In vitro model to correlate viscosity and bile acid-binding capacity of digested water-soluble and insoluble dietary fibres

Supplementation with Lentil (Lens culinaris) Hull Soluble Dietary Fiber Ameliorates Sodium Dextran Sulfate-Induced Colitis and Behavioral Deficits via the Gut-Brain Axis

In this study, the impact of lentil hull soluble dietary fibers (SDFs) on colitis and behavioral deficits in mice was assessed. Structural characterizations of SDFs confirmed that cellulase-modified soluble dietary fiber exhibited better physicochemical properties: more porous microstructure; similar polysaccharide structure; more stable particle size distribution; higher crystallinity; better adsorption capacity; and lower viscosity. Additionally, we explored its potential cognitive benefits via the gut-brain axis by behavioral tests, histopathology, 16S rRNA sequencing, gas chromatography and metabolomics analysis. The results showed that SDFs significantly improved inflammatory symptoms in colon and brain and cognitive behaviors. LSDF had better efficacy than HSDF. LSDF intervention decreased the harmful bacteria abundance (Bacteroides, Flexispira and Escherichia, etc.) and increased beneficial bacteria abundance (Aggregatibacter and Helicobacter, etc.). LSDF also affected brain metabolites through the sphingolipid metabolism. Spearman correlation analysis showed that there was a positive correlation between harmful bacteria with inflammatory factors (LPS, IL-1β, IL-6, and TNF-α, etc.) and sphingolipid metabolites, while beneficial bacteria were positively correlated with brain-derived neurotrophic factor (BDNF), IL-10, and cognitive behavior. This study highlights the value of SDFs in future diet-based therapeutic strategies targeting gut-brain interactions.

Structural characterization and functional properties of resistant dextrins prepared from different starch sources

The molecular structures of different starch sources differ, and the structure of the prepared resistant dextrin is affected. Seven types of starches (corn, wheat, pea, mung bean, tapioca, sweet potato, and potato) were used to prepare resistant dextrins under identical conditions. The physicochemical properties, molecular structure, micromorphology, glucose dialysis retardation index (GDRI), and cholesterol-binding capacity of different starch-resistant dextrins were analyzed and compared. The results revealed that the starch source exerted a greater effect on the structure of the resistant dextrins, and this was primarily attributed to the difference in the content of amylose and amylopectin. Both high amylose and high amylopectin may be the sources of highly resistant dextrins. The microscopic morphology of resistant dextrins were fragmentary, and the original form of starches was completely lost. Additionally, pea resistant dextrin exhibited higher GDRI values and stronger cholesterol-binding capacity compared to other samples.

The impact of choledochal cysts on bile fluid dynamics: A perspective using computational fluid dynamics and surface mapping technique

Choledochal cysts (CCs) are an important risk factor for cholangiocarcinoma, though their etiology remains debated. Given the vital role of bile fluid in digestive processes within the biliary system, examining such mechanisms from the perspective of bile fluid dynamics may offer additional insights for clinical use. This study utilized magnetic resonance imaging (MRI)-based patient-specific scans for detailed reconstruction and further employed the computational fluid dynamic method to assess the physiological functions of each system, including refilling and emptying processes. The impact of bile rheological property was also examined. Key biomechanical parameters—pressure and wall shear stress (WSS)—were displayed on a two-dimensional plane via surface mapping for enhanced visualization and comparative analysis. Outcomes demonstrated a significant reduction in bile flow velocity in CCs patients due to common bile duct's anatomical features and bile's shear-thinning, non-Newtonian nature, with a notable increase in pressure drop observed. In healthy biliary systems, WSS variations were minimal; however, in CCs patients, extreme WSS differences were found, with the highest WSS in the segmental bile duct and the lowest in the dilatation area, presenting a magnitude difference of approximately 1000. CCs one showed WSS levels 100–250 times higher than healthy ones in the common bile duct. Bile rheological properties substantially affect pressure and WSS patterns, particularly WSS, where pathological bile caused a tenfold increase in WSS compared to healthy bile. The findings aimed to enhance the understanding of biliary fluid mechanics in CCs and offer insights into selected fluidic variables for future microfluidic chip experiments.

