Significant correlations between neurophysiology measures were stronger within, rather than between, different neurophysiological examinations. The strongest neurophysiology-symptom correlations occurred between a combination of CNS and visceral sensitivity parameters, and GSRS-IBS total score and pain domain (ρ = 0.40, p < 0.001, and ρ = 0.38, p < 0.001). Associations between GI symptoms in IBS and individual and combinations of neurophysiological factors occurred, primarily in CNS and visceral sensitivity measures, providing new insights into the clinical presentation of IBS.

A Hydrogel Drink With High Fructose Content Generates Higher Exogenous Carbohydrate Oxidation and Lower Dental Biofilm pH Compared to Two Other, Commercially Available, Carbohydrate Sports Drinks

The purpose of this study was to evaluate the substrate oxidation of three commercially available, 14%-carbohydrate sports drinks with different compositions, osmolality, and pH for their impact on dental exposure to low pH. In a cross-over, randomized double-blinded design, 12 endurance athletes (age 31. 2 ± 7.7 years, V ˙ O_2max 65.6 ± 5.0 mL·kg^-1) completed 180 min of cycling at 55% W_max. During the first 100 min of cycling, athletes consumed amylopectin starch (AP), maltodextrin+sucrose (MD+SUC), or maltodextrin+fructose hydrogel (MD+FRU) drinks providing 95 g carbohydrate·h^-1, followed by water intake only at 120 and 160 min. Fuel use was determined using indirect calorimetry and stable-isotope techniques. Additionally, dental biofilm pH was measured using the microtouch method in a subsample of participants (n = 6) during resting conditions before, and at different time intervals up to 45 min following a single bolus of drink. Exogenous carbohydrate oxidation (CHO_EXO) during the 2nd hour of exercise was significantly (P < 0.05) different between all three drinks: MD+FRU (1.17 ± 0.17 g·min^-1), MD+SUC (1.01 ± 0.13 g·min^-1), and AP (0.84 ± 0.11 g·min^-1). At the end of exercise, CHO_EXO and blood glucose concentrations (3.54 ± 0.50, 4.07 ± 0.67, and 4.28 ± 0.47 mmol·L^-1, respectively) were significantly lower post MD+FRU consumption than post MD+SUC and AP consumption (P < 0.05). Biofilm acidogenicity at rest demonstrated a less pronounced pH fall for MD+FRU compared to the acidulant-containing MD+SUC and AP (P < 0.05). In conclusion, while total intake of MD+FRU showed signs of completed uptake before end of monitoring, this was less so for MD+SUC, and not at all the case for AP. Thus, this study showed that despite carbohydrates being encapsulated in a hydrogel, a higher CHO_EXO was observed following MD+FRU drink ingestion compared to AP and MD+SUC consumption upon exposure to the acidic environment of the stomach. This finding may be related to the higher fructose content of the MD+FRU drink compared with the MD+SUC and AP drinks. Furthermore, a carbohydrate solution without added acidulants, which are commonly included in commercial sport drinks, may have less deleterious effects on oral health.

The gut microbiome as a predictor of low fermentable oligosaccharides disaccharides monosaccharides and polyols diet efficacy in functional bowel disorders

PURPOSE OF REVIEW

Fermentable oligosaccharides disaccharides monosaccharides and polyols (FODMAP) dietary restriction ameliorates irritable bowel syndrome (IBS) symptoms; however, not all individuals with IBS respond. Given the gut microbiome's role in carbohydrate fermentation, investigators have evaluated whether the gut microbiome may predict low FODMAP diet efficacy.

RECENT FINDINGS

Gut microbiome fermentation, even to the same carbohydrate, is not uniform across all individuals with several factors (e.g. composition) playing a role. In both children and adults with IBS, studies are emerging suggesting the gut microbiome may predict low FODMAP diet efficacy. However, there is significant heterogeneity in the approaches (study population, microbiome assessment methods, statistical techniques, etc.) used amongst these studies.

SUMMARY

The gut microbiome holds promise as a predictor of low FODMAP diet efficacy. However, further investigation using standardized approaches to evaluate the microbiome while concomitantly assessing other potential predictors are needed to more rigorously evaluate this area.

Effects of supplementing with an 18% carbohydrate-hydrogel drink versus a placebo during whole-body exercise in -5 °C with elite cross-country ski athletes: a crossover study

Background

Whilst the ergogenic effects of carbohydrate intake during prolonged exercise are well-documented, few investigations have studied the effects of carbohydrate ingestion during cross-country skiing, a mode of exercise that presents unique metabolic demands on athletes due to the combined use of large upper- and lower-body muscle masses. Moreover, no previous studies have investigated exogenous carbohydrate oxidation rates during cross-country skiing. The current study investigated the effects of a ¹³C-enriched 18% multiple-transportable carbohydrate solution (1:0.8 maltodextrin:fructose) with additional gelling polysaccharides (CHO-HG) on substrate utilization and gastrointestinal symptoms during prolonged cross-country skiing exercise in the cold, and subsequent double-poling time-trial performance in ~ 20 °C.

