Our aim was to determine the effect of diet on gut microbiota, digestive function and sensations, using an integrated clinical, metagenomics and metabolomics approach. We conducted a cross-over, randomised study on the effects of a Western-type diet versus a fibre-enriched Mediterranean diet. In 20 healthy men, each diet was administered for 2 weeks preceded by a 2-week washout diet. The following outcomes were recorded: (a) number of anal gas evacuations; (b) digestive sensations; (c) volume of gas evacuated after a probe meal; (d) colonic content by magnetic resonance imaging; (e) gut microbiota taxonomy and metabolic functions by shotgun sequencing of faecal samples; (f) urinary metabolites using untargeted metabolomics. As compared to a Western diet, the Mediterranean diet was associated with (i) higher number of anal gas evacuations, (ii) sensation of flatulence and borborygmi, (iii) larger volume of gas after the meal and (iv) larger colonic content. Despite the relatively little difference in microbiota composition between both diets, microbial metabolism differed substantially, as shown by urinary metabolite profiles and the abundance of microbial metabolic pathways. The effects of the diet were less evident in individuals with robust microbiotas (higher beta-diversity). To conclude, healthy individuals tolerate dietary changes with minor microbial modifications at the composition level but with remarkable variation in microbial metabolism.

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.

Background Systemic sclerosis (SSc) is a chronic autoimmune disease characterised by microvascular damage and fibrosis. Mortality in patients with SSc has significantly decreased. Consequently, patients with SSc have longer life expectancy, and health-related quality of life (HrQoL) has become more relevant in the comprehensive management of the disease. Objective To evaluate the impact between gastrointestinal (GI) symptom burden and psychological well-being on HrQoL in patients with SSc. Design Nested cross-sectional study conducted between January and July 2022. Participants A single-centre cohort of 166 patients with SSc, including 103 (55%) with limited cutaneous SSc, 43 (24%) with diffuse SSc and 37 (21%) with sine-sclerosis SSc. Main measures GI symptom burden was assessed using the University of California Los Angeles Scleroderma Clinical Trial Consortium gastrointestinal tract 2.0 (UCLA SCTC GIT 2.0) questionnaire, psychological well-being was measured with the Hospital Anxiety and Depression Scale (HADS), and HrQoL was evaluated using the Short Form 36 (SF-36) questionnaire. Demographic, clinical and immunological data were collected from a prospectively maintained database. Key results Patients with moderate to severe GI symptoms (UCLA SCTC GIT 2.0 score >0.5, n=95, 57%) reported decreased HrQoL in all subdomains except vitality by SF-36, and higher anxiety and depression scores by HADS (all p<0.05). The severity of GI symptom burden and depression were independently associated with a decline in the physical component of QoL (β=−0.273 and β=−0.411, respectively, p<0.01 for both). Only the severity of depression and anxiety (β=−0.482 and β=−0.213, respectively, p<0.05), but not GI symptom burden, were independently associated with a decline in the mental component of QoL. Conclusions Our data suggest that in patients with SSc, GI and psychological burden negatively influence quality of life independently, highlighting the need for a holistic approach to patient’s care.

Postprandial objective abdominal distention is frequently associated with a subjective sensation of abdominal bloating, but the relation between both complaints is unknown. While the bloating sensation has a visceral origin, abdominal distention is a behavioral somatic response, involving contraction and descent of the diaphragm with protrusion of the anterior abdominal wall. Our aim was to determine whether abdominal distention influences digestive sensations. In 16 healthy women we investigated the effect of intentional abdominal distention on experimentally induced bloating sensation (by a meal overload). Participants were first taught to produce diaphragmatic contraction and visible abdominal distention. After a meal overload, sensations of bloating (0 to 10) and digestive well-being (−5 to + 5) were measured during 30-s. maneuvers alternating diaphragmatic contraction and diaphragmatic relaxation. Compared to diaphragmatic relaxation, diaphragmatic contraction was associated with diaphragmatic descent (by 21 + 3 mm; p < 0.001), objective abdominal distension (32 + 5 mm girth increase; p = 0.001), more intense sensation of bloating (7.3 + 0.4 vs. 8.0 + 0.4 score; p = 0.010) and lower digestive well-being (−0.9 + 0.5 vs. −1.9 + 0.5 score; p = 0.028). These results indicate that somatic postural tone underlying abdominal distention worsens the perception of visceral sensations (ClinicalTrials.gov ID: NCT04691882).