Dietary fiber induces a fat preference associated with the gut microbiota.

Eating behavior is essential to human health. However, whether future eating behavior is subjected to the conditioning of preceding dietary composition is unknown. This study aimed to investigate the effect of dietary fiber consumption on subsequent nutrient-specific food preferences between palatable high-fat and high-sugar diets and explore its correlation with the gut microbiota. C57BL/6NJcl male mice were subjected to a 2-week dietary intervention and fed either a control (n = 6) or inulin (n = 6) diet. Afterward, all mice were subjected to a 3-day eating behavioral test to self-select from the simultaneously presented high-fat and high-sugar diets. The test diet feed intakes were recorded, and the mice's fecal samples were analyzed to evaluate the gut microbiota composition. The inulin-conditioned mice exhibited a preference for the high-fat diet over the high-sugar diet, associated with distinct gut microbiota composition profiles between the inulin-conditioned and control mice. The gut microbiota Oscillospiraceae sp., Bacteroides acidifaciens, and Clostridiales sp. positively correlated with a preference for fat. Further studies with fecal microbiota transplantation and eating behavior-related neurotransmitter analyses are warranted to establish the causal role of gut microbiota on host food preferences. Food preferences induced by dietary intervention are a novel observation, and the gut microbiome may be associated with this preference.

Effect of Intake of Bifidobacteria and Dietary Fiber on Resting Energy Expenditure: A Randomized, Placebo-Controlled, Double-Blind, Parallel-Group Comparison Study.

Bifidobacterium animalis subsp. lactis GCL2505 in combination with inulin has been shown to have several health benefits, including an improvement in the intestinal microbiota and a reduction in human visceral fat. Previous studies have suggested that the visceral fat reduction of GCL2505 and inulin may be achieved by improving daily energy expenditure. This parallel, placebo-controlled, randomized, double-blind study was conducted to evaluate the effects of GCL2505 and inulin on resting energy expenditure (REE) in overweight or mildly obese Japanese adults (n = 44). Participants ingested 1 × 1010 colony forming units of GCL2505 and 5.0 g of inulin daily for 4 weeks. REE score at week 4 was set as the primary endpoint. At week 4, the REE score of the GCL2505 and inulin group was significantly higher than that of the placebo group, with a difference of 84.4 kcal/day. In addition, fecal bifidobacteria counts were significantly increased in the GCL2505 and inulin group. Our results indicated that the intake of GCL2505 and inulin improves energy balance, which is known to be a major factor of obesity, by modulating the microbiota in the gut. This is the first report to demonstrate the effects of probiotics and dietary fiber on REE in humans.

Pomegranate Juice Supplemented with Inulin Modulates Gut Microbiota and Promotes the Production of Microbiota-Associated Metabolites in Overweight/Obese Individuals: A Randomized, Double-Blind, Placebo-Controlled Trial.

Pomegranate juice (PJ) and inulin have been reported to ameliorate diet-induced metabolic disorders by regulating gut microbiota dysbiosis. However, there was a lack of clinical evidence for the combined effects of PJ and inulin on regulating gut microbiota in individuals with metabolic disorders. A double-blind, parallel, randomized, placebo-controlled trial was conducted, and 68 overweight/obese individuals (25 ≤ BMI ≤ 35 kg/m2) were randomly assigned to receive 200 mL/d PJ, PJ supplemented with inulin, or placebo for 3 weeks. Our results showed that PJ and PJ+inulin did not significantly alter the levels of anthropometric and blood biochemical indicators after 3 weeks of treatment. However, there was an increasingly significant impact from placebo to PJ to PJ+inulin on the composition of gut microbiota. Detailed bacterial abundance analysis further showed that PJ+inulin treatment more profoundly resulted in significant changes in the abundance of gut microbiota at each taxonomic level than PJ. Moreover, PJ+inulin treatment also promoted the production of microbiota-associated short-chain fatty acids and pomegranate polyphenol metabolites, which correlated with the abundance of the bacterial genus. Our results suggested that PJ supplemented with inulin modulates gut microbiota composition and thus promotes the production of microbiota-associated metabolites that exert potential beneficial effects in overweight/obese subjects.

