Modulation by colonic fermentation of LES function in humans

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

Background

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

Methods

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

Findings

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

Interpretation

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

Funding

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

Understanding and managing patients with overlapping disorders of gut-brain interaction

Disorders of gut-brain interaction (DGBI) are frequently encountered in clinical practice, and recommendations for diagnosis and management are well established. In a large subset of patients, more than one DGBI diagnosis is present. This group of patients with more than one DGBI diagnosis have higher symptom severity and impact than patients with only one DGBI diagnosis, and the management approach is not well established for those with overlapping diagnoses. This Review aims to guide clinicians to understand, recognise, and manage overlapping DGBI by identifying causes and pitfalls of overlap conditions, and presenting potential practical approaches to diagnosis, treatment, and follow-up. Several clinical factors can contribute to finding overlapping DGBI, including the anatomical basis of the Rome diagnostic criteria, the potential confusion of symptom descriptors, and patients' biases towards higher symptom intensity ratings. Overlapping DGBI could also be caused by mechanistic factors such as pathophysiological mechanisms involving multiple gastrointestinal segments, and the effect of disorders in one segment on sensorimotor function in remote gastrointestinal parts, through neural or hormonal signalling. Key initial steps in the management of overlapping DGBI are detailed history taking, which can be facilitated using pictograms; carefully assessing the relative timing and cohesion of different symptoms; and recognising associated psychosocial dysfunction. Unnecessary technical investigations and complex combination treatment schedules should be avoided. Based on the identification of the dominant symptom pattern and putative underlying pathophysiological mechanisms, a single treatment modality should preferably be initiated, considering the efficacy spectrum of different therapies. Follow-up of the patient's condition allows the therapeutic approach to be adjusted as needed, while avoiding unnecessary additional technical investigations.

Gut dysmotility in children with neurological impairment: the nutritional management

Intestinal motility disorders represent a frequent problem in children with neurological impairment. These conditions are characterized by abnormal movements of the gut, which can result in symptoms such as constipation, diarrhea, reflux, and vomiting. The underlying mechanisms leading to dysmotility are various, and the clinical manifestations are often nonspecific. Nutritional management is an important aspect of care for children with gut dysmotility, as it can help to improve their quality of life. Oral feeding, when safe and in the absence of risk of ingestion or severe dysphagia, should always be encouraged. When oral nutrition is insufficient or potentially harmful, it is necessary to switch to an enteral by tube or parenteral nutrition before the onset of malnutrition. In most cases, children with severe gut dysmotility may require feeding via a permanent gastrostomy tube to ensure adequate nutrition and hydration. Drugs may be necessary to help manage gut dysmotility, such as laxatives, anticholinergics and prokinetic agents. Nutritional management of patients with neurological impairment often requires an individualized care plan to optimize growth and nutrition and to improve overall health outcomes. This review tries to sum up most significant neurogenetic and neurometabolic disorders associated with gut dysmotility that may require a specific multidisciplinary care, identifying a proposal of nutritional and medical management.

Effect of intracolonic volume on gastric sensory-motor responses in constipation-predominant irritable bowel syndrome

BACKGROUND

Interaction between gut stimuli may induce symptom overlap in patients with functional gastrointestinal disorders. The aim is to determine the effect of increased volumes of colonic contents on gastric sensory/motor responses and satiety in patients with constipation-predominant irritable bowel syndrome (IBS-C) and overlapping dyspeptic symptoms, and a cohort of healthy subjects.

METHODS

In 15 patients with IBS-C and 10 healthy subjects, the effect of real versus sham colonic filling with gas (1080 ml) on gastric sensitivity (measured by stepwise distensions of the stomach), gastric compliance, abdominal perception, and nutrient drink tolerance was studied on separate days.

RESULTS

In healthy subjects, colonic gas filling induced an increment in gastric sensitivity to distension (mean score 2.0 ± 0.2 before, and 3.0 ± 0.4 after; p = 0.038). In IBS, basal sensitivity was greater and remained unchanged after colonic gas filling (score 4.0 ± 0.1 and 3.8 ± 0.3, respectively; p < 0.001 vs. basal in health). Colonic gas infusion induced abdominal symptoms that were significantly greater in IBS-C (score 2.6 ± 0.1) than in health (score 1.7 ± 0.4; p = 0.027), with minor changes in gastric tone, and no changes in gastric compliance in both groups. Colonic filling produced a profound reduction in nutrient drink tolerance in IBS (791 ± 87 ml sham filling, 491 ± 58 ml gas filling; p < 0.001) but only a minor reduction in health (940 ± 70 ml sham filling, 860 ± 94 ml gas filling; p = 0.223).

CONCLUSIONS & INFERENCES

The volume of the colonic contents modulates satiety in patients with IBS-C, due to a general visceral pan-hypersensitivity. These effects should be considered in the choice of treatment for constipation in these patients.

The Effects of Modifying Amount and Type of Dietary Carbohydrate on Esophageal Acid Exposure Time and Esophageal Reflux Symptoms: A Randomized Controlled Trial

INTRODUCTION

This is the first randomized controlled diet intervention trial to investigate both the amount and type of carbohydrate on symptomatic gastroesophageal reflux disease (GERD).

