Impact of Bile Acid Diarrhea in Patients With Diarrhea-Predominant Irritable Bowel Syndrome on Symptoms and Quality of Life

Diet therapy (The 8×5 Diet) for adults living with bile acid diarrhoea: protocol for a feasibility randomised controlled trial

INTRODUCTION

A national research priority for people living with bile acid diarrhoea (BAD) is effective treatment options to improve their quality of life. This study aims to evaluate the feasibility of conducting a randomised controlled trial (RCT) of a novel healthy dietary pattern (The 8×5 Diet) to inform a future, larger trial.

METHODS AND ANALYSIS

We plan to enrol 76 UK adults living with BAD and ongoing diarrhoea using self-selection sampling and digital technologies. Eligible participants will be assigned to groups using permuted block randomisation using 1:1 allocation to receive either 8 weeks of usual care or The 8×5 Diet using one-to-one, dietitian counselling via a video-conferencing platform and developed digital resources. Randomisation, consent, recruitment, retention and acceptability will be evaluated using data from the RCT and post-trial interviews conducted with those in the intervention group. Secondary outcome exploratory assessment will include health-related quality of life, symptom relief, diarrhoea, diet quality, nutrient intakes and diet satisfaction.

ETHICS AND DISSEMINATION

Ethical approval was granted by the University of Manchester Research Ethics Committee (2024-19094-33261; V1.7, last updated: 24/02/2025).Findings will be disseminated through peer-reviewed publication, conference presentation and social media.

TRIAL REGISTRATION NUMBER

NCT06259396.

Bile acid diarrhea in patients with chronic diarrhea. Current appraisal and recommendations for clinical practice

Bile Acid Diarrhea (BAD) is a common cause of chronic diarrhea, often accompanied by urgency, occasional fecal incontinence, abdominal pain, and fatigue. A nationwide survey has shown limited awareness of BAD within the Italian medical community, prompting a panel of experts to develop a Position Paper that outlines the most practical and cost-saving diagnostic investigations and treatments for this frequently overlooked condition. The document provides an overview of the epidemiology, pathophysiology, clinical manifestations, and classification of the different types of Bile Acid Diarrhea (BAD). A key focus is the diagnostic approach to identifying and managing the many undiagnosed BAD patients in both primary care and specialized medical settings. Finally, the paper addresses the optimal therapeutic strategies for BAD, including traditional bile acid sequestrants and newer, promising treatments.

Beyond metabolic messengers: Bile acids and TGR5 as pharmacotherapeutic intervention for psychiatric disorders

Psychiatric disorders pose a significant global health challenge, exacerbated by the COVID-19 pandemic and insufficiently addressed by the current treatments. This review explores the emerging role of bile acids and the TGR5 receptor in the pathophysiology of psychiatric conditions, emphasizing their signaling within the gut-brain axis. We detail the synthesis and systemic functions of bile acids, their transformation by gut microbiota, and their impact across various neuropsychiatric disorders, including major depressive disorder, general anxiety disorder, schizophrenia, autism spectrum disorder, and bipolar disorder. The review highlights how dysbiosis and altered bile acid metabolism contribute to the development and exacerbation of these neuropsychiatric disorders through mechanisms involving inflammation, oxidative stress, and neurotransmitter dysregulation. Importantly, we detail both pharmacological and non-pharmacological interventions that modulate TGR5 signaling, offering potential breakthroughs in treatment strategies. These include dietary adjustments to enhance beneficial bile acids production and the use of specific TGR5 agonists that have shown promise in preclinical and clinical settings for their regulatory effects on critical pathways such as cAMP-PKA, NRF2-mediated antioxidant responses, and neuroinflammation. By integrating findings from the dynamics of gut microbiota, bile acids metabolism, and TGR5 receptor related signaling events, this review underscores cutting-edge therapeutic approaches poised to revolutionize the management and treatment of psychiatric disorders.

