Chemical features and biological functions of water-insoluble dietary fiber in plant-based foods

Valorization of bioactive compounds from food by-products using supercritical fluid extraction: A technological and industrial perspective

Food loss and waste (FLW) present significant challenges worldwide, affecting food supply, economic efficiency, and environmental sustainability. Supercritical fluid extraction (SFE) offers a promising solution for valorizing food by-products, addressing challenges related to FLW through efficient extraction of bioactive compounds. This review evaluates SFE's efficacy in extracting high-value compounds, including phenolics, terpenes, terpenoids, essential fatty acids, and dietary fibers, from food by-products. In addition, recent technological advancements are explored, with a focus on optimizing processing parameters, pretreatment methods, and integrating sequential extraction techniques to improve SFE efficiency. Industrial applications and the potential for broader commercial adoption are discussed, with attention to scalability, economic feasibility, and regulatory considerations. In conclusion, SFE is presented as a sustainable approach for converting food by-products into high-value bioactives. The integration of complementary technologies and further research on scalability are crucial for overcoming current limitations.

Total dietary fiber of tartary buckwheat alleviates T2DM through the IRS-1/PI3K/AKT pathway and gut microbiota-bile acids-TGR5/FXR axis in db/db mice

Buckwheat dietary fiber has good hypoglycemic activity, with its water-soluble parts and modification widely studied, however, the specific effects and mechanisms of action regarding buckwheat total dietary fiber (BDF) to improve T2DM need to be further explored. In this study, we investigated the improvement of diabetes-related symptoms in db/db mice by 10 % BDF and explored the possible mechanisms. The results showed that hyperglycemia, hyperlipemia, insulin resistance, elevated body weight, severe inflammatory response and impaired intestinal function were significantly improved after 8 weeks of BDF intervention. Moreover, BDF was able to ameliorate the distribution of gut microbiota, enhance the bacteria associated with T2DM, and improve glucose metabolism by altering the levels of the metabolites of gut microbiota, bile acids (BAs), and their receptors, TGR5 and FXR. In addition, BDF activated the hepatic IRS-1/PI3K/AKT pathway which can reduce hepatic gluconeogenesis and promoted glycogen synthesis. Taken together, our results suggest that BDF can alleviate T2DM symptoms by activating the IRS-1/PI3K/AKT pathway and the gut microbiota-BAs-TGR5/FXR axis. The results of this study deepen the exploration of the active ingredients of cereals and suggesting a scientific basis for the development of glucose-lowering functional foods and nutraceuticals.

The alleviation by wheat and oat dietary fiber alone or combined of T2DM symptoms in db/db mice

The effects of wheat and oat dietary fiber (DF) alone or combined on T2DM remain unclear. In this research, db/db diabetic mice were fed with diets containing 10% insoluble wheat dietary fiber (WDF), 10% insoluble oat dietary fiber (ODF), and 10% WODF (mixture of WDF and ODF, WDF : ODF = 1 : 1) for 8 weeks. The results showed that WDF, ODF, and WODF all reduced the body weight and fasting blood glucose (FBG) and improved oral glucose tolerance in db/db mice. WDF and ODF alone further relieved insulin resistance and decreased the levels of glycated hemoglobin A1c (GHbA1c), and glycosylated serum protein (GSP). In addition, WDF and ODF alone decreased the levels of TNF-α, IL-6, and IL-1β in serum. The colon function was improved and similar changes were observed in the gut microbiota structure and abundance in all the DF groups. The change of gut microbiota mainly manifested as reducing F/B ratio at the phylum level, while at the genus level as decreasing Enterococcus, Escherichia-Shigella, Erysipelatoclostridium, and unclassified_f_Lachnospiraceae and increase of norank_f_Muribaculaceae, Bacteroides, and Alistipes. Further testing of colonic bile acids (BAs) revealed that WDF, ODF, and WODF all significantly changed the composition of BAs, mainly reducing the levels of UDCA, HDCA, and 3β-UDCA. WODF further decreased DCA and increased β-MCA, LCA-3S, and 12-KCDCA. Importantly, WODF reduced the values of 12-OH-BAs/non-12-OH-BAs. Moreover, the TGR5 level was up-regulated in both the liver and colon, and the FXR level was up-regulated in the liver while down-regulated in the colon in all the DF groups. Furthermore, for the protein level, IRS-1, p-PI3K/PI3K, and AKT were up-regulated in the liver in all the DF groups, while for the mRNA expression level, GLUT4 was up-regulated, and FOXO1, GSK3β, PEPCK, and PGC-1α were down-regulated. WDF and WODF further up-regulated the mRNA expression levels of GYS and down-regulated that of G6Pase. These results suggested that WDF, ODF, and WODF all can alleviate T2DM through the gutmicrobiota-BAs-TGR5/FXR axis and liver IRS-1/PI3K/AKT pathway in db/db mice. WDF and ODF alone are beneficial for improving glucose metabolism and inflammation indicators, while WODF helps improve BAs' profile more in the colon.

