Modulation of glucagon-like peptide 1 and energy metabolism by inulin and oligofructose: experimental data

Role of the intestinal microbiota in contributing to weight disorders and associated comorbidities

SUMMARYThe gut microbiota is a major factor contributing to the regulation of energy homeostasis and has been linked to both excessive body weight and accumulation of fat mass (i.e., overweight, obesity) or body weight loss, weakness, muscle atrophy, and fat depletion (i.e., cachexia). These syndromes are characterized by multiple metabolic dysfunctions including abnormal regulation of food reward and intake, energy storage, and low-grade inflammation. Given the increasing worldwide prevalence of obesity, cachexia, and associated metabolic disorders, novel therapeutic strategies are needed. Among the different mechanisms explaining how the gut microbiota is capable of influencing host metabolism and energy balance, numerous studies have investigated the complex interactions existing between nutrition, gut microbes, and their metabolites. In this review, we discuss how gut microbes and different microbiota-derived metabolites regulate host metabolism. We describe the role of the gut barrier function in the onset of inflammation in this context. We explore the importance of the gut-to-brain axis in the regulation of energy homeostasis and glucose metabolism but also the key role played by the liver. Finally, we present specific key examples of how using targeted approaches such as prebiotics and probiotics might affect specific metabolites, their signaling pathways, and their interactions with the host and reflect on the challenges to move from bench to bedside.

Fructooligosaccharides benefits on glucose homeostasis upon high-fat diet feeding require type 2 conventional dendritic cells

Diet composition impacts metabolic health and is now recognized to shape the immune system, especially in the intestinal tract. Nutritional imbalance and increased caloric intake are induced by high-fat diet (HFD) in which lipids are enriched at the expense of dietary fibers. Such nutritional challenge alters glucose homeostasis as well as intestinal immunity. Here, we observed that short-term HFD induced dysbiosis, glucose intolerance and decreased intestinal RORγt+ CD4 T cells, including peripherally-induced Tregs and IL17-producing (Th17) T cells. However, supplementation of HFD-fed male mice with the fermentable dietary fiber fructooligosaccharides (FOS) was sufficient to maintain RORγt+ CD4 T cell subsets and microbial species known to induce them, alongside having a beneficial impact on glucose tolerance. FOS-mediated normalization of Th17 cells and amelioration of glucose handling required the cDC2 dendritic cell subset in HFD-fed animals, while IL-17 neutralization limited FOS impact on glucose tolerance. Overall, we uncover a pivotal role of cDC2 in the control of the immune and metabolic effects of FOS in the context of HFD feeding.

Role of Synbiotics (Prebiotics and Probiotics) as Dietary Supplements in Type 2 Diabetes Mellitus Induced Health Complications

Diabetes is a metabolic disorder whose prevalence has become a worrying condition in recent decades. Chronic diabetes can result in serious health conditions such as impaired kidney function, stroke, blindness, and myocardial infarction. Despite a variety of currently available treatments, cases of diabetes and its complications are on the rise. This review article provides a comprehensive account of the ameliorative effect of prebiotics and probiotics individually or in combination i.e. synbiotics on health complications induced by Type 2 Diabetes Mellitus (T2DM). Recent advances in the field underscore encouraging outcomes suggesting the consumption of synbiotics leads to favorable changes in the gut microbiota. These changes result in the production of bioactive metabolites such as short-chain fatty acids (crucial for lowering blood sugar levels), reducing inflammation, preventing insulin resistance, and encouraging the release of glucagon-like peptide-1 in the host. Notably, novel strategies supplementing synbiotics to support gut microbiota are gaining attraction as pivotal interventions in mitigating T2DM-induced health complications. Thus, by nurturing a symbiotic relationship between prebiotics and probiotics i.e. synbiotics, these interventions hold promise in reshaping the microbial landscape of the gut thereby offering a multifaceted approach to managing T2DM and its associated morbidities. Supporting the potential of synbiotics underscores a paradigm shift toward holistic and targeted interventions in diabetes management, offering prospects for improved outcomes and enhanced quality of life for affected individuals. Nevertheless, more research needs to be done to better understand the single and multispecies pre/pro and synbiotics in the prevention and management of T2DM-induced health complications.

Polysaccharides (pectin, mucilage, and fructan inulin) and their fermented products: A critical analysis of their biochemical, gut interactions, and biological functions as antidiabetic agents

Diabetes mellitus is a globally metabolic endocrine syndrome marked by a deficiency of insulin secretion (type-1 DM) or glucose intolerance arising from insulin response impairment (type-2 DM) leading to abnormal glucose metabolism. With an increasing interest in natural dietary components for diabetes management, the identification of novel agents witnessed major discoveries. Plant-derived mucilage, pectin, and inulin are important non-starch polysaccharides that exhibit effective antidiabetic properties often termed soluble dietary fiber (SDF). SDF affects sugar metabolism through multiple mechanisms affecting glucose absorption and diffusion, modulation of carbohydrate metabolizing enzymes (α-amylase and α-glucosidase), ameliorating β-pancreatic cell dysfunction, and improving insulin release or sensitivity. Certain SDFs inhibit dipeptidyl peptidase-4 and influence the expression levels of genes related to glucose metabolism. This review is designed to discuss holistically and critically the antidiabetic effects of major SDF and their underlying mechanisms of action. This review should aid drug discovery approaches in developing novel natural antidiabetic drugs from SDF.

Recent Innovations in Non-dairy Prebiotics and Probiotics: Physiological Potential, Applications, and Characterization

Non-dairy sources of prebiotics and probiotics impart various physiological functions in the prevention and management of chronic metabolic disorders, therefore nutraceuticals emerged as a potential industry. Extraction of prebiotics from non-dairy sources is economical and easily implemented. Waste products during food processing, including fruit peels and fruit skins, can be utilized as a promising source of prebiotics and considered "Generally Recognized As Safe" for human consumption. Prebiotics from non-dairy sources have a significant impact on gut microbiota and reduce the population of pathogenic bacteria. Similarly, next-generation probiotics could also be isolated from non-dairy sources. These sources have considerable potential and can give novel strains of probiotics, which can be the replacement for dairy sources. Such strains isolated from non-dairy sources have good probiotic properties and can be used as therapeutic. This review will elaborate on the potential non-dairy sources of prebiotics and probiotics, their characterization, and significant physiological potential.

