Effects of β-Fructans Fiber on Bowel Function: A Systematic Review and Meta-Analysis

Effect of prebiotic oligosaccharides on bowel habit and the gut microbiota in children with functional constipation (Inside study): study protocol for a randomised, placebo-controlled, multi-centre trial

BACKGROUND

Functional constipation (FC) in children is a common gastrointestinal disorder with a worldwide-pooled prevalence of 9.5%. Complaints include infrequent bowel movements, painful defecation due to hard and/or large stools, faecal incontinence, and abdominal pain. Prebiotic oligosaccharides have been shown to relieve constipation symptoms in young adults and elderly. However, sufficient evidence is lacking linking additional prebiotic intake to improve symptoms in children with FC. We hypothesise that prebiotic oligosaccharides are able to relieve symptoms of constipation in young children as well.

METHODS

In the present randomised, double-blind, placebo-controlled, multi-centre study, we will study the effects of two prebiotic oligosaccharides in comparison to placebo on constipation symptoms in children of 1-5 years (12 to 72 months) of age diagnosed with FC according to the Rome IV criteria for functional gastrointestinal disorders. The primary outcome measure will be change in stool consistency. Secondary outcomes include stool frequency and stool consistency in a number of cases (%). Tertiary outcomes include among others painful defecation, use of rescue medication, and quality of life. In addition, the impact on gut microbiome outcomes such as faecal microbiota composition and metabolites will be investigated. Participants start with a run-in period, after which they will receive supplements delivered in tins with scoops for 8 weeks, containing one of the two prebiotic oligosaccharides or placebo, followed by a 4-week wash-out period.

DISCUSSION

This randomised double-blind, placebo-controlled multi-centre study will investigate the effectiveness of prebiotic oligosaccharides in children aged 1-5 years with FC.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04282551. Registered on 24 February 2020.

Effect of chicory-derived inulin-type fructans on abundance of Bifidobacterium and on bowel function: a systematic review with meta-analyses

Inulin-type fructans are considered to stimulate the growth of beneficial microorganisms, like Bifidobacterium in the gut and support health. However, both the fructan source and chemical structure may modify these effects. A systematic review was conducted to assess the effects of chicory-derived inulin-type fructans consumed either in specific foods or as dietary supplements on abundance of Bifidobacterium in the gut and on health-related outcomes. Three electronic databases and two clinical trial registries were systematically searched until January 2021. Two authors independently selected randomized controlled trials that investigated with a protocol of minimum seven days supplementation the effect of chicory-derived inulin-type fructans on Bifidobacterium abundance in any population. Meta-analyses with random-effects model were conducted on Bifidobacterium abundance and bowel function parameters. We evaluated risk of bias using Cochrane RoB tool. Chicory-derived inulin-type fructans at a dose of 3-20 g/day significantly increased Bifidobacterium abundance in participants with an age range from 0 to 83 years (standardized mean difference: 0.83, 95% CI: 0.58-1.08; p < 0.01; 50 studies; 2525 participants). Significant bifidogenic effects were observed in healthy individuals and in populations with health impairments, except gastrointestinal disorders. Significant beneficial effects on bowel function parameters were observed in healthy subjects. Chicory-derived inulin-type fructans may have significant bifidogenic effects and may beneficially influence bowel function in healthy individuals. PROSPERO registration number CRD42020162892.

Preparation, Structural Characterisation, and Bioactivities of Fructans: A Review

Polysaccharides are important components of higher plants and have attracted increasing attention due to their many nutraceutical benefits in humans. Fructans, heterogeneous fructose polymers that serve as storage carbohydrates in various plants, represent one of the most important types of natural polysaccharides. Fructans have various physiological and therapeutic effects, which are beneficial to health, and have the ability to prevent or treat various diseases, allowing their wide use in the food, nutraceutical, and pharmaceutical industries. This article reviews the occurrence, metabolism, preparation, characterisation, analysis, and bioactivity of fructans. Further, their molecular weight, monosaccharide composition, linkages, and structural determination are described. Taken together, this review provides a theoretical foundation for further research into the structure-function relationships of fructans, as well as valuable new information and directions for further research and application of fructans in functional foods.