Dietary fiber content in clinical ketogenic diets modifies the gut microbiome and seizure resistance in mice

The gut microbiome modulates the anti-seizure effects of the ketogenic diet, but how specific dietary formulations differentially modify the gut microbiome in ways that impact seizure outcome is poorly understood. We find that medical ketogenic infant formulas vary in macronutrient ratio, fat source, and fiber content and differentially promote resistance to 6-Hz seizures in mice. Dietary fiber, rather than fat ratio or source, drives substantial metagenomic shifts in a model human infant microbial community. Addition of fiber to a fiber-deficient ketogenic formula restores seizure resistance, and supplementing protective formulas with excess fiber potentiates seizure resistance. By screening 13 fiber sources and types, we identify metagenomic responses in the model community that correspond with increased seizure resistance. Supplementing with seizure-protective fibers enriches microbial genes related to queuosine biosynthesis and preQ0 biosynthesis and decreases genes related to sucrose degradation and TCA cycle, which are also seen in seizure-protected mice that are fed fiber-containing ketogenic formulas. This study reveals that different formulations of ketogenic diets, and dietary fiber content in particular, differentially impact seizure outcome in mice, likely by modifying the gut microbiome. Understanding interactions between diet, microbiome, and host susceptibility to seizures could inform novel microbiome-guided approaches to treat refractory epilepsy.

Effect of soluble fiber supplementation on lipid parameters in subjects with type 2 diabetes: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND

There is no consensus in the existing literature regarding the effect of soluble fiber on the lipid profile of patients with type 2 diabetes mellitus (T2DM). This systematic review and meta-analysis of randomized controlled trials aimed to assess the effect of soluble fiber on triglycerides (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C) in T2DM patients.

METHODS

PubMed/MEDLINE, Scopus, and ISI Web of sciences were searched for RCTs up to 4 May 2024. Data from RCTs were pooled using the generic inverse variance method and expressed as weighted mean differences (WMD) with 95 % confidence interval (CIs).

RESULTS

Pooled data from 38 RCTs reporting patient outcomes were evaluated for mean effects. Results indicated that soluble fiber significantly altered TG (WMD: -16.97 mg/dL, 95 % CI: -29.16 to -4.78, P = 0.021), HDL-C (WMD: 1.74 mg/dL, 95 % CI: 1.02-2.46, P < 0.001), LDL-C (WMD: -11.14 mg/dL, 95 % CI: -15.41 to -6.87, P < 0.001), and TC (WMD: -13.87 mg/dL, 95 % CI: -17.99 to -9.75, P = 0.027).

CONCLUSIONS

Soluble fiber supplementation has the potential to improve lipid profile in patients with T2DM, and may provide a feasible approach for improving metabolic health in T2DM patients.

Effects of the Intestinal Status and Clinical Factors of Korean Middle-Aged People Through the Consumption of Functional Foods Containing Auricularia auricula-judae Powder: Prospective, Randomized, Open-Label, and Control Comparative Trial

This study aimed to evaluate the effects of functional foods containing Auricularia auricula-judae powder on gut health and clinical indicators in middle-aged and older adults. Participants were randomly assigned to either the intervention group (n = 24) or control group (n = 26), and assessments including anthropometric measurements, blood analyses, and dietary intake surveys were conducted. The intervention group consumed functional foods containing A. auricula-judae powder twice daily for 8 weeks. No statistically significant differences were observed in the gut environmental parameters between the 2 groups. However, reductions in waist circumference (p < 0.021), abdominal obesity (p < 0.006), and triglyceride levels (p < 0.016) in the intervention group were statistically significant. Additionally, an analysis of nutrient intake from meals other than the intervention food revealed a significant increase in dietary fiber (p < 0.043), vitamin B1 (p < 0.027), and folic acid (p < 0.006) intake in the intervention group. Although the intervention improved the selection of body composition and blood parameters, it failed to produce significant changes in constipation outcomes or gut environmental parameters among participants with constipation. In conclusion, the consumption of A. auricula-judae powder-based functional foods resulted in limited yet meaningful improvements, specifically in reducing waist circumference and triglyceride levels.

