Prebiotic Galacto-Oligosaccharides Impact Stool Frequency and Fecal Microbiota in Self-Reported Constipated Adults: A Randomized Clinical Trial

A double-blind intervention trial in healthy women demonstrates the beneficial impact on Bifidobacterium with low dosages of prebiotic galacto-oligosaccharides

Introduction

Galacto-oligosaccharides (GOS) are well-substantiated prebiotic substrates. Multiple studies have demonstrated a positive impact of GOS on gut microbiota composition and activity, so-far mainly related to Bifidobacterium. However, data on the beneficial impact at lower dosages in a healthy female population are limited. The primary aim of the current study was to reveal the effect of low dosages (1.3 and 2.0 g) of GOS on fecal Bifidobacterium abundance in healthy women. Other outcomes included the effect of low dosage of GOS on overall fecal microbiota composition and on self-perceived GI comfort, sleep quality and mental wellbeing.

Method

Eighty-eight healthy women (42-70 years, BMI 18.7-30 kg/m2) were included in this randomized, parallel, double-blind study of 6 weeks. The participants were stratified for fiber intake, BMI and age and randomized to consume either 1.3 or 2.0 g of GOS per day for 3 weeks after a control period of 3 weeks without any intervention. Fecal samples were collected for shotgun metagenomics sequencing at the start (t = -3) and end (t = 0) of the control period and at the end of the intervention period (t = 3). Self-perceived gut comfort, sleep quality, and mental wellbeing were assessed weekly. Hierarchical clustering of principal components was applied to data collected from study participants.

Results

The relative abundance of Bifidobacterium in feces increased significantly after 3 weeks of daily consumption of both 1.3 g (p < 0.01) and 2.0 g GOS (p < 0.01). This was accompanied by a significant shift in the overall microbiota composition for the dosage of 2.0 g GOS (p < 0.01). Participants that showed a larger increase in Bifidobacterium in the intervention period compared to the change in Bifidobacterium in the control period, defined as responders, showed a significant overall difference in initial fecal microbiota composition as compared to non-responders (p = 0.04) and a trend towards lower baseline levels of Bifidobacterium in responders (p = 0.10).

Conclusion

Daily consumption of a low dose of GOS can lead to an increase in the relative abundance of Bifidobacterium in feces of healthy women. Additionally, with 2.0 g GOS, the enrichment of Bifidobacterium is accompanied with a shift in the overall microbiota composition.Clinical trial registration: clinicaltrials.gov, identifier NCT05762965.

Galacto-Oligosaccharides and the Elderly Gut: Implications for Immune Restoration and Health

The increasing prevalence of noncommunicable diseases in the aging population has been correlated with a decline in innate and adaptive immune responses; hence, it is imperative to identify approaches to improve immune function, prevent related disorders, and reduce or treat age-associated health complications. Prebiotic supplementation is a promising approach to modulate the gut microbiome and immune system, offering a potential strategy to maintain the integrity of immune function in older individuals. This review summarizes the current research on prebiotic galacto-oligosaccharide (GOS) immunomodulatory mechanisms mediated by bacterial-derived metabolites, including short-chain fatty acids and secondary bile acids, to maintain immune homeostasis. The potential applications of GOS as immunotherapy for age-related disease prevention in older individuals are also highlighted. This aligns with the global shift toward proactive healthcare and emphasizes the significance of early intervention in directing an individual's health trajectory.

Association between dietary protein intake and constipation: Data from the National Health and nutrition examination survey 2005-2010

BACKGROUND

The association between dietary protein intake and constipation remains inconclusive. The aim of this study was to investigate whether dietary protein intake is associated with constipation.

METHODS

This cross-sectional study included 13,941 adults from the 2005 to 2010 National Health and Nutrition Examination Survey. A weighted logistic regression analysis was used to control for confounding factors. In addition, weighted interaction and stratified analyses were conducted to ascertain the potential modifying factors.

