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

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

Pathophysiological Abnormalities in Functional Dyspepsia Subgroups According to the Rome III Criteria.

OBJECTIVES: The Rome III criteria proposed to subdivide functional dyspepsia (FD) into a postprandial distress syndrome (PDS) group, characterized by the presence of postprandial fullness and/or early satiety, and an epigastric pain syndrome (EPS) group, characterized by the presence of epigastric pain and/or epigastric burning. It has been suggested that different pathophysiological mechanisms underlie the symptom presentations in these subgroups that might determine treatment choices. The aim of this study was to investigate the prevalence of gastric sensorimotor dysfunction in the PDS, EPS, and overlap groups and to evaluate potential differential associations with dyspeptic symptom scores. METHODS: Consecutive FD patients fulfilling Rome III criteria were recruited and they scored frequency of dyspeptic symptoms (postprandial fullness, early satiety, nausea, bloating, epigastric pain, and epigastric burning) over the past 3 months (0-5; 1=once a month or less, 2=two or three times a month, 3=once a week, 4=several times a week, 5=every day). The cumulative symptom score was calculated by adding up the score of these dyspeptic symptoms. Based on these symptom scores, the patients were subdivided into subgroups according to the Rome III consensus: (i) PDS, characterized by postprandial fullness and/or early satiety at least several times a week, (ii) EPS, characterized by epigastric pain and/or epigastric burning at least once a week, and (iii) overlap, fulfilling the criteria for both PDS and EPS. Gastric sensitivity and gastric accommodation were measured using barostat testing, and solid gastric emptying was determined using the [14C]octanoate breath test. RESULTS: A total of 560 FD patients (165 men, age 41.8±0.7 years) were classified into PDS (n=131), EPS (n=50), and overlap (n=379) groups. The prevalence of gastric hypersensitivity, impaired gastric accommodation, and delayed gastric emptying were 37%, 37%, and 23%, respectively, without any differential distribution in Rome III subgroups (P=0.16, P=0.27, and P=0.39 respectively). Comparing the physiological parameters for these gastric sensorimotor functions, there was only a significant difference in the gastric half emptying time between subgroups, with the overlap group having a higher t1/2 (P<0.05) compared with the EPS group. In the overlap group, gastric hypersensitivity was associated with the severity of PDS symptoms (P=0.03), EPS symptoms (P=0.02), and the cumulative symptom score (P=0.02), whereas delayed gastric emptying was associated with nausea (P=0.02) and the cumulative symptom score (P=0.02). CONCLUSIONS: Except for gastric emptying in the overlap group, FD subgroups as defined by the Rome III criteria are not differentially associated with putative pathophysiological mechanisms. These observations question the utility of this classification for guiding therapeutic choices in clinical practice.

A combined nutrient and lactulose challenge test allows symptom-based clustering of patients with irritable bowel syndrome.

OBJECTIVES: The aim of the present pilot study was to evaluate the usefulness of a test meal containing lactulose in the non-invasive assessment of visceral sensitivity in irritable bowel syndrome (IBS), and to identify subsets of IBS patients based on gastrointestinal (GI) symptom generation. METHODS: We included 43 patients with IBS (Rome III) and 29 healthy controls. The fasted subjects were served three test meals consisting of a 400-ml liquid breakfast alone or containing lactulose (15 or 25 g) in a double-blind crossover design. Seven GI symptoms, overall digestive comfort, and exhaled H2/CH4 were assessed at baseline and every 15 min during 4 h after meal intake. Anxiety and depression were assessed only at baseline. A mapping of the seven GI symptoms was done using a Principal Component Analysis (4 h mean area under the curve, AUC). Independently, a hierarchical cluster analysis was performed on the same parameters to identify GI symptom-based IBS clusters. RESULTS: All three tests were well tolerated. The 25 g lactulose challenge enabled discrimination of IBS from healthy controls according to the symptom response. This challenge also enabled clustering of IBS subjects in two subgroups based mainly on bloating, distension, and discomfort symptoms (2,457 (2,043-2,872), 2,450 (1,910-2,990), 2,602 (2,126-3,079) vs. 537 (383-691), 619 (458-780), 643 (432-854); 4 h mean AUC; P<0.0001), overall digestive comfort (1807 (1318-2295) vs. 3350 (2942-3758); 4 h mean AUC; P<0.0001), and anxiety at baseline (9.2 (7.0-11.5) vs. 5.5 (4.2-6.9); Hospital Anxiety and Depression scale anxiety mean scores; P=0.003). This clustering was independent of the Rome III subtype and the amount of exhaled H2/CH4. CONCLUSIONS: The lactulose challenge test seems to be a promising tool to assess visceral sensitivity in IBS, and to subgroup IBS patients based on their symptom pattern.

