In Vitro Fermentation Shows Polyphenol and Fiber Blends Have an Additive Beneficial Effect on Gut Microbiota States.

Polyphenols and fermentable fibers have shown favorable effects on gut microbiota composition and metabolic function. However, few studies have investigated whether combining multiple fermentable fibers or polyphenols may have additive beneficial effects on gut microbial states. Here, an in vitro fermentation model, seeded with human stool combined from 30 healthy volunteers, was supplemented with blends of polyphenols (PP), dietary fibers (FB), or their combination (PPFB) to determine influence on gut bacteria growth dynamics and select metabolite changes. PP and FB blends independently led to significant increases in the absolute abundance of select beneficial taxa, namely Ruminococcus bromii, Bifidobacterium spp., Lactobacillus spp., and Dorea spp. Total short-chain fatty acid concentrations, relative to non-supplemented control (F), increased significantly with PPFB and FB supplementation but not PP. Indole and ammonia concentrations decreased with FB and PPFB supplementation but not PP alone while increased antioxidant capacity was only evident with both PP and PPFB supplementation. These findings demonstrated that, while the independent blends displayed selective positive impacts on gut states, the combination of both blends provided an additive effect. The work outlines the potential of mixed substrate blends to elicit a broader positive influence on gut microbial composition and function to build resiliency toward dysbiosis.

Comparison of prebiotic candidates in ulcerative colitis using an in vitro fermentation model.

AIMS: This study explored the effect of three different prebiotics, the human milk oligosaccharide 2'-fucosyllactose (2'-FL), an oligofructose-enriched inulin (fructo-oligosaccharide, or FOS), and a galacto-oligosaccaride (GOS) mixture, on the faecal microbiota from patients with ulcerative colitis (UC) using in vitro batch culture fermentation models. Changes in bacterial groups and short-chain fatty acid (SCFA) production were compared. METHODS AND RESULTS: In vitro pH controlled batch culture fermentation was carried out over 48 h on samples from three healthy controls and three patients with active UC. Four vessels were run, one negative control and one for each of the prebiotic substrates. Bacterial enumeration was carried out using fluorescence in situ hybridization with flow cytometry. SCFA quantification was performed using gas chromatography mass spectrometry. All substrates had a positive effect on the gut microbiota and led to significant increases in total SCFA and propionate concentrations at 48 h. 2'-FL was the only substrate to significantly increase acetate and led to the greatest increase in total SCFA concentration at 48 h. 2'-FL best suppressed Desulfovibrio spp., a pathogen associated with UC. CONCLUSIONS: 2'FL, FOS, and GOS all significantly improved the gut microbiota in this in vitro study and also led to increased SCFA.

A review on the use of prebiotics in ulcerative colitis.

The gut microbiome in the inflammatory bowel disease, ulcerative colitis (UC), is different to that of healthy controls. Patients with UC have relative reductions in abundance of Firmicutes and Bifidobacterium in the colon, and an increase in sulfate-reducing bacteria. Prebiotics are dietary substrates which are selectively metabolised by the human colonic microbiota to confer health benefits to the host. This review explores our current understanding of the potential benefits of prebiotics on various clinical, biochemical, and microbiological endpoints in UC, including new perspectives gained from recent studies in the field. This review looks to the future and highlights the need for appropriately designed trials to explore this potentially exciting new avenue for the treatment of UC.

Chronic consumption of a blend of inulin and arabinoxylan reduces energy intake in an ad libitum meal but does not influence perceptions of appetite and satiety: a randomised control-controlled crossover trial.

