Opposing diet, microbiome, and metabolite mechanisms regulate inflammatory bowel disease in a genetically susceptible host.

Inflammatory bowel diseases (IBDs) are chronic conditions characterized by periods of spontaneous intestinal inflammation and are increasing in industrialized populations. Combined with host genetics, diet and gut bacteria are thought to contribute prominently to IBDs, but mechanisms are still emerging. In mice lacking the IBD-associated cytokine, interleukin-10, we show that a fiber-deprived gut microbiota promotes the deterioration of colonic mucus, leading to lethal colitis. Inflammation starts with the expansion of natural killer cells and altered immunoglobulin-A coating of some bacteria. Lethal colitis is then driven by Th1 immune responses to increased activities of mucin-degrading bacteria that cause inflammation first in regions with thinner mucus. A fiber-free exclusive enteral nutrition diet also induces mucus erosion but inhibits inflammation by simultaneously increasing an anti-inflammatory bacterial metabolite, isobutyrate. Our findings underscore the importance of focusing on microbial functions-not taxa-contributing to IBDs and that some diet-mediated functions can oppose those that promote disease.

Unravelling specific diet and gut microbial contributions to inflammatory bowel disease.

Inflammatory bowel disease (IBD) is a chronic condition characterized by periods of spontaneous intestinal inflammation and is increasing in industrialized populations. Combined with host genetic predisposition, diet and gut bacteria are thought to be prominent features contributing to IBD, but little is known about the precise mechanisms involved. Here, we show that low dietary fiber promotes bacterial erosion of protective colonic mucus, leading to lethal colitis in mice lacking the IBD-associated cytokine, interleukin-10. Diet-induced inflammation is driven by mucin-degrading bacteria-mediated Th1 immune responses and is preceded by expansion of natural killer T cells and reduced immunoglobulin A coating of some bacteria. Surprisingly, an exclusive enteral nutrition diet, also lacking dietary fiber, reduced disease by increasing bacterial production of isobutyrate, which is dependent on the presence of a specific bacterial species, Eubacterium rectale. Our results illuminate a mechanistic framework using gnotobiotic mice to unravel the complex web of diet, host and microbial factors that influence IBD.

Bowel habits, faecal microbiota and faecal bile acid composition of healthy adults consuming fruit pomace fibres: two-arm, randomised, double-blinded, placebo-controlled trials.

Dietary fibre modulates gastrointestinal (GI) health and function, providing laxation, shifting microbiota, and altering bile acid (BA) metabolism. Fruit juice production removes the polyphenol- and fibre-rich pomace fraction. The effects of orange and apple pomaces on GI outcomes were investigated in healthy, free-living adults. Healthy adults were enrolled in two double-blinded, crossover trials, being randomised by baseline bowel movement (BM) frequency. In the first trial, subjects (n 91) received orange juice (OJ, 0 g fibre/d) or OJ + orange pomace (OJ + P, 10 g fibre/d) for 4 weeks, separated by a 3-week washout. Similarly, in the second trial, subjects (n 90) received apple juice (AJ, 0 g fibre/d) or AJ + apple pomace (AJ + P, 10 g fibre/d). Bowel habit diaries, GI tolerance surveys and 3-d diet records were collected throughout. Fresh faecal samples were collected from a participant subset for microbiota and BA analyses in each study. Neither pomace interventions influenced BM frequency. At Week 4, OJ + P tended to increase (P = 0·066) GI symptom occurrence compared with OJ, while AJ + P tended (P = 0·089) to increase flatulence compared with AJ. Faecalibacterium (P = 0·038) and Negativibacillus (P = 0·043) were differentially abundant between pre- and post-interventions in the apple trial but were no longer significant after false discovery rate (FDR) correction. Baseline fibre intake was independently associated with several microbial genera in both trials. Orange or apple pomace supplementation was insufficient to elicit changes in bowel habits, microbiota diversity or BA of free-living adults with healthy baseline BM. Future studies should consider baseline BM frequency and habitual fibre intake.

Effects of dietary macronutrient profile on apparent total tract macronutrient digestibility and fecal microbiota, fermentative metabolites, and bile acids of female dogs after spay surgery.

