Fructooligosaccharides exhibit more rapid fermentation than long-chain inulin in an in vitro fermentation system. Nutr Res. 2008;28:329-334. [PMID: 19083428 DOI: 10.1016/j.nutres.2008.02.014]

Effect of H2O2/ascorbic acid degradation and gradient ethanol precipitation on the physicochemical properties and biological activities of pectin polysaccharides from Satsuma Mandarin

In this work, three degraded polysaccharides (DMPP-40, DMPP-60, DMPP-80) were successfully obtained by H2O2/ascorbic acid degradation and gradient ethanol precipitation from Satsuma mandarin peel pectin (MPP), and their physicochemical properties, antioxidant and prebiotic activities were investigated. The molecular weight of MPP, DMPP-40, DMPP-60, DMPP-80 were determined to be 336.83 ± 10.57, 18.93 ± 0.54, 26.07 ± 0.83 and 8.71 ± 0.27 kDa, respectively. The ethanol concentration significantly affected the physicochemical properties of DMPPs. DMPP-60 showed the highest yield (69.07 %) and uronic acid content (64.85 %), DMPP-80 showed the lowest molecular weight (8.71 kDa), and the composition and proportion of monosaccharides of DMPPs were significantly different. Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance spectroscopy (1H NMR) confirmed that DMPPs exhibited similar functional groups, while X-ray diffraction (XRD) indicated that DMPP-40 possessed some crystallographic sequences. Scanning electron microscopy (SEM) images directly verified the fragmented structure and reduced surface area of DMPPs. Besides, the H2O2/ascorbic acid treatment could obviously reduce the apparent viscosity and thermal stability of MPP. Meanwhile, the results of bioactivity assay showed that DMPPs possessed better antioxidant activity and probiotics pro-proliferative effects compared with MPP. DMPP-80 could significantly inhibit lipopolysaccharides (LPS)-stimulated production of inflammatory factors (including nitric oxide (NO), interleukin (IL)-6, tumor necrosis factor (TNF)-α and interleukin (IL)-1β) in RAW264.7 cells. Results suggest that the H2O2/ascorbic acid combined with gradient ethanol precipitation has potential applications in degradation and separation of MPP to improve its biological activities.

Modulation of gut-microbiota through probiotics and dietary interventions to improve host health

Dietary patterns play an important role in regards to the modulation and control of the gut microbiome composition and function. The interaction between diet and microbiota plays an important role in order to maintain intestinal homeostasis, which ultimately affect the host's health. Diet directly impacts the microbes that inhabit the gastrointestinal tract (GIT), which then contributes to the production of secondary metabolites, such as short-chain fatty acids, neurotransmitters, and antimicrobial peptides. Dietary consumption with genetically modified probiotics can be the best vaccine delivery vector and protect cells from various illnesses. A holistic approach to disease prevention, treatment, and management takes these intrinsically linked diet-microbes, microbe-microbe interactions, and microbe-host interactions into account. Dietary components, such as fiber can modulate beneficial gut microbiota, and they have resulting ameliorative effects against metabolic disorders. Medical interventions, such as antibiotic drugs can conversely have detrimental effects on gut microbiota by disputing the balance between Bacteroides and firmicute, which contribute to continuing disease states. We summarize the known effects of various dietary components, such as fibers, carbohydrates, fatty acids, vitamins, minerals, proteins, phenolic acids, and antibiotics on the composition of the gut microbiota in this article in addition to the beneficial effect of genetically modified probiotics and consequentially their role in regards to shaping human health. © 2024 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Targeting urinary calcium oxalate crystallization with inulin-type AOFOS from Aspidopterys obcordata Hemsl. for the management of rat urolithiasis

ETHNOPHARMACOLOGICAL RELEVANCE

Calcium oxalate crystals play a key role in the development and recurrence of kidney stones (also known as urolithiasis); thus, inhibiting the formation of these crystals is a central focus of urolithiasis prevention and treatment. Previously, we reported the noteworthy in vitro inhibitory effects of Aspidopterys obcordata fructo oligosaccharide (AOFOS), an active polysaccharide of the traditional Dai medicine Aspidopterys obcordata Hemsl. (commonly known as Hei Gai Guan), on the growth of calcium oxalate crystals.

AIM OF THE STUDY

To investigated the effectiveness and mechanism of AOFOS in treating kidney stones.

MATERIALS AND METHODS

A kidney stones rats model was developed, followed by examining AOFOS transport dynamics and effectiveness in live rats. Additionally, a correlation between the polysaccharide and calcium oxalate crystals was studied by combining crystallization experiments with density functional theory calculations.

RESULTS

The results showed that the polysaccharide was transported to the urinary system. Furthermore, their accumulation was inhibited by controlling their crystallization and modulating calcium ion and oxalate properties in the urine. Consequently, this approach helped effectively prevent kidney stone formation in the rats.

CONCLUSIONS

The present study emphasized the role of the polysaccharide AOFOS in modulating crystal properties and controlling crystal growth, providing valuable insights into their potential therapeutic use in managing kidney stone formation.

Impact of Simulated Human Gastrointestinal Digestion on the Functional Properties of Dietary Fibres Obtained from Broccoli Leaves, Grape Stems, Pomegranate and Tomato Peels

This study aimed to analyse the impact of a simulated human digestion process on the composition and functional properties of dietary fibres derived from pomegranate-peel, tomato-peel, broccoli-stem and grape-stem by-products. For this purpose, a computer-controlled simulated digestion system consisting of three bioreactors (simulating the stomach, small intestine and colon) was utilised. Non-extractable phenols associated with dietary fibre and their influence on antioxidant capacity and antiproliferative activity were investigated throughout the simulated digestive phases. Additionally, the modifications in oligosaccharide composition, the microbiological population and short-chain fatty acids produced within the digestion media were examined. The type and composition of each dietary fibre significantly influenced its functional properties and behaviour during intestinal transit. Notably, the dietary fibre from the pomegranate peel retained its high phenol content throughout colon digestion, potentially enhancing intestinal health due to its strong antioxidant activity. Similarly, the dietary fibre from broccoli stems and pomegranate peel demonstrated anti-proliferative effects in both the small and the large intestines, prompting significant modifications in colonic microbiology. Moreover, these fibre types promoted the growth of bifidobacteria over lactic acid bacteria. Thus, these results suggest that the dietary fibre from pomegranate peel seems to be a promising functional food ingredient for improving human health.

Health-Related Composition and Bioactivity of an Agave Sap/Prickly Pear Juice Beverage

In this study, a beverage made from a combination of Agave sap (AS) and prickly pear juice (PPJ) was analyzed for its nutrients and bioactive and potentially health-promoting compounds. The beverage was evaluated for its ability to act as an antioxidant, regulate glycemic properties, and undergo gut bacterial fermentation in vitro. The major mono- and oligosaccharides present in the beverage were galacturonic acid (217.74 ± 13.46 mg/100 mL), rhamnose (227.00 ± 1.58 mg/100 mL), and fructose (158.16 ± 8.86 mg/mL). The main phenolic compounds identified were protocatechuic acid (440.31 ± 3.06 mg/100 mL) and catechin (359.72 ± 7.56 mg/100 mL). It was observed that the beverage had a low glycemic index (<40) and could inhibit digestive carbohydrases. The combination of ingredients also helped to reduce gas production during AS fermentation from 56.77 cm3 to 15.67 cm3. The major SCFAs produced during fermentation were butyrate, acetate, and propionate, with valerate being produced only during the late fermentation of the AS. This beverage is rich in bioactive compounds, such as polyphenols and dietary fiber, which will bring health benefits when consumed.