Wet-type grinder-treated okara modulates gut microbiota composition and attenuates obesity in high-fat-fed mice

Wet-type grinder (WG) is a nanofiber technology used to atomize dietary fiber-rich materials. WG-treated okara (WGO) exhibits high dispersion and viscosity similar to those of viscous soluble dietary fibers. Here, we studied the effect of WGO supplementation on obesity and gut microbiota composition in high-fat diet (HFD)-fed mice. WGO intake suppressed body weight gain and fat accumulation, improved glucose tolerance, lowered cholesterol levels, and prevented HFD-induced decrease in muscle mass. WGO supplementation also led to cecum enlargement, lower pH, and higher butyrate production. The bacterial 16S ribosomal RNA genes (16S rDNA) were sequenced to determine the gut microbiota composition of the fecal samples. Sequencing of bacterial 16S rDNA revealed that WGO treatment increased the abundance of butyrate producer Ruminococcus and reduced the abundances of Rikenellaceae, Streptococcaceae, and Prevotellaceae, which are related to metabolic diseases. Metabolomics analysis of the plasma of WGO- and cellulose-treated mice were conducted using ultra-high-performance liquid chromatography-mass spectrometry. Metabolic pathway analysis revealed that the primary bile acid biosynthesis pathway was significantly positively regulated by WGO intake instead of cellulose. These results demonstrate that WG is useful for improving functional properties of okara to prevent metabolic syndromes, including obesity, diabetes, and dyslipidemia.

Food intolerance related to gastrointestinal symptoms amongst adults living with bile acid diarrhoea: A cross-sectional study

BACKGROUND

The role of food in managing bile acid diarrhoea (BAD) is poorly understood. The present study explored the prevalence of food intolerance amongst adults with BAD.

METHODS

The study comprised a cross-sectional survey of adults with BAD determined by the 75 selenium homotaurocholic acid test (SeHCAT) living in the UK. Participants anonymously completed an online questionnaire on 39 food items. Frequency of food in general affecting BAD symptoms, as well as frequencies of diarrhoea, abdominal pain, bloating, flatulence and consequential food avoidance after food item ingestion, were assessed. Food group avoidance was also assessed.

RESULTS

There were 434 participants who completed the questionnaire between April and May 2021 of whom 80% reported moderate to severe chronic diarrhoea. Food intolerances were reported by 88.0% (95% confidence interval [CI] = 84.6-90.9) of participants. Diarrhoea was reported most frequently after take-away food, fish and chips, creamy sauces, cream and large quantities of fruit (range 41.0%-33.6%). Lowest frequencies were for potato, avocado, mango, watermelon and pear (range 3.7%-7.4%) for the foods listed in the questionnaire. Similar trends were found for abdominal pain, bloating, flatulence and consequential food avoidance. Symptom-triggering within 30 min of ingestion was more prevalence than after 30 min for almost all foods. Food group avoidance was highest for fatty foods (81.2%; 95% CI = 77.8-85.3) followed by dairy (53.9%; 95% CI = 49.1-58.7).

CONCLUSIONS

Perceived food intolerance amongst adults with BAD and persisting diarrhoeal symptoms is high. Important triggers were meals with a higher fat content and higher-fat dairy products. Diets amongst those with persisting diarrhoeal symptoms may be overly restrictive.

Jatobá-do-cerrado (Hymenaea stigonocarpa Mart.) pulp positively affects plasma and hepatic lipids and increases short-chain fatty acid production in hamsters fed a hypercholesterolemic diet

This study aimed to assess the impact of jatobá pulp, in its fresh (FJ) and extruded (EJ) forms, on lipid metabolism and intestinal fermentation parameters in hamsters. In a 21-day experiment, we determined the parameters of the animal lipid metabolism and colonic production of short chain fatty acids in four different groups. Control (C), fresh pulp (FJ) and extruded pulp (EJ) were fed using hypercholesterolemic diets, and the reference (R) was fed using AIN93 meal. R and C diets contained cellulose, FJ and EJ were added by jatobá pulp as a fiber source. The results showed that FJ and EJ exhibited lower levels of triglycerides, total cholesterol, LDL-c, non-HDL-c serum levels, liver lipids, and liver weight compared to C. The EJ had higher bile acid excretion in stool than the C. EJ and FJ exhibited lower excreted fiber compared to R and C, implying greater fermentation. Furthermore, the production of short-chain fatty acids (SCFA) in the cecum of FJ and EJ animals exceeded that of the C. Acetic and propionic acids were more abundant in the FJ and EJ diets, with FJ producing more butyric acid than the other groups.In conclusion, jatobá pulp maintained at normal levels of total cholesterol, LDL and HDL-associated cholesterol, non-HDL cholesterol, and serum triglycerides, while also reducing the accumulation of hepatic lipids. Jatobá also promoted SCFA formation and fermentation, making it a valuable ingredient for preventing chronic diseases.