Can Diet Alter the Intestinal Barrier Permeability in Healthy People? A Systematic Review.

Dietary factors can modify the function of the intestinal barrier, causing permeability changes. This systematic review analyzed evidence on the link between diet or dietary interventions and changes in intestinal barrier permeability (IBP) in healthy individuals. A systematic search for primary studies was conducted using the virtual databases EMBASE, PubMed, Web of Science, CINAHL, and Scopus. This review adhered to PRISMA 2020 guidelines, assessing the methodological quality using the Newcastle-Ottawa scale for observational studies and ROB 2.0 for randomized clinical trials. Out of 3725 studies recovered, 12 were eligible for review. Chicory inulin and probiotics reduced IBP in adults with a moderate GRADE level of evidence. The opposite result was obtained with fructose, which increased IBP in adults, with a very low GRADE level of evidence. Only intervention studies with different dietary components were found, and few studies evaluated the effect of specific diets on the IBP. Thus, there was no strong evidence that diet or dietary interventions increase or decrease IBP in healthy individuals. Studies on this topic are necessary, with a low risk of bias and good quality of evidence generated, as there is still little knowledge on healthy populations.

The Influence of Soy Isoflavones and Soy Isoflavones with Inulin on Kidney Morphology, Fatty Acids, and Associated Parameters in Rats with and without Induced Diabetes Type 2.

Diabetes mellitus resulting from hyperglycemia stands as the primary cause of diabetic kidney disease. Emerging evidence suggests that plasma concentrations of soy isoflavones, substances with well-established antidiabetic properties, rise following supplemental inulin administration. The investigation encompassed 36 male Sprague-Dawley (SD) rats segregated into two cohorts: non-diabetic and diabetic, induced with type 2 diabetes (high-fat diet + two intraperitoneal streptozotocin injections). Each cohort was further divided into three subgroups (n = 6): control, isoflavone-treated, and isoflavone plus inulin-treated rats. Tail blood glucose and ketone levels were gauged. Upon termination, blood samples were drawn directly from the heart for urea, creatinine, and HbA1c/HbF analyses. One kidney per rat underwent histological (H-E) and immunohistochemical assessments (anti-AQP1, anti-AQP2, anti-AVPR2, anti-SLC22A2, anti-ACC-alpha, anti-SREBP-1). The remaining kidney underwent fatty acid methyl ester analysis. Results unveiled notable alterations in water intake, body and kidney mass, kidney morphology, fatty acids, AQP2, AVPR2, AcetylCoA, SREBP-1, blood urea, creatinine, and glucose levels in control rats with induced type 2 diabetes. Isoflavone supplementation exhibited favorable effects on plasma urea, plasma urea/creatinine ratio, glycemia, water intake, and kidney mass, morphology, and function in type 2 diabetic rats. Additional inulin supplementation frequently modulated the action of soy isoflavones.

The impact of high-fat diet consumption and inulin fiber supplementation on anxiety-related behaviors and liver oxidative status in female Wistar rats.