METHODS

Ninety-eight veterans with symptomatic GERD were randomly assigned to high total/high simple, high total/low simple, low total/high simple, or low total/low simple carbohydrate diet for 9 weeks. The primary outcomes were esophageal acid exposure time (AET) and total number of reflux episodes derived from 24-hour ambulatory pH monitoring. Secondary outcomes were esophageal reflux symptoms rated using the Gastroesophageal Reflux Disease Questionnaire (GERDQ) and GERD Symptom Assessment Scale (GSAS).

RESULTS

Half of the subjects were White and half African American (mean age, 60.0 ± 12.5 years; mean body mass index, 32.7 ± 5.4 kg/m 2 ). There was a significant main effect of diet treatment on AET ( P = 0.001) and on the total number of reflux episodes ( P = 0.003). The change in AET in the high total/low simple group (-4.3% ± 3.8%) differed significantly from the high total/high simple control group (+3.1% ± 3.7%), (P = 0.04). The reduction in simple sugar intake averaged 62 g less per day. Subjects' ratings of symptoms improved in all carbohydrate modification groups, including significant reductions in heartburn frequency, heartburn severity, acid taste in the mouth, lump/pain in the throat or chest, and sleep disturbance.

DISCUSSION

A modification of dietary carbohydrate intake that targeted a substantial reduction in the intakes of simple sugars improved pH monitoring outcomes and symptoms of GERD that profoundly affect daily life. These findings provide a feasible and clinically applicable contribution to the limited objective data existing for efficacious dietary recommendations in the routine treatment and management of GERD.

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

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

The Effect of Rice vs. Wheat Ingestion on Postprandial Gastroesophageal Reflux (GER) Symptoms in Patients with Overlapping GERD-Irritable Bowel Syndrome (IBS)

A randomized crossover study in twenty-one patients (18F, age 50 ± 13 years) with overlapping GERD-IBS was conducted to evaluate the effects of rice noodles (low FODMAPs) vs. wheat noodles (high FODMAPs) on typical GER symptoms, and the correlation between GERD symptoms and intestinal gas production. Results: Heartburn and regurgitation scores were highest in most patients (19/21) during the first 15 min after meals. At 15 min after lunch, wheat was significantly associated with more regurgitation and heartburn than rice. Also, at 15 min after breakfast, wheat aggravated more regurgitation than rice. Wheat ingestion was significantly associated with higher H₂ and CH₄ levels after lunch compared to rice, whereas gas levels before lunch were similar (p > 0.05). The area under the curve of H₂ and CH₄ concentration 15 min after a lunch of wheat moderately correlated with the regurgitation severity at 15-min (r = 0.56, p < 0.05). Conclusion: Wheat induced more GERD symptoms than rice in patients with overlapping GERD-IBS. This effect, immediately developed after lunch, was associated with more intestinal gas production. Thus, a low FODMAPs diet may relieve postprandial GERD symptoms in GERD patients with overlapping IBS. Wheat inducing more regurgitation than rice after breakfast suggests other mechanism(s) besides gut fermentation.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

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

INTRODUCTION

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

MATERIALS

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

RESULTS

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

CONCLUSION

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

Food and Gastroesophageal Reflux Disease

Gastroesophageal reflux disease is a chronic condition with a high prevalence in western countries. Transient lower esophageal sphincter relaxation episodes and a decreased lower esophageal sphincter pressure are the main mechanisms involved. Currently used drugs are efficient on reflux symptoms, but only as long as they are administered, because they do not modify the reflux barrier. Certain nutrients or foods are generally considered to increase the frequency of gastroesophageal reflux symptoms, therefore physicians recommend changes in diet and some patients avoid bothering foods. This review summarizes current knowledge regarding food and gastroesophageal reflux. For example, fat intake increases the perception of reflux symptoms. Regular coffee and chocolate induce gastroesophageal reflux and increase the lower esophageal exposure to acid. Spicy foods might induce heartburn, but the exact mechanism is not known. Beer and wine induce gastroesophageal reflux, mainly in the first hour after intake. For other foods, like fried food or carbonated beverages data on gastroesophageal reflux is scarce. Similarly, there are few data about the type of diet and gastroesophageal reflux. Mediterranean diet and a very low carbohydrate diet protect against reflux. Regarding diet-related practices, consistent data showed that a "short-meal-to-sleep interval" favors reflux episodes, therefore some authors recommend that dinner should be at least four hours before bedtime. All these recommendations should consider patient's weight, because several meta-analyses showed a positive association between increased body mass index and gastroesophageal reflux disease.

Foods Inducing Typical Gastroesophageal Reflux Disease Symptoms in Korea

Background/Aims

Several specific foods are known to precipitate gastroesophageal reflux disease (GERD) symptoms and GERD patients are usually advised to avoid such foods. However, foods consumed daily are quite variable according to regions, cultures, etc. This study was done to elucidate the food items which induce typical GERD symptoms in Korean patients.

Methods

One hundred and twenty-six Korean patients with weekly typical GERD symptoms were asked to mark all food items that induced typical GERD symptoms from a list containing 152 typical foods consumed daily in Korea. All patients underwent upper gastrointestinal endoscopy followed by 24-hour ambulatory esophageal pH monitoring. The definition of “GERD” was if either of the 2 studies revealed evidence of GERD, and “possible GERD” if both studies were negative.