Obesity and estrogen reduction are known to affect the gut microbiota and gut microbial-derived metabolites in some species, but limited information is available in dogs. The aim of this study was to determine the effects of dietary macronutrient profile on apparent total tract macronutrient digestibility, fecal microbiota, and fecal metabolites of adult female dogs after spay surgery. Twenty-eight adult intact female beagles (age: 3.02 ± 0.71 yr, BW: 10.28 ± 0.77 kg; BCS: 4.98 ± 0.57) were used. After a 5-wk baseline phase (week 0), 24 dogs were spayed and randomly allotted to one of three experimental diets (n = 8 per group): 1) control (CO) containing moderate protein and fiber (COSP), 2) high-protein, high-fiber (HPHF), or 3) high-protein, high-fiber plus omega-3 and medium-chain fatty acids (HPHFO). Four dogs were sham-operated and fed CO (COSH). All dogs were fed to maintain BW for 12 wk after spay and then allowed to consume twice that amount for 12 wk. Fecal samples were collected at weeks 0, 12, and 24 for digestibility, microbiota, and metabolite analysis. All data were analyzed using repeated measures and linear mixed models procedure of SAS 9.4, with results reported as a change from baseline. Apparent organic matter and energy digestibilities had greater decreases in HPHF and HPHFO than COSH and COSP. Increases in fecal acetate, total short-chain fatty acids, and secondary bile acids were greater and decreases in primary bile acids were greater in HPHF and HPHFO. Principal coordinates analysis of weighted UniFrac distances revealed that HPHF and HPHFO clustered together and separated from COSH and COSP at weeks 12 and 24, with relative abundances of Faecalibacterium, Romboutsia, and Fusobacterium increasing to a greater extent and Catenibacterium, Bifidobacterium, Prevotella 9, Eubacterium, and Megamonas decreasing to a greater extent in HPHF or HPHFO. Our results suggest that high-protein, high-fiber diets alter nutrient and energy digestibilities, fecal metabolite concentrations, and fecal gut microbiota, but spay surgery had minor effects. Future research is needed to investigate how food intake, nutrient profile, and changes in hormone production influence gut microbiota and metabolites of dogs individually and how this knowledge may be used to manage spayed pets.

Nutrition risk prevalence and nutrition care recommendations for hospitalized and critically-ill patients with COVID-19.

BACKGROUND: Nutritional status is an often-overlooked component in infectious disease severity. Hospitalized or critically ill patients are at higher risk of malnutrition, and rapid assessment and treatment of poor nutritional status can impact clinical outcomes. As it relates to the COVID-19 pandemic, an estimated 5% of these patients require admission to an ICU. Per clinical practice guidelines, nutrition therapy should be a core component of treatment regimens. On account of the urgent need for information relating to the nutritional support of these patients, clinical practice guidance was published based on current critical care guidelines. However, a growing body of literature is now available that may provide further direction for the nutritional status and support in COVID-19 patients. This review, intended for the health care community, provides a heretofore lacking in-depth discussion and summary of the current data on nutrition risk and assessment and clinical practice guidelines for medical nutrition therapy for hospitalized and critically ill patients with COVID-19.

Microbiota populations in supragingival plaque, subgingival plaque, and saliva habitats of adult dogs.

BACKGROUND: Oral diseases are common in dogs, with microbiota playing a prominent role in the disease process. Oral cavity habitats harbor unique microbiota populations that have relevance to health and disease. Despite their importance, the canine oral cavity microbial habitats have been poorly studied. The objectives of this study were to (1) characterize the oral microbiota of different habitats of dogs and (2) correlate oral health scores with bacterial taxa and identify what sites may be good options for understanding the role of microbiota in oral diseases. We used next-generation sequencing to characterize the salivary (SAL), subgingival (SUB), and supragingival (SUP) microbial habitats of 26 healthy adult female Beagle dogs (4.0 ± 1.2 year old) and identify taxa associated with periodontal disease indices. RESULTS: Bacterial species richness was highest for SAL, moderate for SUB, and lowest for SUP samples (p < 0.001). Unweighted and weighted principal coordinates plots showed clustering by habitat, with SAL and SUP samples being the most different from one another. Bacteroidetes, Proteobacteria, Firmicutes, Fusobacteria, Actinobacteria, and Spirochaetes were the predominant phyla in all habitats. Paludibacter, Filifactor, Peptostreptococcus, Fusibacter, Anaerovorax, Fusobacterium, Leptotrichia, Desulfomicrobium, and TG5 were enriched in SUB samples, while Actinomyces, Corynebacterium, Leucobacter, Euzebya, Capnocytophaga, Bergeyella, Lautropia, Lampropedia, Desulfobulbus, Enhydrobacter, and Moraxella were enriched in SUP samples. Prevotella, SHD-231, Helcococcus, Treponema, and Acholeplasma were enriched in SAL samples. p-75-a5, Arcobacter, and Pasteurella were diminished in SUB samples. Porphyromonas, Peptococcus, Parvimonas, and Campylobacter were diminished in SUP samples, while Tannerella, Proteocalla, Schwartzia, and Neisseria were diminished in SAL samples. Actinomyces, Corynebacterium, Capnocytophaga, Leptotrichia, and Neisseria were associated with higher oral health scores (worsened health) in plaque samples. CONCLUSIONS: Our results demonstrate the differences that exist among canine salivary, subgingival plaque and supragingival plaque habitats. Salivary samples do not require sedation and are easy to collect, but do not accurately represent the plaque populations that are most important to oral disease. Plaque Actinomyces, Corynebacterium, Capnocytophaga, Leptotrichia, and Neisseria were associated with higher (worse) oral health scores. Future studies analyzing samples from progressive disease stages are needed to validate these results and understand the role of bacteria in periodontal disease development.