Tactics with Prebiotics for the Treatment of Metabolic Dysfunction-Associated Fatty Liver Disease via the Improvement of Mitophagy

Mitophagy/autophagy plays a protective role in various forms of liver damage, by renovating cellular metabolism linking to sustain liver homeostasis. A characterized pathway for mitophagy is the phosphatase and tensin homolog (PTEN)-induced putative kinase 1 (PINK1)/Parkin-dependent signaling pathway. In particular, PINK1-mediated mitophagy could play an indispensable role in improving the metabolic dysfunction-associated fatty liver disease (MAFLD) which could precede to steatohepatitis (NASH), fibrosis, and hepatocellular carcinoma. In addition, the PI3K/AKT/mTOR pathway might regulate the various characteristics of cellular homeostasis including energy metabolism, cell proliferation, and/or cell protection. Therefore, targeting mitophagy with the alteration of PI3K/AKT/mTOR or PINK1/Parkin-dependent signaling to eliminate impaired mitochondria might be an attractive strategy for the treatment of MAFLD. In particular, the efficacy of prebiotics for the treatment of MAFLD has been suggested to be useful via the modulation of the PI3K/AKT/mTOR/AMPK pathway. Additionally, several edible phytochemicals could activate mitophagy for the improvement of mitochondrial damages, which could also be a promising option to treat MAFLD with providing liver protection. Here, the potential therapeutics with several phytochemicals has been discussed for the treatment of MAFLD. Tactics with a viewpoint of prospective probiotics might contribute to the development of therapeutic interventions.

Effect of Inulin Intervention on Metabolic Control and Methylation of INS and IRS1 Genes in Patients with Type 2 Diabetes Mellitus

BACKGROUND AND AIMS

Currently, treatments are being sought to improve the control of type II diabetes mellitus (T2DM), and inulin has been shown to be effective in reducing glucose levels and other metabolic control parameters. These effects on metabolic control may be associated with changes in the epigenetic modulation of genes of the insulin pathway. Therefore, our objective is to determine the effect of agave inulin in metabolic control parameters and in INS and IRS1 genes' methylation in T2DM patients.

METHODS

This was a longitudinal experimental study with 67 Mexican participants who received an intervention of inulin agave (10 g daily) for 2 months. The methylation of the INS and IRS1 genes was determined by MSP.

RESULTS

For the INS gene, we found a significant decrease in the proportions of T2DM patients with methylated DNA after inulin intervention (p = 0.0001). In contrast, the difference in the proportions of the unmethylated IRS1 gene before and after the inulin intervention was not significant (p = 0.79). On the other hand, we observed changes in the number of T2DM patients' recommended categories for metabolic control depending on the methylation of INS and IRS1 genes before and after treatment with inulin.

CONCLUSION

For the first time, we report the modification in the methylation of two genes, INS and IRS1, of the insulin pathway and provide information on the possible relevant role of epigenetics as a key factor in positive changes in metabolic control parameters by inulin intake in T2DM patients.

Prebiotic oligofructose protects against high-fat diet-induced obesity by changing the gut microbiota, intestinal mucus production, glycosylation and secretion

Obesity is a major risk factor for the development of type 2 diabetes and cardiovascular diseases, and gut microbiota plays a key role in influencing the host energy homeostasis. Moreover, obese mice have a different gut microbiota composition, associated with an alteration of the intestinal mucus layer, which represents the interface between the bacteria and the host. We previously demonstrated that prebiotic treatment with oligofructose (FOS) counteracted the effects of diet-induced obesity, together with changes in the gut microbiota composition, but it is not known if the intestinal mucus layer could be involved. In this study, we found that, in addition to preventing high-fat diet (HFD) induced obesity in mice, the treatment with FOS increased the expression of numerous genes involved in mucus production, glycosylation and secretion, the expression of both secreted and transmembrane mucins, and the differentiation and number of goblet cells. These results were associated with significant changes in the gut microbiota composition, with FOS significantly increasing the relative and absolute abundance of the bacterial genera Odoribacter, Akkermansia, two unknown Muribaculaceae and an unknown Ruminococcaceae. Interestingly, all these bacterial genera had a negative association with metabolic parameters and a positive association with markers of the mucus layer. Our study shows that FOS treatment is able to prevent HFD-induced metabolic disorders, at least in part, by acting on all the processes of the mucus production. These data suggest that targeting the mucus and the gut microbiota by using prebiotics could help to prevent or mitigate obesity and related disorders.

Effects of atherogenic diet supplemented with fermentable carbohydrates on metabolic responses and plaque formation in coronary arteries using a Saddleback pig model

Fermentable carbohydrates are gaining interest in the field of human nutrition because of their benefits in obesity-related comorbidities. The aim of this study was to investigate the influence of fermentable carbohydrates, such as pectin and inulin, in an atherogenic diet on metabolic responses and plaque formation in coronary arteries using a Saddleback pig model. Forty-eight healthy pigs aged five months were divided into four feeding groups (n = 10) and one baseline group (n = 8). Three feeding groups received an atherogenic diet (38% crisps, 10% palm fat, and 2% sugar with or without supplementation of 5% pectin or inulin), and one group received a conventional diet over 15 weeks. Feed intake, weight gain, body condition score, and back fat thickness were monitored regularly. Blood and fecal samples were collected monthly to assess the metabolites associated with high cardiovascular risk and fat content, respectively. At the end of 15 weeks, the coronary arteries of the pigs were analyzed for atherosclerotic plaque formation. Independent of supplementation, significant changes were observed in lipid metabolism, such as an increase in triglycerides, bile acids, and cholesterol in serum, in all groups fed atherogenic diets in comparison to the conventional group. Serum metabolome analysis showed differentiation of the feeding groups by diet (atherogenic versus conventional diet) but not by supplementation with pectin or inulin. Cardiovascular lesions were found in all feeding groups and in the baseline group. Supplementation of pectin or inulin in the atherogenic diet had no significant impact on cardiovascular lesion size. Saddleback pigs can develop naturally occurring plaques in coronary arteries. Therefore, this pig model offers potential for further research on the effects of dietary intervention on obesity-related comorbidities, such as cardiovascular lesions, in humans.

Preparation and nutritional properties of xylooligosaccharide from agricultural and forestry byproducts: A comprehensive review

Xylooligosaccharide (XOS) are functional oligosaccharides with prebiotic activities, which originate from lignocellulosic biomass and have attracted extensive attention from scholars in recent years. This paper summarizes the strategies used in the production of XOS, and introduces the raw materials, preparation methods, and purification technology of XOS. In addition, the biological characteristics and applications of XOS are also presented. The most commonly recommended XOS production strategy is the two-stage method of alkaline pre-treatment and enzymatic hydrolysis; and further purification by membrane filtration to achieve the high yield of XOS is required for prebiotic function. At the same time, new strategies and technologies such as the hydrothermal and steam explosion have been used as pre-treatment methods combined with enzymatic hydrolysis to prepare XOS. XOS have many critical physiological activities, especially in regulating blood glucose, reducing blood lipid, and improving the structure of host intestinal flora.