PURPOSE: Prebiotic foods can be used to increase production of short-chain fatty acids (SCFA) in the gut. Of the SCFA, propionate is credited with the strongest anorectic activity. In previous work, a 50/50 blend of inulin and arabinoxylan was produced (I + AX) that significantly increased propionate production in an in vitro gut model. This study sought to establish whether chronic consumption of a prebiotic blend of I + AX decreases appetite and energy intake and increases intestinal propionate production in human participants. METHODS: MIXSAT (clinicaltrials.gov id: NCT02846454, August 2016) was a double-blind randomised acute-within-chronic crossover feeding trial in healthy adult men (n = 20). Treatments were 8 g per day I + AX for 21 days or weight-matched maltodextrin control. The primary outcome measure was perceived satiety and appetite during an acute study visit. Secondary outcomes were energy intake in an ad libitum meal, faecal SCFA concentration, and faecal microbiota composition. RESULTS: Perceived satiety and appetite were not affected by the intervention. I + AX was associated with a reduction in energy intake in an ad libitum meal, increased faecal SCFA concentration, and an increase in cell counts of Bifidobacteria, Lactobacilli, and other microbial genera associated with health. IMPLICATIONS: Chronic consumption of this blend of prebiotics decreased energy intake in a single sitting. Further studies are needed to confirm mechanism of action and to determine whether this might be useful in weight control.

Impact of inorganic iron and haem on the human gut microbiota; An in vitro batch-culture approach.

Although iron is an essential nutrient for humans, as well as for almost all other organisms, it is poorly absorbed (~15%) from the diet such that most passes through the upper gut into the large intestine. The colonic microbiota is thus exposed to, and potentially influenced by, such residual iron which could have an impact on human health. The aim of the research described here is to determine how the major forms of dietary iron (inorganic iron and haem) influence metabolic activity and composition of the human gut microbiota by utilizing an in vitro parallel, pH-controlled anaerobic batch culture approach. Controlled iron provision was enabled by the design of a 'modified' low-iron gut-model medium whereby background iron content was reduced from 28 to 5 µM. Thus, the impact of both low and high levels of inorganic and haem iron (18-180 µM and 7.7-77 µM, respectively) could be explored. Gut-microbiota composition was determined using next generation sequencing (NGS) based community profiling (16S rRNA gene sequencing) and flow-fluorescent in situ hybridization (FISH). Metabolic-end products (organic acids) were quantified using gas chromatography (GC) and iron incorporation was estimated by inductively coupled plasma optical emission spectroscopy (ICP-OES). Results showed that differences in iron regime induced significant changes in microbiota composition when low (0.1% w/v) fecal inoculation levels were employed. An increase in haem levels from 7.7 to 77 µM (standard levels employed in gut culture studies) resulted in reduced microbial diversity, a significant increase in Enterobacteriaceae and lower short chain fatty acid (SCFA) production. These effects were countered when 18 µM inorganic iron was also included into the growth medium. The results therefore suggest that high-dietary haem may have a detrimental effect on health since the resulting changes in microbiota composition and SCFA production are indicators of an unhealthy gut. The results also demonstrate that employing a low inoculum together with a low-iron gut-model medium facilitated in vitro investigation of the relationship between iron and the gut microbiota.

Gamma aminobutyric acid production by commercially available probiotic strains.

AIMS: Certain bacteria can produce gamma aminobutyric acid (GABA) from glutamate in the human intestinal tract, leading to the possibility of altering GABA levels through diet. To this end, we assessed the ability of seven commercially available probiotic supplements to produce GABA. METHOD AND RESULTS: Probiotic strains were compared for GABA production in pure culture. The bacteria were inoculated at a concentration of 107 CFU ml-1 in 10 ml MRS supplemented with monosodium glutamate (1% w/v), both with and without oligofructose-enriched inulin (OFI) (1% w/v). Two strains with the highest production of GABA were further assessed for 48 h in pH-controlled anaerobic batch cultures inoculated with faecal bacteria. Liquid chromatography-mass spectrometry (LC-MS) was used for quantification of GABA and microbiota composition was determined through 16S rRNA gene sequencing. Levilactobacillus brevis LB01 (CGMCC 16921) and Lactiplantibacillus plantarum 299v (DSM 9843) were the most efficient producers of GABA. High GABA levels (28.32 mmol l-1 ± 0.29) were produced by the probiotic strain L. brevis LB01 at pH 5.4-5.6. This was significantly higher than the levels of GABA produced by L. plantarum (4.8 mmol l-1 ± 6.8) and a negative control (2.9 mM ± 3.1). The addition of OFI did not further stimulate GABA production under the conditions tested. The ability of these strains to produce GABA in-vitro was further evaluated in a faecal microbiota environment. Once again, L.brevis LB01 produced the highest levels of GABA (40.24 mmol l-1 ± 20.98). CONCLUSIONS: L. brevis LB01 was found to be the most efficient probiotic strain, of those tested, for GABA production.