The Degree of Inulin Polymerization Is Important for Short-Term Amelioration of High-Fat Diet (HFD)-Induced Metabolic Dysfunction and Gut Microbiota Dysbiosis in Rats

Inulin, a non-digestible polysaccharide, has gained attention for its prebiotic properties, particularly in the context of obesity, a condition increasingly understood as a systemic inflammatory state linked to gut microbiota composition. This study investigates the short-term protective effects of inulin with different degrees of polymerization (DPn) against metabolic health deterioration and gut microbiota alterations induced by a high-fat diet (HFD) in Sprague Dawley rats. Inulin treatments with an average DPn of 7, 14, and 27 were administered at 1 g/kg of bodyweight to HFD-fed rats over 21 days. Body weight, systemic glucose levels, and proinflammatory markers were measured to assess metabolic health. Gut microbiota composition was analyzed through 16S rRNA gene sequencing. The results showed that inulin27 significantly reduced total weight gain and systemic glucose levels, suggesting a DPn-specific effect on metabolic health. The study also observed shifts in gut microbial populations, with inulin7 promoting several beneficial taxa from the Bifidobacterium genera, whilst inducing a unique microbial composition compared to medium-chain (DPn 14) and long-chain inulin (DPn: 27). However, the impact of inulin on proinflammatory markers and lipid metabolism parameters was not statistically significant, possibly due to the short study duration. Inulin with a higher DPn has a more pronounced effect on mitigating HFD-induced metabolic health deterioration, whilst inulin7 is particularly effective at inducing healthy microbial shifts. These findings highlight the benefits of inulin as a dietary adjuvant in obesity management and the importance of DPn in optimizing performance.

The effect of in vitro simulated colonic pH gradients on microbial activity and metabolite production using common prebiotics as substrates

BACKGROUND

The interplay between gut microbiota (GM) and the metabolization of dietary components leading to the production of short-chain fatty acids (SCFAs) is affected by a range of factors including colonic pH and carbohydrate source. However, there is still only limited knowledge on how the GM activity and metabolite production in the gastrointestinal tract could be influenced by pH and the pH gradient increases along the colon.

RESULTS

Here we investigate the effect of pH gradients corresponding to levels typically found in the colon on GM composition and metabolite production using substrates inulin, lactose, galactooligosaccharides (GOS), and fructooligosaccharide (FOS) in an in vitro colon setup. We investigated 3 different pH regimes (low, 5.2 increasing to 6.4; medium, 5.6 increasing to 6.8 and high, 6.0 increasing to 7.2) for each fecal inoculum and found that colonic pH gradients significantly influenced in vitro simulated GM structure, but the influence of fecal donor and substrate was more pronounced. Low pH regimes strongly influenced GM with the decreased relative abundance of Bacteroides spp. and increased Bifidobacterium spp. Higher in vitro simulated colonic pH promoted the production of SCFAs in a donor- and substrate-dependent manner. The butyrate producer Butyricimonas was enriched at higher pH conditions, where also butyrate production was increased for inulin. The relative abundance of Phascolarctobacterium, Bacteroides, and Rikenellaceae also increased at higher colonic pH, which was accompanied by increased production of propionate with GOS and FOS as substrates.

CONCLUSIONS

Together, our results show that colonic substrates such as dietary fibres influence GM composition and metabolite production, not only by being selectively utilized by specific microbes, but also because of their SCFA production, which in turn also influences colonic pH and overall GM composition and activity. Our work provides details about the effect of the gradients of rising pH from the proximal to distal colon on fermenting dietary substrates in vitro and highlights the importance of considering pH in GM research.

Identification of inulin-responsive bacteria in the gut microbiota via multi-modal activity-based sorting

Prebiotics are defined as non-digestible dietary components that promote the growth of beneficial gut microorganisms. In many cases, however, this capability is not systematically evaluated. Here, we develop a methodology for determining prebiotic-responsive bacteria using the popular dietary supplement inulin. We first identify microbes with a capacity to bind inulin using mesoporous silica nanoparticles functionalized with inulin. 16S rRNA gene amplicon sequencing of sorted cells revealed that the ability to bind inulin was widespread in the microbiota. We further evaluate which taxa are metabolically stimulated by inulin and find that diverse taxa from the phyla Firmicutes and Actinobacteria respond to inulin, and several isolates of these taxa can degrade inulin. Incubation with another prebiotic, xylooligosaccharides (XOS), in contrast, shows a more robust bifidogenic effect. Interestingly, the Coriobacteriia Eggerthella lenta and Gordonibacter urolithinfaciens are indirectly stimulated by the inulin degradation process, expanding our knowledge of inulin-responsive bacteria.

Addition of soluble fiber to standard purified diets is important for gut morphology in mice

Purified diets (PD) increase standardization and repeatability in rodent studies but lead to differences in the phenotype of animals compared to grain-based "chow" diets. PD contain less fiber and are often devoid of soluble fiber, which can impact gut health. Thus, the aim of the present study was to modify the PD AIN93G by addition of soluble fiber, to promote more natural gut development as seen with chow diets. One hundred twenty male C57BL/6J mice were fed over 12 weeks either a chow diet, AIN93G or one of three modified AIN93G with increased fiber content and different ratios of soluble fiber to cellulose. Gut health was assessed through histological and immunohistochemical parameters and gut barrier gene expression. Gut microbiota composition was analyzed and its activity characterized through short chain fatty acid (SCFA) quantification. Feeding AIN93G led to tissue atrophy, a less diverse microbiota and a lower production of SCFA compared to chow diet. The addition of soluble fiber mitigated these effects, leading to intermediate colon and caecum crypt lengths and microbiota composition compared to both control diets. In conclusion, the addition of soluble fibers in PDs seems essential for gut morphology as well as a diverse and functional gut microbiome.

Type and Amount of Dietary Fiber Influence the Hindgut Synthesis of Organic Acids from Fermentable Material of Both Total and Nondietary Origin in a Pig Model of the Adult Human

BACKGROUND

Organic acid synthesis by the hindgut microbiota is commonly believed to be mainly of fermentable material of dietary origin.

OBJECTIVE

This study aimed to determine the hindgut organic acid synthesis from fermentable material of dietary (mainly fiber) or nondietary origin for different types and amounts of dietary fiber in growing pigs used as a model for adult humans.

METHOD

Seven fiber-containing diets were formulated: 4 fiber types (cellulose, gum acacia, oligofructose, and pectin) at 6% of the diet and 3 (gum acacia, oligofructose, and pectin) at 3% as the sole fiber source. Ileal cannulated female pigs (n = 14; Landrace/Large white) were fed the fiber-containing diets (n = 6 pigs/diet) for 11 days (fiber phase) followed by 3 days on a fiber-free diet (fiber-free phase), using a replicated Youden square. Ileal digesta for each phase were collected and fermented in vitro with a pooled fecal microbial inoculum prepared from feces collected during the fiber phase to determine the organic acids synthesized from fermentable material of dietary (fiber phase) and nondietary (fiber-free phase) origins.

RESULTS

The total amount of each individual organic acid synthesized during in vitro hindgut fermentation differed (P ≤ 0.05) across the types and amounts of dietary fiber intake. For example, the amount of acetate was 3.6-fold higher (P ≤ 0.05) for pigs fed the 6% pectin-containing diet than those fed the 6% oligofructose-containing diet. The nondietary substrate contributed between 36% (hexanoate) and 70% (succinate) to the total hindgut organic acid synthesis. The adaptation to the different fiber-containing diets led to different amounts of some organic acids of nondietary origin.