Methods

Twelve elite cross-country ski athletes (6 females, 6 males) performed 120-min of submaximal roller-skiing (69.3 ± 2.9% of \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \dot{\mathrm{V}} $$\end{document}V˙O₂peak) in −5 °C while receiving either 2.2 g CHO-HG·min^− 1 or a non-caloric placebo administered in a double-blind, randomized manner. Whole-body substrate utilization and exogenous carbohydrate oxidation was calculated for the last 60 min of the submaximal exercise. The maximal time-trial (2000 m for females, 2400 m for males) immediately followed the 120-min submaximal bout. Repeated-measures ANOVAs with univariate follow-ups were conducted, as well as independent and paired t-tests, and significance was set at P < 0.05. Data are presented as mean ± SD.

Results

Exogenous carbohydrate oxidation contributed 27.6 ± 6.6% to the total energy yield with CHO-HG and the peak exogenous carbohydrate oxidation rate reached 1.33 ± 0.27 g·min^− 1. Compared to placebo, fat oxidation decreased by 9.5 ± 4.8% with CHO-HG, total carbohydrate oxidation increased by 9.5 ± 4.8% and endogenous carbohydrate utilization decreased by 18.1 ± 6.4% (all P < 0.05). No severe gastrointestinal symptoms were reported in either trial and euhydration was maintained in both trials. Time-trial performance (8.4 ± 0.4 min) was not improved following CHO-HG compared to placebo (− 0.8 ± 3.5 s; 95% confidence interval − 3.0 to 1.5 s; P = 0.46). No sex differences were identified in substrate utilization or relative performance.

Conclusions

Ingestion of an 18% multiple-transportable carbohydrate solution with gelling polysaccharides was found to be well-tolerated during 120 min of submaximal whole-body exercise, but did not improve subsequent maximal double-poling performance.

The Incidence of Sexual Dysfunction in Patients With Irritable Bowel Syndrome

Introduction

Several studies have suggested that patients with irritable bowel syndrome (IBS) frequently have symptoms of sexual dysfunction.

Aim

The current study aims to map the current knowledge about the burden of sexual dysfunction in patients with IBS.

Methods

A literature review was conducted on PubMed and EMBASE using the following search terms or combinations thereof: irritable bowel syndrome; functional colonic disease; sexual function; sexual health; sexual behavior; sexual dysfunction; dyspareunia; erectile dysfunction; quality of life; and questionnaire.

Main Outcome Measure

Sexual dysfunction.

Results

1,273 texts were found, 331 duplicates were removed, and 844 texts were excluded because they did not meet the inclusion criteria, leaving 98 full text articles. These were examined and it was found that 41 fulfilled the criteria. 4 questionnaires were found; Irritable Bowel Syndrome Quality of Life (IBS-QOL) questionnaire, the Irritable Bowel Syndrome – Quality of Life (IBSQOL) questionnaire, the Irritable Bowel Syndrome-36 question (IBS-36) questionnaire, and the Arizona Sexual Experience Scale. Subscores for sexual relations in IBS-QOL ranged from 37.7−100 (11.9) for patients with IBS and 82.2−100 (6.6) for controls. The IBSQOL and IBS-36 subscores for sexual relations ranged from 49.7−90.5 (9) to 3.9−5.4 (0.8) with no healthy controls for comparison. After interventions were implemented, there was an improvement in subscores (the IBS-QOL mean changed to 10.5%, IBSQOL mean changed to 3.8%, and the IBS-36 mean changed to 40%). The study using Arizona Sexual Experience Scale showed that 51% of patients with IBS had sexual dysfunction and also scored lower on the IBSQOL questionnaire.

Conclusion

The information about sexual dysfunction in patients with IBS is sparse and emerges primarily from quality of life questionnaires. It seems as though patients with IBS have more sexual problems compared to controls, but further investigation regarding the extent and type of sexual dysfunction is needed.

Sørensen J, Schantz Laursen B, Drewes AM, et al. The Incidence of Sexual Dysfunction in Patients With Irritable Bowel Syndrome. Sex Med 2019;7:371–383.