Gut microbial modulation by culinary herbs and spices.

Culinary herbs and spices have previously been recognised for their potential impact on health through antioxidant and antimicrobial properties. They may also be promotors of positive microbial modulation by stimulating beneficial gut bacteria during fermentation, increasing the production of short chain fatty acids and thereby exhibiting a prebiotic effect. In the present paper, current literature around herb and spice consumption, gut microbiota modulation and prospective health benefits were reviewed. Herb and spice consumption can positively modulate gut microbes and possibly play an important role in inflammation related afflictions such as obesity. Current literature indicates that few human studies have been conducted to confirm the impact of herb and spice consumption on gut microbiota in connection with prospective health outcomes and inconsistencies in conclusions therefore remain.

The Potential Role of Human Milk Oligosaccharides in Irritable Bowel Syndrome.

Irritable Bowel Syndrome (IBS) is the most common gastrointestinal (GI) disorder in Western populations and therefore a major public health/economic concern. However, despite extensive research, psychological and physiological factors that contribute to the aetiology of IBS remain poorly understood. Consequently, clinical management of IBS is reduced to symptom management through various suboptimal options. Recent evidence has suggested human milk oligosaccharides (HMOs) as a potential therapeutic option for IBS. Here, we review literature concerning the role of HMOs in IBS, including data from intervention and in vitro trials. HMO supplementation shows promising results in altering the gut microbiota and improving IBS symptoms, for instance by stimulating bifidobacteria. Further research in adults is required into HMO mechanisms, to confirm the preliminary results available to date and recommendations of HMO use in IBS.

Overview of the Nomenclature and Network of Contributors to the Development of Bioreactors for Human Gut Simulation Using Bibliometric Tools: A Fragmented Landscape.

The evolution of complex in vitro models of the human gastrointestinal system to interrogate the biochemical functionality of the gut microbiome has augmented our understanding of its role in human physiology and pathology. With 5718 authors from 52 countries, gut bioreactor research reflects the growing awareness of our need to understand the contribution of the gut microbiome to human health. Although a large body of knowledge has been generated from in vitro models, it is scattered and defined by application-specific terminologies. To better grasp the capacity of bioreactors and further our knowledge of the human gastrointestinal system, we have conducted a cross-field bibliometric search and mapped the evolution of human gastrointestinal in vitro research. We present reference material with the aim of identifying key authors and bioreactor types to enable researchers to make decisions regarding the choice of method for simulating the human gut in the context of microbiome functionality.

Development of novel ultra-sensitive IL-11 target engagement assays to support mechanistic PK/PD modeling for an anti-IL-11 antibody therapeutic.

An in-house antibody generation campaign identified a diverse, high affinity set of anti-interleukin-11 (IL-11) monoclonal antibodies (mAbs) to enable successful development of novel, custom ultra-sensitive target engagement assays for detection of "free" (unbound to the dosed anti-IL-11 therapeutic mAb) and "total" (free and mAb-IL-11 complexed form) IL-11 in preclinical species and human. Antibody hits from distinct epitope communities were screened on various platforms, including enzyme-linked immunosorbent assay, Meso Scale Discovery, Simoa HD-1 and Simoa Planar Array (SP-X), and used for assay development and sensitivity optimization. The ultra-sensitive SP-X format achieved a lower limit of quantitation of 0.006 pg/mL, enabling the first reported baseline levels of IL-11 in healthy control plasma determined by custom bioanalytical assays. These newly established baseline levels supported mechanistic pharmacokinetic/pharmacodynamic modeling in mouse, cynomolgus monkey, and human for a greater understanding of preclinical study design and in vivo dynamic interaction of soluble IL-11 with an anti-IL-11 antibody therapeutic candidate. Modeling and simulation also helped refine the utility of assays with respect to their potential use as target engagement biomarkers in the clinic.Abbreviations IL-11: Interleukin-11, TE: Target engagement, PK/PD: Pharmacokinetic/pharmacodynamic, mAb: Monoclonal antibody, NHP: Non-human primate, IgG: Immunoglobulin G, Cyno: Cynomolgulus monkey, GFR: Glomerular filtration rate, BQL: Below quantitation levels, DRM: Disease relevant model, kDa: kilodaltons, SPR: Surface plasmon resonance, pSTAT3: phosphorylated STAT3, IL-11R: Interleukin-11 receptor, TPP: Target product protein, LLOQ: Lower limit of quantitation, RLU: Relative light units.

