In-depth insight into correlations between gut microbiota and dietary fiber elucidates a dietary causal relationship with host health

Functional Characterization of a Highly Efficient Endoglucanase from Bacillus licheniformis BJ2022 and Its Application in the Preparation of Low-Molecular-Weight Konjac Glucomannan

Endoglucanases may not only act on β-1,4-linkages in β-glucan but also target d-glucose in glucomannan, which can expand their utility in the preparation of prebiotics. In this study, a highly efficient endoglucanase (BlGH5) from Bacillus licheniformis BJ2022 was expressed and characterized. BlGH5 exhibited the highest activity at pH 7.0 and 60 °C. It maintained over 80% activity at pH 4.0-7.0 and 30-60 °C. BlGH5 specifically cleaved β-1,4-glycosidic bonds linked to d-glucose. Site-directed mutagenesis results suggested that Arg91, Asn167, Glu168, Trp206, His228, Tyr230, Ser263, and Trp290 are key residues for its binding and catalytic activity. Moreover, BlGH5 displayed high activity against konjac glucomannan (KGM), indicating that BlGH5 could be used to prepare low-molecular-weight konjac glucomannan (KGM-L). Based on the physicochemical properties of KGM and KGM-L, KGM-L was characterized by reduced molecular weight and viscosity. Fecal fermentation experiments demonstrated that KGM and KGM-L could promote the production of short-chain fatty acids (SCFAs). Still, KGM-L was more conducive to the growth of the gut probiotics. In conclusion, we identified an endoglucanase for the degradation of KGM. Results indicated that KGM-L would have superior prebiotic effects. Thus, our study provides a basis for the future development and application of KGM-L as a prebiotic.

Characterization of a novel type 4 resistant starch from tapioca and its obesity-preventive effects through gut microbiota modulation in high-fat diet-treated mice

The rising pandemic of obesity has received significant attention. Yet, more safe and effective targeted strategies must be used to mitigate its impact on individual health and the global disease burden. While the health benefits of resistant starch (RS) are well-documented, the role of RT-90 (a phosphate-modified tapioca RS containing 90.1 % total dietary fiber) in mitigating obesity remains unknown. Accordingly, the physicochemical characteristics and protective effects of RT-90 on obesity were investigated in high-fat diet (HFD)-fed mice. Physicochemical property examinations showed that RT-90 consisted of small, round starch granules (D90: 20.69 ± 0.4 μm) with a crystalline structure, P-O-C stretching, and high peak melting temperature and enthalpy. Additionally, feeding mice with RT-90 significantly decreased body weight, improved oral glucose tolerance test (OGTT), reduced fatty liver and adipose tissue accumulation, lowered oxidative stress and inflammation by upregulating antioxidant enzymes (SOD, catalase, GPx) and anti-inflammatory cytokines (IL-4, IL-10), and enhanced fecal lipids and bile acid excretion. Notably, RT-90 administration in HFD-fed mice was associated with the inhibition of obesity-associated harmful bacteria ([Eubacterium]_xylanophilum group, Allobaculum, Clostridia_UCG-014, Dubosiella) and promotion of short-chain fatty acids (SCFAs)-producing gut flora, including Bifidobacterium, Lactobacillus, Bacteroides, and Parabacteroides, which suggests a possible mechanism by which RT-90 alters gut microbiota to attenuate obesity. These novel findings first revealed that RT-90 facilitates weight loss through its antioxidant, anti-inflammatory, and microbiota modulation abilities. This provides a promising strategy for managing overweight or obesity and holds potential for applications in developing healthy food products.

Advances in prebiotic carbohydrate-based targeted delivery: Overcoming gastrointestinal challenges for bioactive ingredients

Natural bioactive ingredients face challenges in extensive application owing to low oral bioavailability. This can be improved by overcoming gastrointestinal barriers and facilitating targeted release through delivery strategies. This study provides a comprehensive review of targeted delivery systems using prebiotic carbohydrate matrices, focusing on structures, release mechanisms and applications. The bioactive ingredients can be encapsulated into nanohydrogels, nanoparticles, nanoemulsions, micro/nanocapsules and nanofibres to achieve controlled/targeted delivery to predetermined locations via interactions with pH, mucus, microbiome, enzymes and other factors in the colon. In particular, the prebiotic function of carbohydrates is generated by colonic microbiota degradation and fermentation, producing beneficial postbiotics through multiple metabolic pathways. This study provides certain insights into the in-depth development and application of prebiotic carbohydrate-based targeted delivery systems in the fields of food and health.