Potential benefits of using an energy-dense, high-protein formula enriched with β-hydroxy-β-methylbutyrate, fructo-oligosaccharide, and vitamin D for enteral feeding in the ICU: A pilot case-control study in COVID-19 patients

OBJECTIVES

The aim of this study was to investigate the potential benefits of using an energy-dense, high-protein (HP) formula enriched with β-hydroxy-β-methylbutyrate (HMB), fructo-oligosaccharide (FOS), and vitamin D (VitD) for enteral feeding in the intensive care unit (ICU).

METHODS

This was a nested case-control multicenter study. Mechanically ventilated patients with COVID-19 in whom enteral nutrition was not contraindicated and receiving an energy-dense, HP-HMB-FOS-VitD formula (1.5 kcal/mL; 21.5% of calories from protein; n = 53) were matched (1:1) by age (±1 y), sex, body mass index (±1 kg/m²) and Sequential Organ Failure Assessment score (±1 point) and compared with patients fed with a standard HP, fiber-free formula (1.25-1.3 kcal/mL; 20% of calories from protein; n = 53). The primary end point was daily protein intake (g/kg) on day 4. Protein-calorie intake on day 7, gastrointestinal intolerance, and clinical outcomes were addressed as secondary end points.

RESULTS

The use of a HP-HMB-FOS-VitD formula resulted in higher protein intake on days 4 and 7 (P = 0.006 and P = 0.013, respectively), with similar energy intake but higher provision of calories from enteral nutrition at both times (P <0 .001 and P = 0.017, respectively). Gastrointestinal tolerance was superior, with fewer patients fed with a HP-HMB-FOS-VitD formula reporting at least one symptom of intolerance (55 versus 74%; odds ratio [OR], 0.43; 95% confidence interval [CI], 0.18-0.99; P = 0.046) and constipation (38 versus 66%; OR, 0.27; 95% CI, 0.12-0.61; P = 0.002). A lower rate of ICU-acquired infections was also observed (42 versus 72%; OR, 0.29; 95% CI, 0.13-0.65; P = 0.003), although no difference was found in mortality, ICU length of stay, and ventilation-free survival.

CONCLUSIONS

An energy-dense, HP-HMB-FOS-VitD formula provided a more satisfactory protein intake and a higher provision of caloric intake from enteral nutrition than a standard HP formula in mechanically ventilated patients with COVID-19. Lower rates of gastrointestinal intolerance and ICU-acquired infections were also observed.

The effect of multistrain probiotics on functional constipation in the elderly: a randomized controlled trial

BACKGROUND AND OBJECTIVES

Constipation is one of the most common gastrointestinal conditions, particularly among older individuals. This study aimed to evaluate the efficacy and safety of selected multistrain probiotics on functional constipation and laboratory blood parameters in the elderly living in a nursing home.

SUBJECTS AND METHODS

Sixty participants (42 females and 18 males) aged 77.9 ± 8.84 years with functional constipation, who met the eligibility criteria, completed the study. In a double-blind, placebo-controlled, parallel design, each participant was randomized to receive either the selected probiotic mixture (N = 28) or placebo (N = 32) for 12 weeks as an adjunct to their usual diet and medications. The liquid probiotic formulation containing Bifidobacterium animalis subsp. lactis BLC1, Lactobacillus acidophilus LA3 and Lactobacillus casei BGP93 was tested for the first time.

RESULTS

Supplementation of selected probiotics resulted in a slight but nonsignificant increase in cumulative stool frequency compared with placebo. However, after the 71st day of the treatment, the cumulative number of stools was significantly higher in the probiotic group (P < 0.05) when the influence of laxative was excluded. The trend towards an increase in the difference between the two groups, which began 1 week after the probiotic intervention, pointed out to their prolonged effect. There were no significant dependent or independent effects of treatment and time on most of the 27 laboratory blood parameters tested.