Infliximab inhibits activation and effector functions of peripheral blood T cells in vitro from patients with clinically active ulcerative colitis.

Many patients with inflammatory bowel disease (IBD) are undergoing therapy with infliximab, an antibody specific for TNF. However, the exact mechanisms of action of infliximab are not completely understood. The aim of this study was to determine the in vitro effects of infliximab on blood T cells derived from anti-TNF therapy-naïve ulcerative colitis (UC) patients with clinically active disease. Peripheral blood mononuclear cells were stimulated polyclonally or by antigen in the presence or absence of infliximab. The T cell phenotype was investigated by flow cytometry, cytokine secretion was determined by ELISA, and cell proliferation was determined by thymidine assay or CFSE dye. Presence of infliximab resulted in reduced expression of CD25 in CD4(+) and CD8(+) T cell populations and inhibited secretion of IFN-γ, IL-13, IL-17A, TNF as well as granzyme A. Infliximab also suppressed CD4(+) and CD8(+) T cell proliferation. These effects of infliximab were recorded both in T cells activated by polyclonal and antigen-specific stimulation. The effects of infliximab on T cell apoptosis and induction of FOXP3(+) CD4(+) T regulatory cells were ambiguous and depended on the originating cellular source and/or the stimulation mode and strength. In conclusion, infliximab is able to reduce T cell activation as measured by CD25, proliferation and cytokine secretion in vitro from UC patients with clinically active disease. These data suggest that suppression of T cell activity may be important for infliximab-mediated disease remission in patients with UC.

Temporary percutaneous gastric electrical stimulation: a novel technique tested in patients with non-established indications for gastric electrical stimulation.

AIM: To test temporary percutaneous gastric electrical stimulation (TPGES) in patients with drug-refractory nausea/vomiting and nonestablished indications for GES. METHODS: 27 patients (2-81 years) underwent TPGES with electrodes implanted at gastroscopy and received stimulation for 7-21 days with low current settings (5-7 mA) either as open stimulation (n = 14) or randomized to double-blind crossover stimulation (n = 13; ON for 12-14 days, OFF for 12-14 days). Symptoms were recorded daily. Nonresponders were offered another period (14-21 days) with increased stimulation (8-10 mA). RESULTS: Mean lead implantation time was 14 min. Leads were kept implanted for ≤60 days. 22 of 27 evaluable patients had a favorable symptom reduction, preferentially of nausea/vomiting, irrespective of delayed or normal gastric emptying rate: postsurgical gastroparesis 7/8, chronic intestinal pseudo-obstruction 2/2, idiopathic gastroparesis 1/1, functional dyspepsia 6/9, diabetes mellitus 2/2, postsurgical nausea/vomiting 2/2, malformation syndrome 1/1, intestinal neuropathy 1/1, intestinal interstitial cells of Cajal deficiency 0/1. 6 patients had a clear symptom reduction during the ON period compared with stimulation OFF. Four of 7 patients improved with increased stimulation (8-10 mA). Twenty of the 22 responders received a permanent GES implant, 90% of them still being responders at last follow-up. CONCLUSION: TPGES seems promising to study new indications for GES and to select responders/non-responders.