RESULTS

The prevalence of constipation was 7.5% when constipation was defined by stool consistency and 3.5% when constipation was defined by stool frequency. After adjusting for covariates, an increase in dietary protein intake of 10 g was not associated with constipation, as defined by stool frequency (OR = 0.94, 95% CI = 0.54, 1.62) or stool consistency (OR = 1.02, 95% CI = 0.75, 1.39). Subgroup analyses revealed that dietary protein intake was associated with an increase in constipation defined by stool consistency risk in participants who consumed a low amount of carbohydrates (OR = 1.08, 95% CI = 1.02-1.14 for every 10-g increase in protein intake), but a decrease in risk in participants in the moderate-carbohydrate group (OR = 0.94, 95% CI = 0.89-0.99 for every 10-g increase in protein intake), suggesting a significant interaction (p = 0.001).

CONCLUSION & INFERENCES

Dietary protein intake is not associated with stool consistency or frequency-defined constipation. However, the association between dietary protein intake and constipation defined by stool consistency in participants with a low carbohydrate intake differed from that in participants with a moderate carbohydrate intake.

Explorative Characterization of GI Complaints, General Physical and Mental Wellbeing, and Gut Microbiota in Trained Recreative and Competitive Athletes with or without Self-Reported Gastrointestinal Symptoms

The current state of the literature lacks a clear characterization of gastrointestinal (GI) symptoms, gut microbiota composition, and general physical and mental wellbeing in well-trained athletes. Therefore, this study aimed to characterize differences in self-reported symptoms, gut microbiota composition, and wellbeing (i.e., sleep quality, mood, and physical (PHQ) and mental wellbeing) between athletes with and without GI symptoms. In addition, we assessed the potential impact of a 3-week multi-ingredient fermented whey supplement in the GI complaints group, without a control group, on the gut microbiota and self-reported GI symptoms and wellbeing. A total of 50 athletes (24.7 ± 4.5 years) with GI issues (GI group at baseline, GI-B) and 21 athletes (25.4 ± 5.3 years) without GI issues (non-GI group, NGI) were included. At baseline, there was a significant difference in the total gastrointestinal symptom rating scale (GSRS) score (24.1 ± 8.48 vs. 30.3 ± 8.82, p = 0.008) and a trend difference in PHQ (33.9 ± 10.7 vs. 30.3 ± 8.82, p = 0.081), but no differences (p > 0.05) were seen for other outcomes, including gut microbiota metrics, between groups. After 3-week supplementation, the GI group (GI-S) showed increased Bifidobacterium relative abundance (p < 0.05), reported a lower number of severe GI complaints (from 72% to 54%, p < 0.001), and PHQ declined (p = 0.010). In conclusion, well-trained athletes with GI complaints reported more severe GI symptoms than an athletic reference group, without showing clear differences in wellbeing or microbiota composition. Future controlled research should further investigate the impact of such multi-ingredient supplements on GI complaints and the associated changes in gut health-related markers.

Microbiota treatment of functional constipation: Current status and future prospects

Functional constipation (FC) is a common disorder that is characterized by difficult stool passage, infrequent bowel movement, or both. FC is highly prevalent, recurs often, accompanies severe diseases, and affects quality of life; therefore, safe and effective therapy with long-term benefits is urgently needed. Microbiota treatment has potential value for FC treatment. Microbiota treatments include modulators such as probiotics, prebiotics, synbiotics, postbiotics, and fecal microbiota transplantation (FMT). Some probiotics and prebiotics have been adopted, and the efficacy of other microbiota modulators is being explored. FMT is considered an emerging field because of its curative effects; nevertheless, substantial work must be performed before clinical implementation.

Anaerostipes hadrus, a butyrate-producing bacterium capable of metabolizing 5-fluorouracil

Anaerostipes hadrus (A. hadrus) is a dominant species in the human gut microbiota and considered a beneficial bacterium for producing probiotic butyrate. However, recent studies have suggested that A. hadrus may negatively affect the host through synthesizing fatty acid and metabolizing the anticancer drug 5-fluorouracil, indicating that the impact of A. hadrus is complex and unclear. Therefore, comprehensive genomic studies on A. hadrus need to be performed. We integrated 527 high-quality public A. hadrus genomes and five distinct metagenomic cohorts. We analyzed these data using the approaches of comparative genomics, metagenomics, and protein structure prediction. We also performed validations with culture-based in vitro assays. We constructed the first large-scale pan-genome of A. hadrus (n = 527) and identified 5-fluorouracil metabolism genes as ubiquitous in A. hadrus genomes as butyrate-producing genes. Metagenomic analysis revealed the wide and stable distribution of A. hadrus in healthy individuals, patients with inflammatory bowel disease, and patients with colorectal cancer, with healthy individuals carrying more A. hadrus. The predicted high-quality protein structure indicated that A. hadrus might metabolize 5-fluorouracil by producing bacterial dihydropyrimidine dehydrogenase (encoded by the preTA operon). Through in vitro assays, we validated the short-chain fatty acid production and 5-fluorouracil metabolism abilities of A. hadrus. We observed for the first time that A. hadrus can convert 5-fluorouracil to α-fluoro-β-ureidopropionic acid, which may result from the combined action of the preTA operon and adjacent hydA (encoding bacterial dihydropyrimidinase). Our results offer novel understandings of A. hadrus, exceptionally functional features, and potential applications.

