High β-Glucan Barley Supplementation Improves Glucose Tolerance by Increasing GLP-1 Secretion in Diet-Induced Obesity Mice

Edible bird's nest regulates glucose and lipid metabolic disorders via the gut-liver axis in obese mice

Edible bird's nest (EBN) is a traditional food known for its nourishing and functional properties and is found to be involved in anti-oxidation, anti-aging, and anti-influenza mechanisms, immune regulation, and improving cardiovascular diseases, among others. However, the potential of EBN to improve glycolipid metabolism disorders in high-fat-diet induced obesity and the underlying mechanisms remain unexplored. We examined the effects of EBN on glycolipid metabolism in obese mice fed a high-fat diet. Male C57BL/6J mice were fed a high-fat diet for 8 weeks to establish an obesity model. The obese mice were selected and divided into six groups: two model control groups (normal and high-fat diets) and four intervention groups [Neu5Ac and low-, medium-, and high-dose EBN], with 12 mice in each group. After 10 weeks of continuous gavage intervention, only mice in the high-dose EBN intervention group had lower body weight and total fat content, especially visceral fat. Meanwhile, intervention with three doses of EBN reduced serum FBG, TC, LDL, Ox-LDL, IL-1β, IL-6, and TNF-α levels and increased serum HDL levels and energy expenditure. Using the high dosage as a paradigm, EBN intervention increased the sialic acid content in LDL, decreased TMAO in the liver, and increased GLP-1 levels in sera. EBN increased the colonic abundances of Akkermansia, Lactobacillus, and Desulfovibrio and reduced those of Lysinibacillus and Bacillus. The changes in the microbial community contribute to increasing colonic bile acids, reducing lipopolysaccharide synthesis to protect the intestinal barrier, and lowering inflammation levels. Changes were also observed in colonic transcripts and metabolites and liver gene transcripts and metabolites, which were mainly enriched in pathways of glycolipid metabolism, immune function amelioration, inflammatory signal mitigation, circadian rhythm, bile acid metabolism and insulin resistance. Therefore, EBN may enhance the gut microbiota and intestinal immunity, relieve chronic inflammation levels in serum, improve antioxidant capacity and circadian rhythm in the liver, promote bile acid metabolism, and decrease lipid absorption and lipid synthesis via the gut-liver axis. Consequently, this may reduce blood lipid and fat accumulation as well as improve islet function and reduce blood glucose levels.

Highly Soluble β-Glucan Fiber Modulates Mechanisms of Blood Glucose Regulation and Intestinal Permeability

β-glucans found in cereal grains have been previously demonstrated to improve blood glucose control; however, current understanding points to their high viscosity as the primary mechanism of action. In this work, we present a novel, highly soluble, low-viscosity β-glucan fiber (HS-BG fiber) and a preclinical dataset that demonstrates its impact on two mechanisms related to the prevention of hyperglycemia. Our results show that HS-BG inhibits the activity of two key proteins involved in glucose metabolism, the α-glucosidase enzyme and the SGLT1 transporter, thereby having the potential to slow starch digestion and subsequent glucose uptake. Furthermore, we demonstrate in a multi-donor fecal fermentation model that HS-BG is metabolized by several different members of the gut microbiome, producing high amounts of short-chain fatty acids (SCFAs), known agonists of GPR43 receptors in the gut related to GLP-1 secretion. The production of SCFAs was verified in the translational gut model, SHIME®. Moreover, HS-BG fiber fermentation produces compounds that restored permeability in disrupted epithelial cells, decreased inflammatory chemokines (CXCL10, MCP-1, and IL-8), and increased anti-inflammatory marker (IL-10), which could improve insulin resistance. Together, these data suggest that the novel HS-BG fiber is a promising new functional ingredient that can be used to modulate postprandial glycemic responses while the high solubility and low viscosity enable easy formulation in both beverage and solid food matrices.

Gut mycobiome in metabolic diseases: Mechanisms and clinical implication

Obesity, type 2 diabetes mellitus (T2DM) and non-alcoholic fatty liver disease (NAFLD) are three common metabolic diseases with high prevalence worldwide. Emerging evidence suggests that gut dysbiosis may influence the development of metabolic diseases, in which gut fungal microbiome (mycobiome) is actively involved. In this review, we summarize the studies exploring the composition changes of gut mycobiome in metabolic diseases and mechanisms by which fungi affect the development of metabolic diseases. The current mycobiome-based therapies, including probiotic fungi, fungal products, anti-fungal agents and fecal microbiota transplantation (FMT), and their implication in treating metabolic diseases are discussed. We highlight the unique role of gut mycobiome in metabolic diseases, providing perspectives for future research on gut mycobiome in metabolic diseases.