BACKGROUND: Obesity is a worldwide public health problem associated with cognitive and mental health problems in both humans and rats. Studies assessing the effect of fiber supplementation on behavioral deficits and oxidative stress caused by high-fat diet (HFD) consumption in female rats are still scarce. We hypothesized that HFD consumption would lead to anxiety-related behavior and hepatic oxidative stress and that inulin would protect against these changes. We analyzed the impact of HFD-induced obesity combined with fiber supplementation (inulin) on anxiety-related defensive behavior and hepatic oxidative stress. RESULTS: Female rats were fed a high-fat diet (HFD; 45%) for nine weeks to induce obesity. The administration of inulin was found to decrease the adiposity index in both the control and obese groups. The consumption of a HFD combined with inulin supplementation resulted in a reduction in both CAT activity and carbonylated protein levels, leading to a shift in the hepatic redox balance. Interestingly, the behavioral data were conflicting. Specifically, animals that consumed a high-fat diet and received inulin showed signs of impaired learning and memory caused by obesity. The HFD did not impact anxiety-related behaviors in the female rats. However, inulin appears to have an anxiolytic effect, in the ETM, when associated with the HFD. On the other hand, inulin appears to have affected the locomotor activity in the HFD in both open field and light-dark box. CONCLUSION: Our results show that consumption of a HFD induced obesity in female rats, similar to males. However, HFD consumption did not cause a consistent increase in anxiety-related behaviors in female Wistar rats. Treatment with inulin at the dosage used did not exert consistent changes on the behavior of the animals, but attenuated the abdominal WAT expansion and the hepatic redox imbalance elicited by high-fat diet-induced obesity.

Inulin supplementation exhibits increased muscle mass via gut-muscle axis in children with obesity: double evidence from clinical and in vitro studies.

Gut microbiota manipulation may reverse metabolic abnormalities in obesity. Our previous studies demonstrated that inulin supplementation significantly promoted Bifidobacterium and fat-free mass in obese children. We aimed to study gut-muscle axis from inulin supplementation in these children. In clinical phase, the plasma samples from 46 participants aged 7-15 years, were analyzed for muscle biomarkers before and after 6-month inulin supplementation. In parallel, the plausible mechanism of muscle production via gut-muscle axis was examined using macrophage cell line. Bifidobacterium was cultured in semi-refined medium with inulin used in the clinical phase. Cell-free supernatant was collected and used in lipopolysaccharide (LPS)-induced macrophage cell line to determine inflammatory and anti-inflammatory gene expression. In clinical phase, IL-15 and creatinine/cystatin C ratio significantly increased from baseline to the 6th month. In vitro study showed that metabolites derived from Bifidobacterium capable of utilizing inulin contained the abundance of SCFAs. In the presence of LPS, treatment from Bifidobacterium + inulin downregulated TNF-α, IL-6, IL-1ß, and iNOS, but upregulated FIZZ-1 and TGF-ß expression. Inulin supplementation promoted the muscle biomarkers in agreement with fat-free mass gain, elucidating by Bifidobacterium metabolites derived from inulin digestion showed in vitro anti-inflammatory activity and decreased systemic pro-inflammation, thus promoting muscle production via gut-muscle axis response.Clinical Trial Registry number: NCT03968003.

Dietary fibre supplementation enhances radiotherapy tumour control and alleviates intestinal radiation toxicity.

BACKGROUND: Non-toxic approaches to enhance radiotherapy outcomes are beneficial, particularly in ageing populations. Based on preclinical findings showing that high-fibre diets sensitised bladder tumours to irradiation by modifying the gut microbiota, along with clinical evidence of prebiotics enhancing anti-cancer immunity, we hypothesised that dietary fibre and its gut microbiota modification can radiosensitise tumours via secretion of metabolites and/or immunomodulation. We investigated the efficacy of high-fibre diets combined with irradiation in immunoproficient C57BL/6 mice bearing bladder cancer flank allografts. RESULT: Psyllium plus inulin significantly decreased tumour size and delayed tumour growth following irradiation compared to 0.2% cellulose and raised intratumoural CD8+ cells. Post-irradiation, tumour control positively correlated with Lachnospiraceae family abundance. Psyllium plus resistant starch radiosensitised the tumours, positively correlating with Bacteroides genus abundance and increased caecal isoferulic acid levels, associated with a favourable response in terms of tumour control. Psyllium plus inulin mitigated the acute radiation injury caused by 14 Gy. Psyllium plus inulin increased caecal acetate, butyrate and propionate levels, and psyllium alone and psyllium plus resistant starch increased acetate levels. Human gut microbiota profiles at the phylum level were generally more like mouse 0.2% cellulose profiles than high fibre profiles. CONCLUSION: These supplements may be useful in combination with radiotherapy in patients with pelvic malignancy. Video Abstract.