Advances in the pathophysiology, diagnosis and management of chronic diarrhoea from bile acid malabsorption: a systematic review

Bile acid malabsorption (BAM) is an important disorder of digestive pathophysiology as it generates chronic diarrhoea. This condition originates from intricate pathways involving bile acid synthesis and metabolism in the liver and gut, the composition of gut microbiota, enterohepatic circulation and key receptors as farnesoid X receptor (FXR), fibroblast growth factor receptor 4 (FGFR4), and the G-protein bile acid receptor-1 (GPBAR-1). Although symptoms can resemble those related to disorders of gut brain interaction, accurate diagnosis of BAM may greatly benefit the patient. The empiric diagnosis of BAM is primarily based on the clinical response to bile acid sequestrants. Specific tests including the 48-hour fecal bile acid test, serum levels of 7α-hydroxy-4-cholesten-3-one (C4) and fibroblast growth factor 19 (FGF19), and the 75Selenium HomotauroCholic Acid Test (SeHCAT) are not widely available. Nevertheless, lack of diagnostic standardization of BAM may account for poor recognition and delayed management. Beyond bile acid sequestrants, therapeutic approaches include the use of FXR agonists, FGF19 analogues, glucagon-like peptide-1 (GLP-1) receptor agonists, and microbiota modulation. These novel agents can best make their foray into the therapeutic armamentarium if BAM does not remain a diagnosis of exclusion. Ignoring BAM as a specific condition may continue to contribute to increased healthcare costs and reduced quality of life. Here, we aim to provide a comprehensive review of the pathophysiology, diagnosis, and management of BAM.

Managing bile acid diarrhea: aspects of contention

INTRODUCTION

Bile acid diarrhea is a common cause of bowel symptoms and often goes unrecognized or misdiagnosed. Many aspects of management remain contentious.

AREAS COVERED

The primary, idiopathic condition should be suspected in people with functional diarrhea or diarrhea-predominant irritable bowel syndrome. Secondary causes include ileal resection, inflammation, and post-cholecystectomy. Diagnostic tests vary globally, being unavailable in many countries, and further refinement of testing strategy is needed. Management is usually long-term symptom control, rather than reversal of the causative factors, which are still being defined. Bile acid sequestrants remain the main drugs used. They are relatively inexpensive, and better-quality data is now available for colesevelam. However, optimal use, including timing and formulation, needs clarification. The GLP-1 receptor agonist, liraglutide, is also effective, although mechanisms of action and whether this effect is common to other class members is unclear. They are more expensive, and availability varies. FXR agonists can also be effective but require further validation. The role of dietary factors in symptom development is a major patient concern, needing more formal studies.

EXPERT OPINION

To build on recent findings, bile acid diarrhea needs further investment into causes, diagnosis and therapy to guide present and future patient care.

Microbiota-Short Chain Fatty Acid Relationships Underlie Clinical Heterogeneity and Identify Key Microbial Targets in Irritable Bowel Syndrome (IBS)

Background

Identifying microbial targets in irritable bowel syndrome (IBS) and other disorders of gut-brain interaction (DGBI) is challenging due to the dynamic nature of microbiota-metabolite-host interactions. SCFA are key microbial metabolites that modulate intestinal homeostasis and may influence IBS pathophysiology. We aimed to assess microbial features associated with short chain fatty acids (SCFA) and determine if features varied across IBS subtypes and endophenotypes. Among 96 participants who were screened, 71 completed the study. We conducted in-depth investigations of stool microbial metagenomes, stool SCFA, and measurable IBS traits (stool bile acids, colonic transit, stool form) in 41 patients with IBS (IBS with constipation [IBS-C] IBS with diarrhea [IBS-D]) and 17 healthy controls. We used partial canonical correspondence analyses (pCCA), conditioned on transit, to quantify microbe-SCFA associations across clinical groups. To explore relationships between microbially-derived SCFA and IBS traits, we compared gut microbiome-encoded potential for substrate utilization across groups and within a subset of participants selected by their stool characteristics as well as stool microbiomes of patients with and without clinical bile acid malabsorption.

Results

Overall stool microbiome composition and individual taxa abundances differed between clinical groups. Microbes-SCFA associations differed across groups and revealed key taxa including Dorea sp. CAG:317 and Bifidobacterium pseudocatenulatum in IBS-D and Akkermansia muciniphila and Prevotella copri in IBS-C that that may drive subtype-specific microbially-mediated mechanisms. Strongest microbe-SCFA associations were observed in IBS-D and several SCFA-producing species surprisingly demonstrated inverse correlations with SCFA. Fewer bacterial taxa were associated with acetate to butyrate ratios in IBS compared to health. In participants selected by stool form, we demonstrated differential abundances of microbial genes/pathways for SCFA metabolism and degradation of carbohydrates and mucin across groups. SCFA-producing taxa were reduced in IBS-D patients with BAM.