Results

One hundred and twenty-six cases (51 GERD and 75 possible GERD) were enrolled. In 19 (37.3%) of 51 GERD cases and in 17 (22.7%) of 75 possible GERD cases, foods inducing typical GERD symptoms were identified. In the GERD group (n = 19), frequent symptom-inducers were hot spicy stews, rice cakes, ramen noodles, fried foods, and topokki. In the possible GERD group (n = 17), frequent symptom-inducers were hot spicy stews, fried foods, doughnuts, breads, ramen noodles, coffee, pizza, topokki, rice cakes, champon noodles, and hotdogs.

Conclusions

In one-third of GERD patients, foods inducing typical symptoms were identified. Hot spicy stews, rice cakes, ramen noodles, fried foods, and topokki were the foods frequently inducing typical symptoms in Korea. The list of foods frequently inducing typical GERD symptoms needs to be modified based on their own local experiences.

Dietary carbohydrate intake, insulin resistance and gastro-oesophageal reflux disease: a pilot study in European- and African-American obese women

BACKGROUND

Although obesity rates are higher in African-American than European-American women, gastro-oesophageal reflux disease (GERD) and its comorbidities are more prevalent in European-American women. A common denominator for increased adiposity, and consequent insulin resistance, is excess dietary macronutrient intake - which may promote greater prevalence and severity of GERD in women.

AIM

To investigate whether GERD is more robustly associated with dietary carbohydrate intake, particularly dietary simple carbohydrate intake, and insulin resistance in European-American women.

METHODS

About 144 obese women were assessed at baseline and 16 weeks after consuming a high-fat/low-carbohydrate diet. GERD diagnosis and medication usage was confirmed in medical records with symptoms and medications assessed weekly.

RESULTS

About 33.3% (N = 33) of European-American and 20.0% (N = 9) of African-American women had GERD at baseline. Total carbohydrate (r = 0.34, P < 0.001), sugars (r = 0.30, P = 0.005), glycaemic load (r = 0.34, P = 0.001) and HOMA_IR (r = 0.30, P = 0.004) were associated with GERD, but only in European-American women. In response to high-fat/low-carbohydrate diet, reduced intake of sugars was associated with reduced insulin resistance. By the end of diet week 10, all GERD symptoms and medication usage had resolved in all women.

CONCLUSIONS

GERD symptoms and medication usage was more prevalent in European-American women, for whom the relationships between dietary carbohydrate intake, insulin resistance and GERD were most significant. Nevertheless, high-fat/low-carbohydrate diet benefited all women with regard to reducing GERD symptoms and frequency of medication use.

Evaluation of the relationship between major dietary patterns and uninvestigated reflux among Iranian adults

OBJECTIVES

The etiology of uninvestigated reflux is largely unknown. Although diet has been associated with uninvestigated reflux, the role of dietary patterns is not clear yet. The aim of this study was to investigate dietary patterns in relation to uninvestigated reflux among Iranian adults.

METHODS

This cross-sectional study was carried out within the framework of SEPAHAN (Study on the Epidemiology of Psychological, Alimentary Health and Nutrition) among Iranian adults. Dietary data were collected using a self-administered, 106-item, dish-based, semiquantitative food frequency questionnaire. Uninvestigated reflux was considered to be present when an individual reported to be suffering from heartburn sometimes or frequently in the preceding 3 mo. Specific dietary patterns were identified using factor analysis.

RESULTS

Complete information from 3846 individuals was available for statistical analysis. We identified four major dietary patterns: fast food, traditional, vegetarian, and Western. After controlling for potential confounders, no overall significant associations were found between these dietary patterns and uninvestigated reflux. However, participants in the third quintile of the traditional dietary pattern had greater odds of uninvestigated reflux, either in the crude (odds ratio [OR], 1.37; 95% confidence interval [CI], 1.09-1.74) or the adjusted (OR, 1.52; 95% CI, 1.16-2.00) model taking into account different confounders. After controlling for age, men in the second (OR, 1.64; 95% CI, 1.10-2.45) and women in the fourth (OR, 1.47; 95% CI, 1.02-2.11) quintiles of the fast food dietary pattern were more likely to have uninvestigated reflux. Moreover, in the age-adjusted model, men in the second (OR, 1.72; 95% CI, 1.14-2.59) and fourth (OR, 1.56; 95% CI, 1.03-2.35) quintiles, and women in the second (OR, 1.48; 95% CI, 1.08-2.04) quintile of the traditional dietary pattern were at higher risk for being diagnosed with uninvestigated reflux.

CONCLUSION

Although the present study showed no statistically significant associations between major dietary patterns and the risk for uninvestigated reflux, relative positive associations were found between uninvestigated reflux and adherence to either fast food or traditional dietary patterns, suggesting that these contribute to the risk for developing reflux.

Breath Methane Excretion Is not An Accurate Marker of Colonic Methane Production in Irritable Bowel Syndrome

OBJECTIVES

The role of colonic methane production in functional bowel disorders is still uncertain. In small samples of irritable bowel syndrome (IBS) patients, it was shown that methane breath excretion correlates with clinical presentation and delayed gastrointestinal transit time. The aim of this study was to evaluate the relationship between intestinal production and breath excretion of CH4 and to correlate CH4 production with the presence and the severity of symptoms, in a large cohort of IBS patients and in a group of healthy volunteers.

