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Lactose is the main source of calories in milk, an essential nutriedigestion, patients with visceral hypersensitivity nt in infancy and a key part of the diet in populations that maintain the ability to digest this disaccharide in adulthood. Lactase deficiency (LD) is the failure to express the enzyme that hydrolyses lactose into galactose and glucose in the small intestine. The genetic mechanism of lactase persistence in adult Caucasians is mediated by a single C→T nucleotide polymorphism at the LCTbo −13’910 locus on chromosome-2. Lactose malabsorption (LM) refers to any cause of failure to digest and/or absorb lactose in the small intestine. This includes primary genetic and also secondary LD due to infection or other conditions that affect the mucosal integrity of the small bowel. Lactose intolerance (LI) is defined as the onset of abdominal symptoms such as abdominal pain, bloating and diarrhoea after lactose ingestion by an individual with LM. The likelihood of LI depends on the lactose dose, lactase expression and the intestinal microbiome. Independent of lactose digestion, patients with visceral hypersensitivity associated with anxiety or the Irritable Bowel Syndrome (IBS) are at increased risk of the condition. Diagnostic investigations available to diagnose LM and LI include genetic, endoscopic and physiological tests. The association between self-reported LI, objective findings and clinical outcome of dietary intervention is variable. Treatment of LI can include low-lactose diet, lactase supplementation and, potentially, colonic adaptation by prebiotics. The clinical outcome of these treatments is modest, because lactose is just one of a number of poorly absorbed carbohydrates which can cause symptoms by similar mechanisms.

Gluten-related disorders have recently been reclassified with an emerging scientific literature supporting the concept of non-celiac gluten sensitivity (NCGS). New research has specifically addressed prevalence, immune mechanisms, the recognition of non-immunoglobulin E (non-IgE) wheat allergy and overlap of NCGS with irritable bowel syndrome (IBS)-type symptoms. This review article will provide clinicians with an update that directly impacts on the management of a subgroup of their IBS patients whose symptoms are triggered by wheat ingestion.

Bile acids (BAs) are the central signals in enterohepatic communication, and they also integrate microbiota-derived signals into enterohepatic signaling. The tissue distribution and signaling pathways activated by BAs through natural receptors, farsenoid X receptor and G protein–coupled BA receptor 1 (GPBAR1, also known as Takeda G-coupled receptor 5), have led to a greater understanding of the mechanisms and potential therapeutic agents. BA diarrhea is most commonly encountered in ileal resection or disease, in idiopathic disorders (with presentation similar to functional diarrhea or irritable bowel syndrome with diarrhea), and in association with malabsorption such as chronic pancreatitis or celiac disease. Diagnosis of BA diarrhea is based on 75Se-homocholic acid taurine retention, 48-hour fecal BA excretion, or serum 7αC4; the latter being a marker of hepatic BA synthesis. BA diarrhea tends to be associated with higher body mass index, increased stool weight and stool fat, and acceleration of colonic transit. Biochemical markers of increased BA synthesis or excretion are available through reference laboratories. Current treatment of BA diarrhea is based on BA sequestrants, and, in the future, it is anticipated that farsenoid X receptor agonists may also be effective. The optimal conditions for an empiric trial with BA sequestrants as a diagnostic test are still unclear. However, such therapeutic trials are widely used in clinical practice. Some national guidelines recommend definitive diagnosis of BA diarrhea over empirical trial.

This review intends to act as an overview of fructose malabsorption (FM) and its role in the aetiology of diseases including, but not limited to, irritable bowel syndrome (IBS) and infantile colic and the relationship between fructose absorption and the propagation of some cancers. IBS results in a variety of symptoms including stomach pains, cramps and bloating. Patients can be categorised into two groups, depending on whether the patients’ experiences either constipation (IBS-C) or diarrhoea (IBS-D). FM has been proposed as a potential cause of IBS-D and other diseases, such as infantile colic. However, our knowledge of FM is limited by our understanding of the biochemistry related to the absorption of fructose in the small intestine and FM’s relationship with small intestinal bacterial overgrowth. It is important to consider the dietary effects on FM and most importantly, the quantity of excess free fructose consumed. The diagnosis of FM is difficult and often requires indirect means that may result in false positives. Current treatments of FM include dietary intervention, such as low fermentable oligo-, di-, monosaccharides and polyols diets and enzymatic treatments, such as the use of xylose isomerase. More research is needed to accurately diagnose and effectively treat FM. This review is designed with the goal of providing a detailed outline of the issues regarding the causes, diagnosis and treatment of FM.