IMPORTANCE

This work provides new insights into the evolutionary relationships, functional characteristics, prevalence, and potential applications of Anaerostipes hadrus.

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.

Fecal microbiota transplantation combined with prebiotics ameliorates ulcerative colitis in mice

Aim: To investigate the effect of treatment with fecal microbiota transplantation (FMT) and galacto- and fructo-oligosaccharides on ulcerative colitis (UC) in mice. Materials & methods: A total of 90 mice, divided into nine groups, were administered FMT or prebiotics or combined treatment. The disease activity index scores, gut microbiota and inflammation factors were evaluated. Results: The treatment using FMT combined with galacto- and fructo-oligosaccharides in a 9:1 ratio significantly reduced intestinal barrier damage and alleviated symptoms of UC. Lactobacillus and Bifidobacterium and short-chain fatty acids were significantly increased after the combined treatment. Conclusion: The results demonstrate that FMT with prebiotics is a new method for UC treatment.

Functional constipation and the effect of prebiotics on the gut microbiota: a review

Functional constipation is a significant health issue impacting the lives of an estimated 14 % of the global population. Non-pharmaceutical treatment advice for cases with no underlying medical conditions focuses on exercise, hydration and an increase in dietary fibre intake. An alteration in the composition of the gut microbiota is thought to play a role in constipation. Prebiotics are non-digestible food ingredients that selectively stimulate the growth of a limited number of bacteria in the colon with a benefit for host health. Various types of dietary fibre, though not all, can act as a prebiotic. Short-chain fatty acids produced by these microbes play a critical role as signalling molecules in a range of metabolic and physiological processes including laxation, although details are unclear. Prebiotics have a history of safe use in the food industry spanning several decades and are increasingly used as supplements to alleviate constipation. Most scientific research on the effects of prebiotics and gut microbiota has focussed on inflammatory bowel disease rather than functional constipation. Very few clinical studies evaluated the efficacy of prebiotics in the management of constipation and their effect on the microbiota, with highly variable designs and conflicting results. Despite this, broad health claims are made by manufacturers of prebiotic supplements. This narrative review provides an overview of the literature on the interaction of prebiotics with the gut microbiota and their potential clinical role in the alleviation of functional constipation.

Probiotics, prebiotics, and synbiotics in chronic constipation: Outstanding aspects to be considered for the current evidence

This integrative aimed to evaluate the effects and the potential mechanism of action of prebiotics, probiotics, and synbiotics on constipation-associated gastrointestinal symptoms and to identify issues that still need to be answered. A literature search was performed in the PubMed database. Animal models (n = 23) and clinical trials (n = 39) were included. In animal studies, prebiotic, probiotic, and synbiotic supplementation showed a decreased colonic transit time (CTT) and an increase in the number and water content of feces. In humans, inulin is shown to be the most promising prebiotic, while B. lactis and L. casei Shirota probiotics were shown to increase defecation frequency, the latter strain being more effective in improving stool consistency and constipation symptoms. Overall, synbiotics seem to reduce CTT, increase defecation frequency, and improve stool consistency with a controversial effect on the improvement of constipation symptoms. Moreover, some aspects of probiotic use in constipation-related outcomes remain unanswered, such as the best dose, duration, time of consumption (before, during, or after meals), and matrices, as well as their effect and mechanisms on the regulation of inflammation in patients with constipation, on polymorphisms associated with constipation, and on the management of constipation via 5-HT. Thus, more high-quality randomized control trials (RCTs) evaluating these lacking aspects are necessary to provide safe conclusions about their effectiveness in managing intestinal constipation.