Dental chews positively shift the oral microbiota of adult dogs.

Microbiota plays a prominent role in periodontal disease, but the canine oral microbiota and how dental chews may affect these populations have been poorly studied. We aimed to determine the differences in oral microbiota of adult dogs consuming dental chews compared with control dogs consuming only a diet. Twelve adult female beagle dogs (mean age = 5.31 ± 1.08 yr) were used in a replicated 4 × 4 Latin square design consisting of 28-d periods. Treatments (n = 12/group) included: diet only (CT); diet + Bones & Chews Dental Treats (BC; Chewy, Inc., Dania Beach, FL); diet + Dr. Lyon's Grain-Free Dental Treats (DL; Dr. Lyon's, LLC, Dania Beach, FL); and diet + Greenies Dental Treats (GR; Mars Petcare US, Franklin, TN). Each day, one chew was provided 4 h after mealtime. On day 27, breath samples were analyzed for total volatile sulfur compound concentrations using a Halimeter. On day 0 of each period, teeth were cleaned by a veterinary dentist blinded to treatments. Teeth were scored for plaque, calculus, and gingivitis by the same veterinary dentist on day 28 of each period. After scoring, salivary (SAL), subgingival (SUB), and supragingival (SUP) samples were collected for microbiota analysis using Illumina MiSeq. All data were analyzed using SAS (version 9.4) using the Mixed Models procedure, with P < 0.05 considered significant. All dogs consuming chews had lower calculus coverage and thickness, pocket depth and bleeding, plaque thickness, and halitosis compared with CT. In all sites of collection, CT dogs had a higher relative abundance of one or more potentially pathogenic bacteria (Porphyromonas, Anaerovorax, Desulfomicrobium, Tannerella, and Treponema) and lower relative abundance of one or more genera associated with oral health (Neisseria, Corynebacterium, Capnocytophaga, Actinomyces, Lautropia, Bergeyella, and Moraxella) than those fed chews. DL reduced Porphyromonas in SUP and SUB samples. DL and GR reduced Treponema in SUP samples. DL increased Corynebacterium in all sites of collection. BC increased Corynebacterium in SAL samples. DL and GR increased Neisseria in SAL samples. DL increased Actinomyces in the SUB sample. GR increased Actinomyces in SAL samples. Our results suggest that the dental chews tested in this study may aid in reducing periodontal disease risk in dogs by beneficially shifting the microbiota inhabiting plaque and saliva of a dog's oral cavity. These shifts occurred over a short period of time and were correlated with improved oral health scores.

Development of a novel model of cholecystectomy in subsequently ovariectomized mice and characterization of metabolic and gastrointestinal phenotypes: a pilot study.