Systematic Review of the Effects of Exercise and Physical Activity on the Gut Microbiome of Older Adults.

Recent evidence suggests that exercise/physical activity (PA) can beneficially alter the gut microbiome composition of young people, but little is known about its effects in older adults. The aim of this systematic review was to summarize results of human studies that have assessed the effects/associations of PA/exercise on the gut microbiome of older adults and to better understand whether this can help promote healthy ageing. Seven studies were included in the review and overall, exercise and increased amounts of PA were associated with decreases in the abundance of several well-known harmful taxa and increases in the abundance of health-promoting taxa. Altogether, the findings from the included studies suggest that exercise/PA have a beneficial impact on the gut health of older adults by improving the gut microbiome composition. However, due to methodological and sampling disparities, it was not possible to reach a consensus on which taxa were most affected by exercise or PA.

Commentary on: prebiotic effects: metabolic and health benefits.

In 2010, British Journal of Nutrition published a consensus review article entitled Prebiotic effects: metabolic and health benefits(1). This was commissioned by International Life Sciences Institute, Europe and had twenty-one co-authors. The current article summarises how this review was planned and written. It deals with three questions regarding the context/background of the paper; what it told us and what happened next.

Development of a prebiotic blend to influence in vitro fermentation effects, with a focus on propionate, in the gut.

Short chain fatty acids (SCFAs) derived from the human gut microbiota, and in particular propionate, may beneficially influence metabolic processes such as appetite regulation. Development of prebiotics that induce high propionate levels during fermentation is desirable. A total of 11 candidate prebiotics were screened to investigate their fermentation characteristics, with a focus on propionate production in mixed anaerobic batch culture of faecal bacteria. Further to this, a continuous 3-stage colonic fermentation model (simulating the human colon) was used to evaluate changes in microbial ecology, lactate and SCFA production of three 50:50 blends, comprising both slow and rapidly fermented prebiotics. In mixed batch culture: xylo-oligosaccharide, polydextrose and α-gluco-oligosaccharide were associated with the greatest increase in propionate. Polydextrose, α-gluco-oligosaccharide, ß-1,4 glucan and oat fibre induced the greatest reductions in the acetate to propionate ratio. The most bifidogenic prebiotics were the oligosaccharides. Fermentation of a 50:50 blend of inulin and arabinoxylan, through the continuous 3-stage colonic fermentation model, induced a substantial and sustained release of propionate. The sustained release of propionate through the colon, if replicable in vivo, could potentially influence blood glucose, blood lipids and appetite regulation, however, dietary intervention studies are needed. Bifidogenic effects were also observed for the inulin and arabinoxylan blend and an increase synthesis of butyrate and lactate, thus indicating wider prebiotic potential.

Psychobiotic interventions for anxiety in young people: a systematic review and meta-analysis, with youth consultation.

The human gut microbiome influence on brain function and mental health is an emerging area of intensive research. Animal and human research indicates adolescence as a sensitive period when the gut-brain axis is fine-tuned, where dietary interventions to change the microbiome may have long-lasting consequences for mental health. This study reports a systematic review and meta-analysis of microbiota-targeted (psychobiotics) interventions on anxiety in youth, with discussion of a consultation on the acceptability of psychobiotic interventions for mental health management amongst youth with lived experience. Six databases were searched for controlled trials in human samples (age range: 10-24 years) seeking to reduce anxiety. Post intervention outcomes were extracted as standard mean differences (SMDs) and pooled based on a random-effects model. 5416 studies were identified: 14 eligible for systematic review and 10 eligible for meta-analysis (total of 324 experimental and 293 control subjects). The meta-analysis found heterogeneity I2 was 12% and the pooled SMD was -0.03 (95% CI: -0.21, 0.14), indicating an absence of effect. One study presented with low bias risk, 5 with high, and 4 with uncertain risk. Accounting for risk, sensitivities analysis revealed a SMD of -0.16 (95% CI: -0.38, 0.07), indicative of minimal efficacy of psychobiotics for anxiety treatment in humans. There is currently limited evidence for use of psychobiotics to treat anxiety in youth. However, future progress will require a multidisciplinary research approach, which gives priority to specifying mechanisms in the human models, providing causal understanding, and addressing the wider context, and would be welcomed by anxious youths.