Treatable gastrointestinal disorders in patients with symptoms typical for irritable bowel syndrome (IBS) may be overlooked. The prevalence of five gastrointestinal conditions—bile acid diarrhoea (BAD), carbohydrate malabsorption (CM), microscopic colitis (MC), pancreatic exocrine insufficiency (PEI) and small intestinal bacterial overgrowth (SIBO) was systematically assessed from studies including consecutive patients meeting diagnostic criteria for IBS. 4 databases were searched from 1978 to 2020. Studies were included if they evaluated the prevalence of these conditions in secondary healthcare setting. Estimated pooled rates were calculated and statistical heterogeneity between studies was evaluated using Q and I 2 statistics. Seven studies (n = 597) estimated the pooled prevalence for BAD as 41% (95% CI 29–54). 17 studies (n = 5068) estimated that of MC as 3% (95% CI 2–4%). Two studies (n = 478) suggested a rate of 4.6% (range: 1.8–6.1%) for PEI. Using breath testing, 26 studies (n = 6700) and 13 studies (n = 3415) estimated the prevalence of lactose and fructose malabsorption as 54% (95% CI 44–64%) and 43% (95% CI 23–62%); 36 studies (n = 4630) and 22 studies (n = 2149) estimated that of SIBO as 49% (95% CI 40–57%) with lactulose and 19% (95% CI 13–27%) with glucose. Rates of all conditions were significantly higher than in healthy controls. A significant proportion of patients presenting to secondary care with IBS have an organic condition which may account for their symptoms. Failure to exclude such conditions will deny patients effective treatment.

INTRODUCTION:Bile acid sequestrants (BAS) are an option for microscopic colitis (MC) refractory or intolerant to budesonide. There are inconsistent data on the prevalence of bile acid malabsorption (BAM) and utility of bile acid testing in MC. The aim of this systematic review and meta-analysis was to evaluate these outcomes.METHODS:A systematic search of randomized control trials and observational studies of adults with MC treated with BAS was conducted using MEDLINE, Embase, Cochrane, and Scopus from inception to January 22, 2024. Data were extracted on (i) prevalence of BAM, (ii) clinical response and adverse events, and (iii) recurrence after BAS discontinuation. Data were pooled using random-effects models to determine weighted pooled estimates and 95% confidence intervals (CIs).RESULTS:We included 23 studies (1 randomized control trial, 22 observational), with 1,011 patients with MC assessed for BAM and 771 treated with BAS. The pooled prevalence of BAM was 34% (95% CI 0.26-0.42, I2 = 81%). The pooled response rate with BAS induction for all patients with MC, irrespective of BAM, was 62% (95% CI 0.55-0.70, I2 = 71%). There was a higher pooled response rate in patients with BAM compared with those without BAM (P < 0.0001). The pooled rate of BAS-related adverse effects was 9% (95% CI 0.05-0.14, I2 = 58%).DISCUSSION:One-third of patients with MC had BAM, and almost two-thirds of all patients responded to BAS with limited side effects. Patients with MC and BAM were more likely to respond to therapy, supporting the value of bile acid testing.