Conclusion

Keystone taxa responsible for SCFA production differ according to IBS subtype and traits and the IBS microbiome is characterized by reduced functional redundancy. Differences in microbial substrate preferences are also linked to bowel functions. Focusing on taxa that drive SCFA profiles and stool form may be a rational strategy for identifying relevant microbial targets in IBS and other DGBI.

Food intolerance related to gastrointestinal symptoms amongst adults living with bile acid diarrhoea: A cross-sectional study

BACKGROUND

The role of food in managing bile acid diarrhoea (BAD) is poorly understood. The present study explored the prevalence of food intolerance amongst adults with BAD.

METHODS

The study comprised a cross-sectional survey of adults with BAD determined by the 75 selenium homotaurocholic acid test (SeHCAT) living in the UK. Participants anonymously completed an online questionnaire on 39 food items. Frequency of food in general affecting BAD symptoms, as well as frequencies of diarrhoea, abdominal pain, bloating, flatulence and consequential food avoidance after food item ingestion, were assessed. Food group avoidance was also assessed.

RESULTS

There were 434 participants who completed the questionnaire between April and May 2021 of whom 80% reported moderate to severe chronic diarrhoea. Food intolerances were reported by 88.0% (95% confidence interval [CI] = 84.6-90.9) of participants. Diarrhoea was reported most frequently after take-away food, fish and chips, creamy sauces, cream and large quantities of fruit (range 41.0%-33.6%). Lowest frequencies were for potato, avocado, mango, watermelon and pear (range 3.7%-7.4%) for the foods listed in the questionnaire. Similar trends were found for abdominal pain, bloating, flatulence and consequential food avoidance. Symptom-triggering within 30 min of ingestion was more prevalence than after 30 min for almost all foods. Food group avoidance was highest for fatty foods (81.2%; 95% CI = 77.8-85.3) followed by dairy (53.9%; 95% CI = 49.1-58.7).

CONCLUSIONS

Perceived food intolerance amongst adults with BAD and persisting diarrhoeal symptoms is high. Important triggers were meals with a higher fat content and higher-fat dairy products. Diets amongst those with persisting diarrhoeal symptoms may be overly restrictive.

Bile Acid Diarrhea: From Molecular Mechanisms to Clinical Diagnosis and Treatment in the Era of Precision Medicine

Bile acid diarrhea (BAD) is a multifaceted intestinal disorder involving intricate molecular mechanisms, including farnesoid X receptor (FXR), fibroblast growth factor receptor 4 (FGFR4), and Takeda G protein-coupled receptor 5 (TGR5). Current diagnostic methods encompass bile acid sequestrants (BAS), 48-h fecal bile acid tests, serum 7α-hydroxy-4-cholesten-3-one (C4), fibroblast growth factor 19 (FGF19) testing, and 75Selenium HomotauroCholic acid test (75SeHCAT). Treatment primarily involves BAS and FXR agonists. However, due to the limited sensitivity and specificity of current diagnostic methods, as well as suboptimal treatment efficacy and the presence of side effects, there is an urgent need to establish new diagnostic and treatment methods. While prior literature has summarized various diagnostic and treatment methods and the pathogenesis of BAD, no previous work has linked the two. This review offers a molecular perspective on the clinical diagnosis and treatment of BAD, with a focus on FXR, FGFR4, and TGR5, emphasizing the potential for identifying additional molecular mechanisms as treatment targets and bridging the gap between diagnostic and treatment methods and molecular mechanisms for a novel approach to the clinical management of BAD.

Editorial: Bile acid diarrhoea - simplified clinico-biochemical diagnosis

This article is linked to Borup et al paper. To view this article, visit https://doi.org/10.1111/apt.17739

Prospective comparison of diagnostic tests for bile acid diarrhoea

BACKGROUND

Bile acid diarrhoea is often missed because gold standard nuclear medicine tauroselcholic [75-Se] acid (SeHCAT) testing has limited availability. Empirical treatment effect has unknown diagnostic performance, whereas plasma 7α-hydroxy-4-cholesten-3-one (C4) is inexpensive but lacks sensitivity.

