Gut microbiota correlates with energy gain from dietary fibre and appears to be associated with acute and chronic intestinal diseases

Resistant Maltodextrin Consumption in a Double-Blind, Randomized, Crossover Clinical Trial Induces Specific Changes in Potentially Beneficial Gut Bacteria

Background: We have previously reported that the addition of resistant maltodextrin (RMD), a fermentable functional fiber, to the diet increases fecal weight as well as the amount of fecal bifidobacteria. Here, we report on the targeted analysis of changes in potentially beneficial gut bacteria associated with the intervention. Objective: The primary objective of this study was to determine the effect of adding 0, 15 and 25 g RMD to the diets of healthy free-living adults on potentially beneficial gut bacteria. Methods: We expanded on our previously reported microbiota analysis in a double-blind, placebo-controlled feeding study (NCT02733263) by performing additional qPCR analyses targeting fecal lactic acid bacteria (LAB), Akkermansia muciniphila, Faecalibacterium prausnitzii and Fusicatenibacter saccharivorans in samples from 49 participants. Results: RMD resulted in an approximately two-fold increase in fecal Fusicatenibacter saccharivorans (p = 0.024 for 15 g/day RMD and p = 0.017 for 25 g/day RMD). For Akkermansia muciniphila and Faecalibacterium prausnitzii, we obtained borderline evidence that showed increased amounts in participants that had low baseline levels of these bacteria (p < 0.1 for 25 g/day RMD). We did not detect any effects of RMD on LAB. Conclusions: RMD supplementation in healthy individuals increases Fusicatenibacter saccharivorans. Albeit to a lesser extent, RMD at the higher intake level may also increase Akkermansia muciniphila and Faecalibacterium prausnitzii in individuals with low baseline levels of those two species. Potential benefits associated with these microbiota changes remain to be established in studies with quantifiable health-related endpoints.

Resistant Maltodextrin Intake Reduces Virulent Metabolites in the Gut Environment: A Randomized Control Study in a Japanese Cohort

In recent years, there have been many reports on the effects of prebiotics on intestinal health. In particular, the consumption of resistant maltodextrin (RMD) has been reported to be beneficial. However, there has been no comprehensive quantification of the effect of RMD on the intestinal environment. Therefore, this study aimed to quantify the effects of RMD on the intestine, especially the intestinal microbiome and metabolome profiles. A randomized, double-blind, and controlled trial was conducted in 29 Japanese subjects, whose hemoglobin A1c (HbA1c) levels are larger than 6% (Clinical trial no. UMIN000023970, https://upload.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000027589). The subjects consumed RMD or placebo twice per day for 24 weeks. Blood and fecal samples were collected before and after the intake. The intestinal environment was assessed by a metabologenomics approach, involving 16S rRNA gene-based microbiome analysis and mass spectrometry-based metabolome analysis. The intake of RMD increased the levels of Bifidobacterium and Fusicatenibacter and decreased deoxycholate levels. Additionally, intake of RMD lowered the levels of some opportunistic virulent metabolites, such as imidazole propionate and trimethylamine, in subjects with an initially high amount of those metabolites. RMD may have beneficial effects on the gut environment, such as commensal microbiota modulation and reduction of virulence metabolites, which is known as a causative factor in metabolic disorders. However, the effects of RMD partially depend on the gut environmental baseline.

The Microbiota and Gut-Related Disorders: Insights from Animal Models

Over the past decade, the scientific committee has called for broadening our horizons in understanding host–microbe interactions and infectious disease progression. Owing to the fact that the human gut harbors trillions of microbes that exhibit various roles including the production of vitamins, absorption of nutrients, pathogen displacement, and development of the host immune system, particular attention has been given to the use of germ-free (GF) animal models in unraveling the effect of the gut microbiota on the physiology and pathophysiology of the host. In this review, we discuss common methods used to generate GF fruit fly, zebrafish, and mice model systems and highlight the use of these GF model organisms in addressing the role of gut-microbiota in gut-related disorders (metabolic diseases, inflammatory bowel disease, and cancer), and in activating host defense mechanisms and amending pathogenic virulence.