Severe sprue-like enteropathy associated with olmesartan has been reported, but there has been no demonstration of an increased risk by epidemiological studies. To assess, in a nationwide patient cohort, the risk of hospitalisation for intestinal malabsorption associated with olmesartan compared with other angiotensin receptor blockers (ARB) and ACE inhibitors (ACEIs). From the French National Health Insurance claim database, all adult patients initiating ARB or ACEI between 1 January 2007 and 31 December 2012 with no prior hospitalisation for intestinal malabsorption, no serology testing for coeliac disease and no prescription for a gluten-free diet product were included. Incidence of hospitalisation with a discharge diagnosis of intestinal malabsorption was the primary endpoint. 4 546 680 patients (9 010 303 person-years) were included, and 218 events observed. Compared with ACEI, the adjusted rate ratio of hospitalisation with a discharge diagnosis of intestinal malabsorption was 2.49 (95% CI 1.73 to 3.57, p<0.0001) in olmesartan users. This adjusted rate ratio was 0.76 (95% CI 0.39 to 1.49, p=0.43) for treatment duration shorter than 1 year, 3.66 (95% CI 1.84 to 7.29, p<0.001) between 1 and 2 years and 10.65 (95% CI 5.05 to 22.46, p<0.0001) beyond 2 years of exposure. Median length of hospital stay for intestinal malabsorption was longer in the olmesartan group than in the other groups (p=0.02). Compared with ACEI, the adjusted rate ratio of hospitalisation for coeliac disease was 4.39 (95% CI 2.77 to 6.96, p<0.0001) in olmesartan users and increased with treatment duration. Olmesartan is associated with an increased risk of hospitalisation for intestinal malabsorption and coeliac disease.

Background Survival following oesophagectomy for cancer is improving, resulting in increased focus on quality of life and survivorship. Malabsorption syndrome is multifactorial and includes exocrine pancreatic insufficiency (EPI), small intestinal bacterial overgrowth (SIBO) and bile acid malabsorption (BAM). The aim of this study was to evaluate the reported incidence and management of malabsorption syndromes post-oesophagectomy. Methods A systematic search of PubMed, EMBASE, MEDLINE, Scopus and the Cochrane Library evaluating incidence, diagnosis and management of malabsorption was performed for studies published until December 2021. Results Of 464 identified studies, eight studies ( n  = 7 non-randomised longitudinal studies) were included where patients were identified with malnutrition following oesophagectomy. Studies included a combined sample of 328 (range 7–63) patients. Malabsorption syndromes including EPI, SIBO and BAM occurred in 15.9–100%, 37.8–100% and 3.33–100% over 21 days–60 months, 1–24 months and 1–24 months respectively. There was no consensus definition for EPI, SIBO or BAM, and there was variation in diagnostic methods. Diagnostic criteria varied from clinical (gastrointestinal symptoms or weight loss), or biochemical (faecal elastase, hydrogen breath test and Selenium-75-labelled synthetic bile acid measurements). Treatment modalities using pancreatic enzyme replacement, rifaximin or colesevelam showed improvement in symptoms and weight in all studies, where investigated. Conclusions Malabsorption syndromes following oesophagectomy are under-recognised, and thus under-reported. The resultant gastrointestinal symptoms may have a negative effect on post-operative quality of life. Current literature suggests benefit with outlined therapies; however, greater understanding of these conditions, their diagnosis and management is required to further understand which patients will benefit from treatment.

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.

Background Imerslund-Gräsbeck Syndrome (IGS) is a rare autosomal recessive disorder characterized by selective cobalamin (vitamin B12) malabsorption and often accompanied by proteinuria. Mutations in CUBN or AMN genes underlie the condition, which usually manifests in childhood with megaloblastic anemia, failure to thrive, or recurrent infections. Case presentation We report a 15-year-old Iranian boy with a 12-year history of recurrent anemia and intermittent proteinuria. He presented with fatigue, nausea, and anorexia. Laboratory evaluation showed pancytopenia, macrocytic anemia (Hb 7.5 g/dL → 6.9 g/dL), thrombocytopenia (91 × 10³/µL → 38 × 10³/µL), and a severely reduced serum vitamin B12 level (74.4 pg/mL). Liver enzymes were elevated (AST 346 U/L, ALT 225 U/L), while renal function was preserved. Bone marrow aspiration confirmed megaloblastic changes. Despite the lack of confirmatory genetic testing, the diagnosis of IGS was made based on clinical findings and hematologic response. Treatment with intramuscular hydroxocobalamin (1000 mcg/day) and folic acid resulted in marked improvement, with hemoglobin rising to 11.4 g/dL and normalization of blood counts within three weeks. Intermittent proteinuria persisted. Conclusion This case emphasizes the importance of considering IGS in children and adolescents with unexplained macrocytic anemia and proteinuria, particularly in the Middle East where the condition is underdiagnosed. Early recognition and lifelong vitamin B12 supplementation are critical to prevent irreversible complications such as neurological deficits, developmental delay, and growth impairment.