AIMS

To determine diagnostic characteristics of empirical treatment and explore improvements in diagnostics with potential better availability than SeHCAT.

METHODS

This diagnostic accuracy study was part of a randomised, placebo-controlled trial of colesevelam. Consecutive patients with chronic diarrhoea attending SeHCAT had blood and stool sampled. Key thresholds were C4 > 46 ng/mL and SeHCAT retention ≤10%. A questionnaire recorded patient-reported empirical treatment effect. We analysed receiver operating characteristics and explored machine learning applied logistic regression and decision tree modelling with internal validation.

RESULTS

Ninety-six (38%) of 251 patients had SeHCAT retention ≤10%. The effect of empirical treatment assessed with test results for bile acid studies blinded had 63% (95% confidence interval 44%-79%) sensitivity and 65% (47%-80%) specificity; C4 > 46 ng/mL had 47% (37%-57%) and 92% (87%-96%), respectively. A decision tree combining C4 ≥ 31 ng/mL with ≥1.1 daily watery stools (Bristol type 6 and 7) had 70% (51%-85%) sensitivity and 95% (83%-99%) specificity. The logistic regression model, including C4, the sum of measured stool bile acids and daily watery stools, had 77% (58%-90%) sensitivity and 93% (80%-98%) specificity.

CONCLUSIONS

Diagnosis of bile acid diarrhoea using empirical treatment was inadequate. Exploration suggested considerable improvements in the sensitivity of C4-based testing, offering potential widely available diagnostics. Further validation is warranted.

CLINICALTRIALS

gov: NCT03876717.

Recent developments in diagnosing bile acid diarrhea

INTRODUCTION

Bile acid diarrhea (BAD) commonly causes chronic diarrhea. Symptoms may be mistaken for disorders of gut brain interaction. Due to the lack of widely available diagnostic tests and poor recognition of BAD, there is a delay in diagnosis leading to increased healthcare system burden and decreased patient quality of life.

AREAS COVERED

A thorough review of the literature was conducted using PubMed for articles on the biological functions of bile acids, pathophysiology and management of BAD, but focusing on diagnostic testing including 75SeHCAT retention, 7αC4, FGF-19, fecal bile acids, and single stool tests. This narrative review discusses available modalities focusing on noninvasive stool and serum testing that are more widely available and show good sensitivity and specificity for diagnosis of BAD. 75SeHCAT retention is not available in many countries. Alternative diagnostic tests include total and primary fecal bile acid (BA) excretion in 48-hour collection or a single stool sample, serum7αC4 >46 or 52.5 ng/mL, and combination of single stool and serum 7αC4 ±watery stools (Bristol Stool Form Scale 6-7).

EXPERT OPINION

Given the ease of serum and single stool sample acquisition and diagnostic advances, clinical practice should embrace positive diagnosis, rather than BAS therapeutic trial. BAD needs to be considered in diverse gastrointestinal diseases.

Bile acid signalling and its role in anxiety disorders

Anxiety disorder is a prevalent neuropsychiatric disorder that afflicts 7.3%~28.0% of the world's population. Bile acids are synthesized by hepatocytes and modulate metabolism via farnesoid X receptor (FXR), G protein-coupled receptor (TGR5), etc. These effects are not limited to the gastrointestinal tract but also extend to tissues and organs such as the brain, where they regulate emotional centers and nerves. A rise in serum bile acid levels can promote the interaction between central FXR and TGR5 across the blood-brain barrier or activate intestinal FXR and TGR5 to release fibroblast growth factor 19 (FGF19) and glucagon-like peptide-1 (GLP-1), respectively, which in turn, transmit signals to the brain via these indirect pathways. This review aimed to summarize advancements in the metabolism of bile acids and the physiological functions of their receptors in various tissues, with a specific focus on their regulatory roles in brain function. The contribution of bile acids to anxiety via sending signals to the brain via direct or indirect pathways was also discussed. Different bile acid ligands trigger distinct bile acid signaling cascades, producing diverse downstream effects, and these pathways may be involved in anxiety regulation. Future investigations from the perspective of bile acids are anticipated to lead to novel mechanistic insights and potential therapeutic targets for anxiety disorders.