METHODS

A group of 103 IBS patients and a group of 28 healthy volunteers were enrolled. The presence and severity of symptoms and gastrointestinal transit were evaluated in all subjects, who underwent breath H2/CH4 measurement for 7 h after lactulose to identify breath excretors of these gases; H2 and CH4 were also measured in rectal samples to identify colonic producers. Cumulative H2 and CH4 excretion and production were evaluated by the area under the time-concentration curve calculation (AUC).

RESULTS

In IBS patients, CH4 was detected in rectal samples in 48 patients (47%), but only 27 of them (26% of the 103 enrolled patients) excreted this gas with breath. In CH4 producers, the prevalence and severity of symptoms and gastrointestinal transit time were not significantly different with respect to non-producers. IBS subtypes were homogeneously represented in CH4 producers and in non-producers. Healthy volunteers, compared with IBS patients, showed a significantly lower prevalence of CH4 excretion, whereas no difference was found in the prevalence of colonic CH4 production; moreover, in healthy volunteers compared with IBS, CH4 breath excretion and CH4 production were not different in quantitative terms.

CONCLUSION

Our data show that colonic CH4 production is not associated with clinical presentation in IBS patients and does not correlate with symptom severity or with gastrointestinal transit time. Clinical inferences based on breath CH4 excretion should undergo an in-depth revision, as this method is not a good marker of CH4 colonic production.

Gastro-oesophageal reflux symptoms and coeliac disease: no role for routine duodenal biopsy

BACKGROUND

Coeliac disease (CD) has been linked to gastro-oesophageal reflux disease (GORD). Previous studies have demonstrated an increased prevalence of reflux in patients with CD. However data on the risk for CD in patients presenting with reflux are conflicting.

AIMS

The aim of this study was to establish the prevalence of CD in patients with GORD and to elucidate the mechanisms for reflux symptoms in newly diagnosed CD patients.

METHODS

Group A: patients who had undergone routine duodenal biopsy were prospectively recruited between 2004 and 2014. Diagnostic yield was compared with that of a screening cohort. Group B: 32 patients with newly diagnosed CD who had undergone oesophageal manometry and 24-h pH studies were prospectively recruited.

RESULTS

Group A: 3368 patients (58.7% female, mean age 53.4 years) underwent routine duodenal biopsy. Of these patients, 850 (25.2%) presented with GORD. The prevalence of CD among GORD patients was 1.3% (0.7-2.4%), which was not significantly higher than that in the general population (P=0.53). Within the context of routine duodenal biopsy at endoscopy (when corrected for concurrent symptoms, age and sex), reflux was found to be negatively associated with CD [adjusted odds ratio 0.12 (0.07-0.23), P<0.0001]. In group B, 34% of patients complained of reflux. On manometry, 9% had a hypotensive lower oesophageal sphincter and 40.6% had oesophageal motor abnormalities, with 25% significantly hypocontractile. On pH studies, 33% demonstrated reflux episodes.

CONCLUSION

The prevalence of undiagnosed CD among GORD patients is similar to that in the general population, and routine duodenal biopsy cannot be recommended. A significant number of patients with newly diagnosed CD were found to have reflux and/or oesophageal dysmotility on pH/manometry studies; this may explain the high prevalence of reflux symptoms in CD.

The participation of the nitrergic pathway in increased rate of transitory relaxation of lower esophageal sphincter induced by rectal distension in dogs

CONTEXT

The rectal distension in dogs increases the rate of transitory lower esophageal sphincter relaxation considered the main factor causing gastroesophageal reflux.

OBJECTIVES

The aim of this study was evaluate the participation of the nitrergic pathway in the increased transitory lower esophageal sphincter relaxation rate induced by rectal distension in anesthetized dogs.

METHODS

Male mongrel dogs (n = 21), weighing 10-15 kg, were fasted for 12 hours, with water ad libitum. Thereafter, they were anesthetized (ketamine 10 mg.Kg-1 + xylazine 20 mg.Kg-1), so as to carry out the esophageal motility evaluation protocol during 120 min. After a 30-minute basal period, the animals were randomly intravenous treated whith: saline solution 0.15M (1ml.Kg-1), L-NAME (3 mg.Kg-1), L-NAME (3 mg.Kg-1) + L-Arginine (200 mg.Kg-1), glibenclamide (1 mg.Kg-1) or methylene blue (3 mg.Kg-1). Forty-five min after these pre-treatments, the rectum was distended (rectal distension, 5 mL.Kg-1) or not (control) with a latex balloon, with changes in the esophageal motility recorded over 45 min. Data were analyzed using ANOVA followed by Student Newman-Keuls test.

RESULTS

In comparison to the respective control group, rectal distension induces an increase in transitory lower esophageal sphincter relaxation. Pre-treatment with L-NAME or methylene blue prevents (P<0.05) this phenomenon, which is reversible by L-Arginine plus L-NAME. However, pretreating with glibenclamide failed to abolish this process.

CONCLUSIONS

Therefore, these experiments suggested, that rectal distension increases transitory lower esophageal sphincter relaxation in dogs via through nitrergic pathways.

Effect of short-chain fatty acids and acidification on the phasic and tonic motor activity of the human colon

BACKGROUND

The effects of bacterial fermentation on human colonic motor activity could be explained by colonic acidification or short-chain fatty acid (SCFA) production. We compared in healthy volunteers the colonic motor effects of intracolonic infusion of neutral or acidic saline solutions and then of neutral or acidic solutions containing an SCFA mixture.