Relationship between Physicochemical, Techno-Functional and Health-Promoting Properties of Fiber-Rich Fruit and Vegetable By-Products and Their Enhancement by Emerging Technologies

The preparation and processing of fruits and vegetables produce high amounts of underutilized fractions, such as pomace and peel, which present a risk to the environment but constitute a valuable source of dietary fiber (DF) and bioactive compounds. The utilization of these fiber-rich products as functional food ingredients demands the application of treatments to improve their techno-functional properties, such as oil and water binding, and health-related properties, such as fermentability, adsorption, and retardation capacities of glucose, cholesterol, and bile acids. The enhancement of health-promoting properties is strongly connected with certain structural and techno-functional characteristics, such as the soluble DF content, presence of hydrophobic groups, and viscosity. Novel physical, environmentally friendly technologies, such as ultrasound (US), high-pressure processing (HPP), extrusion, and microwave, have been found to have higher potential than chemical and comminution techniques in causing desirable structural alterations of the DF network that lead to the improvement of techno-functionality and health promotion. The application of enzymes was related to higher soluble DF content, which might be associated with improved DF properties. Combined physical and enzymatic treatments can aid solubilization and modifications, but their benefit needs to be evaluated for each DF source and the desired outcome.

The digestive behavior of pectin in human gastrointestinal tract: a review on fermentation characteristics and degradation mechanism

Pectin is widely spread in nature and it develops an extremely complex structure in terms of monosaccharide composition, glycosidic linkage types, and non-glycosidic substituents. As a non-digestible polysaccharide, pectin exhibits resistance to human digestive enzymes, however, it is easily utilized by gut microbiota in the large intestine. Currently, pectin has been exploited as a novel functional component with numerous physiological benefits, and it shows a promising prospect in promoting human health. In this review, we introduce the regulatory effects of pectin on intestinal inflammation and metabolic syndromes. Subsequently, the digestive behavior of pectin in the upper gastrointestinal tract is summarized, and then it will be focused on pectin's fermentation characteristics in the large intestine. The fermentation selectivity of pectin by gut bacteria and the effects of pectin structure on intestinal microecology were discussed to highlight the interaction between pectin and bacterial community. Meanwhile, we also offer information on how gut bacteria orchestrate enzymes to degrade pectin. All of these findings provide insights into pectin digestion and advance the application of pectin in human health.

Physicochemical properties of dietary fiber of bergamot and its effect on diabetic mice

Bergamot (Citrus medica L. var. sarcodactylis) contains different bioactive compounds, and their effects remain unclear. Therefore, the structural and bio-function of bergamot dietary fiber were investigated. A sequential extraction procedure was utilized to obtain soluble dietary fiber (SDF) and insoluble dietary fiber (IDF) from bergamot. The main monosaccharide in SDF and IDF is arabinose. SDF had a porous structure, which enhanced the water and oil holding capacity, as well as the cholesterol and glucose adsorption capacity, which was superior to that of IDF. In db/db diabetic mice, SDF and IDF regulated glucose tolerance and controlled blood glucose levels. Reduction of serum total cholesterol, triglycerides, and low-density lipoprotein cholesterol in SDF and IDF could be observed. In summary, SDF and IDF from bergamot effectively promoted health in patients with diabetes.

Comparative Evaluation on the Bioaccessibility of Citrus Fruit Carotenoids In Vitro Based on Different Intake Patterns

The intake pattern has a great impact on the bioaccessibility of carotenoids from citrus fruit. Here, we compared the bioaccessibility of carotenoids from fresh citrus fruit (FC), fresh citrus juice (FCJ), and not-from-concentrate citrus juice (NCJ) and analyzed the influencing factors. The results demonstrated that particle size, viscosity, and some active components of the samples during digestion are potential factors affecting the bioaccessibility of carotenoids. The total carotenoid bioaccessibility of NCJ (31.45 ± 2.58%) was significantly higher than that of FC (8.11 ± 0.43%) and FCJ (12.43 ± 0.49%). This work demonstrates that NCJ is an appropriate intake pattern to improve the bioaccessibility of carotenoids from citrus fruit. The findings also suggest that adjustment of food intake patterns is an effective way to improve the digestion and absorption of nutrients.

Biological Activities and Emerging Roles of Lignin and Lignin-Based Products─A Review

Bioactive substances, displaying excellent biocompatibility, chemical stability, and processability, could be extensively applied in biomedicine and tissue engineering. In recent years, plant-based bioactive substances such as flavonoids, vitamins, terpenes, and lignin have received considerable attention due to their human health benefits and pharmaceutical/medical applications. Among them is lignin, an amorphous biomacromolecule mainly derived from the combinatorial radical coupling of three phenylpropane units (p-hydroxypenyl, guaiacyl, and syringyl) during lignification. Lignin possesses intrinsic bioactivities (antioxidative, antibacterial, anti-UV activities, etc.) against phytopathogens. Lignin also enhances the plant resistance (adaptability) against environmental stresses. The abundant structural features of lignin offer other significant bioactivities including antitumor and antivirus bioactivities, regulation of plant growth, and enzymatic hydrolysis of cellulose. This Review reports the latest research results on the bioactive potential of lignin and lignin-based substances in biomedicine, agriculture, and biomass conversion. Moreover, the interfacial reactions and bonding mechanisms of lignin with biotissue/cells and other constituents were also discussed, aiming at promoting the conversion or evolution of lignin from industrial wastes to value-added bioactive materials.