Gastrointestinal transit abnormalities are frequently detected in patients with unexplained GI symptoms at a tertiary centre.

The aim of this prospective study was to analyse the yield and utility of a gastrointestinal (GI) transit measurement procedure in clinical practice. Patients referred by gastroenterologists to a tertiary centre for detailed transit measurements were prospectively included. All together 243 patients were enrolled. Body mass index was recorded. The patients were categorized according to the predominant symptom into five groups: diarrhoea, constipation, nausea, vomiting and abdominal pain. The patients recorded their bowel movements and GI symptoms daily during the week before the transit measurement. Percentiles 5 and 95 of the transit values in 83 healthy subjects served as reference values. Widespread abnormalities were found in the five patient groups and 63% of the patients had at least one transit abnormality. The abnormalities were more frequent in men compared with women. Patients with underweight had more motility disturbances compared with other patients. In male and female patients with vomiting a significant delay of transit in the ascending colon was observed compared with healthy subjects. Large-scale transit measurements frequently detect transit abnormalities in clinical practice and may elucidate the relationship between some GI symptoms and abnormal motility.

Health problems associated with irritable bowel syndrome: analysis of a primary care registry.

BACKGROUND: Associations between irritable bowel syndrome and other health problems have been described, but comprehensive reports are missing, especially in primary care. AIMS: To investigate which health problems are associated with irritable bowel syndrome, how they cluster together and when they are typically diagnosed relative to irritable bowel syndrome. METHODS: We used Intego, a general practice registry in Flanders, Belgium. Patients with an irritable bowel syndrome diagnosis (n = 13 701) were matched with controls without gastrointestinal diagnosis and controls with organic gastrointestinal disease. Long-term prevalences of 680 symptoms and diagnoses were compared between patients and controls. Results were summarised using functional enrichment analysis and visualised in a network and we calculated incidence rate ratios in the 10 years before and after the irritable bowel syndrome diagnosis for the network's key components. RESULTS: Various symptoms and infections, but not neoplasms, were enriched in irritable bowel syndrome patients compared to both control groups. We characterised the comorbidities of irritable bowel syndrome as psychosocial health problems, urogenital symptoms and infections, musculoskeletal symptoms and other somatic symptoms. These had a uniform incidence in the years around the irritable bowel syndrome diagnosis, and did not structurally precede or follow irritable bowel syndrome. CONCLUSIONS: Irritable bowel syndrome shares long-term associations with psychosocial health problems, urogenital symptoms and infections, musculoskeletal symptoms and other somatic symptoms in primary care. Clinicians are encouraged to take comorbidities into account when diagnosing and managing irritable bowel syndrome, as this may have important treatment implications.

Heart rate variability characteristics of patients with irritable bowel syndrome and associations with symptoms.

BACKGROUND: Disturbed brain-gut interactions are assumed to be of importance for symptom generation in patients with irritable bowel syndrome (IBS). The autonomic nervous system (ANS) is part of the bidirectional brain-gut communication, but previous studies in IBS show diverging results. We aimed to identify subgroups of IBS patients with distinct ANS characteristics differentiating them from healthy controls (HC), and to study associations between ANS status and symptoms. METHODS: Heart rate variability (HRV) was measured in IBS patients and HC (Holter monitoring: supine and standing positions with controlled respiration and ambulatory 24-hour period). Frequency (5 minutes, supine, standing) and time domains (24 hours, day, night) were analyzed. Validated questionnaires were used to measure gastrointestinal and psychological symptoms in patients. Patients and HC were compared on a univariate and multivariate level (principal component analysis [PCA] and orthogonal partial least squares discriminatory analysis (OPLS-DA)). KEY RESULTS: We analyzed 158 IBS patients (Rome III) and 39 HC. Patients differed significantly from HC in HRV parameters during daytime and in standing position. In the PCA, a majority of patients overlapped with HC, but the weighted means differed (P < .01). A subset of patients (n = 30; 19%) with an aberrant global HRV profile was identified through PCA and OPLS-DA; these patients reported more severe symptoms of frequent (P < .05) and loose stools (P = .03), as well as urgency (P = .01). CONCLUSIONS AND INFERENCES: Altered ANS function was demonstrated in patients with IBS, and this might be of particular relevance for symptoms in a subset of the patients.