The Dietary Management of Patients with Irritable Bowel Syndrome: A Narrative Review of the Existing and Emerging Evidence

Even though irritable bowel syndrome (IBS) has been known for more than 150 years, it still remains one of the research challenges of the 21st century. According to the current diagnostic Rome IV criteria, IBS is characterized by abdominal pain associated with defecation and/or a change in bowel habit, in the absence of detectable organic causes. Symptoms interfere with the daily life of patients, reduce health-related quality of life and lower the work productivity. Despite the high prevalence of approximately 10%, its pathophysiology is only partly understood and seems multifactorial. However, many patients report symptoms to be meal-related and certain ingested foods may generate an exaggerated gastrointestinal response. Patients tend to avoid and even exclude certain food products to relieve their symptoms, which could affect nutritional quality. We performed a narrative paper review of the existing and emerging evidence regarding dietary management of IBS patients, with the aim to enhance our understanding of how to move towards an individualized dietary approach for IBS patients in the near future.

Anxiety and depression in irritable bowel syndrome: Exploring the interaction with other symptoms and pathophysiology using multivariate analyses

BACKGROUND

Anxiety or depression, in other words, psychological distress, are common comorbidities in patients with irritable bowel syndrome (IBS), but their interaction with pathophysiological factors and other symptoms are unclear.

METHODS

Patients with IBS (Rome III criteria), thoroughly characterized regarding pathophysiology (colonic transit time, visceral sensitivity, and autonomic nervous system [ANS] function), symptom profile (IBS severity, somatic symptoms, gastrointestinal [GI]-specific anxiety and fatigue), and quality of life, were explored for differences regarding pathophysiology and symptoms between patients with and without reported psychological distress in univariate and multivariate analyses (Principal Component Analysis [PCA] with Hotelling's T² and Orthogonal Partial Least Squares-Discriminant Analysis [OPLS-DA]).

KEY RESULTS

When using Hospital Anxiety and Depression Scale score ≥8 as cut-off score, including both borderline and clinically significant cases, 345 (44.9%) out of 769 IBS patients reported anxiety, and 198 (25.7%) depression. In univariate analyses, patients reporting psychological distress demonstrated more severe GI and non-GI symptoms, fatigue, GI-specific anxiety and lower quality of life, and differences for some pathophysiological measures. IBS patients with and without reported psychological distress showed significant differences between the multivariate means in symptom reporting (PCA; both P < 0.001), and in pathophysiological measures in patients with and without anxiety (P = 0.018). Visceral hypersensitivity, altered ANS function, more severe GI-specific anxiety, fatigue, and higher somatic non-GI symptoms were the factors that most strongly separated patients with and without psychological distress (OPLS-DA).

CONCLUSIONS AND INFERENCES

Reported anxiety and depression are common in IBS patients, and our study demonstrates that they are interwoven in the complex pathophysiological and clinical picture of IBS.

Differentiation of functional gastrointestinal disorders from healthy volunteers by lactulose hydrogen breath test and test meal

BACKGROUND AND AIM

Functional dyspepsia (FD) is a common disorder of gut-brain interaction with incompletely understood pathophysiology. Consequently, heterogeneous expert opinions on diagnostic tests and assessment of treatment efficacies exist. So far, no consensus about the most relevant diagnostic and outcome tool has been reached. In this study, we aimed to analyze the significance of a combined lactulose hydrogen breath test (LHBT) and liquid meal, yet representing a standardized test in irritable bowel syndrome (IBS), in FD.

METHODS

We analyzed data of 146 FD, 204 IBS patients, and 50 healthy volunteers (HV). All patients underwent LHBT with a meal-drink consisting of 30-g Lactulose and 400-mL Ensure®. Effect of abdominal symptom generation in FD/IBS compared with HV was assessed on a patient-reported Likert-scale.

RESULTS

There was a significant difference between FD/IBS patients and HV in LHBT-induced abdominal pain (odds ratio [OR] 246.9, 95% confidence interval [CI] 26.6-2290.7; OR 161.2, 95% CI 16.9-1534.8), abdominal bloating (OR 384.8, 95% CI 92.9-2135.4; OR 524.1, 95% CI 114.7-3432.3), borborygmi (OR 9.9, 95% CI 2.2-46.9; OR 17.7, 95% CI 4.7-67.4), nausea only in FD (OR 174.4, 95% CI 15.5-5375.5), and diarrhea in IBS only (OR 25.8, 95% CI 2.0-7012.6). Hydrogen production was not significantly different in FD/IBS and HV.

CONCLUSIONS

In this study, we demonstrated significant differences in postprandial symptom generation in FD and IBS compared with HV after LHBT. This does not only allow us to discriminate FD/IBS from HV but may also represent a diagnostic and monitoring tool for FD/IBS in the future, including monitoring of treatment effects.

Fasting breath H2 and gut microbiota metabolic potential are associated with the response to a fermented milk product in irritable bowel syndrome

OBJECTIVES

Aim of this study was to assess the effect of a fermented milk product containing Bifidobacterium lactis CNCM I-2494 (FMP) on gastrointestinal (GI) symptoms and exhaled H2 and CH4 during a nutrient and lactulose challenge in patients with irritable bowel syndrome (IBS).