METHODS

20 healthy volunteers swallowed a probe (with an infusion catheter, 6 perfused catheters and a balloon connected to a barostat) that migrated into the colon. Colonic motor activity was recorded in fasting basal state (1 h), during (3 h) and after (2 h) intracolonic infusion in a random order on two consecutive days of 750 mL of NaCl at pH 7.0 (neutral saline) or 4.5 (acidic saline) in 10 volunteers (first experiment) and of an SCFA mixture (acetic acid 66%, propionic acid 24% and butyric acid 10%; 100 mM) at pH 7.0 or 4.5 in 10 other volunteers (second experiment). We determined for each hour a global motility index (reflecting phasic activity recorded by all catheters), the mean balloon volume (reflecting tonic activity), and the mean number of high-amplitude-propagated contractions (HAPCs).

KEY RESULTS

Intracolonic infusion of neutral or acidic solutions containing saline or an SCFA mixture did not change the global motility index, the barostat balloon volume, or the HAPC number compared with basal values.

CONCLUSIONS & INFERENCES

Under our experimental conditions, these findings suggest that the stimulation of colonic motor activity induced by carbohydrate fermentation is not explained by the acidification of the colonic contents or the resulting production of SCFAs.

Food and symptom generation in functional gastrointestinal disorders: physiological aspects

The response of the gastrointestinal tract (GIT) to ingestion of food is a complex and closely controlled process, which allows optimization of propulsion, digestion, absorption of nutrients, and removal of indigestible remnants. This review summarizes current knowledge on the mechanisms that control the response of the GIT to food intake. During the cephalic phase, triggered by cortical food-related influences, the GIT prepares for receiving nutrients. The gastric phase is dominated by the mechanical effect of the meal volume. Accumulation of food in the stomach activates tension-sensitive mechanoreceptors, which in turn stimulate gastric accommodation and gastric acid secretion through the intrinsic and vago-vagal reflex pathways. After meal ingestion, the tightly controlled process of gastric emptying starts, with arrival of nutrients in the duodenum triggering negative feedback on emptying and stimulating secretion of digestive enzymes through the neural (mainly vago-vagal reflex, but also intrinsic) and endocrine (release of peptides from entero-endocrine cells) pathways. Several types of specialized receptors detect the presence of all main categories of nutrients. In addition, the gastrointestinal mucosa expresses receptors of the T1R and T2R families (taste receptors) and several members of the transient receptor potential channel family, all of which are putatively involved in the detection of specific tastants in the lumen. Activation of nutrient and taste sensors also activates the extrinsic and intrinsic neural, as well as entero-endocrine, pathways. During passage through the small bowel, nutrients are progressively extracted, and electrolyte-rich liquid intestinal content with non-digestible residue is delivered to the colon. The colon provides absorption of the water and electrolytes, storage of non-digestible remnants of food, aboral propulsion of contents, and finally evacuation through defecation.

Fiber and functional gastrointestinal disorders

Despite years of advising patients to alter their dietary and supplementary fiber intake, the evidence surrounding the use of fiber for functional bowel disease is limited. This paper outlines the organization of fiber types and highlights the importance of assessing the fermentation characteristics of each fiber type when choosing a suitable strategy for patients. Fiber undergoes partial or total fermentation in the distal small bowel and colon leading to the production of short-chain fatty acids and gas, thereby affecting gastrointestinal function and sensation. When fiber is recommended for functional bowel disease, use of a soluble supplement such as ispaghula/psyllium is best supported by the available evidence. Even when used judiciously, fiber can exacerbate abdominal distension, flatulence, constipation, and diarrhea.

Dietary and lifestyle factors in functional dyspepsia

Dietary factors are increasingly recognized to have an important role in triggering symptoms in a large proportion of patients with functional dyspepsia. Fatty foods seem to be the main culprits, but other foods (including carbohydrate-containing foods, milk and dairy products, citrus fruits, spicy foods, coffee and alcohol) have also been implicated. However, blind challenge tests do not provide consistent results. Moreover, although patients identify specific foods as triggers of their symptoms, these patients often do not seem to make behavioural adjustments in an attempt to improve symptoms; that is, any differences in dietary intake and lifestyle between patients and healthy individuals are small. Patients with functional dyspepsia exhibit mixed sensory-motor abnormalities, such as gastric hypersensitivity and impaired gastric accommodation of a meal. Nutrients, particularly fat, exacerbate these abnormalities and might thereby trigger postprandial symptoms. Cognitive factors, including anticipation related to previous negative experience with certain foods, might also have a role in triggering symptoms. Studies evaluating the potential beneficial effect of dietary interventions and changes in lifestyle are lacking, and this Review outlines a number of options that could be used as starting points for meaningful large-scale studies in the future.

Different in vitro and in vivo profiles of substituted 3-aminopropylphosphinate and 3-aminopropyl(methyl)phosphinate GABA(B) receptor agonists as inhibitors of transient lower oesophageal sphincter relaxation

BACKGROUND AND PURPOSE

Gastro-oesophageal reflux is predominantly caused by transient lower oesophageal sphincter relaxation (TLOSR) and GABA(B) receptor stimulation inhibits TLOSR. Lesogaberan produces fewer CNS side effects than baclofen, which has been attributed to its affinity for the GABA transporter (GAT), the action of which limits stimulation of central GABA(B) receptors. To understand the structure-activity relationship for analogues of lesogaberan (3-aminopropylphosphinic acids), and corresponding 3-aminopropyl(methyl)phosphinic acids, we have compared representatives of these classes in different in vitro and in vivo models.