Unlocking the potential of low FODMAPs sourdough technology for management of irritable bowel syndrome

Consumption of high FODMAP (Fermentable Oligo-, Di-, and Monosaccharides and Polyols) diet is the leading cause of alteration in the human gut microbiome, thereby, causing irritable bowel syndrome (IBS). Therefore, sourdough technology can be exploited for reduction of FODMAPs in various foods to alleviate the symptoms of IBS. Several microorganisms viz. Pichia fermentans, Lactobacillus fetmentum, Saccharomyces cerevisiae, Torulaspora delbrueckii, Kluyveromyces marxianus etc. have been identified for the production of low FODMAP type II sourdough fermented products. However, more research on regulation of end-product and volatilome profile is required for maximal exploitation of FODMAP-reducing microorganisms. Therefore, the present review is focused on utilisation of lactic acid bacteria and yeasts, alone and in synergy, for the production of low FODMAP sourdough foods. Moreover, the microbial bioprocessing of cereal and non-cereal based low FODMAP fermented sourdough products along with their nutritional and therapeutic benefits have been elaborated. The challenges and future prospects for the production of sourdough fermented low FODMAP foods, thereby, bringing out positive alterations in gut microbiome, have also been discussed.

New Developments in Bile Acid Diarrhea

Bile acid diarrhea (BAD) is characterized by increased frequency of bowel movements, looser stool consistency, urgency, and need for proximity to toilet facilities owing to the severity of the diarrhea, when compared with or relative to irritable bowel syndrome with diarrhea. Consequently, BAD leads to decreased quality of life. The condition is often misdiagnosed as irritable bowel syndrome with diarrhea or functional diarrhea. Patients with BAD have accelerated colonic transit, increased intestinal or colonic mucosal permeability, and altered stool microbiome composition associated with reduced dehydroxylation of primary to secondary bile acids. The established diagnostic test, selenium-75 homocholic acid taurine retention, is not available in the United States. Therefore, 48-hour fecal bile acid excretion has been the gold standard for diagnosis. With recent validation of combined measurement of primary bile acids in a single, random stool in addition to fasting serum 7α-hydroxy-4-cholesten-3-one, a practical point-of-care diagnostic test will soon be available. Randomized controlled trials have documented superiority of colesevelam to placebo and, in a separate study, superiority of the glucagon-like peptide 1 agonist liraglutide compared with colesevelam. Novel experimental approaches for BAD include farnesoid X receptor agonists and fibroblast growth factor 19 analogs. This article updates information on the pathophysiology, mechanisms, manifestations, diagnosis, and treatment of BAD.

Altered gut microbiota-host bile acid metabolism in IBS-D patients with liver depression and spleen deficiency pattern

BACKGROUND

Dysregulation of gut microbiota-host bile acid (BA) co-metabolism is a critical pathogenic factor of diarrhea-predominant irritable bowel syndrome (IBS-D). Traditional Chinese Medicine (TCM), instructed by pattern differentiation, is effective in treating IBS-D, in which liver depression and spleen deficiency (LDSD) is the most prevalent pattern. Still, it is unclear the linkage between the LDSD pattern and the BA metabolic phenotype.

PURPOSE

This study aimed to uncover the biological basis of the LDSD pattern from the BA metabolic perspective.

METHODS

Patients with IBS-D completed questionnaires regarding the irritable bowel severity scoring system (IBS-SSS), stool frequency, Stool Bristol scale, and Self-Rating Scales of mental health. Fasting blood and morning feces were collected to analyze the gut metagenome and BA-related indices/metabolites.

RESULTS

IBS-D patients with LDSD had a higher incidence of BA overexcretion (41% vs. 23% non-LDSD) with significant elevations in fecal total BAs and serum BA precursor 7α-hydroxy-4-cholesten-3-one levels. Compared to controls or non-LDSD patients, LDSD patients had a featured fecal BA profile, with higher proportions of deoxycholic acid (DCA), 7-ketodeoxycholic acid, and lithocholic acid. It is consistent with the BA-metabolizing genomic changes in the LDSD gut microbiota characterized by overabundances of 7-dehydroxylating bacteria and BA-inducible genes (baiCD/E/H). The score of bowel symptoms (stool frequency and abdominal pain) showing greater severity in the LDSD pattern were positively correlated with bai-expressing bacterial abundances and fecal DCA levels separately.