Physicochemical, morpho-structural, and biological characterization of polysaccharides from three Polygonatum spp

Polygonatum species, including P. cyrtonema, P. kingianum, and P. sibiricum, are edible plants with medicinal purposes, which have long been consumed as food due to their high nutritional value. In this study, polysaccharides from P. cyrtonema (PCP), P. kingianum (PKP) and P. sibiricum (PSP) were obtained, and their physicochemical properties and in vitro biological activities were investigated. Our results demonstrated that PCP, PKP, and PSP consist of major fructose and minor glucose, galacturonic acid, and galactose in different molar ratios with the molecular weights of 8.5 × 10³ Da, 8.7 × 10³ Da, and 1.0 × 10⁴ Da, respectively. The three polysaccharides had triple-helical structures with β-d-Fruf, α-d-Glcp, α-d-Galp sugar residues, and an O-acetyl group, and displayed peak-shaped structures in different sizes. They also exhibited thermal, shear-thinning behavior and viscoelastic properties, and PCP presented the highest viscoelasticity. Moreover, they exerted strong free radical-scavenging abilities, and significant reducing capacity. PCP was the strongest, followed by PSP and then PKP. They significantly promoted the polarization of the M1 macrophage, with the effect of PCP ranking first. All three had similar effects on GLP-1 secretion. It is, therefore, necessary to identify the various roles of these three Polygonatum polysaccharides as functional agents based on their bioactivities and physicochemical properties.

Three Polygonatum polysaccharides with different physicochemical properties exert distinct effects on free radical-scavenging abilities and the promotion of M1 macrophage polarization, while they have similar effects on GLP-1 secretion.

Assessing the effects of inulin-type fructan intake on body weight, blood glucose, and lipid profile: A systematic review and meta-analysis of randomized controlled trials

Inulin-type fructan (ITF) intake has been suggested to alleviate several features of metabolic syndrome including obesity, diabetes, and hyperlipidemia; yet, results from the human trials remained inconsistent. We aimed to systematically evaluate the effects of ITF intake on body weight, glucose homeostasis, and lipid profile on human subjects with different health status, including healthy, overweight and obese, prediabetes and diabetes, and hyperlipidemia. Weighted mean differences (WMDs) between ITF and control groups were calculated by a random-effects model. A total of 33 randomized controlled human trials were included. Significant effect of ITF intake was only observed in the diabetics, but not in the other subject groups. Specifically, ITF intervention significantly decreased the WMD of blood glucose (-0.42 mmol/L; 95% CI: -0.71, -0.14; p = .004), total cholesterol (-0.46 mmol/L; 95% CI: -0.75, -0.17; p = .002), and triglycerides (TAG) (-0.21 mmol/L; 95% CI: -0.37, -0.05; p = .01) compared with the control. The stability of these favorable effects of ITF on diabetics was confirmed by sensitivity analysis. Also, ITF tends to lower LDL cholesterol (p = .084). But body weight and blood insulin were not affected by ITF intake. It should be noted that blood glucose, total cholesterol, and LDL cholesterol exhibited high unexplained heterogeneity. In conclusion, ITF intake lowers blood glucose, total cholesterol, and TAG in the people with diabetes, and they may benefit from addition of inulin into their diets, but the underlying mechanisms responsible for these effects are inconclusive.

A high-protein diet containing inulin/oligofructose supports body weight gain associated with lower energy expenditure and carbohydrate oxidation, and alters faecal microbiota in C57BL/6 mice

Prebiotic supplements and high-protein (HP) diets reduce body weight and modulate intestinal microbiota. Our aim was to elucidate the combined effect of an inulin/oligofructose (FOS) and HP diet on body weight gain, energy metabolism and faecal microbiota. Forty male C57BL/6NCrl mice were fed a control (C) diet for 2 weeks and allocated to a C or HP (40 % protein) diet including no or 10 % inulin/FOS (C + I and HP + I) for 4 weeks. Inulin/FOS was added in place of starch and cellulose. Body weight, food intake, faecal energy and nitrogen were determined. Indirect calorimetry and faecal microbiota analysis were performed after 3 weeks on diets. Body weight gain of HP-fed mice was 36 % lower than HP + I- and C-fed mice (P < 0⋅05). Diet digestibility and food conversion efficiency were higher in HP + I- than HP-fed mice (P < 0⋅01), while food intake was comparable between groups. Total energy expenditure (heat production) was 25 % lower in HP + I- than in C-, HP- and C + I-fed mice (P < 0⋅001). Carbohydrate oxidation tended to be 24 % higher in HP- than in HP + I-fed mice (P < 0⋅05). Faecal nitrogen excretion was 31-45 % lower in C-, C + I- and HP + I- than in HP-fed mice (P < 0⋅05). Faecal Bacteroides-Prevotella DNA was 2⋅3-fold higher in C + I- and HP + I- relative to C-fed mice (P < 0⋅05), but Clostridium leptum DNA abundances was 79 % lower in HP + I- than in HP-fed mice (P < 0⋅05). We suggest that the higher conversion efficiency of dietary energy of HP + I but not C + I-fed mice is caused by higher digestibility and lower heat production, resulting in increased body mass.

Microbiota Changes in Fathers Consuming a High Prebiotic Fiber Diet Have Minimal Effects on Male and Female Offspring in Rats

BACKGROUND

Consuming a diet high in prebiotic fiber has been associated with improved metabolic and gut microbial parameters intergenerationally, although studies have been limited to maternal intake with no studies examining this effect in a paternal model.

METHOD

Male Sprague Dawley rats were allocated to either (1) control or (2) oligofructose-supplemented diet for nine weeks and then mated. Offspring consumed control diet until 16 weeks of age. Bodyweight, body composition, glycemia, hepatic triglycerides, gastrointestinal hormones, and gut microbiota composition were measured in fathers and offspring.

RESULTS

Paternal energy intake was reduced, while satiety inducing peptide tyrosine tyrosine (PYY) gut hormone was increased in prebiotic versus control fathers. Increased serum PYY persisted in female prebiotic adult offspring. Hepatic triglycerides were decreased in prebiotic fathers with a similar trend (p = 0.07) seen in female offspring. Gut microbial composition showed significantly reduced alpha diversity in prebiotic fathers at 9 and 12 weeks of age (p < 0.001), as well as concurrent differences in beta diversity (p < 0.001), characterized by differences in Bifidobacteriaceae, Lactobacillaceae and Erysipelotrichaceae, and particularly Bifidobacterium animalis. Female prebiotic offspring had higher alpha diversity at 3 and 9 weeks of age (p < 0.002) and differences in beta diversity at 15 weeks of age (p = 0.04). Increases in Bacteroidetes in female offspring and Christensenellaceae in male offspring were seen at nine weeks of age.

CONCLUSIONS

Although paternal prebiotic intake before conception improves metabolic and microbiota outcomes in fathers, effects on offspring were limited with increased serum satiety hormone levels and changes to only select gut bacteria.

Host/microbiota interactions in health and diseases-Time for mucosal microbiology!

During the last 20 years, a new field of research delineating the importance of the microbiota in health and diseases has emerged. Inappropriate host-microbiota interactions have been shown to trigger a wide range of chronic inflammatory diseases, and defining the exact mechanisms behind perturbations of such relationship, as well as ways by which these disturbances can lead to disease states, both remain to be fully elucidated. The mucosa-associated microbiota constitutes a recently studied microbial population closely linked with the promotion of chronic intestinal inflammation and associated disease states. This review will highlight seminal works that have brought into light the importance of the mucosa-associated microbiota in health and diseases, emphasizing the challenges and promises of expending the mucosal microbiology field of research.