Proteomic Analysis of Midgut of Silkworm Reared on Artificial Diet and Mulberry Leaves and Functional Study of Three UGT Genes

There remains a significant gap in production performance and disease resistance between silkworms reared on artificial diets and those reared on mulberry leaves. This study aims to identify key differential proteins through proteomic analysis of the midgut of silkworms fed artificial diets compared to those fed mulberry leaves. Utilizing molecular docking technology, three anti-nutritional factors that consistently bind to the UGT40B4, UGT340C2, and UGT40A1 proteins were selected, and the differential expression of these UGT genes in response to various anti-nutritional factors was examined. The findings indicate that variations in feed significantly influence the expression of digestive, metabolic, and immune-related proteins within the silkworm midgut. Notably, the expression levels of the UGT40B4, UGT340C2, and UGT40A1 genes vary across different silkworm organs and developmental stages, reflecting their respective physiological roles. Furthermore, the effects of soybean isoflavone, tannic acid, and arabinoxylan on silkworm growth and cocoon quality were found to differ when these substances were incorporated into semi-synthetic feed. This research is anticipated to provide valuable insights for future studies on the role of UGT genes in the silkworm midgut and the formulation of artificial diets for silkworms.

Applications of bacterial cellulose in the food industry and its health-promoting potential

Bacterial cellulose (BC) is a naturally occurring biomaterial with a wide range of potential applications in the food industry because of its exceptional mechanical qualities, unique nanofiber structure, high purity, and outstanding biocompatibility. Beyond its physical attributes, BC has gained interest recently due to research demonstrating its potential health benefits as a functional food ingredient. This article examines the many uses of BC in the food business, with a focus on how it may enhance food texture, operate as a bioactive carrier, and have promise in the packaging sector. Further research was done on the health-promoting properties of BC in functional foods, particularly with regard to its functions as a blood glucose regulator, and gastrointestinal health. This review seeks to bring fresh ideas for the study of bioactive components in the food industry by providing a summary of the existing research and demonstrating the possible role of BC in food. It also suggests future paths for research.

Effects of soybean insoluble dietary fiber and CaCl2 on the structure and properties of low-moisture extruded products

BACKGROUND

Texturized vegetable protein is currently a leading alternative to animal meat. This study examined the effects of soybean insoluble dietary fiber (SIDF) (0% to 20%) and CaCl2 (0% to 1%) on the structure and properties of extruded products made from a soybean protein isolate-wheat gluten (SPI-WG) composite.

RESULTS

The study showed that SIDF (4% to 8%) increased the viscosity of extruded products, enhanced their specific mechanical energy, and improved their rehydration rate and tensile strength compared with a control group. The rehydration rate of the extruded products reached a maximum value of 331.67% in the 8% SIDF, 0.5% CaCl2 groups. The addition of excess SIDF prevented the cross-linking of protein molecules to form a loose network structure. Analysis of the infrared spectrum and intermolecular forces showed that physical interactions between fibers and proteins were the dominant forces, with hydrophobic interactions and hydrogen bonds primarily maintaining the structure of the extruded products. The addition of CaCl2 (0.5%) led to protein aggregation and further improved the rehydration and tensile strength of extruded products.

CONCLUSION

Soybean insoluble dietary fiber can improve the rehydration rate and quality of extruded products. The addition of CaCl2 mitigated the weakening of the protein structure caused by excess SIDF. These results provide a basis for the improvement of the quality of low-moisture-extruded texturized vegetable protein products with a high dietary fiber concentration and a high rehydration rate. © 2024 Society of Chemical Industry.

Effect of Daily Fiber Intake Among Cirrhotic Patients With and Without Portosystemic Shunts

Background

A diet rich in fiber, especially soluble fiber, causes cholestatic liver damage and fibrosis in animal models with intestinal dysbiosis, high serum bile acid concentrations, and congenital portosystemic shunts (PSs), but no data on patients with cirrhosis (CIRs) are available.

Objectives

To investigate whether dietary fiber consumption was associated with clinical outcomes of CIRs and whether their effect differed according to the presence of PSs.

Methods

Daily soluble and insoluble fiber intake was extrapolated from 3-d food diaries in 25 patients with chronic hepatitis (CH) and 80 CIRs outpatient liver transplant candidates abstinent from alcohol and nonviremic for ≥6 mo. In CIRs, the presence of PSs was verified by computed tomography, and the model for end-stage liver disease (MELD) score was calculated at enrollment and after 6 mo.