Three-arm clinical trial of improved flour targeting intestinal microbiota (MALINEA).

The main objective of this project was to compare in the field conditions two strategies of re-nutrition of children with moderate acute malnutrition (MAM) aged from 6 to 24 months, targeting the microbiota in comparison with a standard regimen. A three-arm, open-label, pragmatic randomised trial was conducted in four countries (Niger, CAR, Senegal and Madagascar). Children received for 12 weeks either fortified blended flour (FBF control) = arm 1, or FBF + azithromycin (oral suspension of 20 mg/kg/day daily given with a syringe) for the first 3 days at inclusion = arm 2 or mix FBF with inulin/fructo-oligosaccharides (6 g/day if age ≥12 months and 4 g if age <12 months) = arm 3. For each arm, children aged from 6 to 11 months received 100 g x 2 per day of flours and those aged from 12 to 24 months received 100 g × 3 per day of FBF. The primary endpoint was nutritional recovery, defined by reaching a weight-for-height z-score (WHZ) ≥ -1.5 within 12 weeks. Overall, 881 children were randomised (297, 290 and 294 in arm 1, arm 2 and arm 3, respectively). Three hundred and forty-four children were males (39%) and median/mean age were 14.6/14.4 months (SD = 4.9, IQR = 10.5-18.4). At inclusion, the three arms were comparable for all criteria, but differences were observed between countries. Overall, 44% (390/881) of the children recovered at week 12 from MAM, with no significant difference between the three arms (41.4%, 45.5% and 45.9%, in arm 1, arm 2 and arm 3, respectively, p = 0.47). This study did not support the true advantages of adding a prebiotic or antibiotic to flour. When using a threshold of WHZ ≥ -2 as an exploratory endpoint, significant differences were observed between the three arms, with higher success rates in arms with antibiotics or prebiotics compared to the control arm (66.9%, 66.0% and 55.2%, respectively, p = 0.005).

Effects of inulin on fecal microbiota and specific immunity in cats.

Inulin has potential benefits for alleviating intestinal stress syndrome, constipation, and immunomodulation. However, its effects on cat gastrointestinal tract remain unexplored. Eight healthy adult British short-haired cat were administered 50 mg/kg/d inulin with a basal diet for 21 days, while fecal samples were collected to measure indole and 3-methylindole levels, immune index detection, and fecal microbial diversity on days 0, 7, 14, and 21. The results showed that adding inulin to the diet of cat could cause the increase of sIgA on day 14 (P < 0.05) and enhance their immune performance. In addition, it will also affect the fecal microbiota of the cat. Collinsella abundance was significantly increased, which could indulge ursodeoxycholic acid production. Feeding inulin had no significant effect on the levels of indole and 3-methylindole (P > 0.05). The above results showed that inulin supplementation in cat diet could improve cat health by enhancing immunity and increasing intestinal beneficial flora.

Prebiotic utilisation provides Lactiplantibacillus plantarum a competitive advantage in vitro, but is not reflected by an increased intestinal fitness.

Synbiotics combine the concepts of probiotics and prebiotics to synergistically enhance the health-associated effects of both components. Previously, we have shown that the intestinal persistence of inulin-utilizing L. plantarum Lp900 is significantly increased in rats fed an inulin-supplemented, high-calcium diet. Here we employed a competitive population dynamics approach to demonstrate that inulin and GOS can selectively enrich L. plantarum strains that utilize these substrates for growth during in vitro cultivation, but that such enrichment did not occur during intestinal transit in rats fed a GOS or inulin-supplemented diet. The intestinal persistence of all L. plantarum strains increased irrespective of their prebiotic utilization phenotype, which was dependent on the calcium level of the diet. Analysis of fecal microbiota and intestinal persistence decline rates indicated that prebiotic utilization capacity did not selectively stimulate intestinal persistence in prebiotic supplemented diets. Moreover, microbiota and organic acid profile analyses indicate that the prebiotic utilizing probiotic strains are vastly outcompeted by the endogenous prebiotic-utilizing microbiota, and that the collective enhanced persistence of all L. plantarum strains is most likely explained by their well-established tolerance to organic acids.