Recent advances of cereal β-glucan on immunity with gut microbiota regulation functions and its intelligent gelling application

β-glucan from cereals such as wheat, barley, oats and rye are a water-soluble dietary fiber, which are composed of repeating (1→4)-β-bond β-D-glucopyranosyl units and a single (1→3)-β-D-bond separated unit. β-glucan has a series of physicochemical properties (such as viscosity, gelling properties, solubility, etc.), which can be used as a food gel and fat substitute. Its structure endows the healthy functions, including anti-oxidative stress, lowering blood glucose and serum cholesterol, regulating metabolic syndrome and exerting gut immunity via gut microbiota. Due to their unique structural properties and efficacy, cereal β-glucan are not only applied in food substrates in the food industry, but also in food coatings and packaging. This article reviewed the applications of cereal β-glucan in hydrogels, aerogels, intelligent packaging systems and targeted delivery carriers in recent years. Cereal β-glucan in edible film and gel packaging applications are becoming more diversified and intelligent in recent years. Those advances provide a potential solution based on cereal β-glucan as biodegradable substances for immune regulation delivery system and intelligent gelling material in the biomedicine field.

A fast and simple ion-pair high performance liquid chromatography method for analysis of primary bile salts in in vitro digested bean samples

Bile salts (BS) play a key role in cholesterol and lipid metabolism as well as in many other key metabolic pathways. High performance liquid chromatography (HPLC) is the most common technique used to analyze BS in diverse type of samples. However, current HPLC analysis methods used to analyze and quantify single BS in in vitro digested samples showed poor separation of a complex mixture of BS. In this article, we improved a standard method originally used for quantifying individual BS in food samples subjected to in vitro digestion. We also adapted a method previously developed for BS examination in human blood samples to the analysis of these molecules in chyme samples obtained during simulated gastrointestinal digestion. Our method was simple and achieved a fast and successful separation and quantification of four primary BS (sodium salts of taurocholic, glycocholic, taurochenodeoxycholic and glycochenodeoxycholic acids).•

A method used to analyze bile salts in human blood samples has been adapted to separate and quantify four primary bile salts in in vitro digested bean samples.

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Addition of an ion-pair reagent led to complete separation of glycine and taurine conjugates of chenodeoxycholic and cholic acids within 10 min, and achieved good peak symmetry.

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The minimum BS concentration that could be measured was as low as 0.03125mM.

Polysaccharide Structures and Their Hypocholesterolemic Potential

Several classes of polysaccharides have been described to have hypocholesterolemic potential, namely cholesterol bioaccessibility and bioavailability. This review will highlight the main mechanisms by which polysaccharides are known to affect cholesterol homeostasis at the intestine, namely the effect (i) of polysaccharide viscosity and its influence on cholesterol bioaccessibility; (ii) on bile salt sequestration and its dependence on the structural diversity of polysaccharides; (iii) of bio-transformations of polysaccharides and bile salts by the gut microbiota. Different quantitative structure–hypocholesterolemic activity relationships have been explored depending on the mechanism involved, and these were based on polysaccharide physicochemical properties, such as sugar composition and ramification degree, linkage type, size/molecular weight, and charge. The information gathered will support the rationalization of polysaccharides’ effect on cholesterol homeostasis and highlight predictive rules towards the development of customized hypocholesterolemic functional food.

Investigation of different dietary-fibre-ingredients for the design of a fibre enriched bread formulation low in FODMAPs based on wheat starch and vital gluten

Consumption of fermentable oligo-, di-, monosaccharides and polyols (FODMAPs) often induces symptoms of irritable bowel syndrome (IBS). Since FODMAPs and dietary fibre (DF) share certain characteristics, IBS-patients have a limited intake of DF. Therefore, enrichment of a low FODMAP model bread (based on 84% wheat starch and 16% vital gluten) with various fibres (bamboo, cellulose, psyllium, guar gum) in two different concentrations (3 g/100 g and 6 g/100 g) was investigated. Physico-chemical properties of doughs and breads were analysed (fermentation quality, gluten development, specific volume and hardness), as well as the release of reducing sugars during in vitro digestion. High performance anion exchange chromatography with coupled pulsed amperometric detection (HPAEC-PAD) was used to determine the FODMAP levels (contents of mannitol, sorbitol, fructose in excess of glucose, fructans and α-galactooligosaccharides) of both dough and bread. Prototypes were compared with wheat flour-based breads (bakers’ flour with and without wheat bran addition) to assess the performance of these prototypes. Prototypes showed a decreased quality compared to a baker’s flour control, however, a quality comparable to commercial wheat bran breads was found. This in combination with a lower release of reducing sugars during in vitro digestion underline the potential of fibre enriched breads as part of a healthier and more palateable low FODMAP diet. Furthermore, this study highlights the importance of the type (viscous and insoluble) and the concentration of fibres used. Application of psyllium in a concentration of 3 g/100 g showed the most beneficial impact on both physical (specific volume, hardness after 0 h and 24 h) and nutritional aspects of bread.

