Arabinoxylan combined with different glucans improve lipid metabolism disorder by regulating bile acid and gut microbiota in mice fed with high-fat diet

Lipid metabolism regulation by dietary polysaccharides with different structural properties

Lipid metabolism plays an important role in energy homeostasis maintenance in response to stress. Nowadays, hyperlipidemia-related chronic diseases such as obesity, diabetes, atherosclerosis, and fatty liver pose significant health challenges. Dietary polysaccharides (DPs) have gained attention for their effective lipid-lowering properties. This review examines the multifaceted mechanisms that DPs employ to lower lipid levels in subjects with hyperlipidemia. DPs could directly inhibit lipid intake and absorption, promote lipid excretion, and regulate key enzymes involved in lipid metabolism pathways, including triglyceride and cholesterol anabolism and catabolism, fatty acid oxidation, and bile acid synthesis. Additionally, DPs indirectly improve lipid homeostasis by modulating gut microbiota composition and alleviating oxidative stress. Moreover, the lipid-lowering mechanisms of particular structural DPs (including β-glucan, pectin, glucomannan, inulin, arabinoxylan, and fucoidan) are summarized. The relationship between the structure and lipid-lowering activity of DPs is also discussed based on current researches. Finally, potential breakthroughs and future directions in the development of DPs in lipid-lowering activity are discussed. The paper could provide a reference for further exploring the mechanism of DPs for lipid regulations and utilizing DPs as lipid-lowering dietary ingredients.

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.

Caffeic acid combined with arabinoxylan or β-glucan attenuates diet-induced obesity in mice via modulation of gut microbiota and metabolites

Polyphenols and dietary fibers in whole grains are important bioactive compounds to reduce risks for obesity. However, whether the combination of the two components exhibits a stronger anti-obesity effect remains unclear. Caffeic acid is a major phenolic acid in cereals, and arabinoxylan and β-glucan are biological macromolecules with numerous health benefits. Here, we investigated the effect of caffeic acid combined with arabinoxylan or β-glucan on glucose and lipid metabolism, gut microbiota, and metabolites in mice fed a high-fat diet (HFD). Caffeic acid combined with arabinoxylan or β-glucan significantly reduced the body weight, blood glucose, and serum free fatty acid concentrations. Caffeic acid combined with β-glucan effectively decreased serum total cholesterol levels and hepatic lipid accumulation, modulated oxidative and inflammatory stress, and improved gut barrier function. Compared with arabinoxylan, β-glucan, and caffeic acid alone, caffeic acid combined with arabinoxylan or β-glucan exhibited a better capacity to modulate gut microbiota, including increased microbial diversity, reduced Firmicutes/Bacteroidetes ratio, and increased abundance of beneficial bacteria such as Bifidobacterium. Furthermore, caffeic acid combined with β-glucan reversed HFD-induced changes in microbiota-derived metabolites involving tryptophan, purine, and bile acid metabolism. Thus, caffeic acid and β-glucan had a synergistic anti-obesity effect by regulating specific gut microbiota and metabolites.

The Influence of Polysaccharides on Lipid Metabolism: Insights from Gut Microbiota

SCOPE

Polysaccharides are complex molecules of more than ten monosaccharide residues interconnected through glycosidic linkages formed via condensation reactions. Polysaccharides are widely distributed in various food resources and have gained considerable attention due to their diverse biological activities. This review presented a critical analysis of the existing research literature on anti-obesity polysaccharides and investigates the complex interplay between their lipid-lowering activity and the gut microbiota, aiming to provide a comprehensive overview of the lipid-lowering properties of polysaccharides and the underlying mechanisms of action.

METHODS AND RESULTS

In this review, the study summarized the roles of polysaccharides in improving lipid metabolism via gut microbiota, including the remodeling of the intestinal barrier, reduction of inflammation, inhibition of pathogenic bacteria, reduction of trimethylamine N-oxide (TMAO) production, and regulation of the metabolism of short-chain fatty acids (SCFAs) and bile acids (BAs).