Arsenic and the gastrointestinal tract microbiome

Arsenic is a toxin, ranking first on the Agency for Toxic Substances and Disease Registry and the Environmental Protection Agency Priority List of Hazardous Substances. Chronic exposure increases the risk of a broad range of human illnesses, most notably cancer; however, there is significant variability in arsenic-induced disease among exposed individuals. Human genetics is a known component, but it alone cannot account for the large inter-individual variability in the presentation of arsenicosis symptoms. Each part of the gastrointestinal tract (GIT) may be considered as a unique environment with characteristic pH, oxygen concentration, and microbiome. Given the well-established arsenic redox transformation activities of microorganisms, it is reasonable to imagine how the GIT microbiome composition variability among individuals could play a significant role in determining the fate, mobility and toxicity of arsenic, whether inhaled or ingested. This is a relatively new field of research that would benefit from early dialogue aimed at summarizing what is known and identifying reasonable research targets and concepts. Herein, we strive to initiate this dialogue by reviewing known aspects of microbe-arsenic interactions and placing it in the context of potential for influencing host exposure and health risks. We finish by considering future experimental approaches that might be of value.

Inter-niche and inter-individual variation in gut microbial community assessment using stool, rectal swab, and mucosal samples

The purpose of this study is to evaluate similarities and differences in gut bacterial measurements and stability in the microbial communities of three different types of samples that could be used to assess different niches of the gut microbiome: rectal swab, stool, and normal rectal mucosa samples. In swab-stool comparisons, there were substantial taxa differences with some taxa varying largely by sample type (e.g. Thermaceae), inter-individual subject variation (e.g. Desulfovibrionaceae), or by both sample type and participant (e.g. Enterobacteriaceae). Comparing all three sample types with whole-genome metagenome shotgun sequencing, swab samples were much closer to stool samples than mucosa samples although all KEGG functional Level 1 and Level 2 pathways were significantly different across all sample types (e.g. transcription and environmental adaptation). However, the individual signature of participants was also observed and was largely stable between two time points. Thus, we found that while the distribution of some taxa was associated with these different sampling techniques, other taxa largely reflected individual differences in the microbial community that were insensitive to sampling technique. There is substantial variability in the assessment of the gut microbial community according to the type of sample.

Intake of Bifidobacterium longum and Fructo-oligosaccharides prevents Colorectal Carcinogenesis

INTRODUCTION

We aimed to investigate the effects of intake of yogurt containing Bifidobacterium longum (BB536-y) and fructo-oligosaccharides (FOS) in preventing colorectal carcinogenesis in healthy subjects, and the preventive effects of short-chain fatty acids (SCFA), whose production was enhanced by the intake of BB536-y and FOS, in human colon cancer cell lines.

MATERIALS AND METHODS

The subjects were 27 healthy persons who were divided into a group taking yogurt containing BB536 (BB536-y group; n = 14) and a group taking yogurt containing BB536 and FOS (BB536-y with FOS group; n = 13) once a day for 5 weeks. The feces were sampled before and after the intake to analyze the amount of SCFA in the feces and the profile of intestinal flora, such as putrefactive bacteria and Bacteroides fragilis enterotoxin (ETBF). Subsequently, human colon cancer cell lines (DLD-1 cells, WirDr cells) were cultured in the presence of SCFA (butyric acid, isobutyric acid, acetic acid) in order to evaluate the cell growth-inhibitory activity of SCFA (WST-8 assay) by calculating the IC50 value from the dose-response curve.

RESULTS

Intake of BB536-y increased the total amount of SCFA in the feces and significantly suppressed the detection rate of ETBF and growth of putrefactive bacteria. Intake of BB536-y with FOS was associated with a higher Bifidobacterium detection rate than that of BB536-y alone. The contents of butyric acid, isobutyric acid, and acetic acid, namely, of SCFA, were also decreased. Analysis of the results of culture of DLD-1 cells and WirDr cells in the presence of butyric acid, isobutyric acid, and acetic acid revealed that each of the substances showed significant cell growth-inhibitory activity, with the activity being the highest for butyric acid, followed by that for isobutyric acid and acetic acid.