CONCLUSIONS

Multistrain probiotic supplementation was found to be efficacious, safe and well tolerated in the elderly with functional constipation.

Natural Variation in the Content and Degree of Polymerization of Fructans in Wheat: Potential for Selection of Genotypes with Beneficial Health Composition

Fructans are important biocompounds because of their health-promoting effects as dietary fiber and prebiotics and also because of their harmful effects as fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAP) particularly in people suffering from irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD), and recently as potential triggers of non-celiac wheat/gluten sensitivity. In this work, we have analyzed the fructan contents as well as its degree of polymerization (DP) in a genetically diverse set of wheat varieties, modern and landraces, from different commonly consumed species (N = 124). A significant variation in fructan contents within and between species was observed, with the following relationship: Triticum aestivum (Landraces) > Triticum aestivum (Modern) ≥ Triticum turgidum (Modern) = T. turgidum (Landraces) ≥ Triticum spelta. In addition, a substantial part of the fructans (>50%) showed a DP ≤ 6. Considering that wheat is a major source of fructans, our results can contribute to a better nutritional management of our diets and be a basis for targeted wheat breeding to alter fructan contents.

A comparative study between Fusarium solani and Neocosmospora vasinfecta revealed differential profile of fructooligosaccharide production

Fructooligosaccharides (FOS) are fructose-based oligosaccharides employed as additives to improve the food's nutritional and technological properties. The rhizosphere of plants that accumulate fructopolysaccharides as inulin has been revealed as a source of filamentous fungi. These fungi can produce FOS either by inulin hydrolysis or by biosynthesis from sucrose, including unusual FOS with enhanced prebiotic properties. Here, we investigated the ability of Fusarium solani and Neocosmospora vasinfecta to produce FOS from different carbon sources. Fusarium solani and N. vasinfecta grew preferentially in inulin instead of sucrose, resulting in the FOS production as the result of endo-inulinase activities. N. vasinfecta was also able to produce the FOS 1-kestose and 6-kestose from sucrose, indicating transfructosylating activity, absent in F. solani. Moreover, the results showed how these carbon sources affected fungal cell wall composition and the expression of genes encoding for β-1,3-glucan synthase and chitin synthase. Inulin and fructose promoted changes in fungal macroscopic characteristics partially explained by alterations in cell wall composition. However, these alterations were not directly correlated with the expression of genes related to cell wall synthesis. Altogether, the results pointed to the potential of both F. solani and N. vasinfecta to produce FOS at specific profiles.

Structure and function of non-digestible carbohydrates in the gut microbiome

Together with proteins and fats, carbohydrates are one of the macronutrients in the human diet. Digestible carbohydrates, such as starch, starch-based products, sucrose, lactose, glucose and some sugar alcohols and unusual (and fairly rare) α-linked glucans, directly provide us with energy while other carbohydrates including high molecular weight polysaccharides, mainly from plant cell walls, provide us with dietary fibre. Carbohydrates which are efficiently digested in the small intestine are not available in appreciable quantities to act as substrates for gut bacteria. Some oligo- and polysaccharides, many of which are also dietary fibres, are resistant to digestion in the small intestines and enter the colon where they provide substrates for the complex bacterial ecosystem that resides there. This review will focus on these non-digestible carbohydrates (NDC) and examine their impact on the gut microbiota and their physiological impact. Of particular focus will be the potential of non-digestible carbohydrates to act as prebiotics, but the review will also evaluate direct effects of NDC on human cells and systems.