Neither self-reported atopy nor IgE-mediated allergy are linked to gastrointestinal symptoms in patients with irritable bowel syndrome.

BACKGROUND: Among patients with irritable bowel syndrome (IBS), atopic disease has been proposed as a common comorbidity increasing the IBS symptom burden. We therefore assessed the prevalence of self-reported atopy among patients with IBS as compared to non-IBS controls, and whether atopy and higher serum IgE levels were associated with increased IBS symptom severity. METHODS: Levels of total and specific IgE in serum were measured and questionnaires assessing the presence of atopic disease (ie, eczema, asthma, rhinoconjunctivitis, and pollen allergy), gastrointestinal symptom burden, food intolerance, somatic, and psychological symptoms were completed. KEY RESULTS: In total, 223 patients with IBS and 47 controls participated. Presence of atopic disease was reported in 55% of patients with IBS compared to 40% of controls (P = .07). IBS patients with atopic manifestations (N = 123) had higher total serum IgE levels (median 31 vs 16 kUA /L, P < .001) and higher prevalence of self-reported food intolerance (28% vs 9%, P = .002) than non-atopic IBS patients (N = 100), respectively, but no major difference in gastrointestinal or psychological symptom burden was noted. However, severe somatic symptoms were more common among atopic than non-atopic patients with IBS (38% vs 27%, P = .028). We found no associations between self-reported atopy and IBS symptom severity using linear regression models. CONCLUSIONS & INFERENCES: Atopic disease is common in patients with IBS, but that is also true for subjects without IBS. The presence of atopic disease in IBS is associated with self-reported food intolerance and somatic symptom severity, but unrelated to IBS symptom severity.

Systemic cytokines are elevated in a subset of patients with irritable bowel syndrome but largely unrelated to symptom characteristics.

BACKGROUND: Serum levels of pro-inflammatory cytokines tend to be increased in irritable bowel syndrome (IBS) patients, or subgroups thereof. Still, the link between cytokine levels and IBS symptoms is unclear. We aim to determine systemic cytokine levels in IBS patients and healthy subjects (HS), confirm the presence of a subset of patients with an increased immune activity and to establish if cytokines are linked to IBS symptoms and pathophysiological factors. METHODS: Serum levels of interleukin (IL)-1ß, IL-6, IL-8, tumor necrosis factor (TNF), and IL-10 were measured. All subjects reported IBS symptoms using validated questionnaires and underwent colonic sensorimotor testing. Multivariate supervised orthogonal partial least squares-discriminant analysis (OPLS-DA) and unsupervised principal component analysis (PCA) and hierarchical cluster analysis (HCA) were implemented. KEY RESULTS: Irritable bowel syndrome patients (n = 246) had higher serum levels of IL-1ß, IL-6, IL-8, TNF, and IL-10 compared to HS (n = 21); however, serum cytokine profiles could not discriminate patients from HS. Moreover, cytokine levels were not correlated with symptoms among patients. Supervised OPLS-DA identified 104 patients (40% of patients) and unsupervised HCA analysis identified 49 patients (20%) with an increased immune activity indicated by elevated levels of serum cytokines compared to HS and the other patients. However, irrespective of how patients with increased immune activity were identified they were symptomatically similar to patients with no indication of increased immune activity. CONCLUSIONS & INFERENCES: Serum cytokines are elevated in IBS patients compared to HS. Immune activation characterizes a subset of patients, but modest associations between cytokine profile and symptoms suggest immune activity does not directly influence symptoms in IBS.

Colonic immune cells in irritable bowel syndrome: A systematic review and meta-analysis.