METHODS

We included 125 patients with IBS (Rome III). Fasted subjects were served a 400ml liquid test meal containing 25g lactulose. The intensity of eight GI symptoms and the amount of exhaled H2 and CH4 were assessed before and during 4h after meal intake. The challenge was repeated after 14 days consumption of FMP or a control product in a double-blind, randomized, parallel design. The metabolic potential of fecal microbiota was profiled using 16S MiSeq analysis of samples obtained before and after the intervention.

RESULTS

106 patients with IBS were randomized. No difference between FMP or control groups was found on GI symptoms or breath H2 and CH4 in the whole cohort. A post-hoc analysis in patients stratified according to their fasting H2 levels showed that in high H2 producers (fasting H2 level≥10ppm, n = 35), FMP consumption reduced fasting H2 levels (p = 0.003) and H2 production during the challenge (p = 0.002) and tended to decrease GI discomfort (p = 0.05) vs. control product. The Prevotella/Bacteroides metabolic potential at baseline was higher in high H2 producers (p<0.05) vs. low H2 producers and FMP consumption reduced this ratio (p<0.05) vs. control product.

CONCLUSIONS

The response to a fermented milk product containing Bifidobacterium lactis CNCM I-2494 (FMP) in patients with IBS seems to be associated with the metabolic potential of the gut microbiota.

TRIAL REGISTRATION

ClinicalTrial.gov NCT01252550. These results were presented as congress posters at Digestive Disease Week 2016 in San Diego, USA and United European Gastroenterology Week 2016 in Vienna, Austria.

The Gut Microbiome in Adult and Pediatric Functional Gastrointestinal Disorders

The importance of gut microbiota in gastrointestinal (GI) physiology was well described, but our ability to study gut microbial ecosystems in their entirety was limited by culture-based methods prior to the sequencing revolution. The advent of high-throughput sequencing opened new avenues, allowing us to study gut microbial communities as an aggregate, independent of our ability to culture individual microbes. Early studies focused on association of changes in gut microbiota with different disease states, which was necessary to identify a potential role for microbes and generate novel hypotheses. Over the past few years the field has moved beyond associations to better understand the mechanistic implications of the microbiome in the pathophysiology of complex diseases. This movement also has resulted in a shift in our focus toward therapeutic strategies, which rely on better understanding the mediators of gut microbiota-host cross-talk. It is not surprising the gut microbiome has been implicated in the pathogenesis of functional gastrointestinal disorders given its role in modulating physiological processes such as immune development, GI motility and secretion, epithelial barrier integrity, and brain-gut communication. In this review, we focus on the current state of knowledge and future directions in microbiome research as it pertains to functional gastrointestinal disorders. We summarize the factors that help shape the gut microbiome in human beings. We discuss data from animal models and human studies to highlight existing paradigms regarding the mechanisms underlying microbiota-mediated alterations in physiological processes and their relevance in human interventions. While translation of microbiome science is still in its infancy, the outlook is optimistic and we are advancing in the right direction toward precise mechanism-based microbiota therapies.

Update on Dietary Management of Childhood Functional Abdominal Pain Disorders

Diet plays a significant role for children with functional abdominal pain disorders. A large majority of these children identify at least 1 food that exacerbates their symptoms. Malabsorbed carbohydrates may have both direct and microbiome-mediated physiologic effects. There are several factors associated with carbohydrate symptom generation, including (1) the amount ingested, (2) ingestion with a meal, (3) small intestinal enzymatic activity, (4) consuming the carbohydrate with microorganisms capable of breaking down the carbohydrate, (5) the gut microbiome, and (6) host factors. Therapies include carbohydrate (single and/or comprehensive) restriction, selective prebiotic and/or enzyme supplementation. Fiber supplementation may also be beneficial.

Functional Dyspepsia and Severity of Psychologic Symptoms Associate With Postprandial Symptoms in Patients With Irritable Bowel Syndrome

BACKGROUND & AIMS

Patients with irritable bowel syndrome (IBS) have an increased response of postprandial symptoms to a combined lactulose nutrient challenge test, compared with healthy volunteers. We investigated the associations among comorbid functional dyspepsia (FD), severity of psychologic symptoms, and breath test results in response to this test.

METHODS

We performed a prospective study of 205 patients with IBS (Rome III criteria), 94 of whom also had FD (IBS-FD), and 83 healthy volunteers in Sweden from 2008 through 2015. All participants completed a breath hydrogen test after a 400-mL liquid meal with 25 g lactulose. Gastrointestinal (GI) symptom severity was assessed using a graded scale and digestive comfort was recorded before the meal and every 15 minutes until 240 minutes after the meal. GI symptom scores over time were compared between groups using linear mixed models with anxiety, depression, and somatization as covariates.