CONCLUSION

These mechanisms collectively contributed to the beneficial effects of polysaccharides on lipid metabolism and overall metabolic health. Furthermore, polysaccharide-based nanocarriers combined with gut microbiota have broad prospects for developing targeted and personalized therapies for hyperlipidemia and obesity.

Polysaccharides affect the utilization of β-carotene through gut microbiota investigated by in vitro and in vivo experiments

This study aimed to evaluate the effects of six polysaccharides on the utilization of β-carotene from the perspective of gut microbiota using both in vitro simulated anaerobic fermentation systems and in vivo animal experiments. In the in vitro experiments, the addition of arabinoxylan, arabinogalactan, mannan, inulin, chitosan, and glucan led to a 31.07-79.12% decrease in β-carotene retention and a significant increase in retinol content (0.21-0.99-fold) compared to β-carotene alone. Among them, the addition of chitosan produced the highest level of retinol. In the in vivo experiments, mice treated with the six polysaccharides exhibited a significant increase (2.51-5.78-fold) in serum β-carotene content compared to the group treated with β-carotene alone. The accumulation of retinoids in the serum, liver, and small intestine increased by 13.56-21.61%, 12.64-56.27%, and 7.9%-71.69%, respectively. The expression of β-carotene cleavage enzymes was increased in the liver. Genetic analysis of small intestinal tissue revealed no significant enhancement in the expression of genes related to β-carotene metabolism. In the gut microbiota environment, the addition of polysaccharides generated more SCFAs and altered the structure and composition of the gut microbiota. The correlation analysis revealed a strong association between gut microbes (Ruminococcaceae and Odoribacteraceae) and β-carotene metabolism and absorption. Collectively, our findings suggest that the addition of polysaccharides may improve β-carotene utilization by modulating the gut microbiota.

Natural polysaccharides protect against diet-induced obesity by improving lipid metabolism and regulating the immune system

Unhealthy dietary patterns-induced obesity and obesity-related complications pose a great threat to human health all over the world. Accumulating evidence suggests that the pathophysiology of obesity and obesity-associated metabolic disorders is closely associated with dysregulation of lipid and energy metabolism, and metabolic inflammation. In this review, three potential anti-obesity mechanisms of natural polysaccharides are introduced. Firstly, natural polysaccharides protect against diet-induced obesity directly by improving lipid and cholesterol metabolism. Since the immunity also affects lipid and energy metabolism, natural polysaccharides improve lipid and energy metabolism by regulating host immunity. Moreover, diet-induced mitochondrial dysfunction, prolonged endoplasmic reticulum stress, defective autophagy and microbial dysbiosis can disrupt lipid and/or energy metabolism in a direct and/or inflammation-induced manner. Therefore, natural polysaccharides also improve lipid and energy metabolism and suppress inflammation by alleviating mitochondrial dysfunction and endoplasmic reticulum stress, promoting autophagy and regulating gut microbiota composition. Specifically, this review comprehensively summarizes underlying anti-obesity mechanisms of natural polysaccharides and provides a theoretical basis for the development of functional foods. For the first time, this review elucidates anti-obesity mechanisms of natural polysaccharides from the perspectives of their hypolipidemic, energy-regulating and immune-regulating mechanisms.

