暂无摘要。

The importance of dietary fiber (DF) in animal diets is increasing with the advancement of nutritional research. DF is fermented by gut microbiota to produce metabolites, which are important in improving intestinal health. This review is a systematic review of DF in pig nutrition using in vitro and in vivo models. The fermentation characteristics of DF and the metabolic mechanisms of its metabolites were summarized in an in vitro model, and it was pointed out that SCFAs and gases are the important metabolites connecting DF, gut microbiota, and intestinal health, and they play a key role in intestinal health. At the same time, some information about host-microbe interactions could have been improved through traditional animal in vivo models, and the most direct feedback on nutrients was generated, confirming the beneficial effects of DF on sow reproductive performance, piglet intestinal health, and growing pork quality. Finally, the advantages and disadvantages of different fermentation models were compared. In future studies, it is necessary to flexibly combine in vivo and in vitro fermentation models to profoundly investigate the mechanism of DF on the organism in order to promote the development of precision nutrition tools and to provide a scientific basis for the in-depth and rational utilization of DF in animal husbandry. KEY POINTS: • The fermentation characteristics of dietary fiber in vitro models were reviewed. • Metabolic pathways of metabolites and their roles in the intestine were reviewed. • The role of dietary fiber in pigs at different stages was reviewed.

OBJECTIVE: Abdominal distention results from abdominophrenic dyssynergia (ie, diaphragmatic contraction and abdominal wall relaxation) in patients with disorders of gut-brain interaction. This study aimed to validate a simple biofeedback procedure, guided by abdominothoracic wall motion, for treating abdominal distension.
METHODS: In this randomized, parallel, placebo-controlled trial, 42 consecutive patients (36 women and 6 men; ages 17-64 years) with meal-triggered visible abdominal distension were recruited. Recordings of abdominal and thoracic wall motion were obtained using inductance plethysmography via adaptable belts. The signal was shown to patients in the biofeedback group, who were taught to mobilize the diaphragm. In contrast, the signal was not shown to the patients in the placebo group, who were given a placebo capsule. Three sessions were performed over a 4-week intervention period, with instructions to perform exercises (biofeedback group) or to take placebo 3 times per day (control group) at home. Outcomes were assessed through response to an offending meal (changes in abdominothoracic electromyographic activity and girth) and clinical symptoms measured using daily scales for 7 days.
RESULTS: Patients in the biofeedback group (n = 19) learned to correct abdominophrenic dyssynergia triggered by the offending meal (intercostal activity decreased by a mean ± SE of 82% ± 10%, anterior wall activity increased by a mean ± SE of 97% ± 6%, and increase in girth was a mean ± SE of 108% ± 4% smaller) and experienced improved clinical symptoms (abdominal distension scores decreased by a mean ± SE of 66% ± 5%). These effects were not observed in the placebo group (all, P < .002).
CONCLUSIONS: Abdominothoracic wall movements serve as an effective biofeedback signal for correcting abdominophrenic dyssynergia and abdominal distention in patients with disorders of gut-brain interaction. ClincialTrials.gov, Number: NCT04043208.

The analysis of colonic contents is a valuable tool for the gastroenterologist and has multiple applications in clinical routine. When considering magnetic resonance imaging (MRI) modalities, T2 weighted images are capable of segmenting the colonic lumen, whereas fecal and gas contents can only be distinguished in T1 weighted images. In this paper, we present an end-to-end quasi-automatic framework that comprises all the steps needed to accurately segment the colon in T2 and T1 images and to extract colonic content and morphology data to provide the quantification of colonic content and morphology data. As a consequence, physicians have gained new insights into the effects of diets and the mechanisms of abdominal distension.

Previous studies have shown that a resistant dextrin soluble fibre has prebiotic properties with related health benefits on blood glucose management and satiety. Our aim was to demonstrate the effects of continuous administration of resistant dextrin on intestinal gas production, digestive sensations, and gut microbiota metabolism and composition. Healthy subjects (n = 20) were given resistant dextrin (14 g/d NUTRIOSE®, Roquette Frères, Lestrem, France) for four weeks. Outcomes were measured before, at the beginning, end, and two weeks after administration: anal evacuations of gas during daytime; digestive perception, girth, and gas production in response to a standard meal; sensory and digestive responses to a comfort meal; volume of colonic biomass by magnetic resonance; taxonomy and metabolic functions of fecal microbiota by shotgun sequencing; metabolomics in urine. Dextrin administration produced an initial increase in intestinal gas production and gas-related sensations, followed by a subsequent decrease, which magnified after discontinuation. Dextrin enlarged the volume of colonic biomass, inducing changes in microbial metabolism and composition with an increase in short chain fatty acids-producing species and modulation of bile acids and biotin metabolism. These data indicate that consumption of a soluble fibre induces an adaptative response of gut microbiota towards fermentative pathways with lower gas production.