CONCLUSIONS

The total amount of organic acids synthesized in the hindgut by the resident microbes is influenced by the type and amount of dietary fiber consumed. This study quantifies the interaction between both dietary and nondietary fermentable materials in hindgut fermentation.

Butyrate enhances Clostridioides difficile sporulation in vitro

Short-chain fatty acids (SCFAs) are products of bacterial fermentation that help maintain important gut functions such as maintenance of the intestinal barrier, cell signaling, and immune homeostasis. The main SCFAs acetate, propionate, and butyrate have demonstrated beneficial effects for the host, including its importance in alleviating infections caused by pathogens such as Clostridioides difficile. Despite the potential role of SCFAs in mitigating C. difficile infection, their direct effect on C. difficile remains unclear. Through a set of in vitro experiments, we investigated how SCFAs influence C. difficile growth, sporulation, and toxin production. Similar to previous studies, we observed that butyrate decreased growth of C. difficile strain 630 in a dose-dependent manner. The presence of butyrate also increased C. difficile sporulation, with minimal increases in toxin production. RNA-Seq analysis validated our experimental results, demonstrating increased expression of sporulation-related genes in conjunction with changes in metabolic and regulatory genes, such as a putative carbon starvation protein, CstA. Collectively, these data suggest that butyrate may induce alternative C. difficile survival pathways, modifying its growth ability and virulence to persist in the gut environment. IMPORTANCE Several studies suggest that butyrate may modulate gut infections, such as reducing inflammation caused by the healthcare-associated Clostridioides difficile. While studies in both animal models and human studies correlate high levels of butyrate with reduced C. difficile burden, the direct impact of butyrate on C. difficile remains unclear. Our study demonstrates that butyrate directly influences C. difficile by increasing its sporulation and modifying its metabolism, potentially using butyrate as a biomarker to shift survival strategies in a changing gut environment. These data point to additional therapeutic approaches to combat C. difficile in a butyrate-directed manner.

Dietary fibre definition revisited - The case of low molecular weight carbohydrates

Low molecular weight (LMW) non-digestible carbohydrates (namely, oligosaccharides and inulin) are accepted as dietary fibre in many countries worldwide. The inclusion of oligosaccharides as dietary fibre was made optional within the Codex Alimentarius definition in 2009, which has caused great controversy. Inulin is accepted as dietary fibre by default, due to being a non-digestible carbohydrate polymer. Oligosaccharides and inulin occur naturally in numerous foods and are frequently incorporated into commonly consumed food products for a variety of purposes, such as to increase dietary fibre content. LMW non-digestible carbohydrates, due to their rapid fermentation in the proximal colon, may cause deleterious effects in individuals with functional bowel disorders (FBDs) and, as such, are excluded on the low FODMAP (fermentable oligosaccharides, disaccharides, and polyols) diet and similar protocols. Their addition to food products as dietary fibre allows the use of associated nutrition/health claims, causing a paradox for those with FBDs, which is further complicated by lack of clarity on food labelling. Therefore, this review aimed to discuss whether the inclusion of LMW non-digestible carbohydrates within the Codex definition of dietary fibre is warranted. This review provides justification for the exclusion of oligosaccharides and inulin from the Codex definition of dietary fibre. LMW non-digestible carbohydrates could, instead, be placed in their own category as prebiotics, recognised for their specific functional properties, or considered food additives, whereby they are not promoted for being beneficial for health. This would preserve the concept of dietary fibre being a universally beneficial dietary component for all individuals.

Gamma-irradiation of inulin improves its biological functionality and feasibility as a functional ingredient in synbiotic food

Inulin, a dietary fibre, is widely used as a prebiotic, sugar replacer, and texture modifier in the food industry. In this study, we have shown that irradiation affects the physicochemical properties of inulin, which in turn improves its biological functionality and feasibility as a functional ingredient in synbiotic foods. The biological functionality of 25 kGy-irradiated inulin (IRI) was assessed in terms of antioxidant capacity, protective action against intracellular ROS, and prebiotic activity. Antioxidant assays revealed that irradiated inulin had improved antioxidant activity, which was even greater than that of fructooligosaccharides. Furthermore, IRI was found to be comparatively more effective in maintaining low intracellular ROS levels. The in vitro fermentation studies showed that IRI had higher bifidogenic efficacy than fructooligosaccharides and unirradiated inulin. A synbiotic low-fat yogurt containing IRI (8.5 %) was prepared. In terms of sensory attributes, the developed product was comparable to a commercially available non-synbiotic and high-fat containing product.

Butyrate enhances Clostridioides difficile sporulation in vitro

Short chain fatty acids (SCFAs) are products of bacterial fermentation that help maintain important gut functions such as the intestinal barrier, signaling, and immune homeostasis. The main SCFAs acetate, propionate, and butyrate have demonstrated beneficial effects for the host, including importance in combatting infections caused by pathogens such as Clostridioides difficile . Despite the potential role of SCFAs in mitigating C. difficile infection, their direct effect on C. difficile remains unclear. Through a set of in vitro experiments, we investigated how SCFAs influence C. difficile growth, sporulation, and toxin production. Similar to previous studies, we observed that butyrate decreased growth of C. difficile strain 630 in a dose-dependent manner. The presence of butyrate also increased C. difficile sporulation, with minimal increases in toxin production. RNA-Seq analysis validated our experimental results, demonstrating increased expression of sporulation-related genes in conjunction with alternative metabolic and related C. difficile regulatory pathways, such as the carbon catabolite repressor, CcpA. Collectively, these data suggest that butyrate may signal alternative C. difficile metabolic pathways, thus modifying its growth and virulence to persist in the gut environment.

IMPORTANCE

Several studies suggest that butyrate may be important in alleviating gut infections, such as reducing inflammation caused by the healthcare-associated Clostridioides difficile . While studies in both animal models and human studies correlate high levels of butyrate with reduced C. difficile burden, the direct impact of butyrate on C. difficile remains unclear. Our study demonstrates that butyrate directly influences C. difficile by increasing its sporulation and modifying its metabolism, potentially using butyrate as a biomarker to shift survival strategies in a changing gut environment. These data point to additional therapeutic approaches to combat C. difficile in a butyrate-directed manner.

Apoptosis-Inducing Effects of Short-Chain Fatty Acids-Rich Fermented Pistachio Milk in Human Colon Carcinoma Cells

Pistachio milk (PM), an extraction product of pistachio, is protein- and fat-dense food. Short-chain fatty acids (SCFAs) are known for inducing cytotoxicity and apoptosis in colon carcinoma cells. This study aimed to find an optimal combination of probiotics that can produce a higher amount of SCFAs in PM. In addition, the anti-cancer effect of fermented PM on human colon carcinoma cells (Caco-2) was determined. The combinations of probiotics were as follows: Streptococcus thermophilus + Lactobacillus bulgaricus (C); C + Lactobacillus acidophilus (C-La); C + Lactobacillus gasseri (C-Lg); C + Bifidobacterium bifidum (C-Bb). The results indicated that fermented PM was produced after a short fermentation time in all the probiotics combinations. C-Bb produced up to 1.5-fold more acetate than the other probiotics combinations did. A significant amount of cytotoxicity, i.e., 78, 56, and 29% cell viability was observed in Caco-2 cells by C-Bb-fermented PM at 1, 2.5 and 5%, respectively. C-Bb-fermented PM (5%) induced early and late apoptosis up to 6-fold. Additionally, Caco-2 cells treated with C-Bb-fermented PM significantly induced the downregulation of α-tubulin and the upregulation of cleaved caspase-3, as well as nuclear condensation and fragmentation. Our data suggest that fermented PM, which is rich in acetate, may have the potential as a functional food possessing anti-colon cancer properties.