Protective role of three differently processed corn bran on glucose and lipid concentrations in d-galactose-induced mice model

In this research, the effects of three differently processed corn bran (corn bran soluble hemicellulose (HEM), hemicellulose hydrolyzed by oxalic acid (HOA), Amberlite XAD-2 eluate (XE)) on the changes of glucose and lipid concentrations of d-galactose (d-gal)-induced mice were investigated. The mice were divided into five groups and intragastric administration HEM, HOA, and XE at 200 mg/kg Body Weight (BW) for continuously 6 weeks. Mice were submitted under oral glucose tolerance test (OGTT).Then, the serum insulin, glucagon-like peptide-1(GLP-1), serum C-peptide, hepatic glycogen (HG), muscle glycogen (MG), total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C) of all the mice were detected. As we can see, by inducing with d-gal, the glucose and lipid concentrations of aging mice could be effectively regulated by HEM, HOA, and XE. High degree of esterification feruloylated oligosaccharides has the most obvious effect of regulating glucose and lipid concentrations. PRACTICAL APPLICATIONS: Corn bran has not been fully paid attention owing to the rough taste and the poor water solubility. Actually, corn bran, a renewable resource available in a large quantity, could be a goods source of valuable consumer products. The results of this study indicated that three differently processed corn brans could regulate glucose and lipid concentrations and XE had the most obvious effect of regulating glucose and lipid concentrations. Corn bran could advantage as a new type of environmentally and inexpensive food supplements on reducing blood glucose and lipid concentrations.

Changes in Gut Microbiota and Hormones After Bariatric Surgery: a Bench-to-Bedside Review

Overweight and obesity are among the most prevalent non-communicable diseases which are generally treated successfully by bariatric or sleeve surgery. There are evidences affirming that sleeve surgery can manipulate the pH of the stomach and interact with the metabolism of fatty acids, carbohydrates, and bile acid transfer, leading to the overgrowth of gut microbiota. Therefore, this study aims to review the changes in gut microbiota and hormones after bariatric surgery.

Choice of Laboratory Rodent Diet May Confound Data Interpretation and Reproducibility

The reproducibility of experimental data is challenged by many factors in both clinical and preclinical research. In preclinical studies, several factors may be responsible, and diet is one variable that is commonly overlooked, especially by those not trained in nutrition. In particular, grain-based diets contain complex ingredients, each of which can provide multiple nutrients, non-nutrients, and contaminants, which may vary from batch to batch. Thus, even when choosing the same grain-based diet used in the past by others, its composition will likely differ. In contrast, purified diets contain refined ingredients that offer the ability to control the composition much more closely and maintain consistency from one batch to the next, while minimizing the presence of non-nutrients and contaminants. In this article, we provide several different examples or scenarios showing how the diet choice can alter data interpretation, potentially affecting reproducibility and knowledge gained within any given field of study.

High fat diet induces microbiota-dependent silencing of enteroendocrine cells

Enteroendocrine cells (EECs) are specialized sensory cells in the intestinal epithelium that sense and transduce nutrient information. Consumption of dietary fat contributes to metabolic disorders, but EEC adaptations to high fat feeding were unknown. Here, we established a new experimental system to directly investigate EEC activity in vivo using a zebrafish reporter of EEC calcium signaling. Our results reveal that high fat feeding alters EEC morphology and converts them into a nutrient insensitive state that is coupled to endoplasmic reticulum (ER) stress. We called this novel adaptation 'EEC silencing'. Gnotobiotic studies revealed that germ-free zebrafish are resistant to high fat diet induced EEC silencing. High fat feeding altered gut microbiota composition including enrichment of Acinetobacter bacteria, and we identified an Acinetobacter strain sufficient to induce EEC silencing. These results establish a new mechanism by which dietary fat and gut microbiota modulate EEC nutrient sensing and signaling.

Mice Microbiota Composition Changes by Inulin Feeding with a Long Fasting Period under a Two-Meals-Per-Day Schedule

Water-soluble dietary fiber is known to modulate fecal microbiota. Although there are a few reports investigating the effects of fiber intake timing on metabolism, there are none on the effect of intake timing on microbiota. Therefore, in this study, we examined the timing effects of inulin-containing food on fecal microbiota. Mice were housed under conditions with a two-meals-per-day schedule, with a long fasting period in the morning and a short fasting period in the evening. Then, 10-14 days after inulin intake, cecal content and feces were collected, and cecal pH and short-chain fatty acids (SCFAs) were measured. The microbiome was determined using 16S rDNA sequencing. Inulin feeding in the morning rather than the evening decreased the cecal pH, increased SCFAs, and changed the microbiome composition. These data suggest that inulin is more easily digested by fecal microbiota during the active period than the inactive period. Furthermore, to confirm the effect of fasting length, mice were housed under a one-meal-per-day schedule. When the duration of fasting was equal, the difference between morning and evening nearly disappeared. Thus, our study demonstrates that consuming inulin at breakfast, which is generally after a longer fasting period, has a greater effect on the microbiota.

Neonatal Consumption of Oligosaccharides Greatly Increases L-Cell Density without Significant Consequence for Adult Eating Behavior

Oligosaccharides (OS) are commonly added to infant formulas, however, their physiological impact, particularly on adult health programming, is poorly described. In adult animals, OS modify microbiota and stimulate colonic fermentation and enteroendocrine cell (EEC) activity. Since neonatal changes in microbiota and/or EEC density could be long-lasting and EEC-derived peptides do regulate short-term food intake, we hypothesized that neonatal OS consumption could modulate early EECs, with possible consequences for adult eating behavior. Suckling rats were supplemented with fructo-oligosaccharides (FOS), beta-galacto-oligosaccharides/inulin (GOS/In) mix, alpha-galacto-oligosaccharides (αGOS) at 3.2 g/kg, or a control solution (CTL) between postnatal day (PND) 5 and 14/15. Pups were either sacrificed at PND14/15 or weaned at PND21 onto standard chow. The effects on both microbiota and EEC were characterized at PND14/15, and eating behavior at adulthood. Very early OS supplementation drastically impacted the intestinal environment, endocrine lineage proliferation/differentiation particularly in the ileum, and the density of GLP-1 cells and production of satiety-related peptides (GLP-1 and PYY) in the neonatal period. However, it failed to induce any significant lasting changes on intestinal microbiota, enteropeptide secretion or eating behavior later in life. Overall, the results did not demonstrate any OS programming effect on satiety peptides secreted by L-cells or on food consumption, an observation which is a reassuring outlook from a human perspective.