CONCLUSION

We clarified a differed BA metabolic phenotype in IBS patients with LDSD, which closely correlates with the severity of bowel symptoms. It demonstrates that gut microbiota and host co-metabolism of BAs would provide crucial insight into the biology of the LDSD pattern and its internal relationship with IBS progression.

Potential mechanism of pyrotinib-induced diarrhea was explored by gut microbiome and ileum metabolomics

Pyrotinib is a novel epidermal growth factor receptor/human epidermal growth factor receptor-2 (HER2) tyrosine kinase inhibitor that exhibited clinical efficacy in patients with HER2-positive breast cancer and HER2-mutant/amplified lung cancer. However, severe diarrhea adverse responses preclude its practical use. At present, the mechanism of pyrotinib-induced diarrhea is unknown and needs further study. First, to develop a suitable and reproducible animal model, we compared the effects of different doses of pyrotinib (20, 40, 60 and 80 mg/kg) in Wistar rats. Second, we used this model to examine the intestinal toxicity of pyrotinib. Finally, the mechanism underlying pyrotinib-induced diarrhea was fully studied using gut microbiome and host intestinal tissue metabolomics profiling. Reproducible diarrhea occurred in rats when they were given an 80 mg/kg daily dose of pyrotinib. Using the pyrotinib-induced model, we observed that Lachnospiraceae and Acidaminococcaceae decreased in the pyrotinib groups, whereas Enterobacteriaceae, Helicobacteraceae and Clostridiaceae increased at the family level by 16S rRNA gene sequence. Multiple bioinformatics methods revealed that glycocholic acid, ursodeoxycholic acid and cyclic AMP increased in the pyrotinib groups, whereas kynurenic acid decreased, which may be related to the pathogenesis of pyrotinib-induced diarrhea. Additionally, pyrotinib-induced diarrhea may be associated with a number of metabolic changes mediated by the gut microbiome, such as Primary bile acid biosynthesis. We reported the establishment of a reproducible pyrotinib-induced animal model for the first time. Furthermore, we concluded from this experiment that gut microbiome imbalance and changes in related metabolites are significant contributors to pyrotinib-induced diarrhea.

Bile acid diarrhea - as bad as it gets?

PURPOSE OF REVIEW

Bile acid diarrhea (BAD) is a common but under-recognized gastrointestinal condition that manifests with increased stool frequency and urgency, and a looser stool consistency. The aim of this review is to present recent advances in the pathophysiology, mechanisms, manifestations, diagnosis, and treatment of BAD.

RECENT FINDINGS

Patients with BAD have evidence of accelerated colonic transit, increased gut mucosal permeability, altered stool microbiome composition, and decreased quality of life. Single, random stool measurements of bile acids, alone or in combination with fasting serum 7-alpha-hydroxy-4-cholesten-3-one, have shown good sensitivity and specificity for the diagnosis of BAD. Novel therapeutic approaches include farnesoid X receptor agonists and glucagon-like peptide 1 agonists.

SUMMARY

Recent research has led to a better understanding of the pathophysiology and mechanisms of BAD, which might pave the way towards more targeted treatment strategies for BAD. Newer, more affordable, and easier diagnostic methods facilitate the diagnosis of BAD.

Efficacy and safety of colesevelam for the treatment of bile acid diarrhoea: a double-blind, randomised, placebo-controlled, phase 4 clinical trial

BACKGROUND

Bile acid diarrhoea is a common but overlooked cause of chronic watery diarrhoea. Plasma 7α-hydroxy-4-cholesten-3-one (C4) is an alternative to the gold standard tauroselcholic [⁷⁵Se] acid (SeHCAT) test. Low-certainty evidence supports sequestrant treatment, including colesevelam. We aimed to determine the efficacy and safety of colesevelam in bile acid diarrhoea.