BACKGROUND & AIMS: Increases in mucosal immune cells have frequently been observed in irritable bowel syndrome (IBS) patients. However, this finding is not completely consistent between studies, possibly due to a combination of methodological variability, population differences and small sample sizes. We performed a meta-analysis of case-control studies that compared immune cell counts in colonic biopsies of IBS patients and controls. METHODS: PubMed and Embase were searched in February 2017. Results were pooled using standardized mean difference (SMD) and were considered significant when zero was not within the 95% confidence interval (CI). Heterogeneity was assessed based on I2 statistics where I2  ≤ 50% and I2  > 50% indicated fixed and random effect models, respectively. KEY RESULTS: Twenty-two studies on 706 IBS patients and 401 controls were included. Mast cells were increased in the rectosigmoid (SMD: 0.38 [95% CI: 0.06-0.71]; P = .02) and descending colon (SMD: 1.69 [95% CI: 0.65-2.73]; P = .001) of IBS patients. Increased mast cells were observed in both constipation (IBS-C) and diarrhea predominant IBS (IBS-D). CD3+ T cells were increased in the rectosigmoid (SMD: 0.53 [95% CI: 0.21-0.85]; P = .001) and the descending colon of the IBS patients (SMD: 0.79, 95% CI [0.28-1.30]; P = .002). This was possibly in relation to higher CD4+ T cells in IBS (SMD: 0.33 [95% CI: 0.01-0.65]; P = .04) as there were no differences in CD8+ T cells. CONCLUSIONS & INFERENCES: Mast cells and CD3+ T cells are increased in colonic biopsies of patients with IBS vs non-inflamed controls. These changes are segmental and sometimes IBS-subtype dependent. The diagnostic value of the quantification of colonic mucosal cells in IBS requires further investigation.

Development, content validity, and cross-cultural adaptation of a patient-reported outcome measure for real-time symptom assessment in irritable bowel syndrome.

BACKGROUND: End-of-day questionnaires, which are considered the gold standard for assessing abdominal pain and other gastrointestinal (GI) symptoms in irritable bowel syndrome (IBS), are influenced by recall and ecological bias. The experience sampling method (ESM) is characterized by random and repeated assessments in the natural state and environment of a subject, and herewith overcomes these limitations. This report describes the development of a patient-reported outcome measure (PROM) based on the ESM principle, taking into account content validity and cross-cultural adaptation. METHODS: Focus group interviews with IBS patients and expert meetings with international experts in the fields of neurogastroenterology & motility and pain were performed in order to select the items for the PROM. Forward-and-back translation and cognitive interviews were performed to adapt the instrument for the use in different countries and to assure on patients' understanding with the final items. KEY RESULTS: Focus group interviews revealed 42 items, categorized into five domains: physical status, defecation, mood and psychological factors, context and environment, and nutrition and drug use. Experts reduced the number of items to 32 and cognitive interviewing after translation resulted in a few slight adjustments regarding linguistic issues, but not regarding content of the items. CONCLUSIONS AND INFERENCES: An ESM-based PROM, suitable for momentary assessment of IBS symptom patterns was developed, taking into account content validity and cross-cultural adaptation. This PROM will be implemented in a specifically designed smartphone application and further validation in a multicenter setting will follow.

Subtyping the irritable bowel syndrome by predominant bowel habit: Rome II versus Rome III.