Role of β-glucan content, molecular weight and phytate in the bile acid binding of oat β-glucan

There is controversy about the role of viscosity and co-migrating molecules on the bile acid binding of beta-glucan. Thus, this study aimed to investigate the impact of β-glucan molecular weight and the content of both β-glucan and phytate on the mobility of bile acids by modelling intestinal conditions in vitro. Two approaches were used to evaluate factors underlying this binding effect. The first studied bile acid binding capacity of soluble β-glucan using purified compounds. Viscosity of the β-glucan solution governed mainly the mobility of bile acid since both a decrease in β-glucan concentration and degradation of β-glucan by enzyme hydrolysis resulted in decreased binding. The second approach investigated the trapping of bile acids in the oat bran matrix. Results suggested trapping of bile acids by the β-glucan gel network. Additionally, hydrolysis of phytate was shown to increase bile acid binding, probably due to better extractability of β-glucan in this sample.

An overview on interactions between natural product-derived β-glucan and small-molecule compounds

β-Glucans are widely found in plants and microorganisms, which has a variety of functional activities. During production and application, interactions with other components have a great influence on the structure and functional properties of β-glucan. In this paper, interactions (including non-covalent interaction and free-radical reaction) between natural product derived β-glucan and ascorbic acid, polyphenols, bile acids/salts, metal ion or other compounds were summarized. Besides, the mechanism and influence factors of interactions between β-glucan and small-molecule compounds, and their effects on the functional properties of β-glucan were detailed. This review aims to develop an understanding and practical suggestions on interactions between β-glucan and small-molecule compounds, which is expected to provide a useful reference for processing and application.

Dietary fibre in gastrointestinal health and disease

Epidemiological studies have consistently demonstrated the benefits of dietary fibre on gastrointestinal health through consumption of unrefined whole foods, such as wholegrains, legumes, vegetables and fruits. Mechanistic studies and clinical trials on isolated and extracted fibres have demonstrated promising regulatory effects on the gut (for example, digestion and absorption, transit time, stool formation) and microbial effects (changes in gut microbiota composition and fermentation metabolites) that have important implications for gastrointestinal disorders. In this Review, we detail the major physicochemical properties and functional characteristics of dietary fibres, the importance of dietary fibres and current evidence for their use in the management of gastrointestinal disorders. It is now well-established that the physicochemical properties of different dietary fibres (such as solubility, viscosity and fermentability) vary greatly depending on their origin and processing and are important determinants of their functional characteristics and clinical utility. Although progress in understanding these relationships has uncovered potential therapeutic opportunities for dietary fibres, many clinical questions remain unanswered such as clarity on the optimal dose, type and source of fibre required in both the management of clinical symptoms and the prevention of gastrointestinal disorders. The use of novel fibres and/or the co-administration of fibres is an additional therapeutic approach yet to be extensively investigated.

Mycoprotein ingredient structure reduces lipolysis and binds bile salts during simulated gastrointestinal digestion

Mycoprotein is the fungal biomass obtained by the fermentation of Fusarium venenatum, whose intake has been shown to lower blood lipid levels. This in vitro study aimed to understand the mechanisms whereby mycoprotein can influence lipid digestion by reducing lipolysis and binding to bile salts. Mycoprotein at 30 mg mL^-1 concentration significantly reduced lipolysis after 60 min of simulated intestinal digestion with oil-in-water emulsion (P < 0.001) or 10 min of incubation with tributyrin (P < 0.01). Furthermore, mycoprotein effectively bound bile salts during simulated small intestinal digestion, but only after being exposed to the acidic environment of the preceding gastric phase. However, the extent of bile salts sequestered by mycoprotein was decreased by pepsin and lipase-colipase activity. Besides, extracted mycoprotein proteins showed bile salt binding activity, and proteins with a molecular weight of ∼37 kDa showed resistance to trypsin hydrolysis. Thus, eleven extracted mycoprotein proteins (> 37 kDa) were identified by liquid chromatography-tandem mass spectrometry. In addition, the viscosity of mycoprotein digesta appeared to have no impact on bile salt binding since no statistically significant differences were detected between samples exposed or not to the previous gastric step. This study has identified mechanisms by which mycoprotein can reduce blood lipid levels.

