Consumption of whole grain and cereal fiber have been inversely associated with body weight and obesity measures in observational studies but data from large, long-term randomized interventions are scarce. Among the cereals, rye has the highest fiber content and high rye consumption has been linked to increased production of gut fermentation products, as well as reduced risks of obesity and metabolic disease. The effects on body weight and metabolic risk factors may partly be mediated through gut microbiota and/or their fermentation products. We used data from a randomized controlled weight loss trial where participants were randomized to a hypocaloric diet rich in either high fiber rye foods or refined wheat foods for 12 weeks to investigate the effects of the intervention on gut microbiota composition and plasma short chain fatty acids, as well as the potential association with weight loss and metabolic risk markers. Rye, compared to wheat, induced some changes in gut microbiota composition, including increased abundance of the butyrate producing Agathobacter and reduced abundance of [Ruminococcus] torques group, which may be related to reductions in low grade inflammation caused by the intervention. Plasma butyrate increased in the rye group. In conclusion, intervention with high fiber rye foods induced some changes in gut microbiota composition and plasma short chain fatty acid concentration, which were associated with improvements in metabolic risk markers as a result of the intervention.

Free faecal liquid (FFL) is a condition in horses which manifests as differential defecation of solid and liquid phases of faeces. The etiology of FFL is currently unknown, but deviances in the hindgut microbiota has been suggested to be of importance. The present study aimed to compare the faecal bacterial composition of farm-matched horses with (case, n = 50) and without (control, n = 50) FFL. Samples were collected at three different occasions. The V3 and V4 regions of the 16S rRNA gene were amplified and sequenced using Illumina sequencing. Also, samples were cultivated for detection of Clostridioides difficile and Clostridium perfringens. Analysis revealed similar faecal bacterial composition between case and control horses, but an effect of sampling period (p = 0.0001). Within sampling periods, 14 genera were present in higher or lower proportions in case compared to control horses in at least one sampling period. Compared to controls, case horses had higher relative abundance of Alloprevotella (adjusted p < 0.04) and lower relative abundance of Bacillus spp. (adjusted p < 0.03) in at least two sampling periods. All horses tested negative for C. difficile and C. perfringens by culture of faeces. Further studies are required to establish the clinical relevance of specific bacterial taxa in FFL.

Background Rye intake has been associated with beneficial effects on health in human interventions, possibly due to dietary fiber in rye. In dogs, few studies have explored the effects on health of dietary fiber in general, and rye fiber in particular. The aim of this study was to investigate how inclusion of rye, compared with wheat, influenced fecal microbiota composition, short chain fatty acids (SCFA) and apparent total tract digestibility (ATTD) in dogs. Six male Beagle dogs (mean age 4.6 years, SEM 0.95 years; mean body weight 14.6 kg, SEM 0.32 kg) were fed three experimental diets, each for 21 days, including an adaptation period of six days and with 2–2.5 months between diet periods. The diets were similar regarding energy and protein, but had different carbohydrate sources (refined wheat (W), whole grain rye (R), or an equal mixture of both (RW)) comprising 50% of total weight on a dry matter (DM) basis. The diets were baked and titanium dioxide was added for ATTD determination. Fecal samples were collected before and in the end of each experimental period. Fecal microbiota was analyzed by sequencing 16S rRNA gene amplicons and fecal SCFA by high-performance liquid chromatography. Crude protein, crude fat, neutral detergent fiber, and gross energy (GE) in food and feces were analyzed and ATTD of each was determined. Univariate and multivariate statistical methods were applied in data evaluation. Results Faecal microbiota composition, differed depending on diet (P = 0.002), with samples collected after consumption of the R diet differing from baseline. This was primarily because of a shift in proportion of Prevotella, which increased significantly after consumption of the R diet (P < 0.001). No significant differences were found for SCFA, but there was a tendency (P < 0.06) for higher molar proportions of acetic acid following consumption of the R diet. The ATTD of crude protein, crude fat, neutral detergent fiber, and GE was lower after consumption of the R diet compared with the other diets (P < 0.05). Conclusions Consumption of the R diet, but not RW or W diets, was associated with specific shifts in microbial community composition and function, but also with lower ATTD.