The combined effect of rowing exercise and the intake of functional foods containing inulin on muscle mass and bone mineral density in older Japanese women.

AIM: Aging decreases muscle mass and bone mineral density (BMD), especially in older women. It has been reported that rowing and inulin intake positively affect muscle and bone, respectively. We examined the synergistic effect of rowing and functional food intake, including inulin, on lean body mass, BMD, and physical function parameters in older Japanese women. METHODS: Fifty women aged 65-79 years were divided into four groups with or without inulin intake and rowing. The interventions were carried out for 12 weeks in each group. We assessed lean body mass and BMD using dual-energy X-ray absorptiometry at baseline and after the intervention and examined the changes in the values in each group. RESULTS: Lean body mass in all groups decreased, and the change in lean body mass in the group with rowing and inulin intake was significantly smaller than that in the group without them (-0.05 ± 0.61; -0.83 ± 0.59 kg; P = 0.030). The BMD in the three intervention groups increased after the 12-week intervention. The change in BMD in each of the three intervention groups showed significant differences compared with the control group (Rowing + Inulin: P = 0.03; Rowing + No inulin: P = 0.01; No rowing + Inulin: P < 0.01). CONCLUSIONS: Rowing and the intake of functional foods, including inulin, synergistically prevented a decrease in lean body mass. These factors, individually and additively, might increase BMD in older Japanese women. Geriatr Gerontol Int 2023; 23: 779-787.

Inulin has a beneficial effect by modulating the intestinal microbiome in a BALB/c mouse model.

Food allergy is an important health problem that affects human quality of life and socioeconomic development, and its treatment requires improvement. Intestinal flora dysbiosis is closely associated with food allergies. A sensitised mouse model was established by the intraperitoneal injection of ovalbumin (OVA). The mice were randomly divided into four groups: control, model, high-dose (H), and low-dose (L) inulin. The mice were administered water containing different concentrations of inulin four weeks before the OVA injection. Body weight changes were monitored. After the last OVA injection, the mice were scored for allergic reactions. The levels of total immunoglobulin E (IgE) and diamine oxidase (DAO) in the serum and secretory IgA (sIgA) in the small intestinal mucus were measured, and 16S rRNA sequencing of the faecal flora was performed to evaluate microbial parameters. The intestinal flora biomarkers, correlations between them, and biochemical indicators were analysed. Inulin treatment had no effect on the body weight of OVA-sensitised mice but attenuated allergic reactions and intestinal injury in mice. Compared with the control group, the model group had significantly higher levels of serum DAO and IgE and significantly lower levels of intestinal mucus IgA. IgA levels in the intestinal mucus of mice treated with inulin prior to OVA sensitisation were higher than those in non-inulin-treated OVA-sensitised mice. Furthermore, analysis of operational taxonomic units showed that inulin treatment decreased the abundance of Alloprevotella, Rikenellaceae RC9, Eubacterium siraeum, and Eubacterium xylanophilum, and increased the abundance of Blautia and Lachnospiraceae. Serum DAO levels were positively associated with Eubacterium siraeum, Alloprevotella, Eubacterium xylanophilum, and Odoribacter and negatively associated with Blautia, Tyzzerella, Alistipes, Desulfovibrionaceae, and Ruminococcaceae UCG005. In addition, IgE levels were positively associated with Eubacterium siraeum, Alloprevotella, Eubacterium xylanophilum, Odoribacter, and Citrobacter and negatively associated with Blautia, unclassified Ruminococcaceae, and Alistipes. IgA exhibited significant positive correlation with Blautia, norank_f_Eubacterium coprostanoligenes, Alistipes, norank Desulfovibrionaceae, Muribaculum, and Ruminococcaceae U C G 005 and significant negative correlation with Eubacterim siraeum, Eubacterium xylanophilum, Odoribacter, and Citrobacter. Inulin exerts a protective effect against food allergies in mice, which is partially mediated by alterations in the gut microbiota.