BACKGROUND: Cholecystectomy (XGB) is the most common abdominal surgery performed in the United States and is associated with an increased post-surgery incidence of metabolic and gastrointestinal (GI) diseases. Two main risk factors for XGB are sex (female) and age (40-50 yr), corresponding with onset of menopause. Post-menopausal estrogen loss alone facilitates metabolic dysfunction, but the effects of XGB on metabolic and GI health have yet to be investigated in this population. Study objectives were to (1) identify possible short-term effects of XGB and (2) develop a novel murine model of XGB in human menopause via subsequent ovariectomy (OVX) and assess longitudinal effects of OVX on metabolism, GI physiology, and GI microbiota in XGB mice. METHODS: Female C57BL/6 mice were utilized in two parallel studies (S1&S2). In S1, XGB mice were compared to a non-XGB baseline group after six wk. In S2, mice were XGB at wk0, either sham (SHM) or OVX at wk6, and sacrificed at wk12, wk18, and wk24. Body composition assessment and fresh fecal collections were conducted periodically. Serum and tissues were collected at sacrifice for metabolic and GI health endpoints. RESULTS: Compared to baseline, XGB increased hepatic CYP7A1 and decreased HMGCR relative expression, but did not influence BW, fat mass, or hepatic triglycerides after six wk. In S2, XGB/OVX mice had greater BW and fat mass than XGB/SHM. Cecal microbiota alpha diversity metrics were lower in XGB/OVX mice at wk24 compared the XGB/SHM. No consistent longitudinal patterns in fasting serum lipids, fecal microbial diversity, and GI gene expression were observed between S2 groups. CONCLUSIONS: In addition to developing a novel, clinically-representative model of XGB and subsequent OVX, our results suggest that OVX resulted in the expected phenotype to some extent, but that XGB may modify or mask some responses and requires further investigation.

Effects of novel dental chews on oral health outcomes and halitosis in adult dogs.

Periodontal disease (PD) is the most common clinical condition occurring in adult dogs. The objective of this study was to evaluate the benefits of daily dental chew administration on oral health outcomes in adult dogs. Twelve adult (mean age = 5.31 ± 1.08 yr; mean BW = 13.12 ± 1.39 kg) female beagle dogs were used in a replicated 4 × 4 Latin square design consisting of 28-d periods. On day 0 of each period, teeth were cleaned by a veterinary dentist blinded to treatments. Teeth then were scored for plaque, calculus, and gingivitis by the same veterinary dentist on day 28 of each period. Breath samples were measured for malodor (volatile sulfur compounds) on days 1, 7, 14, 21, and 27 of each period. All dogs consumed the same commercial dry diet throughout the study. Control dogs were offered the diet only (CT), while treatment groups received the diet plus one of three dental chews. Two novel chews (Bones & Chews Dental Treats [BC]; Chewy, Inc., Dania Beach, FL and Dr. Lyon's Grain-Free Dental Treats [DL]; Dr. Lyon's, LLC, Dania Beach, FL) and a leading brand chew (Greenies Dental Treats [GR]; Mars Petcare US, Franklin, TN) were tested. Each day, one chew was provided 4 h after mealtime. All tooth scoring data were analyzed using the Mixed Models procedure of SAS (version 9.4; SAS Institute, Cary, NC). Halimeter data were analyzed using repeated measures using the Mixed Models procedure of SAS and testing for differences due to treatment, time, and treatment * time interaction. Data are reported as LS means ± SEM with statistical significance set at P < 0.05. DL performed at the same level as the leading brand, GR, as both resulted in lower (P < 0.05) plaque coverage and thickness scores, calculus coverage scores, and day 27 volatile sulfur concentrations compared with CT. Additionally, DL reduced (P < 0.05) volatile sulfur compounds on day 14 when compared with CT. BC reduced (P < 0.05) calculus coverage and day 27 volatile sulfur concentrations compared with CT. Our results suggest that the dental chews tested in this study may help slow the development and/or progression of PD in dogs.

Effects of different carbohydrate sources on taurine status in healthy Beagle dogs.

This study evaluated the effects of a grain-based (GB) and grain-free (GF) diet on protein utilization and taurine status in healthy Beagle dogs. Two practical dog diets sufficient in crude protein, sulfur amino acids, and taurine content were formulated with the same ingredients with exception of the carbohydrate sources. The GB contained sorghum, millet, and spelt while potatoes, peas, and tapioca starch were used in the GF. A total of 12 Beagle dogs were used in a completely randomized design with six replicates per treatment. The study consisted of an adaptation period of 2 wk followed by an experimental period of 28 d in which GB and GF were fed to the dogs. At the end of the adaptation period and every 2 wk after it (day 0, day 14, day 28), markers of taurine metabolism were analyzed in whole blood (taurine), plasma (taurine, methionine, and cystine), urine (taurine:creatinine), and fresh fecal samples (primary and secondary bile acids). Fecal samples were collected during the last 6 d of experimental period for digestibly assessment using titanium dioxide as an external marker. Taurine markers and digestibility data were analyzed in a repeated measures model and one-way ANOVA, respectively, using PROC GLIMMIX in SAS (version 9.4). Apparent crude protein digestibility was not affected by treatment, but dogs fed GF diet had lower apparent organic matter digestibility compared with those fed GB (P < 0.05). Greater plasma taurine concentrations were observed at days 14 and 28 compared with day 0; wherein dogs fed GF exhibited greater increase compared to those fed GB (P < 0.05). Whole blood taurine concentrations, plasma methionine concentrations, and urinary taurine:creatinine were also greater at days 14 and 28 compared with day 0 (P < 0.05), but no effect of diet was observed. Total bile acid excretion was similar between GF and GB groups, but dogs fed GF excreted a higher proportion of primary bile acids compared with those fed GB (25.49% vs. 12.09% at day 28, respectively). In summary, overall taurine status was not affected by dietary treatments, however, our results suggest that the higher content of oligosaccharides and soluble fibers in the GF diet may alter the composition of the fecal bile acid pool.