Interaction of exopolysaccharide produced by Lactobacillus plantarum YW11 with whey proteins and functionalities of the polymer complex

Exopolysaccharide (EPS)-producing lactic acid bacteria have been widely used in fermented milk, but interaction between the EPS and milk proteins has not been well studied. In this study, interaction between the EPS from Lactobacillus plantarum YW11 (EPS-YW11) and whey proteins (WP), and functional properties of the EPS-YW11/WP were investigated. The results showed that EPS-YW11 tended to encase WP by ζ-potential analysis with a decrease in the surface charge of the protein fraction (from -26.00 mV to 15.30 mV), and an increase in the melting temperature of the protein fraction (from 76.31 °C to 84.48 °C) as shown by differential scanning calorimetry. Circular dichroism spectrometry showed that the EPS could induce structural change of WP, that is, increment in the content of α-helixes and random coils, There was stronger interaction between EPS-YW11 and WP at higher temperatures (60 °C, 90 °C) due to formation of intermolecular H-bonds and OH stretching vibration as indicated by infrared spectral analysis. A significant improvement in the texture (hardness, springiness, gumminess, resilience, cohesiveness, and chewiness) of the EPS-YW11/WP complex was also observed when compared to that of the EPS or WP alone. This was confirmed by microstructural observation of the EPS-YW11/WP complex that formed branched and porous structures, and it became more complex and stable with increased temperature treatment. Due to the strong interaction the EPS-YW11/WP exhibited improved functionality. This study identifies the potential of the EPS-YW11 to serve as a functional agent in the processing of fermented dairy products with enhanced textural stability and bioactivities such as cholesterol-lowering, antioxidant, and antibiofilm.

Mechanisms of Interactions between Bile Acids and Plant Compounds-A Review

Plant compounds are described to interact with bile acids during small intestinal digestion. This review will summarise mechanisms of interaction between bile acids and plant compounds, challenges in in vivo and in vitro analyses, and possible consequences on health. The main mechanisms of interaction assume that increased viscosity during digestion results in reduced micellar mobility of bile acids, or that bile acids and plant compounds are associated or complexed at the molecular level. Increasing viscosity during digestion due to specific dietary fibres is considered a central reason for bile acid retention. Furthermore, hydrophobic interactions are proposed to contribute to bile acid retention in the small intestine. Although frequently hypothesised, no mechanism of permanent binding of bile acids by dietary fibres or indigestible protein fractions has yet been demonstrated. Otherwise, various polyphenolic structures were recently associated with reduced micellar solubility and modification of steroid and bile acid excretion but underlying molecular mechanisms of interaction are not yet fully understood. Therefore, future research activities need to consider the complex composition and cell-wall structures as influenced by processing when investigating bile acid interactions. Furthermore, influences of bile acid interactions on gut microbiota need to be addressed to clarify their role in bile acid metabolism.

Intake of soluble fibre from chia seed reduces bioaccessibility of lipids, cholesterol and glucose in the dynamic gastrointestinal model simgi®

The role of soluble fibres on hypoglycemic and hypocholesterolemic effects has been widely documented, but the effect on glucose and cholesterol binding capacity of soluble fibre extracted from chia seed mucilage has not been studied until now. In the present research, dynamic gastrointestinal model simgi® combined with absorption static techniques have been used to explore the effect of chia seed mucilage at 0.75 and 0.95% w/w on the bioaccessibility of glucose, dietary lipids and cholesterol along the gastrointestinal tract. Glucose bioaccessibility was reduced when 0.95% of chia mucilage was present in sugar food models. The total reduction of glucose bioaccessibility reached a maximum of 66.7% while glucose dialysis retardation index presented its maximum of 53.4% at the end of small intestine digestion. The in vitro studies with lipid food models, showed that the presence of both, 0.75 and 0.95% of chia seed mucilage caused substantial reductions on the bioaccessibility of free fatty acids (16.8 and 56.1%), cholesterol (18.2 and 37.2% respectively) and bile salts (4.8 and 64.6%), revealing a clear dependence on fibre concentration. These innovative results highlight the potential functionality of the soluble fibre extracted from chia seeds to improve lipid and glycemic profiles and suggest the dietary health benefits of this new soluble fibre source as an ingredient in functional foods designed to reduce the risk of certain non-communicable diseases.

Enzymatic hydrolysis of perilla seed meal yields water-soluble dietary fiber as a potential functional carbohydrate source

This study was conducted with an aim to produce a novel water-soluble fiber (WSF) by enzymatic hydrolysis of perilla seed meal (PSM), which could be used as a functional food material. The cellulose fraction (CF) and hemicellulose fraction (HF) derived from PSM were hydrolyzed using Celluclast 1.5 L and Viscozyme L, respectively. Although WSF produced from PSM had low acetylcholinesterase inhibitory activity, WSF exhibited excellent antioxidant, antidiabetic and anti-dementia activities, and effectively delayed the diffusion of glucose and bile acid from the dialysis membranes. In particular, WSF produced from CF showed a significantly higher bile acid retarding index than pectin, and WSF obtained from HF had low IC₅₀ values for radical scavenging activity and reducing power. Thus, these results suggest that the WSF derived from PSM by enzymatic hydrolysis can be used as functional carbohydrate source such as additive and a dietary supplement in the food industry.