Results

PSs were present in 48 (60%) CIRs. The MELD score after 6 mo, compared with enrollment, had improved in 19 and 10 CIRs with and without PSs, respectively. By adjusting for confounders in logistic regression models we found that improvement in MELD over time was inversely associated with insoluble fiber consumption expressed in milligrams per kilogram (mg/kg) body weight in CIRs without PSs [odds ratio (OR): 0.968; 95% confidence interval (CI): 0.939, 0.997; P = 0.005] but with soluble fiber consumption in CIRs with PSs [OR: 0.946; 95% CI: 0.912, 0.982; P = 0.001]. In CIRs with PSs, soluble fiber consumption was inversely associated with normal serum alkaline phosphatase values at enrollment [OR: 0.964; 95% CI: 0.963, 0.993; P = 0.010]. CHs with normal serum alanine transaminase consumed significantly more soluble fiber (p=0.015) than those with abnormal alanine transaminase.

Conclusions

The clinical impact of dietary fiber changes from beneficial to harmful as the stage of chronic liver disease progresses. In particular, in the advanced cirrhosis stage with PSs, soluble fiber intake appears to significantly influence disease progression and should be kept low.

Effects of Soluble and Insoluble Fibre on Glycolipid Metabolism and Gut Microbiota in High-Fat-Diet-Induced Obese Mice

BACKGROUND

Dietary fibre can alleviate or reduce the risk of obesity and obesity-induced abnormalities in glycolipid metabolism. However, the effects of different types of dietary fibre or their combinations on obesity remain unclear. Here, we explored the effects of different ratios of inulin soluble dietary fibre (ISDF) and barley leaf insoluble dietary fibre (BLIDF) on the body weight, glycolipid metabolism and gut microbiota of obese mice.

METHODS

Seven experimental groups were treated with different combinations of soluble and insoluble fibre, comprising HFD (high-fat diet without dietary fibre), BLIDF, ISDF, I3S1DF (insoluble/soluble = 3:1), I2S2DF (insoluble/soluble = 1:1), I1S3DF (insoluble/soluble = 1:3) and MIX (inulin, BLIDF and matcha powder fibre; insoluble/soluble = 3.6:1) groups.

RESULTS

Our results showed that the BLIDF, ISDF and MIX treatments decreased the body weight gain of the HFD mice significantly after eight-week interventions. All the fibre intervention groups except the MIX group displayed lower fasting blood glucose and glycosylated serum protein levels than the HFD group. BLIDF, ISDF, I3S1DF and I2S2DF improved the glucose tolerance of the mice. Moreover, none of the dietary fibre interventions affected the liver lipid metabolism, while I3S1DF and I1S3DF improved the abnormal serum lipid metabolism. BLIDF, ISDF, I3S1DF and I2S2DF reduced the serum IL-6 levels, and BLIDF and I1S3DF increased SOD activity significantly. Additionally, all the dietary fibre interventions decreased the Firmicutes to Bacteroidota (F/B) ratio and increased the abundance of beneficial gut microbes differently.

CONCLUSIONS

In short, our results suggest that different ratios of soluble and insoluble dietary fibre have unique impacts on mice body weight, glycolipid metabolism, inflammation and gut microbiota. The ratio of soluble to insoluble dietary fibre intake should be considered for specific health goals in the future.

Effects of different fractions of polysaccharides from Dictyophora indusiata on high-fat diet-induced metabolic syndrome in mice

Dictyophora indusiata is a common edible mushroom with great potential in the field of medicine against metabolic disorders, inflammation, and immunodeficiency. Our previous studies have shown that different fractions of the polysaccharide from Dictyophora indusiata (DIP) have various structural characteristics and morphology. However, the impact of the structural features on the protective effects of DIP against metabolic syndrome remains unclear. In this study, three distinct polysaccharide fractions have been extracted from Dictyophora indusiata and a high-fat diet-induced metabolic syndrome (MetS) was constructed in mice. The effects of these fractions on a range of MetS-associated endpoints, including abnormal blood glucose, lipid profiles, body fat content, liver function, intestinal microbiota and their metabolites were investigated. Through correlation analysis, the potential link between the monosaccharide composition of the polysaccharides and their biological activities was determined. The study aimed to explore the potential mechanisms and ameliorative effects of these polysaccharide fractions on MetS, thereby providing statistical evidence for understanding the relationship between monosaccharides composition of Dictyophora indusiata polysaccharides and their potential utility in treating metabolic disorders.