Insights into the fermentation patterns of wheat bran cell wall polysaccharides using an in-vitro batch fermentation model

We aimed to study the structural characteristics and fermentation properties of wheat bran cell wall polysaccharides (CWPs). Sequential extractions of CWPs from wheat bran produced the water-extractable (WE) and alkali-extractable (AE) fractions. The extracted fractions were structurally characterized based on their molecular weight (Mw) and monosaccharide composition. Our findings revealed that the Mw and the ratio of arabinose to xylose (A/X) of AE were higher than those of WE and that the two fractions were mainly composed of arabinoxylans (AXs). The substrates were then subjected to in vitro fermentation by human fecal microbiota. As fermentation progressed, the total carbohydrates of WE were significantly more utilized than that of AE (p < 0.05). The AXs in WE were utilized at a higher rate than those in AE. The relative abundance of Prevotella_9, which can efficiently utilize AXs, was significantly increased in AE. The presence of AXs in AE shifted the balance away from protein fermentation and caused a delay in protein fermentation. Our study demonstrated that wheat bran CWPs can modulate the gut microbiota in a structure-dependent manner. However, future studies should further characterize the fine structure of wheat CWPs to clarify their detailed relationship with gut microbiota and metabolites.

Excessive dietary soluble arabinoxylan impairs the intestinal physical and immunological barriers via activating MAPK/NF-κB signaling pathway in rainbow trout (Oncorhynchus mykiss)

Arabinoxylan (AX) has been deemed as an antinutritional factor, but limited information has addressed the effects of dietary AX on intestinal health of fish. The present study investigated the effects of dietary AX on intestinal mucosal physical and immunological barriers of rainbow trout (Oncorhynchus mykiss). Five isoproteic and isolipidic experimental diets (AXE, AX0, AX2.5, AX5 and AX10) were formulated to contain 0.03% arabinoxylanase as well as 0%, 2.5%, 5% and 10% AX, respectively. Each diet was randomly distributed to triplicate groups of 35 juvenile (average weight 3.14 ± 0.02 g) per tank in a rearing system maintained at 17 ± 1 °C for 9 weeks. Dietary AX supplementation regardless of inclusion levels significantly (P < 0.05) depressed the growth performance and feed utilization. The plasma endothelin-1 and d-lactic acid contents as well as diamino oxidase activity were significantly higher in fish fed diet AX10 compared to fish fed diet AX0. Dietary inclusion of 5-10% AX resulted in decreased intestinal villus height, goblet cell number and desmosome density, increased crypt depth, short and irregular microvilli, widened intercellular space; down-regulated the mRNA levels of occludin in hindgut, claudin3 and ZO-1 in foregut and midgut, but up-regulated the mRNA levels of claudin12 and claudin15 in midgut as well as claudin23 in foregut, midgut and hindgut. Furthermore, dietary 5-10% AX supplementation decreased the midgut and hindgut complement 3, complement 4 and sIgT contents as well as the midgut IgM and hindgut IL-10 contents. Conversely, the hindgut TNF-α and IL-6 contents increased with the rising dietary AX level. RT-qPCR demonstrated that the pro-inflammatory cytokines (IL-1β, IL-6, IL-8, IL-12β, IFN-γ, and TNF-α) and pIgR mRNA levels in midgut and hindgut were up-regulated by dietary AX inclusion of 5-10% AX. Meanwhile, the mRNA levels of p38 MAPK, IκBα, and NF-κB p65 in midgut and hindgut raised gradually with the increasing dietary AX content. The Western blot results showed that the protein expression levels of p38 MAPK and NF-κB generally increased with the rising dietary AX content. Dietary treatment with 0.03% arabinoxylanase did not affect the growth performance and intestinal health of rainbow trout (P > 0.05). In conclusion, excessive dietary AX inclusion (5-10%) increased the intestinal permeability and induced the intestinal inflammatory response via activating MAPK/NF-κB signaling pathway, and ultimately damaged the intestinal barrier function of rainbow trout.