Recent advances in developing butyrogenic functional foods to promote gut health

As one of the major short-chain fatty acids produced via microbial fermentation, butyrate serves as not only a preferred energy substrate but also an important signaling molecule. Butyrate concentrations in circulation, tissues, and gut luminal contents have important pathophysiological implications. The genetic capacity of butyrate biosynthesis by the gut microbiota is frequently compromised during aging and various disorders, such as inflammatory bowel disease, metabolic disorders and colorectal cancer. Substantial efforts have been made to identify potent butyrogenic substrates and butyrate-hyperproducing bacteria to compensate for butyrate deficiency. Interindividual butyrogenic responses exist, which are more strongly predicted by heterogeneity in the gut microbiota composition than by ingested prebiotic substrates. In this review, we catalog major food types rich in butyrogenic substrates. We also discuss the potential of butyrogenic foods with proven properties for promoting gut health and disease management using findings from clinical trials. Potential limitations and constraints in the current research are highlighted. We advocate a precise nutrition approach in designing future clinical trials by prescreening individuals for key gut microbial signatures when recruiting study volunteers. The information provided in this review will be conducive to the development of microbiota engineering approaches for enhancing the sustained production of butyrate.

Optimization of the Ultrasound Operating Conditions for Extraction and Quantification of Fructooligosaccharides from Garlic (Allium sativum L.) via High-Performance Liquid Chromatography with Refractive Index Detector

Dietary interventions have captured the attention of nutritionists due to their health-promoting aspects, in addition to medications. In this connection, supplementation of nutraceuticals is considered as a rational approach to alleviating various metabolic disorders. Among novel strategies, prebiotic-supplemented foods are an encouraging trend in addressing the issue. In the present investigation, prebiotic fructooligosaccharides (FOS) were extracted from garlic (Allium sativum L.) powder using ultrasound-assisted extraction (UAE). The response surface methodology (RSM) was used to optimize the independent sonication variables, i.e., extraction temperature (ET, 80, 90, and 100 °C), amplitude level (AL, 70, 80, and 90%) and sonication time (ST, 10, 15 and 20 min). The maximum FOS yield (6.23 ± 0.52%) was obtained at sonication conditions of ET (80 °C), AL (80%) and ST (10 min), while the minimum yield of FOS was obtained at high operating temperatures and time. The optimized FOS yield (7.19%) was obtained at ET (80 °C), AL (73%) and ST (15 min) after model validation. The influence of sonication parameters, i.e., ET, AL and ST, on FOS yield was evaluated by varying their coded levels from −1 to +1, respectively, for each independent variable. High-performance liquid chromatography with refractive index detector (HPLC-RID) detection and quantification indicated that sucrose was present in high amounts (2.06 ± 0.10 g/100 g) followed by fructose and glucose. Total FOS fractions which included nystose present in maximum concentration (526 ± 14.7 mg/100 g), followed by 1-kestose (428 ± 19.5 mg/100 g) and fructosylnystoses (195 ± 6.89 mg/100 g). Conclusively, garlic is a good source of potential prebiotics FOS and they can be extracted using optimized sonication parameters using ultrasound-assisted techniques with maximum yield percentage.

Advanced "Green" Prebiotic Composite of Bacterial Cellulose/Pullulan Based on Synthetic Biology-Powered Microbial Coculture Strategy

Bacterial cellulose (BC) is a biopolymer produced by different microorganisms, but in biotechnological practice, Komagataeibacter xylinus is used. The micro- and nanofibrillar structure of BC, which forms many different-sized pores, creates prerequisites for the introduction of other polymers into it, including those synthesized by other microorganisms. The study aims to develop a cocultivation system of BC and prebiotic producers to obtain BC-based composite material with prebiotic activity. In this study, pullulan (PUL) was found to stimulate the growth of the probiotic strain Lactobacillus rhamnosus GG better than the other microbial polysaccharides gellan and xanthan. BC/PUL biocomposite with prebiotic properties was obtained by cocultivation of Komagataeibacter xylinus and Aureobasidium pullulans, BC and PUL producers respectively, on molasses medium. The inclusion of PUL in BC is proved gravimetrically by scanning electron microscopy and by Fourier transformed infrared spectroscopy. Cocultivation demonstrated a composite effect on the aggregation and binding of BC fibers, which led to a significant improvement in mechanical properties. The developed approach for "grafting" of prebiotic activity on BC allows preparation of environmentally friendly composites of better quality.

Technological Properties and Composition of Enzymatically Modified Cranberry Pomace

Cranberry pomace obtained after juice production is a good source of dietary fiber and other bioactive compounds. In this study, cranberry pomace was hydrolyzed with Viscozyme® L, Pectinex® Ultra Tropical, Pectinex® Yieldmash Plus, and Celluclast® 1.5L (Novozyme A/S, Denmark). The soluble and insoluble dietary fiber was determined using the Megazyme kit, while the changes in mono-, disaccharide and oligosaccharides’ contents were determined using HPLC-RI; the total phenolic contents were determined by Folin−Ciocalteu’s Assay. Prebiotic activity, using two probiotic strains Lactobacillus acidophilus DSM 20079 and Bifidobacterium animalis DSM 20105, was investigated. The technological properties, such as hydration and oil retention capacity, were evaluated. The enzymatic treatment increased the yield of short-chain soluble saccharides. The highest oligosaccharide content was obtained using Viscozyme® L and Pectinex® Ultra Tropical. All of the tested extracts of cranberry pomace showed the ability to promote growth of selected probiotic bacteria. The insoluble dietary fiber content decreased in all of the samples, while the soluble dietary fiber increased just in samples hydrolyzed with Celluclast® 1.5L. The highest content of total phenolic compounds was obtained using Viscozyme® L and Pectinex® Ultra Tropical (10.9% and 13.1% higher than control, respectively). The enzymatically treated cranberry pomace exhibited lower oil and water retention capacities in most cases. In contrast, water swelling capacity increased by 23% and 70% in samples treated with Viscozyme® L and Celluclast® 1.5L, respectively. Enzymatically treated cranberry pomace has a different composition and technological properties depending on the enzyme used for hydrolysis and can be used in various novel food products.

Fructooligosaccharides on inflammation, immunomodulation, oxidative stress, and gut immune response: a systematic review

CONTEXT

Evidence shows that fructooligosaccharides (FOSs) can modulate inflammatory, oxidative, and immune activity in the gut, possibly leading to a systemic response, improving human health.

OBJECTIVE

To assess the present knowledge of the effects of FOSs on inflammation, immunomodulation, oxidative stress, and gut immune response.

DATA SOURCES

Studies published between December 2000 and January 2020 were systematically searched in four databases: MEDLINE, LILACS, Web of Science, and Scopus. After the screening of 1316 articles, 8 human studies and 20 animal models were included.

DATA EXTRACTION

Data were extracted separately by 2 reviewers. For each study, the design, population, exposures, main results, and conclusion were extracted. The research questions and the risk-of-bias information were also extracted. Additionally, the risk-of-bias were analyzed to guarantee the reliability of this review.