A high-fibre personalised dietary advice given via a web tool reduces constipation complaints in adults

Constipation can greatly impact the quality of life (QoL), which can be relieved by dietary fibres; however, preserving a higher fibre intake remains a challenge. We investigated the effects of a personalised dietary advice (PDA) on fibre intake and mild constipation complaints. A total number of twenty-five adults with mild constipation complaints were included in a 4-week observation period followed by a 4-week personalised intervention. The PDA provided high-fibre alternatives via a web tool. In weeks 1, 4 and 8, dietary intake, constipation complaints and QoL were assessed. Furthermore, participants collected a faecal sample at weeks 1, 4 and 8 to determine microbiota diversity and composition, and short-chain fatty acids (SCFA). Participants completed questions daily for 8 weeks regarding abdominal complaints, stool frequency and stool consistency. Fibre intake in week 8 was significantly higher compared to week 1 (Δ = 5·7 ± 6·7 g, P < 0·001) and week 4 (Δ = 5·2 ± 6·4 g, P < 0·001). Constipation severity and QoL significantly improved at week 8 compared to the observation period (P < 0·001). A higher fibre intake significantly reduced constipation severity (β = -0·031 (-0·05; -0·01), P = 0·001) and the QoL (β = -0·022 (-0·04; -0·01), P = 0·009). Stool consistency (P = 0·040) and abdominal pain (P = 0·030) improved significantly during the intervention period (P = 0·040), but stool frequency did not. Average microbial alpha diversity and composition and SCFA concentrations did not change over time, but indicated individual-specific dynamics. Several SCFAs were associated with constipation complaints. To conclude, a PDA effectively increased fibre intake and subsequently reduced constipation complaints, indicating that guided dietary adjustments are important and feasible in the treatment of mild constipation complaints.

Gastrointestinal Tolerance of Short-Chain Fructo-Oligosaccharides from Sugar Beet: An Observational, Connected, Dose-Ranging Study in Healthy Volunteers

Dietary fibres are important in the human diet with multiple health benefits. This study aimed to determine the gastrointestinal tolerance of short-chain fructo-oligosaccharides (scFOS), well-known prebiotic fibres, at doses up to 40 g/d. An observational, connected, dose-ranging trial was conducted in 116 healthy volunteers. During the first week, the participants were instructed to consume their usual diet. During the second week, half of the subjects consumed 15 g scFOS per day, and the other half consumed 20 g scFOS per day. For the third week, the scFOS dose was doubled for all subjects. Gastrointestinal symptom severity was reported daily, as well as stool consistency and frequency. The results show that scFOS are well tolerated up to 40 g/d; all reported symptoms remained very mild from a clinical perspective. Stool consistency stayed normal, between 3 and 5 on the Bristol stool scale, confirming that no diarrhoea appeared after scFOS intake. Stool frequency also remained within the normal range. In conclusion, scFOS intake is well tolerated up to 40 g/d in healthy subjects. Thanks to their short chains and unique composition, scFOS prebiotic fibres are much better tolerated than other types of inulin-type fructans with longer chains. The digestive tolerance of fibres should be considered when added to foods and beverages.

Chronic constipation in adults: Contemporary perspectives and clinical challenges. 2: Conservative, behavioural, medical and surgical treatment

BACKGROUND

Chronic constipation is a prevalent disorder that affects quality of life of patients and consumes resources in healthcare systems worldwide. In clinical practice, it is still considered a challenge as clinicians frequently are unsure as to which treatments to use and when. Over a decade ago, a Neurogastroenterology and Motility journal supplement devoted to the investigation and management of constipation was published (Neurogastroenterol Motil 2009;21(Suppl 2):1). In October 2018, the 3rd London Masterclass, entitled "Contemporary management of constipation" was held. The faculty members of this symposium were invited to write two reviews to present a collective synthesis of talks presented and discussions held during this meeting. The first review addresses epidemiology, diagnosis, clinical associations, pathophysiology, and investigation.

PURPOSE

The present is the second of these reviews, providing contemporary perspectives and clinical challenges regarding behavioral, conservative, medical, and surgical treatments for patients presenting with constipation. It includes a management algorithm to guide clinical practice.