CONCLUSION

These findings suggest that intake of both BB536-y and BB536-y with FOS prevents colorectal carcinogenesis.How to cite this article: Ohara T, Suzutani T. Intake of Bifidobacterium longum and Fructo-oligosaccharides prevents Colorectal Carcinogenesis. Euroasian J Hepato-Gastroenterol 2018;8(1):11-17.

Screening of Esophageal Varices by Noninvasive Means in Chronic Liver Disease

Introduction

Noninvasive assessment of esophageal varices (EV) decreases the medical and financial burden related to screening and helps in the management of patients with chronic liver diseases (CLDs). In this study, our aim was to assess the utility of the platelet count/spleen diameter index for the noninvasive evaluation of EV.

Materials and methods

In this cross-sectional observational study, a total of 100 CLD patients underwent screening endoscopy for EV in Medicine and Gastroenterology Department, Sylhet MAG Osmani Medical College Hospital, Sylhet, Bangladesh. Platelet count/spleen diameter ratio was assessed in all patients and its diagnostic implication was calculated.

Results

Upper gastrointestinal endoscopy revealed that 45 (45.0%) patients had medium EV followed by 27 (27.0%) that had small EV and 19 (19.0%) patients had large EV. Receiver operator characteristic (ROC) curve was constructed using platelet count/spleen index, which gave a cut-off value of >905. The validity of platelet count/spleen index evaluation of CLD was: Sensitivity 92.3%, specificity 66.7%, accuracy 90.0%, positive predictive value (PPV) and negative predictive value (NPV) were 96.6 and 46.2% respectively. True positive was 84 cases, false positive 3 cases, false negative 7 cases, and true negative 6 cases. If we consider cut-off value as 909 in the evaluation of EV in CLD, then true positive was 85 cases, false positive 3 cases, false negative 6 cases, and true negative 6 cases. From this, by calculation, sensitivity was 93.4%, specificity 66.7%, accuracy 91%, PPV 96.6%, and NPV 50%.

Conclusion

The platelet count/spleen index may be proposed to be a safe and reliable mean of screening of EV in CLD patients; however, case-control study would be required to validate this.

How to cite this article: Hossain E, Ahammed F, Saha SK, Foez SA, Rahim MA, Noor-e-Alam SM, Abdullah AS. Screening of Esophageal Varices by Noninvasive Means in Chronic Liver Disease. Euroasian J Hepato-Gastroenterol 2018;8(1):18-22.

Blastocystis: how do specific diets and human gut microbiota affect its development and pathogenicity?

Blastocystis is an enteric parasite that inhabits the gastrointestinal tract of humans and many animals. This emerging parasite has a worldwide distribution. It is often identified as the most common eukaryotic organism reported in human fecal samples. This parasite is recognized and diagnosed more often than ever before. Furthermore, some strains develop resistance against currently recommended drugs, such as metronidazole; therefore, the use of natural remedies or special diets has many positive aspects that may address this problem. The goal of this review is to compare natural treatments and various diets against the efficacy of drugs, and describe their influence on the composition of the gut microbiota, which affects Blastocystis growth and the occurrence of symptoms. This article reviews important work in the literature, including the classification, life cycle, epidemiology, pathogenesis, pathogenicity, genetics, biology, and treatment of Blastocystis. It also includes a review of the current knowledge about human gut microbiota and various diets proposed for Blastocystis eradication. The literature has revealed that garlic, ginger, some medical plants, and many spices contain the most effective organic compounds for parasite eradication. They work by inhibiting parasitic enzymes and nucleic acids, as well as by inhibiting protein synthesis. The efficacy of any specific organic compound depends on the Blastocystis subtype, and, consequently, on its immunity to treatment. In conclusion, the article discusses the findings that human gut microbiota composition triggers important mechanisms at the molecular level, and, thus, has a crucial influence on the parasitic pathogenicity.