Effects of Prebiotic and Synbiotic Supplementation on Glycaemia and Lipid Profile in Type 2 Diabetes: A Meta-Analysis of Randomized Controlled Trials

Purpose: Diabetes Mellitus (T2DM) as a chronic disease, is on rise in parallel with other non-communicable diseases. Several studies have shown that probiotics and prebiotics might exert beneficial effects in chronic diseases including diabetes. Because of controversial results from different trials, the present study aims to assess the effects of prebiotic/synbiotic consumption on metabolic parameters in patients with type2 diabetes. Methods: A systematic literature search was performed on randomized controlled trial published in PubMed/Medline, SciVerse Scopus, Google scholar, SID and Magiran up to March 2018. Of a total number of 255 studies found in initial literature search, ten randomized controlled trials were included in the meta-analysis. The pooled mean net change were calculated in fasting blood-glucose [FBG], Hemoglobin A1c [HbA1c] and lipid markers (total cholesterol [TC], triglyceride [TG], low-density lipoprotein cholesterol [LDL-C], high density lipoprotein cholesterol [HDL-C]). The meta-analyses was conducted using Revman Software (v5.3). Results: The pooled estimate indicated a significant difference for the mean change in FBG, HbA1c and HDL in treatment group in comparison with control group. Subgroup analysis by intervention showed a significant difference in TG, LDL and HDL (synbiotic group) and in TG, TC, FBG, HDL and HbA1c (prebiotic group) compared with placebo. In another subgroup analysis, high quality studies showed significant reductions in TG, TC, FBG and HbA1c in intervention group compared with placebo group. Conclusion: In summary, diets supplemented with either prebiotics or synbiotics can result in improvements in lipid metabolism and glucose homeostasis in type 2 diabetic patients.

Phytosterols and inulin-enriched soymilk increases glucagon-like peptide-1 secretion in healthy men: double-blind randomized controlled trial, subgroup study

OBJECTIVE

The study aimed to determine the effect of phytosterols and inulin on plasma glucose, insulin, and GLP-1 levels among healthy men after consuming phytosterols and inulin-enriched soymilk for 8 weeks.

RESULTS

A total of 26 men at least 20 years old were randomly assigned into the 2 g/day of phytosterols and 10 g/day of inulin-enriched soymilk (intervention) group or into the standard soymilk (control) group. In the intervention group, the area under the curve of Glucagon-like peptide-1 secretion increased significantly, compared to its baseline (p = 0.003). The area under the curve of insulin secretion also increased but it did not meet statistical significance (p = 0.118). The area under the curves of plasma glucose were similar between pre- and post-test (p = 0.348). In the control group, none of the primary results significantly changed compared to their baseline levels. Trial registration Thai Clinical Trial Registry: TCTR20160319001 date: March 19, 2016, retrospectively registered.

The Neuroendocrinology of the Microbiota-Gut-Brain Axis: A Behavioural Perspective

The human gut harbours trillions of symbiotic bacteria that play a key role in programming different aspects of host physiology in health and disease. These intestinal microbes are also key components of the gut-brain axis, the bidirectional communication pathway between the gut and the central nervous system (CNS). In addition, the CNS is closely interconnected with the endocrine system to regulate many physiological processes. An expanding body of evidence is supporting the notion that gut microbiota modifications and/or manipulations may also play a crucial role in the manifestation of specific behavioural responses regulated by neuroendocrine pathways. In this review, we will focus on how the intestinal microorganisms interact with elements of the host neuroendocrine system to modify behaviours relevant to stress, eating behaviour, sexual behaviour, social behaviour, cognition and addiction.

Chicory Roots for Prebiotics and Appetite Regulation: A Pilot Study in Mice

The objectives of this work are to address the prebiotic effects of chicory ( Cichorium intybus) together with its possible role in appetite control. We compared nine chicory genotypes in order to determine if variations in the content of metabolites in the roasted roots would lead to modifications in release of satiety hormones and in composition of gut microbiota. To this aim, a 5-week dietary-intervention study was achieved using mice fed with distinct chicory-based preparations. A 16S rRNA gene-based metagenetic analysis of fecal microbiota was performed. In vitro gastrointestinal digestions were performed in order to study the effect of chicory intestinal digests on gut hormone regulation in enteroendocrine cells. Firmicutes/Bacteroidetes ratio and gut bacterial groups, such as Alloprevotella, Blautia, Alistipes, and Oscillibacter, were found to be modulated by chicory. On the other hand, CCK and GLP-1 satiety hormones were demonstrated to be significantly increased by chicory in vitro.

Influence of gut microbiota on the development and progression of nonalcoholic steatohepatitis

INTRODUCTION

Nonalcoholic steatohepatitis (NASH) is characterized by the presence of steatosis, inflammation, and ballooning degeneration of hepatocytes, with or without fibrosis. The prevalence of NASH has increased with the obesity epidemic, but its etiology is multifactorial. The current studies suggest the role of gut microbiota in the development and progression of NASH. The aim is to review the studies that investigate the relationship between gut microbiota and NASH. These review also discusses the pathophysiological mechanisms and the influence of diet on the gut-liver axis.

RESULT

The available literature has proposed mechanisms for an association between gut microbiota and NASH, such as: modification energy homeostasis, lipopolysaccharides (LPS)-endotoxemia, increased endogenous production of ethanol, and alteration in the metabolism of bile acid and choline. There is evidence to suggest that NASH patients have a higher prevalence of bacterial overgrowth in the small intestine and changes in the composition of the gut microbiota. However, there is still a controversy regarding the microbiome profile in this population. The abundance of Bacteroidetes phylum may be increased, decreased, or unaltered in NASH patients. There is an increase in the Escherichia and Bacteroides genus. There is depletion of certain taxa, such as Prevotella and Faecalibacterium.

CONCLUSION

Although few studies have evaluated the composition of the gut microbiota in patients with NASH, it is observed that these individuals have a distinct gut microbiota, compared to the control groups, which explains, at least in part, the genesis and progression of the disease through multiple mechanisms. Modulation of the gut microbiota through diet control offers new challenges for future studies.

Gastrointestinal Transit Time, Glucose Homeostasis and Metabolic Health: Modulation by Dietary Fibers

Gastrointestinal transit time may be an important determinant of glucose homeostasis and metabolic health through effects on nutrient absorption and microbial composition, among other mechanisms. Modulation of gastrointestinal transit may be one of the mechanisms underlying the beneficial health effects of dietary fibers. These effects include improved glucose homeostasis and a reduced risk of developing metabolic diseases such as obesity and type 2 diabetes mellitus. In this review, we first discuss the regulation of gastric emptying rate, small intestinal transit and colonic transit as well as their relation to glucose homeostasis and metabolic health. Subsequently, we briefly address the reported health effects of different dietary fibers and discuss to what extent the fiber-induced health benefits may be mediated through modulation of gastrointestinal transit.