BACKGROUND: The agreement between subtyping irritable bowel syndrome (IBS) patients based on Rome II criteria versus Rome III criteria is unknown. AIM: To compare IBS subtyping based on Rome II versus III criteria. METHODS: The Rome II Modular Questionnaire and the Bristol Stool Form Scale (one-week diary cards) were completed by 249 IBS patients. Based on the Rome II criteria, patients were defined as having diarrhoea- or constipation-predominant IBS, or alternating IBS. Based on the Rome III criteria, patients were divided into IBS with constipation, IBS with diarrhoea, mixed IBS or unsubtyped IBS. Agreement between Rome II and Rome III was assessed with kappa statistics. RESULTS: Based on Rome II there were 92 diarrhoea-predominant IBS, 45 constipation-predominant IBS and 112 alternating IBS, and based on Rome III 97 IBS with diarrhoea, 77 IBS with constipation, 16 mixed IBS and 59 unsubtyped IBS. The agreement between Rome II and Rome III subgroups was 46% (kappa = 0.19). Changes from the constipation to the diarrhoea subgroups and vice versa were uncommon (8% of patients). The majority of changes occurred from/to the alternating IBS, mixed IBS and unsubtyped IBS subgroups. CONCLUSION: There is poor agreement between subtyping of IBS patients based on Rome II versus Rome III criteria.

Nutrient-dependent enhancement of rectal sensitivity in irritable bowel syndrome (IBS).

Food-related gastrointestinal symptoms are common in irritable bowel syndrome (IBS), but the mechanisms behind this are unclear. Enhanced colorectal sensitivity after duodenal lipid administration in IBS patients has been demonstrated. However, the effects of a regular meal on colorectal sensitivity in these patients and the importance of the composition of the meal are not known. On two separate days, 10 IBS patients and 11 controls randomly received a liquid meal (800 kcal), containing 60% calories from fat (fatty meal) or carbohydrate (carbohydrate meal). Using a barostat rectal sensitivity was assessed during four separate distension sequences before, immediately after and 30 and 60 min after the meal. In the patients, the discomfort (P = 0.04) and the pain thresholds (P = 0.007) were gradually reduced after the fatty meal, whereas only a tendency in the same direction was seen after the carbohydrate meal. In patients VAS ratings for pain increased after the fatty meal (P = 0.03), but not after carbohydrates. In the controls, sensory thresholds were not affected by the meals. In IBS, a liquid meal enhances rectal sensitivity, and this seems to be partly nutrient dependent as a fatty meal has more pronounced effects than a carbohydrate meal. This might be of relevance for their postprandial symptoms.

Percutaneous implantation of gastric electrodes - a novel technique applied in animals and in patients.

Temporary electrodes implanted under general anaesthesia, or via an oral or percutaneous endoscopic gastrostomy route have been used for testing of gastric electrical stimulation (GES). We have developed a principle for percutaneous electrode implantation. Leads were constructed so that the tip could be anchored to the gastric submucosa under gastroscopic control. Acute experiments were performed in anaesthetized pigs. Three patients referred for nausea and/or vomiting and non-established indications for GES (chronic intestinal pseudo-obstruction, functional dyspepsia without gastroparesis) were evaluated. Electrode function was tested by recording and stimulation techniques. In the pigs, a slow-wave (SW) rhythm (3 min(-1)) was recorded with decrease in frequency at the end of the experiments. In the patients, implantation time from start of gastroscopy to end of electrode placement was 12-20 min. Electrode distance varied from 12 to 45 mm. Gastric electromyography showed a regular SW rhythm of about 3 min(-1). Antral pressure waves had intervals being multiples of the SW-to-SW time. With temporary GES for 7-9 days, weekly frequency of the referral symptoms decreased >80% in two patients and 33% in one patient. Temporary percutaneous gastric leads can easily be implanted and may be used for testing of GES and study of gastric electrophysiology.

CD4+CD25+ regulatory T cells in irritable bowel syndrome patients.