RESULTS

Average levels of all GI symptoms varied over time among all groups (P < .0001). Patients with IBS-FD had higher levels of bloating (P = .004), abdominal pain (P = .005), and lower levels of digestive comfort (P < .01) than patients with only IBS. We observed a difference in increase in abdominal pain from baseline between IBS-FD and IBS groups (P = .013). Anxiety levels were associated with levels of all symptoms (all P < .025) except abdominal pain, which was associated with somatization severity (P < .0001). Furthermore, anxiety levels associated with level of exhaled hydrogen (P = .0042).

CONCLUSIONS

In a prospective study of patients with IBS, we found those with FD to have increased GI symptoms before and after a liquid meal with lactulose. Anxiety and somatization have an independent additional effect. The presence of comorbid FD and levels of psychologic symptoms affect reports of food-related symptoms in patients with IBS. ClinicalTrial.gov no: NCT01252550.

Fermentable Sugar Ingestion, Gas Production, and Gastrointestinal and Central Nervous System Symptoms in Patients With Functional Disorders

BACKGROUND & AIMS

Functional gastrointestinal disorders (FGID) are defined by broad phenotypic descriptions and exclusion of recognizable disease. FGIDs cause multi-organ symptoms and abnormal results in a wide range of laboratory tests, indicating broad mechanisms of pathogenesis. Many patients with FGID develop symptoms following ingestion of fermentable sugars; we investigated the associations between symptoms and intestinal gas production following sugar provocation tests to elucidate mechanisms of FGID.

METHODS

We performed fructose and lactose breath tests in 2042 patients with a diagnosis of FGID (based on Rome III criteria), referred to a gastroenterology practice from January 2008 through December 2011. Medical and diet histories were collected from all subjects. Breath samples were collected before and each hour after, for 5 hours, subjects ingested fructose (35 g) and lactose (50 g) dissolved in 300 mL water. Hydrogen and methane gas concentrations were measured and GI and non-GI symptoms were registered for 5 hours following sugar ingestion. Symptom and gas time profiles were compared, treelet transforms were used to derive data-related symptom clusters, and the symptom severity of the clusters were analyzed for their association with breath gas characteristics.

RESULTS

We identified 11 GI and central nervous system (CNS) symptom profiles and hydrogen and methane breath concentrations that changed significantly with time following sugar ingestion. Treelet transform analysis identified 2 distinct clusters, based on GI and CNS symptoms. The severity scores for the GI and CNS symptoms correlated following ingestion of sugars (all, P < .0001). However, only the GI symptoms associated with hydrogen and methane gas production (all, P < .0001).

CONCLUSIONS

In an analysis of breath test results from more than 2000 patients with FGIDs, we identified clusters of GI and CNS symptoms in response to fructose of lactose ingestion. The association between specific symptoms and breath gas concentrations indicate distinct mechanisms of FGID pathogenesis, such as changes in the microbiome or mechanical and chemical sensitization. ClinicalTrials.gov ID: NCT02085889.

Visceral hypersensitivity is associated with GI symptom severity in functional GI disorders: consistent findings from five different patient cohorts

OBJECTIVE

Our aim was to evaluate the association between visceral hypersensitivity and GI symptom severity in large cohorts of patients with functional GI disorder (FGID) and to adjust for psychological factors and general tendency to report symptoms.

DESIGN

We included five cohorts of patients with FGIDs (IBS or functional dyspepsia; n=1144), who had undergone visceral sensitivity testing using balloon distensions (gastric fundus, descending colon or rectum) and completed questionnaires to assess GI symptom severity, non-GI somatic symptoms, anxiety and depression. Subjects were divided into sensitivity tertiles based on pain/discomfort thresholds. GI symptom severity was compared between sensitivity tertiles in each cohort and corrected for somatisation, and anxiety and depression.

RESULTS

In all five cohorts, GI symptom severity increased gradually with increasing visceral sensitivity, with significant differences in GI symptom severity between the sensitivity tertiles (p<0.0001), with small to medium effect sizes (partial η²: 0.047-0.11). The differences between sensitivity tertiles remained significant in all cohorts after correction for anxiety and depression, and also after correction for non-GI somatic symptom reporting in all of the cohorts (p<0.05).

CONCLUSIONS

A gradual increase in GI symptom severity with increasing GI sensitivity was demonstrated in IBS and functional dyspepsia, which was consistent across several large patient groups from different countries, different methods to assess sensitivity and assessments in different parts of the GI tract. This association was independent of tendency to report symptoms or anxiety/depression comorbidity. These findings confirm that visceral hypersensitivity is a contributor to GI symptom generation in FGIDs.