Bile acid-retention by native and modified oat and barley β-glucan

Foods rich in cereal β-glucan are efficient dietary tools to help reduce serum cholesterol levels and hence the risk of cardiovascular diseases. However, β-glucan undergoes various reactions during food processing, which alter its viscous properties and interactions with components of the gastrointestinal tract. It has been proposed in the literature that oxidation and partial hydrolysis increase β-glucan's bile acid-binding activity, and therefore its effectiveness in lowering cholesterol. Here, the passage kinetics of a bile salt mix across a dialysis membrane was studied with or without oat and barley β-glucan extracts, native or modified (partial hydrolysis and oxidations by sodium periodate or TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl)). Bile acid-retention turned out to be purely a function of viscosity, with the most viscous native extracts exhibiting the strongest retardation of bile acid permeation. Opposite of what was suggested in the literature, oxidation and molecular weight reduction do not seem to increase the bile acid-binding capability of β-glucan.

Roasting carob flour decreases the capacity to bind glycoconjugates of bile acids

Carob is the fruit obtained from Ceratonia siliqua L. and it is a source of bioactive compounds that have been linked to several health promoting effects, including lowering blood cholesterol concentration.

In vitro study for investigating the impact of decreasing the molecular weight of oat bran dietary fibre components on the behaviour in small and large intestine

The objective of this work was to evaluate the role of β-glucan molecular weight (M_w) and the presence of other carbohydrates on the physiological functionality of oat bran via an in vitro digestion study.

Bile salts in digestion and transport of lipids

Because of their unusual chemical structure, bile salts (BS) play a fundamental role in intestinal lipid digestion and transport. BS have a planar arrangement of hydrophobic and hydrophilic moieties, which enables the BS molecules to form peculiar self-assembled structures in aqueous solutions. This molecular arrangement also has an influence on specific interactions of BS with lipid molecules and other compounds of ingested food and digestive media. Those comprise the complex scenario in which lipolysis occurs. In this review, we discuss the BS synthesis, composition, bulk interactions and mode of action during lipid digestion and transport. We look specifically into surfactant-related functions of BS that affect lipolysis, such as interactions with dietary fibre and emulsifiers, the interfacial activity in facilitating lipase and colipase anchoring to the lipid substrate interface, and finally the role of BS in the intestinal transport of lipids. Unravelling the roles of BS in the processing of lipids in the gastrointestinal tract requires a detailed analysis of their interactions with different compounds. We provide an update on the most recent findings concerning two areas of BS involvement: lipolysis and intestinal transport. We first explore the interactions of BS with various dietary fibres and food emulsifiers in bulk and at interfaces, as these appear to be key aspects for understanding interactions with digestive media. Next, we explore the interactions of BS with components of the intestinal digestion environment, and the role of BS in displacing material from the oil-water interface and facilitating adsorption of lipase. We look into the process of desorption, solubilisation of lipolysis, products and formation of mixed micelles. Finally, the BS-driven interactions of colloidal particles with the small intestinal mucus layer are considered, providing new findings for the overall assessment of the role of BS in lipid digestion and intestinal transport. This review offers a unique compilation of well-established and most recent studies dealing with the interactions of BS with food emulsifiers, nanoparticles and dietary fibre, as well as with the luminal compounds of the gut, such as lipase-colipase, triglycerides and intestinal mucus. The combined analysis of these complex interactions may provide crucial information on the pattern and extent of lipid digestion. Such knowledge is important for controlling the uptake of dietary lipids or lipophilic pharmaceuticals in the gastrointestinal tract through the engineering of novel food structures or colloidal drug-delivery systems.

Manipulation of the dry bean (Phaseolus vulgaris L.) matrix by hydrothermal and high-pressure treatments: Impact on in vitro bile salt-binding ability

The capacity of high-fiber foods to sequester BS during digestion is considered a mechanism to lower serum-cholesterol. We investigated the effect of hydrothermal (HT) and high-hydrostatic-pressure (HHP) on the bile salt (BS)-binding ability of dry beans, and how this relates to changes in bean microstructure, fiber content (insoluble-IDF/soluble-SDF), and viscosity. HT and HHP-600 MPa led to significant IDF reduction, including resistant starch (RS), whereas 150-450 MPa significantly increased RS, without modifying IDF/SDF content. Microscopy analysis showed that heating disrupted the bean cell wall integrity, protein matrix and starch granules more severely than 600 MPa; however, tightly-packed complexes of globular starch granules-protein-cell wall fiber formed at HHP ≤ 450 MPa. While HT significantly reduced BS-binding efficiency despite no viscosity change, HHP-treatments maintained or enhanced BS-retention. 600 MPa-treatment induced the maximum BS-binding ability and viscosity. These results demonstrate that BS-binding by beans is not solely based on their fiber content or viscosity, but is influenced by additional microstructural factors.