EXPERIMENTAL APPROACH

The compounds were characterized in terms of GABA(B) agonism in vitro. Binding to GATs and cellular uptake was done using rat brain membranes and slices respectively. TLOSR was measured in dogs, and CNS side effects were evaluated as hypothermia in mice and rats.

KEY RESULTS

3-Aminopropylphosphinic acids inhibited TLOSR with a superior therapeutic index compared to 3-aminopropyl(methyl)phosphinic acids. This difference was most likely due to differential GAT-mediated uptake into brain cells of the former but not latter. In agreement, 3-aminopropyl(methyl)phosphinic acids were much more potent in producing hypothermia in rats even when administered i.c.v.

CONCLUSIONS AND IMPLICATIONS

An enhanced therapeutic window for 3-aminopropylphosphinic acids compared with 3-aminopropyl(methyl)phosphinic acids with respect to inhibition of TLOSR was observed and is probably mechanistically linked to neural cell uptake of the former but not latter group of compounds. These findings offer a platform for discovery of new GABA(B) receptor agonists for the treatment of reflux disease and other conditions where selective peripheral GABA(B) receptor agonism may afford therapeutic effects.

Food choice as a key management strategy for functional gastrointestinal symptoms

Recognition of food components that induce functional gut symptoms in patient's functional bowel disorders (FBD) has been challenging. Food directly or indirectly provides considerable afferent input into the enteric nervous system. There is an altered relationship between the afferent input and perception/efferent response in FBD. Defining the nature of food-related stimuli may provide a means of minimizing such an input and gut symptoms. Using this premise, reducing the intake of FODMAPs (fermentable oligo-, di-, and mono-saccharides and polyols)--poorly absorbed short-chain carbohydrates that, by virtue of their small molecular size and rapid fermentability, will distend the intestinal lumen with liquid and gas--improves symptoms in the majority of patients. Well-developed methodologies to deliver the diet via dietician-led education are available. Another abundant source of afferent input is natural and added food chemicals (such as salicylates, amines, and glutamates). Studies are needed to assess the efficacy of the low food chemical dietary approach. A recent placebo-controlled trial of FODMAP-poor gluten provided the first valid evidence that non-celiac gluten intolerance might actually exist, but its prevalence and underlying mechanisms require elucidation. Food choice via the low FODMAP and potentially other dietary strategies is now a realistic and efficacious therapeutic approach for functional gut symptoms.

Up-regulation of intestinal type 1 taste receptor 3 and sodium glucose luminal transporter-1 expression and increased sucrose intake in mice lacking gut microbiota

The chemosensory components shared by both lingual and intestinal epithelium play a critical role in food consumption and the regulation of intestinal functions. In addition to nutrient signals, other luminal contents, including micro-organisms, are important in signalling across the gastrointestinal mucosa and initiating changes in digestive functions. A potential role of gut microbiota in influencing food intake, energy homeostasis and weight gain has been suggested. However, whether gut microbiota modulates the expression of nutrient-responsive receptors and transporters, leading to altered food consumption, is unknown. Thus, we examined the preference for nutritive (sucrose) and non-nutritive (saccharin) sweet solutions in germ-free (GF, C57BL/6J) mice compared with conventional (CV, C57BL/6J) control mice using a two-bottle preference test. Then, we quantified mRNA and protein expression of the sweet signalling protein type 1 taste receptor 3 (T1R3) and α-gustducin and Na glucose luminal transporter-1 (SGLT-1) of the intestinal epithelium of both CV and GF mice. Additionally, we measured gene expression of T1R2, T1R3 and α-gustducin in the lingual epithelium. We found that, while the preference for sucrose was similar between the groups, GF mice consumed more of the high concentration (8 %) of sucrose solution than CV mice. There was no difference in either the intake of or the preference for saccharin. GF mice expressed significantly more T1R3 and SGLT-1 mRNA and protein in the intestinal epithelium compared with CV mice; however, lingual taste receptor mRNA expression was similar between the groups. We conclude that the absence of intestinal microbiota alters the expression of sweet taste receptors and GLUT in the proximal small intestine, which is associated with increased consumption of nutritive sweet solutions.

Fermentation of starch stimulates propagated contractions in the human colon

BACKGROUND

In healthy humans, up to 30 g of daily ingested starch escape small intestinal digestion, and are fermented in the colon. This physiological starch malabsorption could modify colonic motility through metabolites such as short-chain fatty acids produced by fermentation.

METHODS

Ten healthy volunteers swallowed a probe, consisting of an infusion catheter, six perfused catheters and a balloon connected to a barostat. On two consecutive days colonic motility was recorded in fasting subjects in the basal state (1 h), and then during (3 h), and after (2 h) the intracolonic infusion of 750 mL of isoosmotic and isovolumetric solutions containing sodium chloride with or without 15 g wheat starch. We determined (i) the volume of hydrogen and methane exhaled in breath, (ii) a global motility index and the number of high amplitude propagated contractions (HAPCs), and (iii) the mean balloon volume, reflecting the tonic motor activity.