Perspective: Physiologic Importance of Short-Chain Fatty Acids from Nondigestible Carbohydrate Fermentation.

In recent years, it has become increasingly obvious that dietary fiber or nondigestible carbohydrate (NDC) consumption is critical for maintaining optimal health and managing symptoms of metabolic disease. In accordance with this, the US FDA released its first official definition of dietary fiber in 2016 for regulation of Nutrition and Supplement Facts labels. Included in this definition is the requirement of an isolated or synthetic NDC to produce an accepted physiologic health benefit, such as improved laxation or reduced fasting cholesterol concentrations, upon consumption. Even though NDC fermentation and production of short-chain fatty acids elicit many physiologic effects, including serving as a source of energy for colonocytes, curbing glycemic response and satiety, promoting weight loss, enhancing mineral absorption, reducing systemic inflammation, and improving intestinal health, the process of fermentation is not considered a physiologic endpoint. Instead, expensive and laborious clinical trials must be conducted and an accepted physiologic benefit observed. In this review, we discuss the physiologic importance of NDC fermentation through extensive examination of clinical evidence and propose that the degree of fermentability of an NDC, rather than the endpoints of a clinical trial, may be appropriate for classifying it as a dietary fiber.

Effects of a Saccharomyces cerevisiae fermentation product on fecal characteristics, nutrient digestibility, fecal fermentative end-products, fecal microbial populations, immune function, and diet palatability in adult dogs1.

Yeast products may serve as functional ingredients due to their benefits on host health but vary greatly in source, composition, and functionality, justifying research in host species of interest. In this study, a Saccharomyces cerevisiae fermentation product (SCFP) was investigated as a dietary supplement for adult dogs. Adult female beagles (n = 12; mean age = 3.3 ± 0.8 yr; mean BW = 10.3 ± 0.68 kg) were fed the same diet, but supplemented with three levels of SCFP (125, 250, and 500 mg/d) or a placebo (sucrose) via gelatin capsules in a replicated 4 × 4 Latin square design. Fecal samples for nutrient digestibility, fecal characteristics and microbial populations as well as blood samples for immune indices were collected after a 21-d adaptation phase in each period. A separate palatability test was conducted to examine palatability of an SCFP-containing diet (0.2% of diet). All data, except for palatability data, were analyzed by Mixed Models procedure of SAS (version 9.4). A paired t-test was conducted to analyze data from the palatability test. Supplementation of SCFP did not affect total tract apparent macronutrient and energy digestibilities or fecal characteristics. Fecal phenol and total phenol + indole concentrations decreased linearly with SCFP dosage (P < 0.05). Relative abundance of Bifidobacterium was greater (P < 0.05), while Fusobacterium was lower (P < 0.05) in SCFP-supplemented dogs. Total white blood cell counts were decreased by SCFP (P < 0.05). The percentage of natural killer cells and antigen-presenting cells were not altered by SCFP. However, when comparing control vs. all SCFP treatments, SCFP-supplemented dogs had greater (P < 0.05) major histocompatibility complex class II presenting B cell and monocyte populations than control dogs. IFN-γ secreting helper and cytotoxic T cells increased linearly with SCFP consumption (P < 0.05). Immune cells derived from SCFP-supplemented dogs produced less (P < 0.05) TNF-α than those from control dogs when cells were stimulated with agonists of toll-like receptors 2, 3, 4, and 7/8. A linear increase (P < 0.05) in serum IgE with SCFP dosage was noted. In the palatability test, a 1.9:1 consumption ratio was observed for the SCFP-containing diet vs. control diet, demonstrating a preference (P < 0.05) for SCFP. Results of this study suggest that SCFP supplementation may be beneficial to adult dogs by positively altering gut microbiota, enhancing immune capacity and reducing inflammation.