Functional response to a microbial synbiotic in the gastrointestinal system of children: a randomized clinical trial

BACKGROUND

Oral microbial therapy has been studied as an intervention for a range of gastrointestinal disorders. Though research suggests that microbial exposure may affect the gastrointestinal system, motility, and host immunity in a pediatric population, data have been inconsistent, with most prior studies being in neither a randomized nor placebo-controlled setting. The aim of this randomized, placebo-controlled study was to evaluate the efficacy of a synbiotic on increasing weekly bowel movements (WBMs) in constipated children.

METHODS

Sixty-four children (3-17 years of age) were randomized to receive a synbiotic (n = 33) comprising mixed-chain length oligosaccharides and nine microbial strains, or placebo (n = 31) for 84 days. Stool microbiota was analyzed on samples collected at baseline and completion. The primary outcome was a change from baseline of WBMs in the treatment group compared to placebo.

RESULTS

Treatment increased (p < 0.05) the number of WBMs in children with low baseline WBMs, despite broadly distinctive baseline microbiome signatures. Sequencing revealed that low baseline microbial richness in the treatment group significantly anticipated improvements in constipation (p = 0.00074).

CONCLUSIONS

These findings suggest the potential for (i) multi-species-synbiotic interventions to improve digestive health in a pediatric population and (ii) bioinformatics-based methods to predict response to microbial interventions in children.

IMPACT

Synbiotic microbial treatment improved the number of spontaneous weekly bowel movements in children compared to placebo. Intervention induced an increased abundance of bifidobacteria in children, compared to placebo. All administered probiotic species were enriched in the gut microbiome of the intervention group compared to placebo. Baseline microbial richness demonstrated potential as a predictive biomarker for response to intervention.

The Effect of Fiber Supplementation on Chronic Constipation in Adults: An Updated Systematic Review and Meta-Analysis of Randomized Controlled Trials

BACKGROUND

Chronic constipation is a prevalent disorder that remains challenging to treat. Studies suggest increasing fiber intake may improve symptoms, although recommendations on the fiber type, dose, and treatment duration are unclear.

OBJECTIVES

We investigated the effects of fiber supplementation on stool output, gut transit time, symptoms, and quality of life in adults with chronic constipation via a systematic review and meta-analysis of randomized controlled trials (RCTs).

METHODS

Studies were identified using electronic databases, backward citation, and hand searches of abstracts. RCTs reporting administration of fiber supplementation in adults with chronic constipation were included. Risks of bias (RoB) was assessed with the Cochrane RoB 2.0 tool. Results were synthesized using risk ratios (RRs), mean differences, or standardized mean differences (SMDs) and 95% CIs using a random-effects model.

RESULTS

Sixteen RCTs with 1251 participants were included. Overall, 311 of 473 (66%) participants responded to fiber treatment and 134 of 329 (41%) responded to control treatment [RR: 1.48 (95% CI: 1.17, 1.88; P = 0.001); I2 = 57% (P = 0.007)], with psyllium and pectin having significant effects. A higher response to treatment was apparent in fiber groups compared to control groups irrespective of the treatment duration, but only with higher fiber doses (>10 g/d). Fiber increased stool frequency [SMD: 0.72 (95% CI: 0.36, 1.08; P = 0.0001); I2 = 86% (P < 0.00001)]; psyllium and pectin had significant effects, and improvement was apparent only with higher fiber doses and greater treatment durations (≥4 weeks). Fiber improved stool consistency (SMD: 0.32; 95% CI: 0.18, 0.46; P < 0.0001), particularly with higher fiber doses. Flatulence was higher in fiber groups compared to control groups(SMD: 0.80; 95% CI: 0.47, 1.13; P < 0.00001).

CONCLUSIONS

Fiber supplementation is effective at improving constipation. Particularly, psyllium, doses >10 g/d and treatment durations of at least 4 weeks appear optimal, though caution is needed when interpreting the results due to considerable heterogeneity. These findings provide promising evidence on the optimal type and regime of fiber supplementation, which could be used to standardize recommendations to patients. The protocol for this review is registered at PROSPERO as CRD42020191404.