Prebiotics and diets low in fermentable oligo-, di-, mono-saccharides and polyols (low-FODMAP diet) might reduce symptoms in patients with functional gastrointestinal disorders, despite reports that some nonabsorbable, fermentable meal products (prebiotics) provide substrates for colonic bacteria and thereby increase gas production. We performed a randomized, parallel, double-blind study of patients with functional gastrointestinal disorders with flatulence. We compared the effects of a prebiotic supplement (2.8 g/d Bimuno containing 1.37 g beta-galactooligosaccharide) plus a placebo (Mediterranean-type diet (prebiotic group, n = 19) vs a placebo supplement (2.8 g xylose) plus a diet low in FODMAP (low-FODMAP group, n = 21) for 4 weeks; patients were then followed for 2 weeks. The primary outcome was effects on composition of the fecal microbiota, analyzed by 16S sequencing. Secondary outcomes were intestinal gas production and digestive sensations. After 4 weeks, we observed opposite effects on microbiota in each group, particularly in relation to the abundance of Bifidobacterium sequences (increase in the prebiotic group and decrease in the low-FODMAP group; P = .042), and Bilophila wadsworthia (decrease in the prebiotic group and increase in the low-FODMAP group; P = .050). After 4 weeks, both groups had statistically significant reductions in all symptom scores, except reductions in flatulence and borborygmi were not significant in the prebiotic group. Although the decrease in symptoms persisted for 2 weeks after patients discontinued prebiotic supplementation, symptoms reappeared immediately after patients discontinued the low-FODMAP diet. Intermittent prebiotic administration might therefore be an alternative to dietary restrictions for patients with functional gut symptoms. ClinicalTrials.gov no.: NCT02210572.

Background: The metabolic activity of colonic microbiota is influenced by diet; however, the relationship between metabolism and colonic content is not known. Our aim was to determine the effect of meals, defecation, and diet on colonic content. Methods:In 10 healthy subjects, two abdominal MRI scans were acquired during fasting, 1 week apart, and after 3 days on low-and high-residue diets, respectively. With each diet, daily fecal output and the number of daytime anal gas evacuations were measured. On the first study day, a second scan was acquired 4 hours after a test meal (n=6) or after 4 hours with nil ingestion (n=4). On the second study day, a scan was also acquired after a spontaneous bowel movement.Results: On the low-residue diet, daily fecal volume averaged 145 ± 15 mL; subjects passed 10.6 ± 1.6 daytime anal gas evacuations and, by the third day, non-gaseous colonic content was 479 ± 36 mL. The high-residue diet increased the three parameters to 16.5 ± 2.9 anal gas evacuations, 223 ± 19 mL fecal output, and 616 ± 55 mL non-gaseous colonic content (P<.05 vs low-residue diet for all). On the low-residue diet, non-gaseous content in the right colon had increased by 41 ± 11 mL, 4 hours after the test meal, whereas no significant change was observed after 4-hour fast (−15 ± 8 mL; P=.006 vs fed). Defecation significantly reduced the non-gaseous content in distal colonic segments. Conclusion & Inferences:Colonic content exhibits physiologic variations with an approximate 1/3 daily turnover produced by meals and defecation, superimposed over diet-related day-to-day variations. K E Y W O R D Scolonic content, diet, fecal output, intestinal gas, meals

The availability of substrates induces an adaptation of the colonic microbiota activity in bacterial metabolism, which produces less gas and associated issues. Clinical trials.gov NCT02618239.

Our data demonstrate temporal summation effects of food residues on intestinal gas production. Hence, intestinal gas production depends on pre-existing and on recent colonic loads of fermentable foodstuffs.

Goal:To determine the effect of a prebiotic chicory-derived inulin-type fructan on the tolerance of intestinal gas.Background:Subjects with gas-related complaints exhibit impaired handling of intestinal gas loads and we hypothesized that inulin would have a beneficial effect.Study:Placebo-controlled, parallel, randomized, double-blind trial. Subjects with abdominal symptoms and reduced tolerance of intestinal gas (selected by a pretest) received either inulin (8 g/d, n=18) or maltodextrin as a placebo (8 g/d, n=18) for 4 weeks. A gas challenge test (4 h jejunal gas infusion at 12 mL/min while measuring abdominal symptoms and gas retention for 3 h) was performed before and at the end of the intervention phase. Gastrointestinal symptoms and bowel habits (using daily questionnaires for 1 wk) and fecal bifidobacteria counts were measured before and at the end of the intervention.Results:Inulin decreased gas retention during the gas challenge test (by 22%; P=0.035 vs. baseline), while the placebo did not, but the intergroup difference was not statistically significant (P=0.343). Inulin and placebo reduced the perception of abdominal sensations in the gas challenge test to a similar extent (by 52% and 43%, respectively). Participants reported moderate gastrointestinal symptoms and normal bowel habits during baseline examination, and these findings remained unchanged in both groups during the intervention. Inulin led to a higher relative abundance of bifidobacteria counts (P=0.01 vs. placebo).Conclusions:A daily dose of inulin that promotes bifidobacteria growth and may improve gut function, is well tolerated by subjects with gastrointestinal complaints.

Esophageal involvement is common in myositis patients, but it correlates poorly with esophageal symptoms. Specific clinical and serologic groups have different manometric features. Muscle Nerve 56: 386-392, 2017.

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.

Intestinal gas homeostasis is a highly dynamic process by which a large proportion of the gas produced by bacterial fermentation of meal residues is rapidly absorbed into the blood and/or metabolized by gas-consuming microorganisms, and only a relatively modest proportion is eliminated per anus. These data contribute to clarify the complex dynamics of intestinal gas and may help interpret the pathophysiology of gas-related symptoms.