METHODS

In this randomised, double-blind, placebo-controlled, investigator-initiated phase 4 trial of the sequestrant colesevelam in bile acid diarrhoea (SINBAD), we enrolled consecutive patients aged 18-79 years without inflammatory bowel disease attending SeHCAT testing for suspected bile acid diarrhoea at four Danish secondary care centres. Participants were randomly allocated 1:1 to receive 12 days of treatment with colesevelam (overencapsulated tablets of 625 mg) or placebo, with the starting dose of two capsules twice daily and titrated to effect during the first 5 days of treatment. A pharmacist independent of the clinical investigators generated a randomisation list on the web page randomization.com using block randomisation (randomisation was not stratified). C4 and SeHCAT diagnostic results were blinded during treatment. We treated all patients with diarrhoea, with a daily mean of 3·0 or more bowel movements or 1·0 or more watery bowel movements (Bristol stool scale type 6 and 7). Remission was defined as the absence of both these criteria during treatment days 6-12. The primary outcome was the intention-to-treat remission rate in bile acid diarrhoea diagnosed by C4 concentration greater than 46 ng/mL. A secondary outcome was the intention-to-treat remission rate in bile acid diarrhoea diagnosed by SeHCAT retention of 10% or less. This trial is registered with ClinicalTrials.gov, NCT03876717.

FINDINGS

Between Oct 25, 2018, and July 1, 2021, 168 patients were randomly assigned to receive colesevelam (n=84) or placebo (n=84). 41 patients had C4 concentration greater than 46 ng/mL (22 assigned to the colesevelam group and 19 to the placebo group). For the C4-defined primary outcome, 14 (64%) of 22 participants receiving colesevelam versus three (16%) of 19 participants receiving placebo achieved remission (adjusted odds ratio 9·1, 95% CI 1·9-62·8; p=0·011). For the SeHCAT-defined secondary outcome, 75 of the 168 participants had retention of less than 10% (37 assigned to the colesevelam group and 38 assigned to the placebo group); 22 (59%) of 37 participants receiving colesevelam achieved remission versus five (13%) of 38 participants receiving placebo (adjusted odds ratio 11·1, 95% CI 3·4-45·6; p=0·00020). There were no serious adverse events. Common adverse events were transient. For patients receiving colesevelam within the primary outcome population, five had abdominal pain, nine had bloating, and four had nausea. For patients receiving placebo, four had abdominal pain, four had bloating, and one had nausea. No participants with bile acid diarrhoea withdrew due to adverse events.

INTERPRETATION

Colesevelam was superior to placebo at inducing remission of bile acid diarrhoea diagnosed with C4 concentration greater than 46 ng/mL. Secondary outcome data suggest similar efficacy treating SeHCAT-defined bile acid diarrhoea. Colesevelam was safe during the treatment.

FUNDING

Fabrikant Vilhelm Pedersen og hustrus mindelegat; recommended by the Novo Nordisk Foundation.

Approach to Disorders of Gut-Brain Interaction

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

Comparison of biochemical, microbial and mucosal mRNA expression in bile acid diarrhoea and irritable bowel syndrome with diarrhoea

OBJECTIVE

There are altered mucosal functions in irritable bowel syndrome with diarrhoea (IBS-D); ~30% of patients with IBS-D have abnormal bile acid (BA) metabolism (ABAM) and diarrhoea (summarised as BAD).

AIM

To compare biochemical parameters, gastrointestinal and colonic transit, rectal sensation and pathobiological mechanisms in IBS-D without ABAM and in BAD (serum 7C4>52 ng/mL).

DESIGN

In patients with Rome III criteria of IBS-D, we compared biochemical features, colonic transit, rectal sensation, deep genotype of five BA-related genes, ileal and colonic mucosal mRNA (differential expression (DE) analysis) and stool dysbiosis (including functional analysis of microbiome). Results in BAD were compared with IBS-D without ABAM.

RESULTS

Compared with 161 patients with IBS-D without ABAM, 44 patients with BAD had significantly faster colonic transit, lower microbial alpha diversity, different compositional profile (beta diversity) and higher Firmicutes to Bacteroidetes ratio with evidence of decreased expression of bile acid thiol ligase (involved in transformation of primary to secondary BAs) and decreased sulfatases. In BAD (compared with IBS-D without ABAM), terminal ileal biopsies showed downregulation of SLC44A5 (a BA transporter), and ascending colon biopsies showed upregulation in barrier-weakening genes (CLDN2), serine protease inhibitors, immune activation, cellular differentiation and a cellular transporter (FABP6; BA binding). No DE of genes was documented in descending colon biopsies. The two groups had similar rectal sensation.