The interplay between intestinal bacteria and host metabolism in health and disease: lessons from Drosophila melanogaster

All higher organisms negotiate a truce with their commensal microbes and battle pathogenic microbes on a daily basis. Much attention has been given to the role of the innate immune system in controlling intestinal microbes and to the strategies used by intestinal microbes to overcome the host immune response. However, it is becoming increasingly clear that the metabolisms of intestinal microbes and their hosts are linked and that this interaction is equally important for host health and well-being. For instance, an individual's array of commensal microbes can influence their predisposition to chronic metabolic diseases such as diabetes and obesity. A better understanding of host-microbe metabolic interactions is important in defining the molecular bases of these disorders and could potentially lead to new therapeutic avenues. Key advances in this area have been made using Drosophila melanogaster. Here, we review studies that have explored the impact of both commensal and pathogenic intestinal microbes on Drosophila carbohydrate and lipid metabolism. These studies have helped to elucidate the metabolites produced by intestinal microbes, the intestinal receptors that sense these metabolites, and the signaling pathways through which these metabolites manipulate host metabolism. Furthermore, they suggest that targeting microbial metabolism could represent an effective therapeutic strategy for human metabolic diseases and intestinal infection.

Digestion-resistant maltodextrin effects on colonic transit time and stool weight: a randomized controlled clinical study

PURPOSE

Increased awareness of the importance of dietary fibre has led to increased interest in "functional" fibre components like digestion-resistant maltodextrin (RMD). This randomized, placebo-controlled, double-blind study assessed the effects of RMD in the colonic transit time (CTT) and defecation characteristics (frequency, stool volume and consistency).

METHODS

Sixty-six healthy adult volunteers (32 men) who did not have a daily defecation habit had a 7-day run-in period before the 21-day intervention period with RMD or placebo. CTT and segmental CTT (SCTT) were assessed by a single abdominal X-ray film taken at the end of both periods after radiopaque marker ingestion. Defecation characteristics and intestinal functions were also assessed, which were self-reported by patients. Intragroup comparisons were evaluated by Student's paired t test, Bonferroni test and Chi-square test, while time comparisons by analysis of variance (ANOVA) and time-by-treatment interaction by repeated-measures ANOVA.

RESULTS

Fifty-seven subjects were assessed for CTT (placebo, n = 28; RMD, n = 29). In the RMD group, the total CTT, left SCTT and rectosigmoidal SCTT decreased significantly compared to baseline (p < 0.01 each; -13.3, -4.7, -8.7 h, respectively). Significant differences between groups were observed in total CTT and left SCTT. Significant time-by-treatment interaction was observed in the RMD group for stool volume (p = 0.014), increasing 56 % compared to baseline (p < 0.01), while remained unchanged in the placebo group. Stool consistency was improved only in the RMD group (p < 0.01). No adverse effects related to study products were observed.

CONCLUSIONS

The results show that RMD improved CTT, stool volume, stool consistency and some intestinal functions in a healthy population.

Effects of almond and pistachio consumption on gut microbiota composition in a randomised cross-over human feeding study

The modification of microbiota composition to a 'beneficial' one is a promising approach for improving intestinal as well as overall health. Natural fibres and phytochemicals that reach the proximal colon, such as those present in various nuts, provide substrates for the maintenance of healthy and diverse microbiota. The effects of increased consumption of specific nuts, which are rich in fibre as well as various phytonutrients, on human gut microbiota composition have not been investigated to date. The objective of the present study was to determine the effects of almond and pistachio consumption on human gut microbiota composition. We characterised microbiota in faecal samples collected from volunteers in two separate randomised, controlled, cross-over feeding studies (n 18 for the almond feeding study and n 16 for the pistachio feeding study) with 0, 1·5 or 3 servings/d of the respective nuts for 18 d. Gut microbiota composition was analysed using a 16S rRNA-based approach for bacteria and an internal transcribed spacer region sequencing approach for fungi. The 16S rRNA sequence analysis of 528 028 sequence reads, retained after removing low-quality and short-length reads, revealed various operational taxonomic units that appeared to be affected by nut consumption. The effect of pistachio consumption on gut microbiota composition was much stronger than that of almond consumption and included an increase in the number of potentially beneficial butyrate-producing bacteria. Although the numbers of bifidobacteria were not affected by the consumption of either nut, pistachio consumption appeared to decrease the number of lactic acid bacteria (P< 0·05). Increasing the consumption of almonds or pistachios appears to be an effective means of modifying gut microbiota composition.