Function of Akkermansia muciniphila in type 2 diabetes and related diseases

The prevalence of type 2 diabetes (T2D) is increasing worldwide, with many patients developing long-term complications that affect their cardiovascular, urinary, alimentary, and other systems. A growing body of literature has reported the crucial role of gut microbiota in metabolic diseases, one of which, Akkermansia muciniphila, is considered the "next-generation probiotic" for alleviating metabolic disorders and the inflammatory response. Although extensive research has been conducted on A. muciniphila, none has summarized its regulation in T2D. Hence, this review provides an overview of the effects and multifaceted mechanisms of A. muciniphila on T2D and related diseases, including improving metabolism, alleviating inflammation, enhancing intestinal barrier function, and maintaining microbiota homeostasis. Furthermore, this review summarizes dietary strategies for increasing intestinal A. muciniphila abundance and effective gastrointestinal delivery.

Current progress in the hypoglycemic mechanisms of natural polysaccharides

Unhealthy dietary pattern-induced type 2 diabetes mellitus poses a great threat to human health all over the world. Accumulating evidence has revealed that the pathophysiology of type 2 diabetes mellitus is closely associated with the dysregulation of glucose metabolism and energy metabolism, serious oxidative stress, prolonged endoplasmic reticulum stress, metabolic inflammation and intestinal microbial dysbiosis. Most important of all, insulin resistance and insulin deficiency are two key factors inducing type 2 diabetes mellitus. Nowadays, natural polysaccharides have gained increasing attention owing to their numerous health-promoting functions, such as hypoglycemic, energy-regulating, antioxidant, anti-inflammatory and prebiotic activities. Therefore, natural polysaccharides have been used to alleviate diet-induced type 2 diabetes mellitus. Specifically, this review comprehensively summarizes the underlying hypoglycemic mechanisms of natural polysaccharides and provides a theoretical basis for the development of functional foods. For the first time, this review elucidates hypoglycemic mechanisms of natural polysaccharides from the perspectives of their regulatory effects on glucose metabolism, insulin resistance and mitochondrial dysfunction.

Metabolomic Characteristics of Cecum Contents in High-Fat-Diet-Induced Obese Mice Intervened with Different Fibers

The aim of this study was to demonstrate the effect of single or mixed fibers (arabinoxylan, β-glucan, xyloglucan, and inulin) on the metabolome of cecum content in mice with obesity caused by a high-fat diet. Twenty-eight six-week-old male mice were divided randomly into seven groups (n = 4/group), including a normal-diet group (CON), a high-fat-diet group (HFD), and groups with the same high-fat diet but supplemented with arabinoxylan (HFAX), arabinoxylan + β-glucan (HFAβ), arabinoxylan + xyloglucan (HFAG), xyloglucan (HFXG), and xyloglucan + inulin (HFXI). A total of 66 molecules were identified and quantified in cecum content by proton nuclear magnetic resonance (1 H-NMR). The metabolomic profiles combined with statistical analysis revealed compounds distinguishing the control group from those supplemented with fibers. In detail, a high-fat diet could significantly elevate the concentrations of acetone and methionine (p < 0.05) while decreasing the levels of methanol, arabinose, acetate, and 3-hydroxyphenylacetate (p < 0.05) in the cecum contents of mice. Compared to HFD, the supplementation caused higher levels of fumarate and hypoxanthine (p < 0.05) and lower levels of phenylacetate, acetate, fucose, formate, proline, betaine, and trimethylamine N-oxide (TMAO) (p < 0.05). An enrichment analysis highlighted that the pathways mainly altered were amino sugar metabolism, aspartate metabolism, and arginine and proline metabolism. In conclusion, non-starch polysaccharide (NSP) supplementation could change the metabolomic profiles of cecum contents in obese mice as a result of a high-fat diet. Moreover, mixed NSPs exhibited more beneficial effects than singular form on gut metabolism.