Impact of Cashew (Anacardium occidentale L.) by-Product on Composition and Metabolic Activity of Human Colonic Microbiota In Vitro Indicates Prebiotic Properties

Cashew apple by-product (CAB) is an important agro-industrial waste still underutilized, although it has been characterized as source of a variety of nutrients and bioactive compounds. This study evaluated the capability of freeze-dried CAB (FCAB) submitted to a simulated gastrointestinal digestion of inducing changes in relative abundance of distinct microbial groups found as part of human colonic microbiota, as well as in pH and short-chain fatty acid production during a 24-h in vitro fermentation using a pooled human fecal inocula. FCAB increased the relative abundance of Bifidobacterium and Lactobacillus/Enterococcus during colonic fermentation, besides to decrease the relative abundance of Bacteroides/Prevotella, Eubacterium rectale/Clostridium coccoides, and Clostridium histolyticum. FCAB increased the counts of lactic acid bacteria and decreased the counts of Enterobacteriaceae during colonic fermentation. Furthermore, FCAB decreased pH and increased the production of short-chain fatty acids in colonic fermentation media. These effects could be linked to contents of dietary fibers and the presence of fructans and different phenolic compounds found in FCAB. These results showed that FCAB induced positive alterations in composition and metabolic activity of human colonic microbiota in vitro, which indicate prebiotic properties.

Flexibility of Gut Microbiota in Ageing Individuals during Dietary Fiber Long-Chain Inulin Intake

SCOPE

During ageing, dysbiosis in the intestinal microbiota may occur and impact health. There is a paucity of studies on the effect of fiber on the elderly microbiota and the flexibility of the aged microbiota upon prebiotic intake. It is hypothesized that chicory long-chain inulin consumption can change microbiota composition, microbial fermentation products, and immunity in the elderly.

METHODS AND RESULTS

A double-blind, placebo-controlled trial is performed in healthy individuals (55-80 years), in which microbiota composition is studied before, during, and after two months of chicory long-chain inulin consumption. Fecal short chain fatty acid concentrations, T cell subsets, and antibody responses against a Hepatitis B (HB) vaccine are measured as well. Inulin consumption modified the microbiota composition, as measured by 16S rRNA sequencing. Participants consuming inulin have higher microbial diversity and a relatively higher abundance of the Bifidobacterium genus, as well as Alistipes shahii, Anaerostipes hadrus, and Parabacteroides distasonis. While the immune responses remain unchanged, the isobutyric acid levels, an undesired fermentation product, tend to be lower in the inulin group.

CONCLUSIONS

Overall, it is shown that the gut microbiota composition is still sensitive to chicory long-chain inulin induced changes in an ageing population, although this did not translate into an improved immune response to an HB vaccine.

Effects of Low and High FODMAP Diets on Human Gastrointestinal Microbiota Composition in Adults with Intestinal Diseases: A Systematic Review

A diet high in non-digestible carbohydrates is known to promote health, in part through its effect on the gut microbiome. While substantially proven for healthy individuals, these effects are more ambiguous in subjects with intestinal diseases. At the same time, a diet low in these fermentable carbohydrates, the low FODMAP (acronym for Fermentable Oligo-, Di-, Mono-saccharides, And Polyols) diet, is gaining popularity as a treatment option for symptom relief in irritable bowel syndrome and inflammatory bowel disease. There are, however, several indications that this diet induces effects opposite to those of prebiotic supplementation, resulting in gut microbiome changes that might be detrimental. Here, we provide a systematic review of the effects of low and high FODMAP diets on human gastrointestinal microbiota composition in adults with intestinal diseases, through literature screening using the databases PubMed, Embase, and Web of Science. We summarize study findings on dietary impact in patients, including the effect on bacterial taxa and diversity. In general, similar to healthy subjects, restricting non-digestible carbohydrate intake in patients with intestinal diseases has opposite effects compared to prebiotic supplementation, causing a reduction in bifidobacteria and an increase in bacteria associated with dysbiosis. Future studies should focus on assessing whether the induced microbial changes persist over time and have adverse effects on long-term colonic health.