The aetiology of the irritable bowel syndrome (IBS) is incompletely understood. A low-grade colonic inflammation is frequently seen, but it is unclear to what extent this phenomenon contributes to the pathophysiology of IBS. CD4(+)CD25(+) regulatory T cells (Treg) are implicated to play an important role in suppressing intestinal inflammation. We, therefore, examined whether the intestinal inflammatory process in IBS patients is the result of an altered function and/or frequency of CD25(+) Treg cells. Patients with IBS (n = 34), fulfilling the Rome II criteria, were compared with controls (n = 26). The suppressive activity of blood CD25(+) Treg cells was determined and the frequency of colonic and blood CD25(+) Treg cells was analysed by flow cytometry. The expression of the Treg marker, FOXP3 mRNA, in colonic biopsies was determined by reverse transcription-polymerase chain reaction. Blood CD25(+) Treg cells from IBS patients suppressed the proliferation of blood CD4(+)CD25(low/-) T cells. Similar frequencies of CD25(+) Treg cells were recorded in mucosa and blood of IBS patients and controls. FOXP3 mRNA was equally expressed in the colonic mucosa of patients with IBS and controls. In conclusion, the low-grade intestinal inflammation recorded in patients with IBS is not associated with an altered function or frequency of CD25(+) Treg cells.

Elevated motility-related transmucosal potential difference in the upper small intestine in the irritable bowel syndrome.

The pathophysiology of irritable bowel syndrome (IBS) is complex and incompletely known. Very little has been studied regarding the role of submucous neuronal activity. We therefore measured small intestinal transmural potential difference (PD, reflecting mainly electrogenic chloride secretion), and its linkage with fasting motor activity [migrating motor complex (MMC)] in controls (n = 16) and patients with IBS [n = 23, 14 diarrhoea predominant (d-IBS) and nine constipation predominant (c-IBS)]. Transmural-PD and its relation to MMC phase III was measured by modified multilumen manometry for 3 h in the fasting state using one jejunal and one duodenal infusion line as flowing electrodes. The amplitude and duration of motor phase III was similar in controls and IBS patients, but the propagation speed of phase III was higher in IBS patients. In IBS patients, maximal PD during MMC phase III was significantly elevated in both the duodenum and jejunum (P < 0.05) and the PD decline after phase III was significantly prolonged in the jejunum (P < 0.01). The PD elevation was seen in both duodenum and jejunum in d-IBS patients, but only in the jejunum in the c-IBS patients. On the basis of previous modelling studies, we propose that the enhanced secretion may reflect disturbed enteric network behaviour in some patients with IBS.

New insights into the pathogenesis and pathophysiology of irritable bowel syndrome.

The pathogenesis and pathophysiology of irritable bowel syndrome is complex and still incompletely known. Potential pathogenetic factors include genes, infectious events, psychological symptoms and other loosely defined environmental factors. Both alterations at the central and peripheral level are thought to contribute to the symptoms of irritable bowel syndrome, including psychosocial factors, abnormal gastrointestinal motility and secretion, and visceral hypersensitivity. Today irritable bowel syndrome is viewed upon as a disorder of dysregulation of the so-called brain-gut axis, involving abnormal function in the enteric, autonomic and/or central nervous systems, with peripheral abnormalities probably dominating in some patients and disturbed central processing of signals from the periphery in others. Lines of evidence also suggest that inflammation within the gastrointestinal tract may be of great importance in at least subgroups of irritable bowel syndrome patients. To conclude, a complex picture of the pathogenesis and pathophysiology of irritable bowel syndrome is emerging, with interactions between several different alterations resulting in the divergent symptom pattern in these patients.

Nutritional aspects in patients with functional gastrointestinal disorders and motor dysfunction in the gut. Working team report of the Swedish Motility Group (SMoG).

In reviews regarding the management of patients with functional gastrointestinal disorders and motility disturbances within the gut nutritional aspects and dietary advice is often put forward as being of great importance. However, there are relatively few high-quality, interventional studies in the literature supporting an important role for general dietary advice to improve symptoms in these patients. Nutritional supplementation to patients with malnutrition due to severe dysfunction of the gastrointestinal tract is of course less controversial, even though different views on how this should be performed exist. The content of this article is based on presentations given by the authors during the second meeting of the Swedish Motility Group held in Gothenburg in March 2005, and aims to give an overview on the role of dietary advice and nutritional supplementation to patients with gastrointestinal dysfunction of different severity.