Interaction between dietary fiber and bifidobacteria in promoting intestinal health

Bifidobacteria are considered as probiotics due to their role in promoting intestinal health, including regulating intestinal flora, controlling glycolipid metabolism, anti-colitis effects. Dietary fiber is considered as prebiotic favoring gut health. It also can be used as carbon source to support the growth and colonization of probiotics like bifidobacteria. However, because of genetic diversity, different bifidobacterial species differ in their ability to utilize dietary fiber. Meanwhile, dietary fiber with different structural properties has different effects on the bifidobacteria proliferation. The interaction between dietary fiber and bifidobacteria will consequently lead to a synergistic or antagonistic function in promoting intestinal health, therefore affecting the application of combined use of dietary fiber and bifidobacteria. In this case, we summarize the biological function of bifidobacteria, and their interaction with different dietary fiber in promoting gut health, and finally provide several strategies about their combined use.

Effects of sulfated polysaccharides from Laminaria japonica on regularating the gut microbiotan and alleviating intestinal inflammation in obese mice

Due to their known health-enhancing properties, Laminaria japonica polysaccharides (LJP) may alleviate obesity via unknown mechanisms. This study aimed to investigate beneficial LJP effects and mechanism(s) of action using an animal obesity model (ICR mice fed a high-fat diet). First, LJP were confirmed to consist of sulfated polysaccharides via infrared spectroscopy. Next, LJP administration to mice was found to induce weight loss, reduce liver fat accumulation, and support healthy obesity-related blood serum indicator levels. Notably, LJP treatment significantly reduced TC and LDL levels and significantly increased HDL, LPL, UCP-2, and PPAR-α levels. Furthermore, examinations of tissues of LJP-treated mice revealed significantly reduced intestinal tissue inflammation as compared to corresponding results obtained for untreated obese controls. Additionally, LJP treatment relieved colonic shortening and reduced colonic levels of inflammatory factors TNF-α and IL-6. Further exploration of LJP treatment effects on mouse gut microbiota conducted via fecal 16S rRNA gene sequence-based gut microbiome profiling analysis revealed that LJP treatment increased the Bacteroidetes/Firmicutes ratio and increased gut abundances of probiotics Bacteroides acidifaciens, s_Lactobacillus intestinalis, and s_Lactobacillus murinus. In conclusion, these results collectively suggest that LJP use as a food supplement may alleviate obesity and related gut microbiota dysbiosis and intestinal inflammatory disorders.

Therapeutic potential of non-starch polysaccharides on type 2 diabetes: from hypoglycemic mechanism to clinical trials

Non-starch polysaccharides (NSPs) have been reported to exert therapeutic potential on managing type 2 diabetes mellitus (T2DM). Various mechanisms have been proposed; however, several studies have not considered the correlations between the anti-T2DM activity of NSPs and their molecular structure. Moreover, the current understanding of the role of NSPs in T2DM treatment is mainly based on in vitro and in vivo data, and more human clinical trials are required to verify the actual efficacy in treating T2DM. The related anti-T2DM mechanisms of NSPs, including regulating insulin action, promoting glucose metabolism and regulating postprandial blood glucose level, anti-inflammatory and regulating gut microbiota (GM), are reviewed. The structure-function relationships are summarized, and the relationships between NSPs structure and anti-T2DM activity from clinical trials are highlighted. The development of anti-T2DM medication or dietary supplements of NSPs could be promoted with an in-depth understanding of the multiple regulatory effects in the treatment/intervention of T2DM.

Insights on preparation, structure and activities of Gracilaria lemaneiformis polysaccharide

Gracilaria lemaneiformis is a kind of edible economic red algae, which is rich in polysaccharide, phycobiliprotein, pigments, minerals and other nutrients and functional components. Polysaccharide is one of the main active components of Gracilaria lemaneiformis, which has been reported to present various physiological bioactivities, including regulation of glycolipid metabolism, immune, anti-tumor, anti-inflammatory and other biological activities. This paper aims to provide a brief summary of extraction, purification, structural characteristics, and physiological activities of Gracilaria lemaneiformis polysaccharide (GLP). This article is able to provide theoretical basis for the future research and exploitation of GLP, and improve its potential development to promote the healthy and sustainable processing and high value utilization industry of Gracilaria lemaneiformis.