Effects of high-pressure microfluidization treatment on the structural, physiochemical properties of insoluble dietary fiber in highland barley bran

High-pressure microfluidization treatment (HPMT) was performed on the insoluble dietary fiber (IDF) of highland barley bran (HBB), with conditions set at 60 MPa (IDF-60), 120 MPa (IDF-120), and two consecutive high-pressure treatments at 120 MPa (IDF-120-2), respectively. Then the particle size, structural, physicochemical and adsorption properties of different IDF samples were analyzed. After HPMT, the particle size of IDF samples gradiently decreased (p < 0.05), and part of IDF was transferred into soluble dietary fiber (SDF), accompanied by the decrease of hemicellulose and lignin content. In addition, the morphology of the IDF samples became more fragmented and wrinkled, and the two consecutive treatments at 120 MPa significantly damaged the crystalline structure of the IDF. Moreover, the adsorption capacities to water, oil, cholesterol, and NO2- were basically enhanced with the increase of treatment pressure and treatment number. The IDF-120-2 sample had the strongest water/oil-holding, swelling, and cholesterol trapping capacities, and the IDF-120 showed strongest NO2- trapping capacity (pH = 2). Through the correlation analysis, the adsorption capacities were positively to the particle size and SDF content, and negatively correlated with the specific surface area (SSA) and IDF content. The adsorption capacities of IDF for the four substances were positively correlated with each other.

Metabolome biomarkers linking dietary fibre intake with cardiometabolic effects: results from the Danish Diet, Cancer and Health-Next Generations MAX study

Biomarkers associated with dietary fibre intake, as complements to traditional dietary assessment tools, may improve the understanding of its role in human health. Our aim was to discover metabolite biomarkers related to dietary fibre intake and investigate their association with cardiometabolic risk factors. We used data and samples from the Danish Diet Cancer and Health Next Generation (DCH-NG) MAX-study, a one-year observational study with evaluations at baseline, six and 12 months (n = 624, 55% female, mean age: 43 years, 1353 observations). Direct associations between fibre intake and plasma concentrations of 2,6-dihydroxybenzoic acid (2,6-DHBA) and indolepropionic acid were observed at the three time-points. Both metabolites showed an intraclass-correlation coefficient (ICC) > 0.50 and were associated with the self-reported intake of wholegrain cereals, and of fruits and vegetables, respectively. Other metabolites associated with dietary fibre intake were linolenoyl carnitine, 2-aminophenol, 3,4-DHBA, and proline betaine. Based on the metabolites associated with dietary fibre intake we calculated predicted values of fibre intake using a multivariate, machine-learning algorithm. Metabolomics-based predicted fibre, but not self-reported fibre values, showed negative associations with cardiometabolic risk factors (i.e. high sensitivity C-reactive protein, systolic and diastolic blood pressure, all FDR-adjusted p-values <0.05). Furthermore, different correlations with gut microbiota composition were observed. In conclusion, 2,6-DHBA and indolepropionic acid in plasma may better link dietary fibre intake with its metabolic effects than self-reported values. These metabolites may represent a novel class of biomarkers reflecting both dietary exposure and host and/or gut microbiota characteristics providing a read-out that is differentially related to cardiometabolic risk.

Preparation and characterization of soluble dietary fiber from tiger nut residues, showing enhanced antioxidant activity and metal-ion-binding properties

To improve the utilization of soluble dietary fiber (SDF) from tiger nut residues, the response surface methodology was used to optimize the conditions of superfine grinding to produce SDF with antioxidant and metal-ion-binding properties. The yield was increased (30.56%) and the average particle diameter of SDF was decreased (D50: 32.80 μm) under the optimal conditions (a proportion of grinding medium of 100%, a feeding mass of 0.90 kg, a grinding time of 20 min, and a moisture content of 8.00%). In addition, superfine grinding substantially modified the surface morphology and increased the SDF content and the proportion of monosaccharides by decreasing the molecular weight. Moreover, superfine grinding remarkably enhanced the in vitro antioxidant activities (ABTS+, DPPḤ, and ·OH) of the SDF, which also exhibited favorable metal-ion-binding properties (Ca2+, Zn2+, and Co2+). These results suggest that superfine grinding can be used as a technique to modify dietary fiber to manufacture functional SDF.