Effectiveness of Fiber Supplementation for Constipation, Weight Loss, and Supporting Gastrointestinal Function: A Narrative Review of Meta-Analyses

Objective

The purpose of this narrative review is to determine whether published meta-analyses support the use of fiber supplementation in the treatment of constipation, weight loss, and dietary support for gastrointestinal disorders such as irritable bowel syndrome (IBS) and inflammatory bowel disease.

Methods

A PubMed search from January 1, 1980, to July 31, 2019, was conducted with the following search strategy: (fiber OR fibre) AND (meta-analysis OR systematic review) AND (constipation OR body weight OR obesity OR irritable bowel syndrome OR inflammatory bowel disease). Meta-analyses that provided quantitative statistical analysis with a measured effect size were retrieved and accepted into this review. The following was extracted and entered into an Excel spreadsheet: number of publications included in the meta-analysis, number of total participants, fiber type and daily dose, pooled treatment effects for clinical endpoints, or summary relative risks.

Results

Eighteen meta-analyses support dietary fiber supplementation for patients with constipation, weight loss, and IBS, but the significant heterogeneity and publication bias undermine the support for using dietary fiber supplementation in these conditions.

Conclusion

This narrative review of meta-analyses finds some benefits for recommending fiber supplementation to patients with constipation, obesity, and IBS, but significant heterogeneity and publication bias undermine this support.

Effect of chicory inulin-type fructan-containing snack bars on the human gut microbiota in low dietary fiber consumers in a randomized crossover trial

BACKGROUND

The low intake of dietary fiber compared to recommended amounts has been referred to as the dietary fiber gap. The addition of fiber to snack foods could favorably alter gut microbiota and help individuals meet intake recommendations.

OBJECTIVES

Our objective was to examine the effect of low- and moderate-dose fiber-containing snack bars, comprising mainly chicory root inulin-type fructans (ITF), on gut microbiota in healthy adults with habitual low dietary fiber intake using 16S ribosomal RNA-based approaches.

METHODS

In 2 separate 4-wk, placebo-controlled, double-blind, crossover trials, 50 healthy adults with low dietary fiber intake were randomly assigned to receive isocaloric snack bars of either moderate-dose fiber (7 g/d) or control in Trial 1 (n = 25) or low-dose fiber (3 g/d) or control in Trial 2 (n = 25), with 4-wk washout periods. Fecal microbiota composition and inferred function, fecal SCFA concentration, gastrointestinal (GI) symptoms, dietary intake, and quality of life were measured.

RESULTS

Compared with the control group, the moderate-dose group showed significant differences across multiple microbial taxa, most notably an increased relative abundance of the Bifidobacterium genus from (mean ± SEM) 5.3% ± 5.9% to 18.7% ± 15.0%. With low-dose ITF, significant increases in Bifidobacterium were no longer present after correction for multiple comparisons but targeted analysis with qPCR showed a significant increase in Bifidobacterium. Predictive functional profiling identified changes in predicted function after intake of the moderate- but not the low-dose bar. Fecal SCFAs were affected by time but not treatment. There were no between-group differences in GI symptoms. Importantly, fiber intake increased significantly with the moderate- and low-dose bars.

CONCLUSIONS

In healthy adults, adding 3 or 7 g ITF to snack bars increased Bifidobacterium, a beneficial member of the gut microbial community. The addition of ITF to food products could help reduce the dietary fiber gap prevalent in modern life.This trial was registered at clinicaltrials.gov as NCT03042494.

Applying Differential Neural Networks to Characterize Microbial Interactions in an Ex Vivo Gastrointestinal Gut Simulator