DATA ANALYSIS

A qualitative analysis revealed that FOSs can increase bifidobacteria counts and short-chain fatty acids in the gut, stimulate IgA secretion in the colon, and decrease proinflammatory cytokines, thus influencing metabolic diseases.

CONCLUSION

Studies suggest that FOS supplementation is positively associated with an anti-inflammatory and antioxidant effect, thus enhancing the gut immune system, which may be beneficial for the host's health.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration nos 42020209865 and 42020220369.

Viability, Storage Stabilityand In Vitro Gastrointestinal Tolerance of Lactiplantibacillus plantarum Grown in Model Sugar Systems with Inulin and Fructooligosaccharide Supplementation

This study aims to investigate the effects of inulin and fructooligosaccharides (FOS) supplementation on the viability, storage stability, and in vitro gastrointestinal tolerance of Lactiplantibacillus plantarum in different sugar systems using 24 h growth and 10 days survival studies at 37 °C, inulin, and FOS (0%, 0.5%, 1%, 2%, 3% and 4%) supplementation in 2%, 3%, and 4% glucose, fructose, lactose, and sucrose systems. Based on the highest percentage increase in growth index, sucrose and lactose were more suitable sugar substrates for inulin and FOS supplementation. In survival studies, based on cell viability, inulin supplementation showed a better protective effect than FOS in 3% and 4% sucrose and lactose systems. Four selected sucrose and lactose systems supplemented with inulin and FOS were used in a 12-week storage stability study at 4 °C. Inulin (3%, 4%) and FOS (2%, 4%) supplementation in sucrose and lactose systems greatly enhanced the refrigerated storage stability of L. plantarum. In the gastrointestinal tolerance study, an increase in the bacterial survival rate (%) showed that the supplementation of FOS in lactose and sucrose systems improved the storage viability of L. plantarum. Both inulin and FOS supplementation in sucrose and lactose systems improved the hydrophobicity, auto-aggregation, co-aggregation ability of L. plantarum with Escherichia coli and Enterococcus faecalis.

The Prebiotic Potential of Inulin-type Fructans: A Systematic Review

Inulin-type fructans (ITF), including short-chain fructooligosaccharides (scFOS), oligofructose, and inulin, are commonly used fibers that are widely regarded as prebiotic for their ability to be selectively utilized by the intestinal microbiota to confer a health benefit. However, the literature thus far lacks a thorough discussion of the evidence from human clinical trials for the prebiotic effect of ITF, including both effects on the intestinal microbiota composition as well as the intestinal and extraintestinal (e.g., glucose homeostasis, lipids, mineral absorption and bone health, appetite and satiety, inflammation and immune function, and body composition) benefits. Additionally, there is a lack of discussion regarding aspects such as the effect of ITF chain length on its intestinal and extraintestinal effects. The overall objective of this systematic review was to summarize the prebiotic potential of ITF based on the results of human clinical trials in healthy adult populations. Evidence from studies included in the current review suggest that ITF have a prebiotic effect on the intestinal microbiota, promoting the abundances of Bifidobacterium, Lactobacillus, and Faecalibacterium prausnitzii. Beneficial health effects reported following ITF intake include improved intestinal barrier function, improved laxation, increased insulin sensitivity, decreased triglycerides and an improved lipid profile, increased absorption of calcium and magnesium, and increased satiety. While there is some evidence for differing effects of ITF based on chain length, lack of direct comparisons and detailed descriptions of physicochemical properties limit the ability to draw conclusions from human clinical studies. Future research should focus on elucidating the mechanisms by which the intestinal microbiota mediates or modifies the effects of ITF on human health and the contribution of individual factors such as age and metabolic health to move towards personalization of prebiotic application.

Frutalose®, a mixture of fructans obtained from enzymatic hydrolysis of chicory inulin, and normal defecation: evaluation of a health claim pursuant to Article 13(5) of Regulation (EC) No 1924/2006

Following an application from Sensus B.V. (Royal Cosun), submitted for authorisation of a health claim pursuant to Article 13(5) of Regulation (EC) No 1924/2006 via the Competent Authority of the Netherlands, the EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA) was asked to deliver an opinion on the scientific substantiation of a health claim related to Frutalose® and maintenance of normal defecation. The scope of the application was proposed to fall under a health claim based on newly developed scientific evidence. The Panel considers that Frutalose®, a mixture of fructans obtained from enzymatic hydrolysis of chicory inulin, is sufficiently characterised. The claimed effect proposed by the applicant is 'contributes to regular bowel function by increasing stool frequency'. The proposed target population is 'the general healthy adult population'. Maintenance of normal defecation is a beneficial physiological effect provided that it does not result in diarrhoea. One human intervention study showed an effect of Frutalose® on the maintenance of normal defecation by increasing stool frequency and improving stool consistency (softer stools) when consumed daily at a dose of 15 g for 8 weeks. The results have not been replicated in other studies. There is a plausible mechanism by which Frutalose® could exert the claimed effect. The Panel concludes that the evidence provided is insufficient to establish a cause and effect relationship between the consumption of Frutalose® and maintenance of normal defecation under the proposed conditions of use.

Soluble Fiber Inulin Consumption Limits Alterations of the Gut Microbiota and Hepatic Fatty Acid Metabolism Caused by High-Fat Diet

Diet shapes the gut microbiota which impacts hepatic lipid metabolism. Modifications in liver fat content are associated with metabolic disorders. We investigated the extent of dietary fat and fiber-induced alterations in the composition of gut microbiota and hepatic fatty acids (FAs). Mice were fed a purified low-fat diet (LFD) or high-fat diet (HFD) containing non-soluble fiber cellulose or soluble fiber inulin. HFD induced hepatic decreases in the amounts of C14:0, C16:1n-7, C18:1n-7 and increases in the amounts of C17:0, C20:0, C16:1n-9, C22:5n-3, C20:2n-6, C20:3n-6, and C22:4n-6. When incorporated in a LFD, inulin poorly affected the profile of FAs. However, when incorporated in a HFD, it (i) specifically led to an increase in the amounts of hepatic C18:0, C22:0, total polyunsaturated FAs (PUFAs), total n-6 PUFAs, C18:3n-3, and C18:2n-6, (ii) exacerbated the HFD-induced increase in the amount of C17:0, and (iii) prevented the HFD-induced increases in C16:1n-9 and C20:3n-6. Importantly, the expression/activity of some elongases and desaturases, as well as the gut microbiota composition, were impacted by the dietary fat and fiber content. To conclude, inulin modulated gut microbiota and hepatic fatty acid composition, and further investigations will determine whether a causal relationship exists between these two parameters.

Fermentation Kinetics of Selected Dietary Fibers by Human Small Intestinal Microbiota Depend on the Type of Fiber and Subject

SCOPE

An underexplored topic is the investigation of health effects of dietary fibers via modulation of human small intestine (SI) microbiota. A few previous studies hint at fermentation of some dietary fibers in the distal SI of humans and pigs. Here the potential of human SI microbiota to degrade dietary fibers and produce metabolites in vitro is investigated.