Our aim was to determine the reliability of plain abdominal radiographs for the evaluation of abdominal gas content in patients with functional digestive symptoms.
Abdominal CT scan scout views, mimicking a conventional plain abdominal radiograph, were obtained from 30 patients both during episodes of abdominal distension and basal conditions. Physicians (n = 50) were instructed to rate the estimated volume of gas in the 60 images presented in random sequence using a scale graded from 0 to ≥600 ml.
The gas volumes estimated in the scout views differed from those measured by CT by a median of 90 (95% CI 70-102) ml, and the misestimation was not related to the absolute volume in the image. The accuracy of the observers, measured by their mean misestimation, was not related to their specialty or the training status (misestimation by 96 (95% CI 85-104) ml in staff vs 78 (70-106) ml in residents; p = 0.297). The accuracy was independent of the order of presentation of the images. Gas volume measured by CT in the images obtained during episodes of abdominal distension differed by a median of 39 (95% CI 29-66) ml from those during basal conditions, and this difference was misestimated by a median of 107 (95% CI 94-119) ml. The accuracy of these estimations was not related to the absolute gas volumes (R = -0.352; p < 0.001) or the magnitude of the differences.
Plain abdominal radiographs have limited value for the evaluation of abdominal gas volume in patients with functional gut disorders.

Visible abdominal distension has been attributed to: (A) distorted perception, (B) intestinal gas accumulation, or (C) abdominophrenic dyssynergia (diaphragmatic push and anterior wall relaxation).
A pool of consecutive patients with functional gut disorders and visible abdominal distension included in previous studies (n = 139) was analyzed. Patients (61 functional bloating, 74 constipation-predominant irritable bowel syndrome and 4 with alternating bowel habit) were evaluated twice, under basal conditions and during a self-reported episode of visible abdominal distension; static abdominal CT images were taken in 104 patients, and dynamic EMG recordings of the abdominal walls in 76, with diaphragmatic activity valid for analysis in 35.
(A) Objective evidence of abdominal distension was obtained by tape measure (increase in girth in 138 of 139 patients), by CT imaging (increased abdominal perimeter in 96 of 104 patients) and by abdominal EMG (reduced activity, i.e., relaxation, in 73 of 76 patients). (B) Intestinal gas volume was within ±300 ml from the basal value in 99 patients, and above in 5 patients, who nevertheless exhibited a diaphragmatic descent. (C) Diaphragmatic contraction was detected in 34 of 35 patients by EMG (increased activity) and in 82 of 103 patients by CT (diaphragmatic descent).
In most patients complaining of episodes of visible abdominal distention: (A) the subjective claim is substantiated by objective evidence; (B) an increase in intestinal gas does not justify visible abdominal distention; (C) abdominophrenic dyssynergia is consistently evidenced by dynamic EMG recording, but static CT imaging has less sensitivity.

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.
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.
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).
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.

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.

Healthy plant-based diets rich in fermentable residues may induce gas-related symptoms, possibly mediated by the gut microbiota. We previously showed that consumption of a fermented milk product (FMP) containing Bifidobacterium animalis subsp. lactis CNCM I-2494 and lactic acid bacteria improved gastrointestinal (GI) comfort in response to a flatulogenic dietary challenge in healthy individuals. To study the effects of the FMP on gut microbiota activity from those participants, we conducted a metatranscriptomic analysis of fecal samples (n = 262), which were collected during the ingestion of a habitual diet and two series of a 3-day high-residue challenge diet, before and following 28-days of FMP consumption. Most of the FMP species were detected or found enriched upon consumption of the product. FMP mitigated the effect of a flatulogenic diet on gas-related symptoms in several ways. First, FMP consumption was associated with the depletion of gas-producing bacteria and increased hydrogen to methane conversion. It also led to the upregulation of activities such as replication and downregulation of functions related to motility and chemotaxis. Furthermore, upon FMP intake, metabolic activities such as carbohydrate metabolism, attributed to B. animalis and S. thermophilus, were enriched; these activities were coincidentally found to be negatively associated with several GI symptoms. Finally, a more connected microbial ecosystem or mutualistic relationship among microbes was found in responders to the FMP intervention. Taken together, these findings suggest that consumption of the FMP improved the tolerance of a flatulogenic diet through active interactions with the resident gut microbiota.