The structure of mixed microbial cultures—such as the human gut microbiota—is influenced by a complex interplay of interactions among its community members. The objective of this study was to propose a strategy to characterize microbial interactions between particular members of the community occurring in a simulator of the human gastrointestinal tract used as the experimental system. Four runs were carried out separately in the simulator: two of them were fed with a normal diet (control system), and two more had the same diet supplemented with agave fructans (fructan-supplemented system). The growth kinetics of Lactobacillus spp., Bifidobacterium spp., Salmonella spp., and Clostridium spp. were assessed in the different colon sections of the simulator for a nine-day period. The time series of microbial concentrations were used to estimate specific growth rates and pair-wise interaction coefficients as considered by the generalized Lotka-Volterra (gLV) model. A differential neural network (DNN) composed of a time-adaptive set of differential equations was applied for the nonparametric identification of the mixed microbial culture, and an optimization technique was used to determine the interaction parameters, considering the DNN identification results and the structure of the gLV model. The assessment of the fructan-supplemented system showed that microbial interactions changed significantly after prebiotics administration, demonstrating their modulating effect on microbial interactions. The strategy proposed here was applied satisfactorily to gain quantitative and qualitative knowledge of a broad spectrum of microbial interactions in the gut community, as described by the gLV model. In the future, it may be utilized to study microbial interactions within mixed cultures using other experimental approaches and other mathematical models (e.g., metabolic models), which will yield crucial information for optimizing mixed microbial cultures to perform certain processes—such as environmental bioremediation or modulation of gut microbiota—and to predict their dynamics.

Interactions of probiotics and prebiotics with the gut microbiota

The gut microbiota (GM) composition varies among individuals and is influenced by intrinsic (genetics, age) and extrinsic (environment, diet, lifestyle) factors. An imbalance or dysbiosis is directly associated with the development of several illnesses, due to the potential increase in intestinal permeability leading to a systemic inflammation triggered by higher levels of circulating lipopolysaccharides and changes in the immune response caused by an overgrowth of a specific genus or of pathogens. These mechanisms may increase symptoms in gastrointestinal disorders or reduce glucose tolerance in metabolic diseases. Diet also has a significant impact on GM, and functional foods, namely prebiotics and probiotics, are a novel approach to reestablish the indigenous microbiota. Prebiotics, like inulin and polyphenols, are selectively utilized by GM, releasing short-chain fatty acids (SCFA) and other metabolites which may reduce the intestinal lumen pH, inhibit growth of pathogens, and enhance mineral and vitamin bioavailability. Probiotic microorganism may increase the microbial diversity of GM and improve the integrity of the intestinal barrier, leading to an improvement of baseline and pathologic inflammation. In this chapter, we will discuss the potential roles of prebiotics and probiotics in health and diseases throughout an individual's lifetime and proposed mechanisms of action.

Effect of fructans, prebiotics and fibres on the human gut microbiome assessed by 16S rRNA-based approaches: a review

The inherent and diverse capacity of dietary fibres, nondigestible oligosaccharides (NDOs) and prebiotics to modify the gut microbiota and markedly influence health status of the host has attracted rising interest. Research and collective initiatives to determine the composition and diversity of the human gut microbiota have increased over the past decade due to great advances in high-throughput technologies, particularly the 16S ribosomal RNA (rRNA) sequencing. Here we reviewed the application of 16S rRNA-based molecular technologies, both community wide (sequencing and phylogenetic microarrays) and targeted methodologies (quantitative PCR, fluorescent in situ hybridisation) to study the effect of chicory inulin-type fructans, NDOs and specific added fibres, such as resistant starches, on the human intestinal microbiota. Overall, such technologies facilitated the monitoring of microbiota shifts due to prebiotic/fibre consumption, though there are limited community-wide sequencing studies so far. Molecular studies confirmed the selective bifidogenic effect of fructans and galactooligosaccharides (GOS) in human intervention studies. Fructans only occasionally decreased relative abundance of Bacteroidetes or stimulated other groups. The sequencing studies for various resistant starches, polydextrose and beta-glucan showed broader effects with more and different types of gut microbial species being enhanced, often including phylotypes of Ruminococcaceae. There was substantial variation in terms of magnitude of response and in individual responses to a specific fibre or NDO which may be due to numerous factors, such as initial presence and relative abundance of a microbial type, diet, genetics of the host, and intervention parameters, such as intervention duration and fibre dose. The field will clearly benefit from a more systematic approach that will support defining the impact of prebiotics and fibres on the gut microbiome, identify biomarkers that link gut microbes to health, and address the personalised response of an individual's microbiota to prebiotics and dietary fibres.