Retention of Primary Bile Acids by Lupin Cell Wall Polysaccharides Under In Vitro Digestion Conditions

Interference of dietary fibres with the enterohepatic circulation of bile acids is proposed as a mechanism for lowering cholesterol. We investigated how lupin hull and cotyledon dietary fibres interact with primary bile acids using an in vitro model under simulated upper gastrointestinal conditions. Cell wall polysaccharides were isolated and extracted to separate pectin-like, hemicellulosic, and lignocellulosic structures. Lupin hull consisted mainly of structural components rich in cellulose. The viscosity of the in vitro digesta of lupin hull was low, showing predominantly liquid-like viscoelastic properties. On the other hand, lupin cotyledon fibre retarded bile acid release due to increased viscosity of the in vitro digesta, which was linked with high contents of pectic polymers forming an entangled network. Molecular interactions with bile acids were not measured for the hull but for the cotyledon, as follows: A total of 1.29&nbsp;µmol/100&nbsp;mg&nbsp;DM of chenodesoxycholic acids were adsorbed. Molecular interactions of cholic and chenodesoxycholic acids were evident for lignin reference material but did not account for the adsorption of the lupin cotyledon. Furthermore, none of the isolated and fractionated cell wall materials showed a significant adsorptive capacity, thus disproving a major role of lupin cell wall polysaccharides in bile acid adsorption.

In Vitro Interactions of Dietary Fibre Enriched Food Ingredients with Primary and Secondary Bile Acids

Dietary fibres are reported to interact with bile acids, preventing their reabsorption and promoting their excretion into the colon. We used a method based on in vitro digestion, dialysis, and kinetic analysis to investigate how dietary fibre enriched food ingredients affect the release of primary and secondary bile acids as related to viscosity and adsorption. As the main bile acids abundant in humans interactions with glyco- and tauroconjugated cholic acid, chenodesoxycholic acid and desoxycholic acid were analysed. Viscous interactions were detected for apple, barley, citrus, lupin, pea, and potato derived ingredients, which slowed the bile acid release rate by up to 80%. Adsorptive interactions of up to 4.7 μmol/100 mg DM were significant in barley, oat, lupin, and maize preparations. As adsorption directly correlated to the hydrophobicity of the bile acids the hypothesis of a hydrophobic linkage between bile acids and dietary fibre is supported. Delayed diffusion in viscous fibre matrices was further associated with the micellar properties of the bile acids. As our results indicate changes in the bile acid pool size and composition due to interactions with dietary fibre rich ingredients, the presented method and results could add to recent fields of bile acid research.

In vitro and in vivo testing of the hypocholesterolemic activity of ergosterol- and β-glucan-enriched extracts obtained from shiitake mushrooms (Lentinula edodes)

Herein, two shiitake fractions were obtained: the ergosterol-enriched fraction exerted higher in vitro hypocholesterolemic activity and the β-glucan-enriched fraction reduced the cholesterol levels in mice.

Differentiation of Adsorptive and Viscous Effects of Dietary Fibres on Bile Acid Release by Means of In Vitro Digestion and Dialysis

To explain the cholesterol-reducing effects of dietary fibres, one of the major mechanisms proposed is the reduced reabsorption of bile acids in the ileum. The interaction of dietary fibres with bile acids is associated with their viscous or adsorptive effects. Since these fibre characteristics are difficult to investigate in vivo, suitable in vitro methodologies can contribute to understanding the mechanistic principles. We compared the commonly used centrifugal approach with a modified dialysis method using dietary fibre-rich materials from different sources (i.e., barley, citrus, lupin, and potato). Digestion was simulated in vitro with oral, gastric, and small intestinal digestion environments. The chyme was dialysed and released bile acids were analysed by high-performance liquid chromatography. The centrifugation method showed adsorptive effects only for cholestyramine (reference material) and a high-fibre barley product (1.4 µmol taurocholic acid/100 mg dry matter). Alternatively, the dialysis approach showed higher values of bile acid adsorption (2.3 µmol taurocholic acid/100 mg dry matter) for the high-fibre barley product. This indicated an underestimated adsorption when using the centrifugation method. The results also confirmed that the dialysis method can be used to understand the influence of viscosity on bile acid release. This may be due to entrapment of bile acids in the viscous chyme matrix. Further studies on fibre structure and mechanisms responsible for viscous effects are required to understand the formation of entangled networks responsible for the entrapment of the bile acids.