KEY RESULTS

[median (IQR)] Compared to the basal period, colonic infusion of starch or saline did not modify the colonic motility index and tone. However, the number of HAPCs was significantly higher during and after infusion of starch than of saline [4.5 (2.75-6.5) vs 0.96 (0-2.66)/5 h, starch vs saline respectively; P = 0.011].

CONCLUSIONS & INFERENCES

In healthy humans, colonic fermentation of a physiological malabsorbed amount of starch has no effect on the tonic and phasic colonic motor activities, but produces a significant increase in the number of HAPCs. This may participate in the physiological propulsion of colonic contents.

Microflora modulation of motility

That gastrointestinal motility can influence the gut microbiota has been known for decades and the clinical consequences of impaired motility, in terms of the bacterial population of the small intestine, amply illustrated by the syndrome of small intestinal bacterial overgrowth which so commonly accompanies diffuse intestinal motility disorders. As the importance of the microbiota to homeostasis in health and to a variety of disease states is increasingly appreciated and as the full diversity and biology of this "hidden organ" have been revealed by molecular methodologies, the true nature of the interaction between the microbiota and motility is being re-examined and the complexity of this relationship exposed. In health, as well as in disease states, this is a truly bi-directional relationship: not only can gut motor patterns influence the microbiota but changes in the microbiota can exert profound influences on gut sensori-motor function.

Fructose malabsorption: true condition or a variance from normality

Fructose exists in food naturally or as a sweetening additive. It has been thought that fructose malabsorption may cause the gastrointestinal symptoms seen in patients with irritable bowel syndrome. However, fructose malabsorption is still poorly understood, and clinicians are still uncertain of its role. This review attempts to clarify the relation between fructose malabsorption and symptoms in normal individuals and patients with irritable bowel syndrome. The main problem lies in the diagnosis. First, there is no definite cut off value for the breath tests. Second, we are unsure of the normal absorptive capacity of fructose in normal individuals. Normal individuals will have a degree of fructose malabsorption with or without symptoms depending on the dose of fructose used. From earlier studies, 25 g of fructose seems to be the cut-off dose to investigate fructose malabsorption, with a positive breath test at this dose suggesting abnormally low capacity to absorb fructose. This low level may be difficult to exclude from the daily diet, resulting in symptoms of fructose malabsorption.

Are rice and spicy diet good for functional gastrointestinal disorders?

Rice- and chili-containing foods are common in Asia. Studies suggest that rice is completely absorbed in the small bowel, produces little intestinal gas and has a low allergenicity. Several clinical studies have demonstrated that rice-based meals are well tolerated and may improve gastrointestinal symptoms in functional gastrointestinal disorders (FGID). Chili is a spicy ingredient commonly use throughout Asia. The active component of chili is capsaicin. Capsaicin can mediate a painful, burning sensation in the human gut via the transient receptor potential vanilloid-1 (TRPV1). Recently, the TRPV1 expressing sensory fibers have been reported to increase in the gastrointestinal tract of patients with FGID and visceral hypersensitivity. Acute exposure to capsaicin or chili can aggravate abdominal pain and burning in dyspepsia and IBS patients. Whereas, chronic ingestion of natural capsaicin agonist or chili has been shown to decrease dyspeptic and gastroesophageal reflux disease (GERD) symptoms. The high prevalence of spicy food in Asia may modify gastrointestinal burning symptoms in patients with FGID. Studies in Asia demonstrated a low prevalence of heartburn symptoms in GERD patients in several Asian countries. In conclusion rice is well tolerated and should be advocated as the carbohydrate source of choice for patients with FGID. Although, acute chili ingestion can aggravate abdominal pain and burning symptoms in FGID, chronic ingestion of chili was found to improve functional dyspepsia and GERD symptoms in small randomized, controlled studies.

Gastrointestinal targets of appetite regulation in humans

The aim of this paper is to describe and discuss relevant aspects of the assessment of physiological functions - and related biomarkers - implicated in the regulation of appetite in humans. A short introduction provides the background and the present state of biomarker research as related to satiety and appetite. The main focus of the paper is on the gastrointestinal tract and its functions and biomarkers related to appetite for which sufficient data are available in human studies. The first section describes how gastric emptying, stomach distension and gut motility influence appetite; the second part describes how selected gastrointestinal peptides are involved in the control of satiety and appetite (ghrelin, cholecystokinin, glucagon-like peptide, peptide tyrosin-tyrosin) and can be used as potential biomarkers. For both sections, methodological aspects (adequacy, accuracy and limitation of the methods) are described. The last section focuses on new developments in techniques and methods for the assessment of physiological targets involved in appetite regulation (including brain imaging, interesting new experimental approaches, targets and markers). The conclusion estimates the relevance of selected biomarkers as representative markers of appetite regulation, in view of the current state of the art.

No effect of added beta-glucan or of fructooligosaccharide on appetite or energy intake

BACKGROUND

An increase in gastrointestinal viscosity or colonic fermentation is suggested to improve appetite control and reduce food intake. It has been proposed that beta-glucan and fructooligosaccharide (FOS) are food ingredients that increase gastrointestinal viscosity and colonic fermentation, but the results are inconclusive.

OBJECTIVE

The objective was to test the effect of FOS, beta-glucan, or a combination thereof on appetite ratings and food intake over 2 consecutive days.