METHODS AND RESULTS

Fructans, galacto-oligosaccharides, lemon pectins, and isomalto/malto-polysaccharides are subjected to in vitro batch fermentations inoculated with ileostomy effluent from five subjects. Fiber degradation products, formation of bacterial metabolites, and microbiota composition are determined over time. Galacto- and fructo-oligosaccharides are rapidly utilized by the SI microbiota of all subjects. At 5h of fermentation, 31%-82% of galacto-oligosaccharides and 29%-89% fructo-oligosaccharides (degree of polymerization DP4-8) are utilized. Breakdown of fructo-oligosaccharides/inulin DP ≥ 10, lemon pectin, and iso-malto/maltopolysaccharides only started after 7h incubation. Degradation of different fibers result in production of mainly acetate, and changed microbiota composition over time.

CONCLUSION

Human SI microbiota have hydrolytic potential for prebiotic galacto- and fructo-oligosaccharides. In contrast, the higher molecular weight fibers inulin, lemon pectin, and iso-malto/maltopolysaccharides show slow fermentation rate. Fiber degradation kinetics and microbiota responses are subject dependent, therefore personalized nutritional fiber based strategies are required.

In vitro ileal and caecal fermentation of fibre substrates in the growing pig given a human-type diet

This study characterised the in vitro ileal fermentability of different substrates in the growing pig, adopted as an animal model for the adult human, and compared in vitro ileal and caecal fermentation in the pig. Substrates (arabinogalactan (AG), cellulose, fructo-oligosaccharide (FOS), inulin, mucin, citrus pectin and resistant starch) were fermented in vitro (ileal 2 h and caecal 24 h) with an ileal or caecal inoculum prepared from ileal or caecal digesta collected from growing pigs (n 5) fed a human-type diet for 15 d. The organic matter (OM) fermentability and production of organic acids were determined. In general, there was considerable in vitro ileal fermentation of fibre, and the substrates differed (P < 0·001) for both in vitro ileal and caecal OM fermentability and for organic acid production. Pectin had the greatest in vitro ileal OM fermentability (26 %) followed by AG, FOS and resistant starch (15 % on average), and cellulose, inulin and mucin (3 % on average). The fermentation of FOS, inulin and mucin was greater for in vitro caecal fermentation compared with the ileal counterpart (P ≤ 0·05). In general, the organic acid production was higher for in vitro caecal fermentation (P ≤ 0·05). For instance, the in vitro ileal acetic acid production represented 4–46 % of in vitro caecal production. Energy from fibre fermentation of 0·6–11 kJ/g substrate fermented could be expected in the ileum of the pig. In conclusion, substrates are fermented in both the ileum and caecum. The degree of fermentation varies among substrates, especially for in vitro ileal fermentation.

A prebiotic, short-chain fructo-oligosaccharides promotes peak bone mass and maintains bone mass in ovariectomized rats by an osteogenic mechanism

In preclinical studies, fructooligosaccharide (FOS) showed beneficial skeletal effects but its effect on peak bone mass (PBM) and bone loss caused by estrogen (E2) deficiency has not been studied, and we set out to study these effects in rats. Short-chain (sc)-FOS had no effect on body weight, body composition, and energy metabolism of ovary intact (sham) and ovariectomized (OVX) rats. scFOS did not affect serum and urinary calcium and phosphorus levels, and on calcium absorption, although an increasing trend was noted in the sham group. Sham and OVX rats given scFOS had better skeletal parameters than their respective controls. scFOS treatment resulted in a higher bone anabolic response but had no effect on the catabolic parameters. scFOS increased serum levels of a short-chain fatty acid, butyrate which is known to have osteogenic effect. Our study for the first time demonstrates that in rats scFOS at the human equivalent dose enhances PBM and protects against E2 deficiency-induced bone loss by selective enhancement of new bone formation, and implicates butyrate in this process.

Changes in the Fecal Metabolome Are Associated with Feeding Fiber Not Health Status in Cats with Chronic Kidney Disease

The objective was to determine the effects of feeding different fiber sources to cats with chronic kidney disease (CKD) compared with healthy cats (both n = 10) on fecal metabolites. A cross-over within split-plot study design was performed using healthy and CKD cats (IRIS stage 1, 2, and 3). After cats were fed a complete and balanced dry food designed to aid in the management of renal disease for 14 days during a pre-trial period, they were randomly assigned to two fiber treatments for 4 weeks each. The treatment foods were formulated similar to pre-trial food and contained 0.500% betaine, 0.586% oat beta glucan, and either 0.407% short chain fructooligosaccharides (scFOS) fiber or 3.44% apple pomace. Both treatment foods had similar crude fiber (2.0 and 2.1% for scFOS and apple pomace, respectively) whereas soluble fiber was 0.8 and 1.6%, respectively. At baseline, CKD had very little impact on the fecal metabolome. After feeding both fiber sources, some fecal metabolite concentrations were significantly different compared with baseline. Many fecal uremic toxins decreased, although in healthy cats some increased; and some more so when feeding apple pomace compared with scFOS, e.g., hippurate, 4-hydroxyhippurate, and 4-methylcatechol sulfate; the latter was also increased in CKD cats. Changes in secondary bile acid concentrations were more numerous in healthy compared with CKD cats, and cats in both groups had greater increases in some secondary bile acids after consuming apple pomace compared with scFOS, e.g., tauroursodeoxycholate and hyocholate. Although changes associated with feeding fiber were more significant than changes associated with disease status, differential modulation of the gut-kidney axis using dietary fiber may benefit cats.

Comparison of the prebiotic properties of native chicory and synthetic inulins using swine fecal cultures

Inulin-type fructans are known to exert different effects on the fermentation profile depending on the average and range of the degree of polymerization (DP). Here, swine fecal cultures were used to investigate the prebiotic properties of native chicory inulin (NIN), extracted from the chicory root, and synthetic inulin (SIN), which has a narrower DP distribution than NIN. Both NIN and SIN showed prebiotic effects, but NIN exhibited a significant decrease in pH and increase in the production of propionate and butyrate compared to SIN. There were also differences in the production of succinate and lactate, the precursors of propionate and butyrate, and the relative abundance of associated genes. Furthermore, NIN induced the growth of certain species of Bifidobacterium and Lactobacillus more strongly than SIN. These results suggest that NIN and SIN exhibit different prebiotic properties due to differences in DP, and that NIN might be more beneficial to host health.

Production of Short Chain Fructo-oligosaccharides from Inulin of Chicory Root Using Fungal Endoinulinase

Short chain fructo-oligosaccharides (SC-FOS) are the potential prebiotics possessing diverse applications in both food and feed industries. The present study was aimed to extract inulin from chicory roots followed by its conversion into SC-FOS applying endoinulinase from Aspergillus fumigatus. The inulin was extracted from chicory roots through boiling in hot water, followed by precipitation with ethanol at room temperature or freezing condition. Maximum yield (42%) of inulin was obtained with three volumes of chilled absolute ethanol at room temperature. HPLC analysis of enzymatic hydrolysate detected kestose (GF2), nystose (GF3), and other FOS having higher degree of polymerization (DP). Maximum GF2 (5.79 mg/ml) was detected at temperature 50 °C, pH 5.5 with 2 U of enzyme dose after 6 h of hydrolysis; while maximum GF3 (4.33 mg/ml) was recorded at 60 °C, 5.5 pH with 0.5 U enzyme dose after 2 h of hydrolysis. Nevertheless, complete hydrolysis of inulin was noticed with 99% total oligosaccharide yield at 55 °C, 5.5 pH with 0.5 U enzyme dose after 4 h of hydrolysis with negligible amount of mono- and di-saccharides. The present finding demonstrated the process for higher yield of inulin from chicory roots followed by its conversion into SC-FOS applying fungal endoinulinase.