Dietary fiber and polyphenols from whole grains: effects on the gut and health improvements

Cereals are the main source of energy in the human diet. Compared to refined grains, whole grains retain more beneficial components, including dietary fiber, polyphenols, proteins, vitamins, and minerals. Dietary fiber and bound polyphenols (biounavailable) in cereals are important active substances that can be metabolized by the gut microorganisms and affect the intestinal environment. There is a close relationship between the gut microbiota structures and various disease phenotypes, although the consistency of this link is affected by many factors, and the specific mechanisms are still unclear. Remodeling unfavorable microbiota is widely recognized as an important way to target the gut and improve diseases. This paper mainly reviews the interaction between the gut microbiota and cereal-derived dietary fiber and polyphenols, and also summarizes the changes to the gut microbiota and possible molecular mechanisms of related glycolipid metabolism. The exploration of single active ingredients in cereals and their synergistic health mechanisms will contribute to a better understanding of the health benefits of whole grains. It will further help promote healthier whole grain foods by cultivating new varieties with more potential and optimizing processing methods.

Structural characteristics and biological activities of polysaccharides from barley: a review

Barley (Hordeum vulgare L.) is rich in starch and non-starch polysaccharides (NSPs), especially β-glucan and arabinoxylan. Genotypes and isolation methods may affect their structural characteristics, properties and biological activities. The structure-activity relationships of NSPs in barley have not been paid much attention. This review summarizes the extraction methods, structural characteristics and physicochemical properties of barley polysaccharides. Moreover, the roles of barley β-glucan and arabinoxylan in the immune system, glucose metabolism, regulation of lipid metabolism and absorption of mineral elements are summarized. This review may help in the development of functional products in barley.

Doxorubicin-loaded zymosan nanoparticles: Synergistic cytotoxicity and modulation of apoptosis and Wnt/β-catenin signaling pathway in C26 colorectal cancer cells

Zymosan is a β-glucan isolated from Saccharomyces cerevisiae that could be employed for drug delivery. We synthesized zymosan nanoparticles and measured their structural and morphological properties using XRD, UV-Vis spectroscopy, TEM and AFM. The loading of doxorubicin (DOX) onto the nanoparticles was confirmed by FT-IR, and the DOX release was shown to be pH-dependent. The effect of these agents on C26 cell viability was evaluated by MTT tests and the expression of genes connected with the Wnt/β-catenin pathway and apoptosis were analyzed by RT-qPCR and Western blotting. Treatments were able to suppress the proliferation of C26 cells, and the zymosan nanocarriers loaded with DOX enhanced the anti-proliferative effect of DOX in a synergistic manner. Zymosan nanoparticles were able to suppress the expression of cyclin D1, VEGF, ZEB1, and Twist mRNAs. Treatment groups upregulated the expression of caspase-8, while reducing the Bax/Bcl-2 ratio, thus promoting apoptosis. In conclusion, zymosan nanoparticles as DOX nanocarriers could provide a more targeted drug delivery through pH-responsiveness, and showed synergistic cytotoxicity by modifying Wnt/β-catenin signaling and apoptosis.

Microbiota modulation by dietary oat beta-glucan prevents steatotic liver disease progression

Background & Aims

Changes in gut microbiota in metabolic dysfunction-associated steatotic liver disease (MASLD) are important drivers of disease progression towards fibrosis. Therefore, reversing microbial alterations could ameliorate MASLD progression. Oat beta-glucan, a non-digestible polysaccharide, has shown promising therapeutic effects on hyperlipidemia associated with MASLD, but its impact on gut microbiota and most importantly MASLD-related fibrosis remains unknown.

Methods

We performed detailed metabolic phenotyping, including assessments of body composition, glucose tolerance, and lipid metabolism, as well as comprehensive characterization of the gut-liver axis in a western-style diet (WSD)-induced model of MASLD and assessed the effect of a beta-glucan intervention on early and advanced liver disease. Gut microbiota were modulated using broad-spectrum antibiotic treatment.