Inulin Improves Diet-Induced Hepatic Steatosis and Increases Intestinal Akkermansia Genus Level.

Hepatic steatosis is characterized by triglyceride accumulation within hepatocytes in response to a high calorie intake, and it may be related to intestinal microbiota disturbances. The prebiotic inulin is a naturally occurring polysaccharide with a high dietary fiber content. Here, we evaluate the effect of inulin on the intestinal microbiota in a non-alcoholic fatty liver disease model. Mice exposed to a standard rodent diet or a fat-enriched diet, were supplemented or not, with inulin. Liver histology was evaluated with oil red O and H&E staining and the intestinal microbiota was determined in mice fecal samples by 16S rRNA sequencing. Inulin treatment effectively prevents liver steatosis in the fat-enriched diet group. We also observed that inulin re-shaped the intestinal microbiota at the phylum level, were Verrucomicrobia genus significantly increased in the fat-diet group; specifically, we observed that Akkermansia muciniphila increased by 5-fold with inulin supplementation. The family Prevotellaceae was also significantly increased in the fat-diet group. Overall, we propose that inulin supplementation in liver steatosis-affected animals, promotes a remodeling in the intestinal microbiota composition, which might regulate lipid metabolism, thus contributing to tackling liver steatosis.

Yogurt Enriched with Inulin Ameliorated Reproductive Functions and Regulated Gut Microbiota in Dehydroepiandrosterone-Induced Polycystic Ovary Syndrome Mice.

The effects of synbiotic yogurt supplemented with inulin on the pathological manifestations and gut microbiota-bile acid axis were investigated using a dehydroepiandrosterone (DHEA)-induced polycystic ovary syndrome (PCOS) mice model. Female C57BL/6J mice were injected subcutaneously with DHEA at a dose of 6 mg/100 g BW for 20 days to establish a PCOS mouse model. Then, the PCOS mice were treated with yogurt containing inulin (6% w/w) at 15 mL/kg BW for 24 days. Results showed that supplementation of synbiotic yogurt enriched with inulin to PCOS mice decreased the body weight gain, improved estrus cycles and ovary morphology, and reduced the levels of luteinizing hormone while increasing the levels of follicle-stimulating hormone and interleukin-22 in serum. At the genus level, synbiotic yogurt increased the relative abundance of Lactobacillus, Bifidobacterium, and Akkermansia. PICRUSt analysis indicated that KEGG pathways including bile acid biosynthesis were changed after inulin-enriched synbiotic yogurt supplementation. Synbiotic yogurt enriched with inulin also modulated the bile acid profiles. In conclusion, inulin-enriched synbiotic yogurt alleviated reproductive dysfunction and modulated gut microbiota and bile acid profiles in PCOS mice.

Improvement in glucose metabolism in adult male offspring of maternal mice fed diets supplemented with inulin via regulation of the hepatic long noncoding RNA profile.