Fructans Exacerbate Symptoms in a Subset of Children With Irritable Bowel Syndrome

BACKGROUND & AIMS

Dietary fructans exacerbate symptoms in some, but not all, adults with irritable bowel syndrome (IBS). We sought to determine whether fructans worsen symptoms in children with IBS and whether clinical and psychosocial factors, and/or gas production, can identify those who are fructan sensitive.

METHODS

We performed a double-blind placebo-controlled (maltodextrin) cross-over trial of 23 children with IBS, based on pediatric Rome III criteria, from September 2014 through December 2016. At baseline, participants completed 1-week pain and stool diaries and a 3-day food record and psychosocial factors (depression, anxiety, and somatization) were measured. Subjects were randomly assigned to groups that were provided meals for 72 hours containing either fructans or maltodextrin (0.5 g/kg; maximum, 19 g). Following a washout period of 10 days or more, the subjects received the meal they were not given during the first study period (crossed over). Gastrointestinal symptoms and breath hydrogen and methane production were captured during each meal period. Fructan sensitivity was defined as an increase of 30% or more in abdominal pain frequency following fructan ingestion.

RESULTS

Subjects had more mean episodes of abdominal pain/day during the fructan-containing diet (3.4 ± 2.6) vs the maltodextrin-containing diet (2.4 ± 1.7) (P < .01), along with more severe bloating (P < .05) and flatulence (P = .01). Hydrogen (but not methane) production was greater while subjects were on the fructan-containing diet (617 ± 305 ppm∗h) than the maltodextrin-containing diet (136 ± 78 ppm*h) (P < .001). Eighteen subjects (78.2%) had more frequent abdominal pain while on the fructan-containing diet and 12 (52.2%) qualified as fructan sensitive. We found no difference between fructan-sensitive and fructan-insensitive subjects in baseline abdominal pain or bowel movement characteristics, dietary intake, psychosocial parameters, IBS subtype, or gas production.

CONCLUSIONS

In a randomized controlled trial of children with IBS, we found fructans to exacerbate several symptoms. However, fructan sensitivity cannot be identified based on baseline gastrointestinal symptoms, dietary intake, psychosocial factors, or gas production. Clinicaltrials.gov no: NCT02842281.

Validation of Fatigue Impact Scale with various item sets - a Rasch analysis

PURPOSE

Fatigue is a symptom in patients with chronic gastrointestinal (GI) and liver diseases. Different instruments have been developed to assess the severity of fatigue and the 40-item Fatigue Impact Scale (FIS) is among the most widely used. Shorter versions of FIS include the 21-item Modified Fatigue Impact Scale (MFIS), and an eight-item version for everyday use. The study aimed to assess construct validity, reliability, and sufficiency of the raw score of the original FIS with 40 items, and examine the sufficiency of the 21 items from the Modified scale and the eight items of the Daily Fatigue Impact Scale (D-FIS), all of which are embedded in the 40-item scale.

METHODS

Patients with chronic GI or liver disease (n = 354) completed the FIS with 40 items. The majority (57%) was under the age of 55 years and approximately half were females (48%). Various item sets of FIS were derived which showed fit to the Rasch model.

RESULTS

Local dependency and multidimensionality in FIS and the 21-item Modified scale were resolved with a testlet solution but the D-FIS showed local dependency and multidimensionality and differential item functioning (DIF) still remained. Two new item sets fulfilling unidimensionality and no DIF are suggested, one with 15 items and a six-item scale for daily use. The transformation table shows score-interval scale estimates for all these item sets.

CONCLUSIONS

Both the FIS and the Modified scale can be used to measure fatigue albeit requiring some adjustment for DIF. The eight-item D-FIS is more problematic, and its summed score is not valid. Alternative 15- and 6-item versions presented in this paper can offer valid summed scores, and the transformation table allows transformation of raw scores and comparisons across all versions. Implications for rehabilitation The Fatigue Impact Scale and the Modified Fatigue Impact Scale can be used to measure fatigue after adjustments for differential item functioning. Alternative 15- and 6-item versions of Fatigue Impact Scale offer valid summed scores. The summed score for the Daily Fatigue Impact Scale is not valid. A transformation table with raw scores and Rasch transformed interval scale metric makes it possible to compare scores derived from the Fatigue Impact Scale, the Modified Fatigue Impact Scale and the proposed 15- and 6-item versions of Fatigue Impact Scale for research and/or clinical use.

Lactulose Breath Test Gas Production in Childhood IBS Is Associated With Intestinal Transit and Bowel Movement Frequency

OBJECTIVES

In adults with irritable bowel syndrome (IBS), bacterial gas production (colonic fermentation) is related to both symptom generation and intestinal transit. Whether gas production affects symptom generation, psychosocial distress, or intestinal transit in childhood IBS is unknown.