Protective effects of insoluble dietary fiber from cereal bran against DSS-induced chronic colitis in mice: From inflammatory responses, oxidative stress, intestinal barrier, and gut microbiota

Insoluble dietary fiber (IDF) is a crucial component of cereals, and IDF from cereal bran (IDF-CB) has been reported to have multiple biological activities. However, the effect of IDF-CB on chronic colitis remains underexplored. The study aimed to investigate the impact of IDFs from wheat bran (WBIDF), rice bran (RBIDF), millet bran (MBIDF) and oat bran (OBIDF) on chronic colitis induced by dextran sulfate sodium (DSS). Our findings demonstrated that IDFs-CB supplementation mitigated DSS-induced weight loss and reduced lesions in the colon and spleen. Levels of proinflammatory cytokines (IL-1β, IL-6, IL-8, and TNF-α) and oxidative stress markers (MPO, iNOS and MDA)were decreased, and anti-inflammatory cytokine (IL-10) and T-SOD activity were increased after IDF-CB inclusion. Furthermore, IDFs-CB restored intestinal barrier function by regulating gene expression (up-regulated Muc-2, ZO-1 and Occludin, and down-regulated Claudin-1 and Claudin-4). Additionally, we analyzed the gut microbiota and SCFAs composition. WBIDF, MBIDF and OBIDF inhibited the growth of Muribaculaceae_unclassified, Bacteroides and Parasutterella. Conversely, IDFs-CB promoted the growth of Candidatus_Saccharimonas and norank_f__norank_o__Clostridia_UCG-014. Notably, WBIDF enhanced the abundance of Allobaculum, while MBIDF and OBIDF increased the abundance of Lachnospiraceae_NK4A136. Moreover, supplementation with IDFs-CB significantly elevated certain SCFA concentrations-particularly acetic acid and isohexanoic acid. Our results suggested that IDF-CB effectively alleviated DSS-induced chronic colitis; among them，WBIDF exhibited superior efficacy followed by OBIDF，MBIDF，and RBIDF. This study provides a theoretical foundation for dietary recommendations for patients suffering from inflammatory bowel disease.

The Impact of Ganoderma lucidum (Curtis) P. Karst. Supplementation on the Technological, Chemical, and Quality Parameters of Wheat Bread

This study explores the incorporation of Ganoderma lucidum (Curtis) P. Karst. (Reishi mushroom) into wheat bread to develop a functional food with enhanced nutritional value. Reishi powder was added to bread formulations at levels of 3%, 6%, 9%, and 12% to assess its effects on physicochemical, nutritional, and sensory properties. The 12% Reishi supplementation resulted in a twofold increase in total dietary fibre (from 7.21 g to 17.08 g per 100 g dry matter) and significant (p < 0.05) elevations in mineral content, particularly calcium (68%), iron (32%), and manganese (61.9%). Carbohydrate content decreased markedly by 27%, contributing to a 19.33% reduction in caloric value. Reishi addition improved bread yield and reduced baking losses, enhancing production efficiency. However, higher Reishi levels negatively impacted bread volume, possibly due to interference with gluten network formation. An increase in crumb moisture was observed, contributing to extended freshness. Sensory evaluation revealed that loaves of bread containing up to 6% Reishi were acceptable to consumers, whereas higher levels detrimentally affected flavour and aroma. Therefore, Reishi-enriched bread, particularly with 6% supplementation, presents a promising functional alternative to conventional wheat bread, optimising nutritional benefits while maintaining consumer acceptability.

Dietary fiber content in clinical ketogenic diets modifies the gut microbiome and seizure resistance in mice

The gut microbiome is emerging as an important modulator of the anti-seizure effects of the classic ketogenic diet. However, many variations of the ketogenic diet are used clinically to treat refractory epilepsy, and how different dietary formulations differentially modify the gut microbiome in ways that impact seizure outcome is poorly understood. We find that clinically prescribed ketogenic infant formulas vary in macronutrient ratio, fat source, and fiber content and also in their ability to promote resistance to 6-Hz psychomotor seizures in mice. By screening specific dietary variables for their effects on a model human infant microbial community, we observe that dietary fiber, rather than fat ratio or source, drives substantial metagenomic shifts. Addition of dietary fiber to a fiber-deficient ketogenic formula restores seizure resistance, and supplementing protective ketogenic formulas with excess dietary fiber further potentiates seizure resistance. By screening 13 fiber sources and types, we identify distinct subsets of metagenomic responses in the model human infant microbial community that correspond with increased seizure resistance in mice. In particular, supplementation with seizure-protective fibers enriches microbial representation of genes related to queuosine biosynthesis and preQ0 biosynthesis and decreases representation of microbial genes related to sucrose degradation, which is also seen in seizure-protected mice that are fed fiber-containing ketogenic infant formulas. Overall, this study reveals that different formulations of clinical ketogenic diets, and dietary fiber content in particular, differentially impact seizure outcome in mice, likely through modification of the gut microbiome. Understanding interactions between dietary components of the ketogenic diet, the gut microbiome, and host susceptibility to seizures could inform novel microbiome-guided approaches to treat refractory epilepsy.