Anxiety, Depression, and the Microbiome: A Role for Gut Peptides

The complex bidirectional communication between the gut and the brain is finely orchestrated by different systems, including the endocrine, immune, autonomic, and enteric nervous systems. Moreover, increasing evidence supports the role of the microbiome and microbiota-derived molecules in regulating such interactions; however, the mechanisms underpinning such effects are only beginning to be resolved. Microbiota-gut peptide interactions are poised to be of great significance in the regulation of gut-brain signaling. Given the emerging role of the gut-brain axis in a variety of brain disorders, such as anxiety and depression, it is important to understand the contribution of bidirectional interactions between peptide hormones released from the gut and intestinal bacteria in the context of this axis. Indeed, the gastrointestinal tract is the largest endocrine organ in mammals, secreting dozens of different signaling molecules, including peptides. Gut peptides in the systemic circulation can bind cognate receptors on immune cells and vagus nerve terminals thereby enabling indirect gut-brain communication. Gut peptide concentrations are not only modulated by enteric microbiota signals, but also vary according to the composition of the intestinal microbiota. In this review, we will discuss the gut microbiota as a regulator of anxiety and depression, and explore the role of gut-derived peptides as signaling molecules in microbiome-gut-brain communication. Here, we summarize the potential interactions of the microbiota with gut hormones and endocrine peptides, including neuropeptide Y, peptide YY, pancreatic polypeptide, cholecystokinin, glucagon-like peptide, corticotropin-releasing factor, oxytocin, and ghrelin in microbiome-to-brain signaling. Together, gut peptides are important regulators of microbiota-gut-brain signaling in health and stress-related psychiatric illnesses.

Gut microbiota as a potential target of metabolic syndrome: the role of probiotics and prebiotics

Metabolic syndrome (MS) comprises central obesity, increased plasma glucose levels, hyperlipidemia and hypertension, and its incidence is increasing due to changes in lifestyle and dietary structure in recent years. MS has been proven to be associated with an increased incidence of cardiovascular diseases and type 2 diabetes mellitus, leading to morbidity and mortality. In this manuscript, we review recent studies concerning the role of the gut microbiota in MS modulation. Manipulation of the gut microbiota through the administration of prebiotics or probiotics may assist in weight loss and reduce plasma glucose and serum lipid levels, decreasing the incidence of cardiovascular diseases and type 2 diabetes mellitus. To the best of our knowledge, short-chain fatty acids (SCFAs), bile salt hydrolase (BSH), metabolic endotoxemia and the endocannabinoid (eCB) system are essential in regulating the initiation and progression of MS through the normalization of adipogenesis and the regulation of insulin secretion, fat accumulation, energy homeostasis, and plasma cholesterol levels. Therefore, the gut microbiota may serve as a potential therapeutic target for MS. However, further studies are needed to enhance our understanding of manipulating the gut microbiota and the role of the gut microbiota in MS prevention and treatment.

Combined Effects of a Dietary Fiber Mixture and Wheat Albumin in a Rat Model of Type 2 Diabetes Mellitus

As bioactive ingredients of functional foods, dietary fiber and wheat albumin (WA) are known to suppress hyperglycemia in patients with type 2 diabetes mellitus. The combined effects of these bioactive ingredients were examined using an animal model of type 2 diabetes mellitus. First, oral starch tolerance tests (OSTTs) with the simultaneous intake of a dietary fiber mixture (DF) and WA were performed as an acute study. Male Goto-Kakizaki rats received a soluble starch solution [700 mg/kg body weight (bw)] containing DF and/or WA (each 300 mg/kg bw). In these OSTTs, the combined intake of DF and WA suppressed hyperglycemia much more effectively than each separate intake. Second, in a chronic intake study, diets containing DF and/or WA were administered to male Zucker diabetic fatty rats over 84 d. The combined effects of DF and WA were not observed in glycosylated hemoglobin concentration levels or fasting blood glucose levels, but appeared as an improvement in liver lipid contents. Variations in the liver lipid contents were similarly reflected in those of the plasma lipid concentrations. In conclusion, this study found that the simultaneous intake of bioactive DF and WA improved the postprandial hyperglycemia and the chronic lipid metabolism disorders in rat models of type 2 diabetes mellitus.

The Gut Microbiome and Obesity

The gut microbiome consists of trillions of bacteria which play an important role in human metabolism. Animal and human studies have implicated distortion of the normal microbial balance in obesity and metabolic syndrome. Bacteria causing weight gain are thought to induce the expression of genes related to lipid and carbohydrate metabolism thereby leading to greater energy harvest from the diet. There is a large body of evidence demonstrating that alteration in the proportion of Bacteroidetes and Firmicutes leads to the development of obesity, but this has been recently challenged. It is likely that the influence of gut microbiome on obesity is much more complex than simply an imbalance in the proportion of these phyla of bacteria. Modulation of the gut microbiome through diet, pre- and probiotics, antibiotics, surgery, and fecal transplantation has the potential to majorly impact the obesity epidemic.

Prebiotics in the management of components of the metabolic syndrome

Components of the metabolic syndrome (MetS), including abdominal obesity, low-grade chronic systemic inflammation, altered glucose metabolism, dyslipidemia and high blood pressure, are major threats to healthy aging in modern societies. The connection between MetS components and gut microflora is now acknowledged and multiple therapeutic strategies have been proposed to change the composition of the gut microbiota in order to promote optimal metabolic health. Prebiotics have the ability to favour growth of beneficial bacteria, especially short-chain fatty-acids (SCFA) producers. Increased SCFA in the gut is associated with improved satiety and weight loss, reduced systemic inflammation by increasing the gut barrier function, and improved glucose and lipid metabolism. The objective of this review is to examine the recent literature in order to determine the types and doses of prebiotics that could be recommended for the management of MetS. A review of the literature was executed using the MEDLINE database and clinical trials from 2013 to 2017 were selected for analysis. In conclusion, a daily supplementation of 10g of inulin, resistant starches or fructo-oligosaccharide-enriched inulin could have beneficial effects on MetS components in individuals with type 2 diabetes. In healthy subjects or in individuals with the MetS, the results are too heterogeneous and scarce to be able to set any specific recommendations. More clinical studies are needed to better understand the role of prebiotics in the management of MetS components.

Chronic treatment with prebiotics, probiotics and synbiotics attenuated cardiac dysfunction by improving cardiac mitochondrial dysfunction in male obese insulin-resistant rats

PURPOSE

In metabolic syndrome, the composition of gut microbiota has been disrupted, and is associated with left ventricular (LV) dysfunction. Several types of prebiotics, probiotics, and synbiotics have been shown to exert cardioprotection by restoring gut microbiota from dysbiosis and reducing systemic inflammation. However, the effects of prebiotics such as xylooligosaccharides (XOS); probiotics such as Lactobacillus paracasei STII01 HP4, and synbiotics on metabolic and LV function in obese insulin-resistant rats have not been investigated. In this study, we hypothesized that prebiotics and probiotics improve metabolic parameters, heart rate variability (HRV), blood pressure (BP), and LV function by attenuating cardiac mitochondrial dysfunction, systemic inflammation, and oxidative stress, and that synbiotics provide greater efficacy than a single regimen in obese insulin resistance.