Effectiveness and safety of light vegetarian diet on functional constipation with gastrointestinal damp-heat pattern: An exploratory study protocol for randomized controlled trial

INTRODUCTION

Functional constipation (FC) is one of the common gastrointestinal disorders that affects people of almost every age. Persistent FC significantly affects quality of life and well-being along with economic burden on patients as well as health care system. Therapeutic efficacy of currently used treatment strategies becomes limited shortly after their discontinuation as constipation occurs again as a result of inappropriate dietary habits. Previous studies have revealed that light vegetarian diet (LVD) can significantly improve both typical and atypical subtypes of major traditional Chinese medicine (TCM) FC syndrome such as gastrointestinal damp-heat syndrome. This protocol aims at exploratorily investigating effectiveness and safety of LVD following a rigorous clinical trial.

METHODS AND DESIGN

Total 92 patients in each of the 2 subtypes will be recruited in China-Japan Friendship Hospital for participating in this prospective, placebo-controlled, randomized trial and exploratory study. The patients in each subtype will be randomly divided into 4 groups according to 1:1:1:1 ratio with allocation concealment, which are drug + diet group, drug group, placebo + diet group and placebo group. Patients in the group with diet intervention will be required to strictly follow the LVD. The study will continue for a period of 28 days, including a drug or placebo supervised intervention and a 14th-day telephone follow-up. During the intervention, patients will be required to record a designed diary for controlling the diet quality (DQ) and analyzing the defecation. The study will focus investigation of complete spontaneous bowel movements (CSBM) per week as its primary outcome and constipation-related symptom rating scale (CSS), TCM syndrome scale (TCMSS), 48-hour gastrointestinal transit time (48-hour GITT), high resolution anorectal manometry (HRAM) and fecal flora detection (FFD) will be included in secondary outcomes. Furthermore, the study will also determine safety, DQ and compliance indicators.

ETHICS AND DISSEMINATION

This study has been approved by China-Japan Friendship Hospital clinical research ethics committee (No. 2017-46-1). A SPIRIT checklist is available for this protocol.

TRIAL REGISTRATION NUMBER

ChiCTR1800019686 in Chinese Clinical Trial Registry (WHO ICTRP member).

Efficacy of Polydextrose Supplementation on Colonic Transit Time, Bowel Movements, and Gastrointestinal Symptoms in Adults: A Double-Blind, Randomized, Placebo-Controlled Trial

The addition of fiber is one of the most important dietary means to relieve constipation through lifestyle modification. Polydextrose (PDX) has been reported in several studies to increase fecal bulk, soften stools, and increase the number of defecations. However, there are few studies on the effect of PDX on colonic transit time (CTT). Therefore, the aim of this study was to demonstrate the effect of PDX on CTT and other aspects of gastrointestinal function during two weeks (Day 1 to Day 14), preceded by a 2-week run-in period (Day -14 to Day -1). A total of 192 adults who were diagnosed with functional constipation per Rome III criteria were recruited for the study. Participants were randomized equally into 4 groups (12 g, 8 g, or 4 g of PDX or placebo per day). The primary endpoint was CTT, assessed using radio-opaque markers and abdominal X-rays on Day 0, the baseline; and Day 15, the end of the intervention. Secondary outcomes that were measured using inventories were the patient assessment of constipation symptoms and quality of life, bowel function index, relief of constipation, bowel movement frequency (BMF), stool consistency, degree of straining, and proportion of bowel movements. Ancillary parameters and harms were also evaluated. The recruited population was not sufficiently constipated (e.g., baseline values for CTT and BMF of 42 h and 8.7 BMF/week, respectively). Despite this limitation, our results demonstrated an increased number of bowel movements when supplemented with PDX at a dosage of 12 g per day for 2 weeks. This dosage also consistently improved the secondary outcomes that were measured using inventories at Day 15, compared with the baseline. No serious or significant adverse events were reported during the study.