Supplementation of Inulin with Various Degree of Polymerization Ameliorates Liver Injury and Gut Microbiota Dysbiosis in High Fat-Fed Obese Mice

The chain length of fructan determines its different physiological effects. This study is to explore the effects of low-performance inulin [LPI, degree of polymerization (DP) ≤ 9] and high-performance inulin (HPI, DP ≥ 23) on obesity-associated liver injury of high-fat diet (HFD) feeding mice and its underlying mechanism. Eight weeks of supplementation of C57BL/6J mice with HPI, relative to LPI (p < 0.05), caused the more efficient improvement against the HFD-induced liver insulin resistance through activating IRS1/PI3K/Akt pathway and reduced protein expressions of inflammatory factors nuclear factor-kappaB (NF-κB) and interleukin-6 (IL-6) in the liver. HPI exhibited the more positive effects on liver steatosis by inhibiting acetyl-CoA carboxylase (ACC), fatty acid synthase (FAS), and sterol regulatory element binding protein 1 (SREBP1) in comparison with LPI (p < 0.05). HPI also increased acetic acid, propionic acid, and butyric acid levels in the colon of HFD-fed mice (p < 0.05). Compared to LPI, HPI feeding of HFD-fed mice led to the more effective decrease in the Firmicutes abundance from 72.1% to 34.5%, but a more significant increase in the Bacteroidetes population from 19.8 to 57.1% at the phyla level, and increased the abundance of Barnesiella, Bacteroides, and Parabacteroides at the genus level (p < 0.05). Depending on DP, HPI exerts the more positive regulation on liver injury and gut microbiota dysfunction than LPI.

Prebiotics in the Infant Microbiome: The Past, Present, and Future

The latest definition of a prebiotic is "a substrate that is selectively utilized by host microorganisms conferring a health benefit"; it now includes non-food elements and is applicable to extra-intestinal tissues. Prebiotics are recognized as a promising tool in the promotion of general health and in the prevention and treatment of numerous juvenile diseases. Prebiotics are considered an immunoactive agent, with the potential for long-lasting effects extending past active administration of the prebiotic. Because of its extremely low risk of serious adverse effects, ease of administration, and strong potential for influencing the composition and function of the microbiota in the gut and beyond, the beneficial clinical applications of prebiotics are expanding. Prebiotics are the third largest component of human breast milk. Preparations including galactooligosaccharides (GOS), fructooligosaccharides (FOS), 2'-fucosyllactose, lacto-N-neo-tetraose are examples of commonly used and studied products for supplementation in baby formula. In particular, the GOS/FOS combination is the most studied. Maintaining a healthy microbiome is essential to promote homeostasis of the gut and other organs. With more than 1,000 different microbial species in the gut, it is likely more feasible to modify the gut microbiota through the use of certain prebiotic mixtures rather than supplementing with a particular probiotic strain. In this review, we discuss the latest clinical evidence regarding prebiotics and its role in gut immunity, allergy, infections, inflammation, and functional gastrointestinal disorders.

Comparative prebiotic activity of mixtures of cereal grain polysaccharides

The main components of the non-starch polysaccharide (NSP) fraction of wheat flour are arabinoxylan (AX) and β-glucan. These are also present in other cereal grains, but their proportions vary with AX being the major component in wheat and rye and β-glucan in barley and oats. Therefore, it was hypothesised that these NSPs could act synergistically when fermented in vitro at the ratios present in the major foods consumed, resulting in increased prebiotic activity. AX and β-glucan were therefore tested in in vitro fermentation studies to assess their prebiotic activity when used individually and/or in different ratios. Short-chain fatty-acids (SCFAs) produced from in vitro fermentation were measured using HPLC and bacterial populations were measured using flow cytometry with fluorescence in situ hybridisation (Flow-FISH). Fermentation of AX alone resulted in a significant bifidogenic activity and increased concentrations of SCFAs, mainly acetate, after 8-24 h of fermentation, however β-glucan alone did not show prebiotic activity. The greatest prebiotic activity, based on concentration of total SCFAs and increases in total bacteria as well as beneficial Bifidobacterium and Clostridium coccoides/Eubacterium groups, was observed when AX and β-glucan were combined at a 3:1 ratio, which corresponds to their ratios in wheat flour which is major source of cereal fibre in the diet. This indicates that the population of bacteria in the human GI tract may be modulated by the composition of the fibre in the diet, to maximise the prebiotic potential.

Prebiotics: tools to manipulate the gut microbiome and metabolome

The human gut is an ecosystem comprising trillions of microbes interacting with the host. The composition of the microbiota and their interactions play roles in different biological processes and in the development of human diseases. Close relationships between dietary modifications, microbiota composition and health status have been established. This review focuses on prebiotics, or compounds which selectively encourage the growth of beneficial bacteria, their mechanisms of action and benefits to human hosts. We also review advances in synthesis technology for human milk oligosaccharides, part of one of the most well-characterized prebiotic–probiotic relationships. Current and future research in this area points to greater use of prebiotics as tools to manipulate the microbial and metabolic diversity of the gut for the benefit of human health.

The Short-Chain Fatty Acid Acetate in Body Weight Control and Insulin Sensitivity

The interplay of gut microbiota, host metabolism, and metabolic health has gained increased attention. Gut microbiota may play a regulatory role in gastrointestinal health, substrate metabolism, and peripheral tissues including adipose tissue, skeletal muscle, liver, and pancreas via its metabolites short-chain fatty acids (SCFA). Animal and human data demonstrated that, in particular, acetate beneficially affects host energy and substrate metabolism via secretion of the gut hormones like glucagon-like peptide-1 and peptide YY, which, thereby, affects appetite, via a reduction in whole-body lipolysis, systemic pro-inflammatory cytokine levels, and via an increase in energy expenditure and fat oxidation. Thus, potential therapies to increase gut microbial fermentation and acetate production have been under vigorous scientific scrutiny. In this review, the relevance of the colonically and systemically most abundant SCFA acetate and its effects on the previously mentioned tissues will be discussed in relation to body weight control and glucose homeostasis. We discuss in detail the differential effects of oral acetate administration (vinegar intake), colonic acetate infusions, acetogenic fiber, and acetogenic probiotic administrations as approaches to combat obesity and comorbidities. Notably, human data are scarce, which highlights the necessity for further human research to investigate acetate’s role in host physiology, metabolic, and cardiovascular health.