BackgroundRye intake has been associated with beneficial effects on health in human interventions, possibly due to soluble dietary fiber in rye. In dogs, few studies have explored the effects on health of dietary fiber in general, and rye fiber in particular. The aim of this study was to investigate how inclusion of rye, compared with wheat, influenced fecal microbiota composition, short chain fatty acids (SCFA) and apparent total tract digestibility (ATTD) in dogs. Six male Beagle dogs (mean age 4.6 years, SEM 0.95 years; mean body weight 14.6 kg, SEM 0.32 kg) were fed three experimental diets, each for 21 days, including an adaptation period of six days. The diets were as similar as possible regarding energy and protein, but had different carbohydrate sources (refined wheat (W), whole grain rye (R), or an equal mixture of both (RW)) comprising 50% of total weight on a dry matter (DM) basis. The diets were baked and titanium dioxide was added for ATTD determination. Fecal samples were collected before and in the end of each experimental period. Fecal microbiota was analyzed by sequencing 16S rRNA gene amplicons and fecal SCFA by high-performance liquid chromatography. Crude protein, crude fat, neutral detergent fiber, and gross energy (GE) in food and feces were analyzed and ATTD of each was determined. Univariate and multivariate statistical methods were applied in data evaluation.Results:Microbiota composition, in feces, differed depending on diet (P=0.002), with samples collected after consumption of the R diet differing from baseline. This was primarily because of a shift in proportion of Prevotella, which increased significantly after consumption of the R diet (P<0.001). No significant differences were found for SCFA, but there was a tendency (P<0.06) for higher molar proportions of acetic acid following consumption of the R diet. The ATTD of crude protein, crude fat, neutral detergent fiber, and GE was lower after consumption of the R diet compared with the other diets (P<0.05).Conclusions:Consumption of the R diet, but not RW or W diets, was associated with specific shifts in microbial community composition and function, but also with lower ATTD.

Objectives Irritable bowel syndrome (IBS) symptoms have been associated with fermentable oligo-, di-, monosaccharides and polyols (FODMAPs) as well as gluten. We aimed to evaluate the effects of provocations with diets rich in such components on IBS symptoms. We further aimed to study effects of FODMAPs and gluten on microbiota and if the microbiota composition was related to the severity of IBS symptoms. Methods A double-blind, placebo-controlled, randomised three-way crossover design (n = 110) was conducted. From run-in and throughout the study, IBS subjects maintained a diet with minimal FODMAP content and no gluten. Participants were block-randomised to one-week interventions with FODMAPs (50 g/day), gluten (17.3 g/day) or placebo, separated by one week of wash-out. Fecal samples were collected after each study week and analyzed for gut microbiota composition by sequencing of 16S rRNA gene amplicons. IBS symptoms were monitored by the IBS severity scoring system (IBS-SSS). Results In subjects with moderate to severe IBS (n = 103), FODMAPs caused higher total IBS-SSS (mean [SE] = 240 [9]) than placebo (208 [9]; p = 0.00056) or gluten (198 [9]; p = 0.013), but with no difference between gluten and placebo (p = 1.0). Relative abundance of Anaerostipes, Bifidobacterium and Faecalibacterium were higher after FODMAP compared to placebo. We found no difference in gut microbiota composition between gluten and placebo and no significant correlations between genera and severity of IBS-SSS. Conclusions In subjects with IBS, FODMAPs had an adverse but modest effect on typical IBS symptoms, whereas gluten had no effect. The microbiota composition was affected by the FODMAP but not the gluten intervention, in comparison to placebo. None of these differences were correlated to the severity of symptoms reflected in IBS-SSS, suggesting no apparent link between gut microbiota composition and IBS symptoms following intervention. Funding Sources Formas and the Swedish Research Council.