Cholestyramine decreases apparent total tract macronutrient digestibility and alters fecal characteristics and metabolites of healthy adult dogs.

Absorption of dietary lipids in the small intestine is dependent on the emulsification by bile acids (BA) and the formation of chylomicrons. Cholestyramine is a common drug used in humans-and potentially dogs-to treat BA malabsorption associated with chronic diarrhea. It is known to bind BA to form insoluble complexes, preventing their reabsorption and possibly proper emulsification and absorption of dietary fats. The objective of this study was to evaluate the effects of cholestyramine on 1) macronutrient apparent total tract digestibility (ATTD), and 2) fecal characteristics and metabolites of healthy adult dogs. We hypothesized that cholestyramine would decrease ATTD of fat and organic matter (OM), increase fecal dry matter (DM) content, and increase fecal output. Twelve healthy beagles (3.2 ± 0.8 yr; 10.4 ± 0.9 kg) were used in a randomized crossover design. All procedures were approved by the University of Illinois Institutional Animal Care and Use Committee before the study. The study included a baseline period and two 14-d experimental periods separated by a 14-d washout. All dogs were fed the same experimental diet, formulated to meet all nutrient needs recommended by AAFCO, throughout the study. Dogs were randomized into 2 groups [diet only (control) or diet + 11.4 g/d cholestyramine (8 g/d active ingredient)] in Period 1 and received the other treatment in Period 2. During the washout, all dogs were fed the diet only. Dogs were fed once daily (0800 h) to maintain BW. Total fecal output was collected during the last 4 d of each period for ATTD analysis. On day 14 of each of period, fresh fecal and blood samples were collected for metabolite analysis. Dogs fed cholestyramine had lower (P < 0.001) ATTD of DM, OM, energy, crude protein, and fat and lower (P < 0.01) fecal scores (firmer stools) than controls. Dogs fed cholestyramine had greater (P < 0.01) as-is and dry fecal output than controls. Dogs fed cholestyramine had lower (P < 0.05) fecal ammonia and phenol concentrations, but greater (P < 0.05) fecal indole, acetate, butyrate, and total short-chain fatty acid concentrations than controls. Fecal DM% and pH were greater (P < 0.01) in dogs fed cholestyramine. Our results indicate that cholestyramine, when given with a meal, is safe and well tolerated but significantly decreases nutrient digestibility and alters fecal characteristics. Future studies are required to explore the effects of cholestyramine on dogs with gastrointestinal disease.

Effects of prebiotic inulin-type fructans on blood metabolite and hormone concentrations and faecal microbiota and metabolites in overweight dogs.

Because obesity is associated with many co-morbidities, including diabetes mellitus, this study evaluated the second-meal effect of a commercial prebiotic, inulin-type fructans, and the effects of the prebiotic on faecal microbiota, metabolites and bile acids (BA). Nine overweight beagles were used in a replicated 3×3 Latin square design to test a non-prebiotic control (cellulose) against a low (equivalent to 0·5 % diet) and high dose (equivalent to 1·0 % diet) of prebiotic over 14-d treatments. All dogs were fed the same diet twice daily, with treatments provided orally via gelatin capsules before meals. On days 13 or 14 of each period, fresh faecal samples were collected, dogs were fed at 08.00 hours and then challenged with 1 g/kg body weight of maltodextrin in place of the 16.00 hours meal. Repeated blood samples were analysed for glucose and hormone concentrations to determine postprandial incremental AUC (IAUC) data. Baseline glucose, insulin and active glucagon-like peptide-1 levels were similar between all groups (P>0·10). Glucose and insulin IAUC after glucose challenge appeared lower following the high dose, but did not reach statistical relevance. Prebiotic intervention resulted in an increase in relative abundance of some Firmicutes and a decrease in the relative abundance of some Proteobacteria. Individual and total faecal SCFA were significantly increased (P<0·05) following prebiotic supplementation. Total concentration of excreted faecal BA tended to increase in dogs fed the prebiotic (P=0·06). Our results indicate that higher doses of inulin-type prebiotics may serve as modulators of gut microbiota, metabolites and BA pool in overweight dogs.