Composition of Whole Grain Dietary Fiber and Phenolics and Their Impact on Markers of Inflammation

Inflammation is an important biological response to any tissue injury. The immune system responds to any stimulus, such as irritation, damage, or infection, by releasing pro-inflammatory cytokines. The overproduction of pro-inflammatory cytokines can lead to several diseases, e.g., cardiovascular diseases, joint disorders, cancer, and allergies. Emerging science suggests that whole grains may lower the markers of inflammation. Whole grains are a significant source of dietary fiber and phenolic acids, which have an inverse association with the risk of inflammation. Both cereals and pseudo-cereals are rich in dietary fiber, e.g., arabinoxylan and β-glucan, and phenolic acids, e.g., hydroxycinnamic acids and hydroxybenzoic acids, which are predominantly present in the bran layer. However, the biological mechanisms underlying the widely reported association between whole grain consumption and a lower risk of disease are not fully understood. The modulatory effects of whole grains on inflammation are likely to be influenced by several mechanisms including the effect of dietary fiber and phenolic acids. While some of these effects are direct, others involve the gut microbiota, which transforms important bioactive substances into more beneficial metabolites that modulate the inflammatory signaling pathways. Therefore, the purpose of this review is twofold: first, it discusses whole grain dietary fiber and phenolic acids and highlights their potential; second, it examines the health benefits of these components and their impacts on subclinical inflammation markers, including the role of the gut microbiota. Overall, while there is promising evidence for the anti-inflammatory properties of whole grains, further research is needed to understand their effects fully.

Effect of modified okara insoluble dietary fibre on the quality of yoghurt

The aim of this study was to investigate the potential of adding soya bean dregs insoluble dietary fibre (IDF) modified by jet cavitation combined with cellulase to yoghurt to improve its functional properties (Yoghurt was prepared by adding 10 μL of yoghurt fermenter to 100 mL of milk, fermented to pH 4.5 in a constant temperature incubator at 42 °C, and then stored in a refrigerator at 4 °C after adding IDF separately). The results showed that the modified IDF had a rough structure with high water-holding capacity and sodium cholate adsorption capacity. The addition of modified IDF improved the pH, hardness, and elasticity of the yoghurt. During the entire storage period, the titratable acidity and whey precipitation rate of the modified IDF yoghurt gradually increased, and antioxidant activity gradually decreased, and its titratable acidity, whey precipitation rate, and antioxidant activity had a significant advantage compared with those of the blank group yoghurt. In conclusion, the modified soya bean dregs IDF-added yoghurt prepared by jet cavitation combined with the cellulase method has the potential for sodium cholate adsorption capacity and antioxidant activity, which can confer unique functional properties and improve the pH, texture, and reduce whey precipitation of yoghurt. This study provides a scientific basis for the application of soya bean dregs IDF as a fibre fortifier in yoghurt production and suggests innovative ideas for the design of functional dairy products.

Dietary Fiber and Its Potential Role in Obesity: A Focus on Modulating the Gut Microbiota

Dietary fiber is a carbohydrate polymer with ten or more monomeric units that are resistant to digestion by human digestive enzymes, and it has gained widespread attention due to its significant role in health improvement through regulating gut microbiota. In this review, we summarized the interaction between dietary fiber, gut microbiota, and obesity, and the beneficial effects of dietary fiber on obesity through the modulation of microbiota, such as modifying selective microbial composition, producing starch-degrading enzymes, improving gut barrier function, reducing the inflammatory response, reducing trimethylamine N-oxide, and promoting the production of gut microbial metabolites (e.g., short chain fatty acids, bile acids, ferulic acid, and succinate). In addition, factors affecting the gut microbiota composition and metabolites by dietary fiber (length of the chain, monosaccharide composition, glycosidic bonds) were also concluded. Moreover, strategies for enhancing the biological activity of dietary fiber (fermentation technology, ultrasonic modification, nanotechnology, and microfluidization) were subsequently discussed. This review may provide clues for deeply exploring the structure-activity relationship between dietary fiber and antiobesity properties by targeting specific gut microbiota.