DESIGN

In a 4-way balanced-order, crossover, double-blind design, 21 healthy volunteers [mean body mass index (in kg/m(2)) 25.9] consumed a meal-replacement bar at 0900 and an ad libitum lunch at 1300 on 2 consecutive days. On day 1 only, the subjects consumed a second (identical) bar at 1700 and a fixed snack at 1900. The control bar contained 0.3 g beta-glucan from 6.8 g oats (control), and the 3 equicaloric test bars contained an additional 0.9 g beta-glucan (from 8.0 g barley), 8 g FOS, or 0.9 g beta-glucan + 8 g FOS. Appetite scores and subsequent ad libitum test meal intakes were measured. Viscosities in response to bar consumption were determined under simulated gastric conditions. The results were analyzed by analysis of covariance.

RESULTS

The addition of beta-glucan, FOS, or a combination thereof did not affect appetite ratings or food intake, although the addition of beta-glucan to the bar doubled gastric viscosity (841 compared with 351 mPa . s).

CONCLUSIONS

Consumption of beta-glucan, FOS, or a combination thereof in meal-replacement bars at the levels tested for 2 consecutive days does not improve appetite control. Efficacy may have improved if the consumption period was longer, if the content of beta-glucan was greater, or if a form of beta-glucan that generates even higher gastric viscosity was consumed. This trial was registered at (clinicaltrials.gov) as NCT00776256.

Removing lactose from milk does not delay bowel function or harden stool consistency in lactose-tolerant women

OBJECTIVES

To investigate whether removing lactose from milk delays bowel function in lactose-tolerant women. We also examined how well the participants' subjective evaluation of the stool consistency according to the Bristol Stool Form Scale correlated with values obtained by dry matter analysis and penetrometry.

SUBJECTS AND METHODS

A randomized double-blind cross-over trial. Thirty-three lactose-tolerant women consumed, in random order, 800 ml of lactose-free or ordinary milk per day for 2 weeks, with their main meal, but otherwise followed a lactose-free diet. The subjects estimated stool consistency according to the Bristol Stool Form Scale, registered stool frequency and gastrointestinal symptoms and collected stool samples.

RESULTS

The mean intake of lactose was 3.5 and 38.4 g/day during the lactose-free and the ordinary milk periods, respectively. There were no statistically significant differences between the lactose-free and the ordinary milk periods in stool frequency, gastrointestinal symptoms, stool hardness or faecal dry matter. Faecal pH was lower during the lactose-free milk period than in the ordinary milk period. The subjective estimation of stool hardness correlated well with the values obtained by dry matter analysis and penetrometry.

CONCLUSIONS

Lactose-free milk does not delay bowel function in lactose-tolerant women. The Bristol Stool Form Scale is a useful method of evaluating stool hardness.

A very low-carbohydrate diet improves gastroesophageal reflux and its symptoms

Obese patients with gastroesophageal reflux disease (GERD) may experience resolution of symptoms utilizing a very low-carbohydrate diet. The mechanism of this improvement is unknown. This studied aimed to prospectively assess changes in distal esophageal acid exposure and GERD symptoms among obese adults initiating a very low-carbohydrate diet. We studied obese individuals with GERD initiating a diet containing less than 20 g/day of carbohydrates. Symptom severity was assessed using the GERD Symptom Assessment Scale--Distress Subscale (GSAS-ds). Participants underwent 24-hr esophageal pH probe testing and initiated the diet upon its completion. Within 6 days, a second pH probe test was performed. Outcomes included changes in the Johnson-DeMeester score, percentage total time with a pH<4 in the distal esophagus, and GSAS-ds scores. Eight participants were enrolled. Mean Johnson-DeMeester score decreased from 34.7 to 14.0 (P=0.023). Percentage time with pH<4 decreased from 5.1% to 2.5% (P=0.022). Mean GSAS-ds score decreased from 1.28 to 0.72 (P=0.0004). These data suggest that a very low-carbohydrate diet in obese individuals with GERD significantly reduces distal esophageal acid exposure and improves symptoms.

Colonic fermentation influences lower esophageal sphincter function in gastroesophageal reflux disease

BACKGROUND & AIMS

Colonic fermentation of carbohydrates is known to influence gastric and esophageal motility in healthy subjects. This study investigated the effects of colonic fermentation induced by oral administration of fructooligosaccharides (FOS) in patients with gastroesophageal reflux disease (GERD).

METHODS

In the cross-over design used in the study, 9 patients with symptomatic GERD were administered a low-residue diet (i.e., 10 g fiber/day) during 2, 7-day periods, receiving either 6.6 g of FOS or placebo 3 times daily after meals. Each period was separated by a wash out of at least 3 weeks. On day 7, esophageal motility and pH were recorded in fasting conditions and after a test meal containing 6.6 g of FOS or placebo. Breath hydrogen concentrations (reflecting colonic fermentation) and plasma concentrations of glucagon-like peptide 1 (GLP-1), peptide YY, and cholecystokinin were monitored.

RESULTS

Compared with placebo, FOS led to a significant increase in the number of transient lower esophageal sphincter relaxations (TLESRs) and reflux episodes, esophageal acid exposure, and the symptom score for GERD. The integrated plasma response of GLP-1 was significantly higher after FOS than placebo.

CONCLUSIONS

Colonic fermentation of indigestible carbohydrates increases the rate of TLESRs, the number of acid reflux episodes, and the symptoms of GERD. Although different mechanisms are likely to be involved, excess release of GLP-1 may account, at least in part, for these effects.