METHODS

Rats were fed with either normal diet or high-fat diet (HFD) for 12 weeks and then rats in each dietary group were randomly subdivided into four subgroups to receive either a vehicle, prebiotics, probiotics, or synbiotics for another 12 weeks. Metabolic parameters, BP, HRV, LV function, cardiac mitochondrial function, systemic inflammation, and oxidative stress were determined.

RESULTS

HFD-fed rats had obese insulin resistance with markedly increased systemic inflammatory marker [Serum LPS; ND; 0.6 ± 0.1 EU/ml vs. HFD; 5.7 ± 1.2 EU/ml (p < 0.05)], depressed HRV, and increased BP and LV dysfunction [%ejection fraction; ND; 93 ± 2% vs. HFD; 83 ± 2% (p < 0.05)]. Prebiotics, probiotics, and synbiotics attenuated insulin resistance by improving insulin sensitivity and lipid profiles. All interventions also improved HRV, BP, LV function [%ejection fraction; HFV; 81 ± 2% vs. HFPE; 93 ± 3%, HFPO; 92 ± 1%, HFC; 92 ± 2% (p < 0.05)] by attenuating mitochondrial dysfunction, oxidative stress, and systemic inflammation in obese insulin-resistant rats.

CONCLUSION

Prebiotics, probiotics, and synbiotics shared similar efficacy in reducing insulin resistance and LV dysfunction in obese insulin-resistant rats.

Supplementation of oligofructose, but not sucralose, decreases high-fat diet induced body weight gain in mice independent of gustducin-mediated gut hormone release

SCOPE

Enteroendocrine cells sense nutrients through taste receptors similar to those on the tongue. Sweet and fatty acid taste receptors (FFAR) coupled to the gustatory G-protein, gustducin, on enteroendocrine cells play a role in gut hormone release. We studied if supplementation of artificial (sucralose) or prebiotic (oligofructose; OFS) sweeteners target gustducin-mediated signaling pathways to alter gut hormone release and reduce obesity-associated disorders.

METHODS AND RESULTS

Wild-type (WT) and α-gustducin knockout (α-gust^-/- ) mice were fed a high-fat diet and gavaged once daily (8 wk) with water or equisweet concentrations of sweeteners. OFS but not sucralose decreased body weight gain (-19 ± 3%, p < 0.01), fat pad mass (-55 ± 6%, p < 0.001), and insulin resistance (-39 ± 5%, p < 0.001) independent of α-gustducin. Neither sweetener improved glucose intolerance, while solely OFS improved the disturbed colonic permeability. OFS decreased (-65 ± 8%, p < 0.001) plasma glucagon-like peptide 1 (GLP-1) but not ghrelin and peptide YY (PYY) levels in WT mice. Cecal acetate and butyrate levels were reduced by OFS in both genotypes suggesting enhanced uptake of SCFAs that may target FFAR2 (upregulated expression) in adipose tissue.

CONCLUSION

OFS, but not sucralose, reduced body weight gain and decreased intestinal permeability, but not glucose intolerance. Effects were not mediated by altered gut hormone levels or gustducin-mediated signaling. Artificial sweeteners do not affect gut hormone levels and are metabolically inert in mice on a high-fat diet. In contrast, prebiotic oligosaccharides (OFS) prevent body weight gain but not glucose intolerance. Alterations in sweet and short-chain fatty acid receptors (FFAR) (studied in WT and α-gust^-/- mice) that regulate gut hormone levels are not mandatory for the positive effects of OFS. Enhanced uptake of SCFAs may favor interaction with FFAR2/3 on adipose tissue to induce weight loss.

Oligofructose as an adjunct in treatment of diabetes in NOD mice

In type 1 diabetes, restoration of normoglycemia can be achieved if the autoimmune attack on beta cells ceases and insulin requirement is met by the residual beta cells. We hypothesize that an adjunctive therapy that reduces insulin demand by increasing insulin sensitivity will improve the efficacy of an immunotherapy in reversing diabetes. We tested the gut microbiota-modulating prebiotic, oligofructose (OFS), as the adjunctive therapy. We treated non-obese diabetic mice with an immunotherapy, monoclonal anti-CD3 antibody (aCD3), with or without concurrent dietary supplement of OFS. After 8 weeks of OFS supplement, the group that received both aCD3 and OFS (aCD3 + OFS) had a higher diabetes remission rate than the group that received aCD3 alone. The aCD3 + OFS group had higher insulin sensitivity accompanied by reduced lymphocytic infiltrate into the pancreatic islets, higher beta-cell proliferation rate, higher pancreatic insulin content, and secreted more insulin in response to glucose. The addition of OFS also caused a change in gut microbiota, with a higher level of Bifidobacterium and lower Clostridium leptum. Hence, our results suggest that OFS can potentially be an effective therapeutic adjunct in the treatment of type 1 diabetes by improving insulin sensitivity and beta-cell function, leading to improved glycemic control.

Inulin oligofructose attenuates metabolic syndrome in high-carbohydrate, high-fat diet-fed rats

Prebiotics alter bacterial content in the colon, and therefore could be useful for obesity management. We investigated the changes following addition of inulin oligofructose (IO) in the food of rats fed either a corn starch (C) diet or a high-carbohydrate, high-fat (H) diet as a model of diet-induced metabolic syndrome. IO did not affect food intake, but reduced body weight gain by 5·3 and 12·3 % in corn starch+inulin oligofructose (CIO) and high-carbohydrate, high-fat with inulin oligofructose (HIO) rats, respectively. IO reduced plasma concentrations of free fatty acids by 26·2 % and TAG by 75·8 % in HIO rats. IO increased faecal output by 93·2 %, faecal lipid excretion by 37·9 % and weight of caecum by 23·4 % and colon by 41·5 % in HIO rats. IO improved ileal morphology by reducing inflammation and improving the density of crypt cells in HIO rats. IO attenuated H diet-induced increases in abdominal fat pads (C 275 (sem 19), CIO 264 (sem 40), H 688 (sem 55), HIO 419 (sem 32) mg/mm tibial length), fasting blood glucose concentrations (C 4·5 (sem 0·1), CIO 4·2 (sem 0·1), H 5·2 (sem 0·1), HIO 4·3 (sem 0·1) mmol/l), systolic blood pressure (C 124 (sem 2), CIO 118 (sem 2), H 152 (sem 2), HIO 123 (sem 3) mmHg), left ventricular diastolic stiffness (C 22·9 (sem 0·6), CIO 22·9 (sem 0·5), H 27·8 (sem 0·5), HIO 22·6 (sem 1·2)) and plasma alanine transaminase (C 29·6 (sem 2·8), CIO 32·1 (sem 3·0), H 43·9 (sem 2·6), HIO 33·6 (sem 2·0) U/l). IO attenuated H-induced increases in inflammatory cell infiltration in the heart and liver, lipid droplets in the liver and plasma lipids as well as impaired glucose and insulin tolerance. These results suggest that increasing soluble fibre intake with IO improves signs of the metabolic syndrome by decreasing gastrointestinal carbohydrate and lipid uptake.