Impact of dietary supplementation with resistant dextrin (NUTRIOSE®) on satiety, glycaemia, and related endpoints, in healthy adults.

PURPOSE: Resistant dextrin (RD) supplementation has been shown to alter satiety, glycaemia, and body weight, in overweight Chinese men; however, there are limited data on its effects in other demographic groups. Here, we investigated the effects of RD on satiety in healthy adults living in the United Kingdom. METHODS: 20 normal weight and 16 overweight adults completed this randomised controlled cross-over study. Either RD (14 g/day NUTRIOSE® FB06) or maltodextrin control was consumed in mid-morning and mid-afternoon preload beverages over a 28-day treatment period with crossover after a 28-day washout. During 10-h study visits (on days 1, 14, and 28 of each treatment period), satietogenic, glycaemic and anorectic hormonal responses to provided meals were assessed. RESULTS: Chronic supplementation with RD was associated with higher fasted satiety scores at day 14 (P = 0.006) and day 28 (P = 0.040), compared to control. RD also increased satiety after the mid-morning intervention drink, but it was associated with a reduction in post-meal satiety following both the lunch and evening meals (P < 0.01). The glycaemic response to the mid-morning intervention drink (0-30 min) was attenuated following RD supplementation (P < 0.01). Whilst not a primary endpoint we also observed lower systolic blood pressure at day 14 (P = 0.035) and 28 (P = 0.030), compared to day 1, following RD supplementation in the normal weight group. Energy intake and anthropometrics were unaffected. CONCLUSIONS: RD supplementation modified satiety and glycaemic responses in this cohort, further studies are required to determine longer-term effects on body weight control and metabolic markers. CLINICALTRIALS. GOV REGISTRATION: NCT02041975 (22/01/2014).

Assessment of stool collection and storage conditions for in vitro human gut model studies.

BACKGROUND: The role of the gut microbiota in health and disease is becoming increasingly apparent. Faeces is the most accessible sample to collect from human volunteers for studying the gut microbiota. However, the impact of stool collection and storage conditions on microbial and metabolic profiles have not been fully evaluated. By understanding the effect of different stool collection and storage conditions on microbial and metabolic composition, we can consider these parameters in the design of in vitro fermentation studies. METHODS: Stool samples from 3 volunteers were stored under 5 different conditions to mimic methods that researchers may use to collect and store stool samples for study of the gut microbiota, including: fresh sample used within 10 min; stored on wet ice (4 °C) for 60 min; stored in an anaerobic chamber in a temperature-controlled bag (4 °C) for 60 min; freezing at -20 °C for 60 min and freezing at -20 °C for 60 min and then at -80 °C for 2 weeks. The stored samples were added to basal medium in batch culture fermenters alone (negative control) or with 5 g 2'-Fucosyllactose (2'FL) Human Milk Oligosaccharide (HMO) (as a positive fermentation control). Samples were collected at 3 timepoints (0, 12 and 24 h) for analysis by Flow Cytometry-Fluorescent In Situ Hybridisation (FC-FISH) and 1H-Nuclear Magnetic Resonance (NMR) spectroscopy to assess the impact on microbial and metabolic profiles, respectively. RESULTS: Freezing stool significantly impacted microbial numbers and activity during in vitro fermentations, whereas storing the stool on wet ice (4 °C) or in an anaerobic chamber at 4 °C for 60 min had minimal effects on microbial and metabolic profiles throughout the 24 h batch culture fermentation experiments. DISCUSSION: For in vitro batch culture fermentation studies where it may not be practical or possible to use fresh stool, either storing the stool on wet ice (4 °C) or in an anaerobic chamber at 4 °C for 60 min could be plausible alternatives to maintain microbial and metabolic profiles for analysis.