METHODS

Children (ages 7-17 years) with pediatric Rome III IBS completed validated psychosocial questionnaires and a 2-week daily diary capturing pain and stooling characteristics. Stool form determined IBS subtype. Subjects then completed a 3-hour lactulose breath test for measurement of total breath hydrogen and methane production. Carmine red was used to determine whole intestinal transit time.

RESULTS

A total of 87 children (mean age 13 ± 2.6 [standard deviation] years) were enrolled, of whom 50 (57.5%) were girls. All children produced hydrogen and 51 (58.6%) produced methane. Hydrogen and methane production did not correlate with either abdominal pain frequency/severity or psychosocial distress. Hydrogen and methane production did not differ significantly by IBS subtype. Methane production correlated positively with whole intestinal transit time (r = 0.31, P < 0.005) and inversely with bowel movement frequency (r = -0.245, P < 0.05). Methane production (threshold 3 ppm) as a marker for identifying IBS-C had a sensitivity of 60% and specificity of 42.9%.

CONCLUSIONS

Lactulose breath test total methane production may serve as a biomarker of whole intestinal transit time and bowel movement frequency in children with IBS. In children with IBS, lactulose breath test hydrogen and methane production did not, however, correlate with abdominal pain, IBS subtype, or psychosocial distress.

Emerging studies of human visceral nociceptors

Animal studies have led to significant advances in our understanding of pain mechanisms in the intestine that could lead to altered signaling in disorders such as irritable bowel syndrome. However, how these translate to the human afferent nervous system is unclear. Recent studies have demonstrated that it is possible to use a variety of techniques, including electrophysiological recordings, to begin to examine these concepts in humans. This mini-review examines these studies to explore how well animal studies translate to humans suffering from irritable bowel syndrome, highlights some of the advantages and technical limitations of these approaches, and identifies some priorities for future studies using human tissues.

Fecal incontinence in irritable bowel syndrome: Prevalence and associated factors in Swedish and American patients

BACKGROUND

Fecal incontinence (FI) is a prevalent but poorly recognized problem in the general population with profound negative effects on daily life. The prevalence of FI in irritable bowel syndrome (IBS) and its association with clinical, demographic, and pathophysiological factors remain largely unknown.

METHODS

One US (n=304) and one Swedish (n=168) patient cohort fulfilling Rome III criteria for IBS completed Rome III diagnostic questions on FI and IBS symptoms, and questionnaires on IBS symptom severity, quality of life, anxiety and depression, and work productivity impairment. The patients also underwent assessments of colorectal sensitivity and motility.

KEY RESULTS

Fecal incontinence ≥ one day per month was reported by 19.7% (USA) and 13.7% (Sweden) of IBS patients. These proportions rose to 43.4% and 29.8% if patients with less frequent FI were included. Fecal incontinence prevalence was higher in older age groups, with a clear increase above age 40. Irritable bowel syndrome patients with FI reported greater overall IBS symptom severity, more frequent and loose stools, and greater urgency. Negative effects of FI on quality of life, psychological distress, and work productivity were demonstrated. No associations were found between colorectal physiology and FI.

CONCLUSIONS & INFERENCES

Fecal incontinence is common in IBS patients, and similar to previous general population reports, the major risk factors for FI in IBS are older age, rectal urgency, and loose, frequent stools. When IBS patients have comorbid FI, the impact on quality of life, psychological symptoms, and work impairment appears greater.

Systemic symptoms in irritable bowel syndrome: An investigative study on the role of enterocyte disintegrity, endotoxemia and inflammation

Irritable bowel syndrome (IBS) is often accompanied by extra-intestinal symptoms, including fatigue and musculoskeletal pain. The present study aimed to investigate whether these symptoms were associated with markers of enterocyte disintegrity, endotoxemia and inflammation. Patients with IBS were recruited consecutively from our outpatient clinic (n=94) and compared with a group of healthy controls (n=20). Habitual symptoms were assessed using the IBS Severity Scoring System, the Fatigue Impact Scale and Visual Analogue Scales for measuring musculoskeletal pain. A lactulose challenge test was performed to induce post-prandial symptoms, and blood samples were obtained prior to and 90 min following lactulose ingestion to determine levels of intestinal fatty acid binding protein (iFABP), lipopolysaccharide (LPS), the LPS co-receptor soluble cluster of differentiation (sCD) 14, monocyte chemoattractant protein-1 (MCP-1) and calprotectin. Habitual symptom scores were high among the included patients, and lactulose ingestion induced significantly more symptoms in the patient group compared with the healthy control group (P=0.0001). Serum levels of iFABP were reduced in IBS patients compared with healthy controls, prior to and following lactulose ingestion (P=0.0002 and P=0.0001, respectively). Following lactulose ingestion, iFABP levels decreased in IBS patients (P=0.0001) and in healthy controls (P=0.02). Fasting levels of LPS, sCD14, MCP-1 and calprotectin were not significantly different between IBS patients and healthy controls. However, following lactulose ingestion, LPS levels increased in healthy controls (P=0.03), whereas MCP-1 levels decreased in IBS patients (P=0.008). Intestinal and extra-intestinal symptom severities were not correlated with levels of circulating biomarkers. No assessed biomarker in the present study appeared to be associated with symptom development in IBS patients. However, the implications of the low levels of iFABP observed require further investigation.