Fructooligosaccharides and wheat bran fed at similar fermentation levels differentially affect the expression of genes involved in transport, signaling, apoptosis, cell proliferation, and oncogenesis in the colon epithelia of healthy Fischer 344 rats

The influence of the source of fermentable material (FM) on the luminal concentrations of their end products and its effects on colon cell metabolism and disease susceptibility is not well characterized. We hypothesized that total fermentation but not the source (type) of FM would be the main factor in determining cellular /molecular outcomes in the healthy colon epithelia. The main aim of this study was to elucidate the role of two different sources of FM, fructooligosaccharides (FOS) and wheat bran (WB), on the expression of genes involved in short chain fatty acid (SCFA) transport, G-protein signaling, apoptosis, cell proliferation and oncogenesis in colon epithelia of healthy rats. Male Fischer 344 rats (n = 10/group) were fed AIN-93G control (0% FM) or experimental diets containing WB (~1%, 2%, or 5% FM) or FOS (~2%, 5%, or 8% FM). Rats were killed after 6 weeks and the colon mucosa was assessed for the expression of target genes using real-time quantitative polymerase chain reaction. By comparison to the control, dose-related changes of mRNA levels were found in rats fed FOS-based diets, including: (a) upregulation of three SCFA transporters (Smct2, Mct1 and Mct4) but downregulation of Mct2, (b) upregulation of Gpr109a and downregulation of Gpr120, Gpr43, Gprc5a, Rgs2 and Rgs16, (c) upregulation of apoptosis-related genes including Bcl2, Bcl2-like 1, Bak1, Caspase 3, Caspase 8 and Caspase 9, (d) downregulation of the oncogenes and metastasis genes Ros1, Fos, Cd44, Fn1 and Plau, and (e) downregulation of several genes involved in cellular proliferation including Hbegf, Hoxb13, Cgref1, Wfdc1, Tgm3, Fgf7, Nov and Lumican. In contrast, rats fed WB-based diets resulted in dose-related upregulation of mRNA levels of Smct2, Rgs16, Gprc5a, Gpr109a, Bcl2-like 1, Caspase 8, and Fos. Additionally, different gene expression responses were observed in rats fed FOS and WB at 2% and 5% FM. Over all, these gene changes elicited by FOS and WB were independent of the expression of the tumor suppressor Tp53. These results suggest that fermentation alone is not the sole determinant of gene responses in the healthy rat colon.

Purification, Characterization, Prebiotic Preparations and Antioxidant Activity of Oligosaccharides from Mulberries

A water-soluble oligosaccharide termed EMOS-1a was prepared by enzymatic hydrolysis of polysaccharides purified from mulberries by column chromatography. The chemical structure of the purified fraction was investigated by ultraviolet spectroscopy, Fourier-transform infrared spectroscopy, and gas chromatography-mass spectrometry, which indicated that galactose was the main constituent of EMOS-1a. Chemical analyses showed that the uronic acid and sulfate content of EMOS-1a were 5.6% and 8.35%, respectively, while gel permeation chromatography showed that EMOS-1a had an average molecular weight of 987 Da. The antioxidant activities of EMOS-1a were next investigated, and EMOS-1a exhibited concentration-dependent 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity, Trolox equivalent antioxidant capacity, and ferric reducing antioxidant power. The level of proliferation of Lactobacillus rhamnosus reached 1420 ± 16% when 4% (w/v) EMOS-1a was added, where the number of colonies in MRS (de Man, Rogosa, and Sharpe) medium with no added oligosaccharide was defined as 100% proliferation. These results indicate that the oligosaccharide EMOS-1a could be used as a natural antioxidant in prebiotic preparations.

Infant Complementary Feeding of Prebiotics for theMicrobiome and Immunity

Complementary feeding transitions infants from a milk-based diet to solid foods, providing essential nutrients to the infant and the developing gut microbiome while influencing immune development. Some of the earliest microbial colonisers readily ferment select oligosaccharides, influencing the ongoing establishment of the microbiome. Non-digestible oligosaccharides in prebiotic-supplemented formula and human milk oligosaccharides promote commensal immune-modulating bacteria such as Bifidobacterium, which decrease in abundance during weaning. Incorporating complex, bifidogenic, non-digestible carbohydrates during the transition to solid foods may present an opportunity to feed commensal bacteria and promote balanced concentrations of beneficial short chain fatty acid concentrations and vitamins that support gut barrier maturation and immunity throughout the complementary feeding window.

Determination of the prebiotic activity of wheat arabinogalactan peptide (AGP) using batch culture fermentation

Purpose

To test the prebiotic activity of wheat arabinogalactan-peptide (AGP), which is a soluble dietary fibre composed of arabinogalactan polysaccharide linked to a 15-residue peptide, which accounts for up to 0.4% of the dry weight of wheat flour.

Methods

The prebiotic activity of AGP prepared from white wheat flour was tested using in vitro fermentation by colonic bacteria in automated pH-controlled anaerobic stirred batch cultures and compared to fructooligosaccharide (FOS) and wheat flour arabinoxylan (AX). Bacterial populations were measured using fluorescence in situ hybridisation (flow-FISH) and short chain fatty acid (SCFA) concentrations were measured using HPLC.

Results

Fermentation of AGP resulted in a significant bifidogenic activity and increased concentrations of SCFAs, mainly acetate after 24 h of fermentation.

Conclusions

These results were comparable to those obtained with AX and confirm the prebiotic potential of AGP. Furthermore, fermentation of a mixture of AGP and AX was faster compared to the single substrates and more similar to FOS, indicating that combinations of fermentable carbohydrates with different structures are potentially more effective as prebiotics than single substrates.

Electronic supplementary material

The online version of this article (10.1007/s00394-019-01908-7) contains supplementary material, which is available to authorized users.

Influence of acid depolymerization parameters on levan molar mass distribution and its utilization by bacteria

Levan is a fructan composed of β -(2, 6) linkages in its main chain. Its health properties, especially its prebiotic potential can be partially modified by changing its molar mass distribution. Given that native levan is rarely fermented by probiotic bacteria, especially lactic acid bacteria (LAB), levanoligosaccharides (LOS) were produced by mild acid hydrolysis. The response surface methodology (RSM) was applied to determine the optimum parameters for depolymerization. Gel permeation chromatography (GPC) was used to characterize the LOS produced and to show the differences between inulin and levan. The prebiotic potential of four fractions of LOS with different molar mass distributions was investigated. MRS (Mann Rogosa Sharpe) medium supplemented with the LOS were inoculated with bacterial strains and growth was monitored by measuring the turbidity of the cultures. The utilization of oligofructans was also confirmed by RP-UHPLC-UV-ESI-MS (liquid chromatography coupled with mass spectrometry) measurements of LOS derivatized with 1-phenyl-3-methyl-5-pyrazolone (PMP). It was observed that the degree of polymerization of LOS has an influence on the growth of the tested bacteria.

Review article: short chain fatty acids as potential therapeutic agents in human gastrointestinal and inflammatory disorders

BACKGROUND

Butyrate, propionate and acetate are short chain fatty acids (SCFA), important for maintaining a healthy colon and are considered as protective in colorectal carcinogenesis. However, they may also regulate immune responses and the composition of the intestinal microbiota. Consequently, their importance in a variety of chronic inflammatory diseases is emerging.

AIMS

To review the physiology and metabolism of SCFA in humans, cellular and molecular mechanisms by which SCFA may act in health and disease, and approaches for therapeutic delivery of SCFA.

METHODS

A PubMed literature search was conducted for clinical and pre-clinical studies using search terms: 'dietary fibre', short-chain fatty acids', 'acetate', 'propionate', 'butyrate', 'inflammation', 'immune', 'gastrointestinal', 'metabolism'.

RESULTS

A wide range of pre-clinical evidence supports roles for SCFA as modulators of not only colonic function, but also multiple inflammatory and metabolic processes. SCFA are implicated in many autoimmune, allergic and metabolic diseases. However, translating effects of SCFA from animal studies to human disease is limited by physiological and dietary differences and by the challenge of delivering sufficient amounts of SCFA to the target sites that include the colon and the systemic circulation. Development of novel targeted approaches for colonic delivery, combined with postbiotic supplementation, may represent desirable strategies to achieve adequate targeted SCFA delivery.

CONCLUSIONS

There is a large array of potential disease-modulating effects of SCFA. Adequate targeted delivery to the sites of action is the main limitation of such application. The ongoing development and evaluation of novel delivery techniques offer potential for translating promise to therapeutic benefit.