Effect of prebiotic intake on gut microbiota, intestinal permeability and glycemic control in children with type 1 diabetes: study protocol for a randomized controlled trial

BACKGROUND

The gut microbiome is increasingly recognized as a contributor to disease states. Patients with type 1 diabetes (DM1) have distinct gut microbiota in comparison to non-diabetic individuals, and it has been linked to changes in intestinal permeability, inflammation and insulin resistance. Prebiotics are non-digestible carbohydrates that alter gut microbiota and could potentially improve glycemic control in children with DM1. This pilot study aims to determine the feasibility of a 12-week dietary intervention with prebiotics in children with DM1.

METHODS/DESIGN

This pilot study is a single-centre, randomized, double-blind, placebo-controlled trial in children aged 8 to 17 years with DM1 for at least one year. Participants will be randomized to receive either placebo (maltodextrin 3.3 g orally/day) or prebiotics (oligofructose-enriched inulin 8 g orally/day; Synergy1, Beneo, Mannheim, Germany). Measures to be assessed at baseline, 3 months and 6 months include: anthropometric measures, insulin doses/regimens, frequency of diabetic ketoacidosis, frequency of severe hypoglycemia, average number of episodes of hypoglycemia per week, serum C-peptide, HbA1c, serum inflammatory markers (IL-6, IFN-gamma, TNF-alpha, and IL-10), GLP-1 and GLP-2, intestinal permeability using urine assessment after ingestion of lactulose, mannitol and 3-O-methylglucose, and stool sample collection for gut microbiota profiling.

DISCUSSION

This is a novel pilot study designed to test feasibility for a fully powered study. We hypothesize that consumption of prebiotics will alter gut microbiota and intestinal permeability, leading to improved glycemic control. Prebiotics are a potentially novel, inexpensive, low-risk treatment addition for DM1 that may improve glycemic control by changes in gut microbiota, gut permeability and inflammation.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT02442544 . Registered on 10 March 2015.

Inflammation Meets Metabolic Disease: Gut Feeling Mediated by GLP-1

Chronic diseases, such as obesity and diabetes, cardiovascular, and inflammatory bowel diseases (IBD) share common features in their pathology. Metabolic disorders exhibit strong inflammatory underpinnings and vice versa, inflammation is associated with metabolic alterations. Next to cytokines and cellular stress pathways, such as the unfolded protein response (UPR), alterations in the enteroendocrine system are intersections of various pathologies. Enteroendocrine cells (EEC) have been studied extensively for their ability to regulate gastrointestinal motility, secretion, and insulin release by release of peptide hormones. In particular, the L-cell-derived incretin hormone glucagon-like peptide 1 (GLP-1) has gained enormous attention due to its insulinotropic action and relevance in the treatment of type 2 diabetes (T2D). Yet, accumulating data indicate a critical role for EEC and in particular for GLP-1 in metabolic adaptation and in orchestrating immune responses beyond blood glucose control. EEC sense the lamina propria and luminal environment, including the microbiota via receptors and transporters. Subsequently, mediating signals by secreting hormones and cytokines, EEC can be considered as integrators of metabolic and inflammatory signaling. This review focuses on L cell and GLP-1 functions in the context of metabolic and inflammatory diseases. The effects of incretin-based therapies on metabolism and immune system are discussed and the interrelation and common features of metabolic and immune-mediated disorders are highlighted. Moreover, it presents data on the impact of inflammation, in particular of IBD on EEC and discusses the potential role of the microbiota as link between nutrients, metabolism, immunity, and disease.

Impact of the gut microbiota on inflammation, obesity, and metabolic disease

The human gut harbors more than 100 trillion microbial cells, which have an essential role in human metabolic regulation via their symbiotic interactions with the host. Altered gut microbial ecosystems have been associated with increased metabolic and immune disorders in animals and humans. Molecular interactions linking the gut microbiota with host energy metabolism, lipid accumulation, and immunity have also been identified. However, the exact mechanisms that link specific variations in the composition of the gut microbiota with the development of obesity and metabolic diseases in humans remain obscure owing to the complex etiology of these pathologies. In this review, we discuss current knowledge about the mechanistic interactions between the gut microbiota, host energy metabolism, and the host immune system in the context of obesity and metabolic disease, with a focus on the importance of the axis that links gut microbes and host metabolic inflammation. Finally, we discuss therapeutic approaches aimed at reshaping the gut microbial ecosystem to regulate obesity and related pathologies, as well as the challenges that remain in this area.

Probiotics and Prebiotics: Present Status and Future Perspectives on Metabolic Disorders

Metabolic disorders, including type 2 diabetes (T2DM) and cardiovascular disease (CVD), present an increasing public health concern and can significantly undermine an individual's quality of life. The relative risk of CVD, the primary cause of death in T2DM patients, is two to four times higher in people with T2DM compared with those who are non-diabetic. The prevalence of metabolic disorders has been associated with dynamic changes in dietary macronutrient intake and lifestyle changes over recent decades. Recently, the scientific community has considered alteration in gut microbiota composition to constitute one of the most probable factors in the development of metabolic disorders. The altered gut microbiota composition is strongly conducive to increased adiposity, β-cell dysfunction, metabolic endotoxemia, systemic inflammation, and oxidative stress. Probiotics and prebiotics can ameliorate T2DM and CVD through improvement of gut microbiota, which in turn leads to insulin-signaling stimulation and cholesterol-lowering effects. We analyze the currently available data to ascertain further potential benefits and limitations of probiotics and prebiotics in the treatment of metabolic disorders, including T2DM, CVD, and other disease (obesity). The current paper explores the relevant contemporary scientific literature to assist in the derivation of a general perspective of this broad area.

Gut feedback mechanisms and food intake: a physiological approach to slow carbohydrate bioavailability

Glycemic carbohydrates in foods are an important macronutrient providing the biological fuel of glucose for a variety of physiological processes. A classification of glycemic carbohydrates into rapidly digestible carbohydrate (RDC) and slowly digestible carbohydrate (SDC) has been used to specify their nutritional quality related to glucose homeostasis that is essential to normal functioning of the brain and critical to life. Although there have been many studies and reviews on slowly digestible starch (SDS) and SDC, the mechanisms of their slow digestion and absorption were mostly investigated from the material side without considering the physiological processes of their in vivo digestion, absorption, and most importantly interactions with other food components and the gastrointestinal tract. In this article, the physiological processes modulating the bioavailability of carbohydrates, specifically the rate and extent of their digestion and absorption as well as the related locations, in a whole food context, will be discussed by focusing on the activities of the gastrointestinal tract including glycolytic enzymes and glucose release, sugar sensing, gut hormones, and neurohormonal negative feedback mechanisms. It is hoped that a deep understanding of these physiological processes will facilitate the development of innovative dietary approaches to achieve desired carbohydrate or glucose bioavailability for improved health.

Dietary fibers influence the intestinal SCFAs and plasma metabolites profiling in growing pigs

Dietary fibers (DFs), widely used as food additives to replace fat, can benefit metabolic disorders.