Amino Acid Formula Containing Synbiotics in Infants with Cow's Milk Protein Allergy: A Systematic Review and Meta-Analysis.

Cow's milk protein allergy (CMPA) is associated with dysbiosis of the infant gut microbiome, with allergic and immune development implications. Studies show benefits of combining synbiotics with hypoallergenic formulae, although evidence has never been systematically examined. This review identified seven publications of four randomised controlled trials comparing an amino acid formula (AAF) with an AAF containing synbiotics (AAF-Syn) in infants with CMPA (mean age 8.6 months; 68% male, mean intervention 27.3 weeks, n = 410). AAF and AAF-Syn were equally effective in managing allergic symptoms and promoting normal growth. Compared to AAF, significantly fewer infants fed AAF-Syn had infections (OR 0.35 (95% CI 0.19-0.67), p = 0.001). Overall medication use, including antibacterials and antifectives, was lower among infants fed AAF-Syn. Significantly fewer infants had hospital admissions with AAF-Syn compared to AAF (8.8% vs. 20.2%, p = 0.036; 56% reduction), leading to potential cost savings per infant of £164.05-£338.77. AAF-Syn was associated with increased bifidobacteria (difference in means 31.75, 95% CI 26.04-37.45, p < 0.0001); reduced Eubacterium rectale and Clostridium coccoides (difference in means -19.06, 95% CI -23.15 to -14.97, p < 0.0001); and reduced microbial diversity (p < 0.05), similar to that described in healthy breastfed infants, and may be associated with the improved clinical outcomes described. This review provides evidence that suggests combining synbiotics with AAF produces clinical benefits with potential economic implications.

Impact of 2'-Fucosyllactose on Gut Microbiota Composition in Adults with Chronic Gastrointestinal Conditions: Batch Culture Fermentation Model and Pilot Clinical Trial Findings.

Intestinal dysbiosis has been described in patients with certain gastrointestinal conditions including irritable bowel syndrome (IBS) and ulcerative colitis. 2'-fucosyllactose (2'-FL), a prebiotic human milk oligosaccharide, is considered bifidogenic and butyrogenic. To assess prebiotic effects of 2'-FL, alone or in combination with probiotic strains (potential synbiotics), in vitro experiments were conducted on stool from healthy, IBS, and ulcerative colitis adult donors. In anaerobic batch culture fermenters, Bifidobacterium and Eubacterium rectale-Clostridium coccoides counts, and short-chain fatty acids (SCFAs) including butyrate increased during fermentation with 2'-FL and some of the 2'-FL/probiotic combinations. In a subsequent open-label pilot trial, the effect of a 2'-FL-containing nutritional formula was evaluated in twelve adults with IBS or ulcerative colitis. Gastrointestinal Quality of Life Index (GIQLI) total and gastrointestinal symptoms domain scores, stool counts of Bifidobacterium and Faecalibacterium prausnitzii, and stool SCFAs including butyrate, increased after six weeks of intervention. Consistent with documented effects of 2'-FL, the batch culture fermentation experiments demonstrated bifidogenic and butyrogenic effects of 2'-FL during fermentation with human stool samples. Consumption of the 2'-FL-containing nutritional formula by adults with IBS or ulcerative colitis was associated with improvements in intra- and extra-intestinal symptoms, and bifidogenic and butyrogenic effects.

Shaping the Future of Probiotics and Prebiotics.

Recent and ongoing developments in microbiome science are enabling new frontiers of research for probiotics and prebiotics. Novel types, mechanisms, and applications currently under study have the potential to change scientific understanding as well as nutritional and healthcare applications of these interventions. The expansion of related fields of microbiome-targeted interventions, and an evolving landscape for implementation across regulatory, policy, prescriber, and consumer spheres, portends an era of significant change. In this review we examine recent, emerging, and anticipated trends in probiotic and prebiotic science, and create a vision for broad areas of developing influence in the field.