Maternal overnutrition during pregnancy and lactation is an important risk factor for the later development of metabolic disease, especially diabetes, among mothers and their offspring. As a fructan-type plant polysaccharide, inulin has prebiotic functions and is widely used as a natural antidiabetic supplement. However, to date, the mechanism of maternal inulin treatment in the livers of offspring has not been addressed, especially with respect to long noncoding RNAs (lncRNAs). In this study, female C57BL6/J mice were fed either a high-fat diet (HFD) with or without inulin supplementation or a standard rodent diet (SD) during gestation and lactation. After the offspring were weaned, they were fed a SD for 5 weeks. At 8 weeks of age, the glucose metabolism indexes of the offspring were assessed, and their livers were collected to assay lncRNA and mRNA profiles to investigate the effects of early maternal inulin intervention on offspring. Our results indicate that male offspring from HFD-fed dams displayed glucose intolerance and an insulin resistance phenotype at 8 weeks of age. Early maternal inulin intervention improved glucose metabolism in male offspring of mothers fed a HFD during gestation and lactation. The lncRNA and mRNA profile data revealed that compared with the offspring from HFD dams, offspring from the early inulin intervention dams had 99 differentially expressed hepatic lncRNAs and 529 differentially expressed mRNAs. The differentially expressed lncRNA-mRNA coexpression analysis demonstrated that early maternal inulin intervention may change hepatic lncRNA expression in offspring; there lncRNAs are involved in metabolic pathways and the AMP-activated protein kinase signaling pathway. Importantly, the early maternal inulin intervention alleviated glucose metabolism by inhibiting the lncRNA Serpina4-ps1/let-7b-5p/Ppargc1a as a competing endogenous RNA in male offspring.

Dietary inulin supplementation modulates the composition and activities of carbohydrate-metabolizing organisms in the cecal microbiota of broiler chickens.

Inulin is a highly effective prebiotic and an attractive alternative to antibiotic growth promoters for increasing production and maintaining health in chickens. However, how inulin elicits its effects on members of the intestinal microbiota is unknown, even though their importance for energy metabolism and the health of chickens is well documented. A combination of 16S rRNA Illumina sequencing and transcriptomic analysis was used to investigate the effects of supplementing a corn-based basal diet with 1, 2, or 4% inulin or 400 ppm bacitracin on the composition, diversity and activities of carbohydrate-metabolizing organisms (CMOs) in the cecal microbiota of broiler chickens. We found that members of Bacteroides were the most abundant non-starch degrading CMOs, contributing 43.6-52.1% of total glycoside hydrolase genes and 34.6-47.1% activity to the meta-transcriptomes of chickens in the different dietary groups, although members of Parabacteroides, Prevotella, Alistipes, Clostridium, Barnesiella, Blastocystis, Faecalibacterium and others were also actively involved. Inulin and bacitracin inclusion in the basal diet did not change significantly the composition or diversity of these CMOs. Inulin supplementation at three levels promoted the activities of Bacteroides, Prevotella and Bifidobacterium, and 2% level appears to be the most optimal dosage for bifidobacterial activity.

Yeast ß-glucan reduces obesity-associated Bilophila abundance and modulates bile acid metabolism in healthy and high-fat diet mouse models.

Emerging evidence links dietary fiber with altered gut microbiota composition and bile acid signaling in maintaining metabolic health. Yeast ß-glucan (Y-BG) is a dietary supplement known for its immunomodulatory effect, yet its impact on the gut microbiota and bile acid composition remains unclear. This study investigated whether dietary forms of Y-BG modulate these gut-derived signals. We performed 4-wk dietary supplementation in healthy mice to evaluate the effects of different fiber composition (soluble vs. particulate Y-BG) and dose (0.1% vs. 2%). We found that 2% particulate Y-BG induced robust gut microbiota community shifts with elevated liver Cyp7a1 mRNA abundance and bile acid synthesis. These diet-induced responses were notably different when compared with the prebiotic inulin, and included a marked reduction in fecal Bilophila abundance which we demonstrated as translatable to obesity in population-scale American Gut and TwinsUK clinical cohorts. This prompted us to test whether 2% Y-BG maintained metabolic health in mice fed 60% HFD over 13 wk. Y-BG consistently altered the gut microbiota composition and reduced Bilophila abundance, with trends observed in improvement of metabolic phenotype. Notably, Y-BG improved insulin sensitization and this was associated with enhanced ileal Glpr1r mRNA accumulation and reduced Bilophila abundance. Collectively, our results demonstrate that Y-BG modulates gut microbiota community composition and bile acid signaling, but the dietary regime needs to be optimized to facilitate clinical improvement in metabolic phenotype in an aggressive high-fat diet animal model.NEW & NOTEWORTHY The study shows that dietary Y-BG supplementation modulated gut microbiota, bile acid metabolism and associated signaling pathways. Y-BG significantly reduced Bilophila abundance which is associated with obesity in human cohorts. Correlation analysis confirmed functional interactions between bile acid composition, gut microbiota, and metabolic phenotype, although clinical benefit did not reach significance in an aggressive obesity model. Gut microbiota and bile acids correlated with metabolic parameters, indicating future potential of dietary Y-BG modulation of metabolic pathways.