CONCLUSION

Though sharing clinical symptoms with IBS-D, BAD is associated with biological differences and mechanisms that have potential to enhance diagnosis and treatment targeting barrier dysfunction, inflammatory and microbial changes.

The impact of treatment with bile acid sequestrants on quality of life in patients with bile acid diarrhoea

BACKGROUND

Bile acid diarrhoea (BAD) can be severely debilitating and negatively affect patients' quality of life (QoL). We carried out a multi-centre prospective study exploring QoL outcomes in patients with BAD after treatment with colesevelam.

METHODS

Patients with or without a positive 23-seleno-25-homotaurocholic acid (SeHCAT) scan were recruited and categorised into four groups: SeHCAT negative control group (CG), idiopathic BAD, post-cholecystectomy (PC) and post-terminal ileal resection for Crohn's disease (CD). Patients with a positive SeHCAT were treated with colesevelam and dosing was titrated to symptomatic response. Patients were reviewed at 4- and 8-weekly intervals and QoL was evaluated by EQ-5D-3L, SF-36, IBDQ-32 at each visit (where relevant). Patients with a negative SeHCAT (CG cohort) completed one set of questionnaires before being discharged from the study.

RESULTS

47 patients (BAD = 24, PC = 12, CD = 11) completed paired QoL questionnaires before and after treatment and 30 CG patients completed a baseline questionnaire. There was a significant improvement in IBDQ-32 mean scores before and after treatment in CD patients [134.6 (95%CI 112.5-156.6) and 158.4 (136.1-180.6), respectively (p = 0.007). Following treatment, BAD patients had significantly improved mean SF-36 scores in the "Role limitation due to physical health" dimension (p = 0.02) and in the overall mental component summary (p = 0.03). Prior to starting treatment, BAD patients had the lowest scores in the 'activity' dimension of the EQ-5D-3L (p = 0.04), which improved significantly after treatment (p = 0.002). Overall, the BAD and CD cohort showed improved mean scores with treatment in all components of the SF-36 and EQ-5D-3L, while the PC cohort showed a general decline in mean scores after treatment. 55% of patients clinically responded to treatment of which 41.7%, 58.3% and 81.8% responded from the BAD, PC and CD groups respectively. Correlations between those deemed as responders with improvements on the SF-36 and EQ-5D dimensions were not statistically significant.

CONCLUSION

Our results demonstrate improved QoL in the BAD and CD cohort with treatment. Further larger studies are recommended specifically investigating the PC cohort and whether patients may improve with newer treatments such as FXR agonists. Trial registration Ethical approval REC Ref: 16/LO/1325.

Pathophysiology and Clinical Management of Bile Acid Diarrhea

Bile acid malabsorption (BAM) represents a common cause of chronic diarrhea whose prevalence is under-investigated. We reviewed the evidence available regarding the pathophysiology and clinical management of bile acid diarrhea (BAD). BAD results from dysregulation of the enterohepatic recirculation of bile acids. It has been estimated that 25–33% of patients with functional diarrhea and irritable bowel syndrome with diarrhea have BAM. Currently, the selenium homotaurocholic acid test is the gold standard for BAD diagnosis and severity assessment. However, it is an expensive method and not widely available. The validation of the utility in the clinical practice of several other serum markers, such as 7α-hydroxy-4-cholesten-3-one (C4) and the fibroblast growth factor 19 (FGF19) is ongoing. The first-line treatment of patients with BAD is bile acid sequestrants. Patients that are refractory to first-line therapy should undergo further diagnostics to confirm the diagnosis and to treat the underlying cause of BAD. An early and correct diagnosis of BAD would improve patient’s quality of life, avoiding additional diagnostic tests that burden health care systems. Considering the limited availability and tolerability of specific medications for BAD treatment, future research is awaited to identify other therapeutic approaches, such as gut microbiota modulating therapies.