Gastrointestinal symptoms predictors of health-related quality of life in pediatric patients with functional gastrointestinal disorders

OBJECTIVES

To investigate the patient-reported multidimensional gastrointestinal symptoms predictors of generic health-related quality of life (HRQOL) in pediatric patients with functional gastrointestinal disorders (FGIDs).

METHODS

The Pediatric Quality of Life Inventory™ (PedsQL™) Gastrointestinal Symptoms Scales and PedsQL™ 4.0 Generic Core Scales were completed in a 9-site study by 259 pediatric patients with functional constipation, functional abdominal pain (FAP), or irritable bowel syndrome (IBS). Gastrointestinal Symptoms Scales measuring stomach pain, stomach discomfort when eating, food and drink limits, trouble swallowing, heartburn and reflux, nausea and vomiting, gas and bloating, constipation, blood in poop, and diarrhea were identified as clinically important symptom differentiators from healthy controls based on prior findings, and subsequently tested for bivariate and multivariate linear associations with overall HRQOL.

RESULTS

Gastrointestinal symptoms were differentially associated with decreased HRQOL in bivariate analyses for the three FGIDs. In predictive models utilizing hierarchical multiple regression analyses controlling for age, gender, and race/ethnicity, gastrointestinal symptoms differentially accounted for an additional 47, 40, and 60 % of the variance in patient-reported HRQOL for functional constipation, FAP, and IBS, respectively, reflecting large effect sizes. Significant individual gastrointestinal symptoms predictors were identified after controlling for the other gastrointestinal symptoms in the FGID-specific predictive models.

CONCLUSIONS

Gastrointestinal symptoms represent potentially modifiable predictors of generic HRQOL in pediatric patients with FGIDs. Identifying the condition-specific gastrointestinal symptoms that are the most important predictors from the patient perspective facilitates a patient-centered approach to targeted interventions designed to ameliorate impaired overall HRQOL.

Biomarkers to distinguish functional constipation from irritable bowel syndrome with constipation

Treatments for functional constipation (FC) and irritable bowel syndrome with constipation (IBS-C) differ, but symptom criteria do not reliably distinguish between them; some regard FC and IBS-C as parts of a single constipation spectrum. Our goal was to review studies comparing FC and IBS-C to identify possible biomarkers that separate them. A systematic review identified 15 studies that compared physiologic tests in FC vs IBS-C. Pain thresholds were lower in IBS-C than FC for 3/5 studies and not different in 2/5. Colonic motility was decreased more in FC than IBS-C for 3/3 studies, and whole gut transit was delayed more in FC than IBS-C in 3/8 studies and not different in 5/8. Pelvic floor dyssynergia was unrelated to diagnosis. Sympathetic arousal, measured in only one study, was greater in IBS-C than FC. The most reliable separation of FC from IBS-C was shown by a novel new magnetic resonance imaging technique described in this issue of the journal. These authors showed that drinking one liter of polyethylene glycol laxative significantly increased water content in the small intestine, volume of contents in the ascending colon, and time to first evacuation in FC vs IBS-C; and resulted in less colon motility and delayed whole gut transit in FC compared to IBS-C. Although replication is needed, this well-tolerated, non-invasive test promises to become a new standard for differential diagnosis of FC vs IBS-C. These data suggest that FC and IBS-C are different disorders rather than points on a constipation spectrum.

Advances in understanding role of brain-derived neurotrophic factor in physiological and pathological processes in the intestinal tract

Brain-derived neurotrophic factor is a kind of neurotrophic substance. In recent years, besides the central nervous system, brain-derived neurotrophic factor was also found to be expressed abundantly in the gastrointestinal tract, and it plays an important role in the development of the enteric nervous system and in regulating intestinal motility and visceral sensitivity. In this article, we review the role of brain-derived neurotrophic factor in the intestinal tract, and discuss its possible role in the pathogenesis of irritable bowel syndrome, with an aim to provide new ideas for clinical treatment of gastrointestinal diseases.