Prebiotic Inulin Supplementation and Peripheral Insulin Sensitivity in adults at Elevated Risk for Type 2 Diabetes: A Pilot Randomized Controlled Trial.

Prediabetes affects 84.1 million adults, and many will progress to type 2 diabetes (T2D). The objective of this proof-of-concept trial was to determine the efficacy of inulin supplementation to improve glucose metabolism and reduce T2D risk. Adults (n = 24; BMI: 31.3 ± 2.9 kg/m2; age: 54.4 ± 8.3 years) at risk for T2D were enrolled in this controlled feeding trial and consumed either inulin (10 g/day) or placebo (maltodextrin, 10 g/day) for six weeks. Assessments included peripheral insulin sensitivity, fasting glucose, and insulin, HOMA-IR, in vivo skeletal muscle substrate preference, Bifidobacteria copy number, intestinal permeability, and endotoxin concentrations. Participant retention was 92%. There were no baseline group differences except for fasting insulin (p = 0.003). The magnitude of reduction in fasting insulin concentrations with inulin (p = 0.003, inulin = Δ-2.9, placebo = Δ2.3) was attenuated after adjustment for baseline concentrations (p = 0.04). After adjusting for baseline values, reduction in HOMA-IR with inulin (inulin = Δ-0.40, placebo=Δ0.27; p = 0.004) remained significant. Bifidobacteria 16s increased (p = 0.04; inulin = Δ3.1e9, placebo = Δ-8.9e8) with inulin supplementation. Despite increases in gut Bifidobacteria, inulin supplementation did not improve peripheral insulin sensitivity. These findings question the need for larger investigations of inulin and insulin sensitivity in this population.

Effect of inulin-type fructans on appetite in patients with type 2 diabetes: a randomised controlled crossover trial.

The aim of the study was to investigate the effect of prebiotic fibres on appetite-regulating hormones, subjective feeling of appetite and energy intake in subjects with type 2 diabetes. Data presented are secondary outcomes of a study investigating the effect of prebiotics on glucagon-like peptide-1 and glycaemic regulation. We conducted a randomised and placebo-controlled crossover trial to evaluate the effects of 16 g/d of inulin-type fructans or a control supplement (maltodextrin) for 6 weeks in randomised order, with a 4-week washout period in-between, on appetite in thirty-five men and women with type 2 diabetes. Data were collected at visits before and after each treatment: plasma concentration of the satiety-related peptides ghrelin and peptide YY (PYY) were assessed during a standardised mixed meal. The subjective sensation of appetite was evaluated in response to an ad libitum lunch by rating the visual analogue scale. Twenty-nine individuals (twelve women) were included in the analyses. Compared to control treatment, the prebiotics did not affect ghrelin (P =0⋅71) or the ratings of hunger (P = 0⋅62), satiety (P = 0⋅56), fullness (P = 0⋅73) or prospective food consumption (P = 0⋅98). Energy intake also did not differ between the treatments. However, the response of PYY increased significantly after the control treatment with mean (sem) 11⋅1 (4⋅3) pg/ml when compared to the prebiotics -0⋅3 (4⋅3) pg/ml (P = 0⋅013). We observed no effect of inulin-type fructans on appetite hormones, subjective feeling of appetite or energy intake in patients with type 2 diabetes.