Results

Oat beta-glucan supplementation did not affect WSD-induced body weight gain or glucose intolerance and the metabolic phenotype remained largely unaffected. Interestingly, oat beta-glucan dampened MASLD-related inflammation, which was associated with significantly reduced monocyte-derived macrophage infiltration and fibroinflammatory gene expression, as well as strongly reduced fibrosis development. Mechanistically, this protective effect was not mediated by changes in bile acid composition or signaling, but was dependent on gut microbiota and was lost upon broad-spectrum antibiotic treatment. Specifically, oat beta-glucan partially reversed unfavorable changes in gut microbiota, resulting in an expansion of protective taxa, including Ruminococcus, and Lactobacillus followed by reduced translocation of Toll-like receptor ligands.

Conclusions

Our findings identify oat beta-glucan as a highly efficacious food supplement that dampens inflammation and fibrosis development in diet-induced MASLD. These results, along with its favorable dietary profile, suggest that it may be a cost-effective and well-tolerated approach to preventing MASLD progression and should be assessed in clinical studies.

Impact and Implications

Herein, we investigated the effect of oat beta-glucan on the gut-liver axis and fibrosis development in a mouse model of metabolic dysfunction-associated steatotic liver disease (MASLD). Beta-glucan significantly reduced inflammation and fibrosis in the liver, which was associated with favorable shifts in gut microbiota that protected against bacterial translocation and activation of fibroinflammatory pathways. Together, oat beta-glucan may be a cost-effective and well-tolerated approach to prevent MASLD progression and should be assessed in clinical studies.

Arabinoxylan as well as β-glucan in barley promotes GLP-1 secretion by increasing short-chain fatty acids production

Barley is rich in soluble dietary fiber including β-glucan and arabinoxylan. Barley β-glucan is fermented by gut bacteria and, thereby contributes to an effect on intestinal bacterial composition and short-chain fatty acids (SCFAs). It also increases GLP-1 secretion via SCFAs receptor. However, few studies have focused on barley arabinoxylan. Therefore, we have investigated the effects of arabinoxylan from barley on intestinal fermentability and GLP-1 secretion. C57BL/6J mice were fed a high-fat diet containing arabinoxylan-dominant barley flour without β-glucan (bgl) and high β-glucan-containing barley flour (BF) for 12 weeks. We conducted oral glucose tolerance test (OGTT) to measure insulin and GLP-1 concentrations. The concentration of SCFAs in the cecum contents was also determined. Furthermore, we measured mRNA expression assay GLP-1 secretion using real-time PCR. The OGTT result showed that GLP-1 concentrations at 60 min were increased in mice fed bgl and BF. Acetic acid and total SCFAs concentrations in the cecum contents were increased in both the barley groups, and butyric acid was increased in the bgl group. Furthermore, the bgl and BF groups had increased Gpr43, a receptor for SCFAs, and NeuroD which is involved in L cell differentiation. These results show arabinoxylan as well as β-glucan is involved in the SCFAs-mediated increase in GLP-1 secretion upon barley consumption.

Diet-Related Changes of Short-Chain Fatty Acids in Blood and Feces in Obesity and Metabolic Syndrome

Obesity-related illnesses are one of the leading causes of death worldwide. Metabolic syndrome has been associated with numerous health issues. Short-chain fatty acids (SCFAs) have been shown to have multiple effects throughout the body, both directly as well as through specific G protein-coupled receptors. The main SCFAs produced by the gut microbiota are acetate, propionate, and butyrate, which are absorbed in varying degrees from the large intestine, with some acting mainly locally and others systemically. Diet has the potential to influence the gut microbial composition, as well as the type and amount of SCFAs produced. High fiber-containing foods and supplements increase the production of SCFAs and SCFA-producing bacteria in the gut and have been shown to have bodyweight-lowering effects. Dietary supplements, which increase SCFA production, could open the way for novel approaches to weight loss interventions. The aim of this review is to analyze the variations of fecal and blood SCFAs in obesity and metabolic syndrome through a systematic search and analysis of existing literature.

Consumption of barley flour increases gut fermentation and improves glucose intolerance via the short-chain fatty acid receptor GPR43 in obese male mice

The ameliorative effect of barley intake on glucose intolerance is attenuated when Gpr43 is deficient.

The Role of Short-Chain Fatty Acids of Gut Microbiota Origin in Hypertension

Hypertension is a significant risk factor for cardiovascular and cerebrovascular diseases, and its development involves multiple mechanisms. Gut microbiota has been reported to be closely linked to hypertension. Short-chain fatty acids (SCFAs)-the metabolites of gut microbiota-participate in hypertension development through various pathways, including specific receptors, immune system, autonomic nervous system, metabolic regulation and gene transcription. This article reviews the possible mechanisms of SCFAs in regulating blood pressure and the prospects of SCFAs as a target to prevent and treat hypertension.