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Special Issue "Microbiome and Human Health"

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A special issue of Nutrients (ISSN 2072-6643).

Deadline for manuscript submissions: closed (31 January 2015)

Special Issue Editor

Guest Editor
Prof. Dr. Christine Edwards

Human Nutrition, School of Medicine, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow G31 2ER, UK
Phone: 44 141 2010709

Special Issue Information

Dear Colleagues,

The key role of the human gut microbiome in a range of chronic diseases—including obesity, cardiovascular disease, cancer, inflammatory bowel disease, irritable bowel syndrome, allergy, and potentially autoimmune diseases—has become apparent over the last few years since the use of Next Generation Sequencing and bioinformatics has allowed detailed analysis of the genome of the bacteria without the need to grow and isolate species. The addition of transcriptomics and metabolomics allows data to be collected not only on the bacteria present, but also their metabolism and potential bioactive products. However, more traditional targeted bacterial metabolite studies continue to provide important information to help elucidate the mechanisms by which bacteria in the gut can influence human health. This SpecialIssue will cover the colonization of the gut and the factors which influence the microbiome, its metabolic activities, and related biomarkers of health.

Prof. Dr. Christine Edwards
Guest Editor

Submission

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. Papers will be published continuously (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are refereed through a peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Nutrients is an international peer-reviewed Open Access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1500 CHF (Swiss Francs).

Keywords

  • gut microbiome
  • gut bacterial metabolism
  • factors affecting gut colonization
  • dietary influences on gut bacteria
  • gut bacteria and disease outcomes:
  • actions of gut bacterial metabolites

Published Papers (19 papers)

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Research

Jump to: Review

Open AccessArticle The Effect of Lactobacillus plantarum 299v on the Incidence of Clostridium difficile Infection in High Risk Patients Treated with Antibiotics
Nutrients 2015, 7(12), 10179-10188; doi:10.3390/nu7125526
Received: 10 June 2015 / Revised: 24 September 2015 / Accepted: 10 October 2015 / Published: 4 December 2015
Cited by 1 | PDF Full-text (957 KB) | HTML Full-text | XML Full-text
Abstract
Background: Lactobacillus plantarum 299v (LP299v) has been used in order to reduce gastrointestinal symptoms during antibiotic exposure. However, it remains controversial whether or not probiotics are effective in the prevention of Clostridium difficile infections (CDI) among patients receiving antibiotics. The aim of [...] Read more.
Background: Lactobacillus plantarum 299v (LP299v) has been used in order to reduce gastrointestinal symptoms during antibiotic exposure. However, it remains controversial whether or not probiotics are effective in the prevention of Clostridium difficile infections (CDI) among patients receiving antibiotics. The aim of this study was to analyze the CDI among patients receiving antibiotics and hospitalized in the period before and after starting routine use of LP299v as a prevention of this infection. Methods: Among 3533 patients hospitalized in the nephrology and transplantation ward during a two-year period, 23 patients with CDI were diagnosed and enrolled in this retrospective study. Since November 2013, prevention of CDI with oral use of LP299v was performed in all patients treated with antibiotics and who were at a high risk of developing CDI. The observation period was divided into two twelve-month intervals before and after initiation of the use of LP299v as a prophylactic against CDI. Results: A significant (p = 0.0001) reduction of the number of cases of CDI was found after routinely using LP299v (n = 2; 0.11% of all hospitalized patients) compared with the previous twelve-month period of observation (n = 21; 1.21% of all hospitalized patients). Conclusions: Routine use of LP299v during treatment with antibiotics may prevent C. difficile infection in the nephrology and transplantation ward. Full article
(This article belongs to the Special Issue Microbiome and Human Health)
Open AccessArticle Prebiotics Modulate the Effects of Antibiotics on Gut Microbial Diversity and Functioning in Vitro
Nutrients 2015, 7(6), 4480-4497; doi:10.3390/nu7064480
Received: 22 April 2015 / Revised: 18 May 2015 / Accepted: 27 May 2015 / Published: 4 June 2015
Cited by 4 | PDF Full-text (533 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Intestinal bacteria carry out many fundamental roles, such as the fermentation of non-digestible dietary carbohydrates to produce short chain fatty acids (SCFAs), which can affect host energy levels and gut hormone regulation. Understanding how to manage this ecosystem to improve human health [...] Read more.
Intestinal bacteria carry out many fundamental roles, such as the fermentation of non-digestible dietary carbohydrates to produce short chain fatty acids (SCFAs), which can affect host energy levels and gut hormone regulation. Understanding how to manage this ecosystem to improve human health is an important but challenging goal. Antibiotics are the front line of defence against pathogens, but in turn they have adverse effects on indigenous microbial diversity and function. Here, we have investigated whether dietary supplementation—another method used to modulate gut composition and function—could be used to ameliorate the side effects of antibiotics. We perturbed gut bacterial communities with gentamicin and ampicillin in anaerobic batch cultures in vitro. Cultures were supplemented with either pectin (a non-fermentable fibre), inulin (a commonly used prebiotic that promotes the growth of beneficial bacteria) or neither. Although antibiotics often negated the beneficial effects of dietary supplementation, in some treatment combinations, notably ampicillin and inulin, dietary supplementation ameliorated the effects of antibiotics. There is therefore potential for using supplements to lessen the adverse effects of antibiotics. Further knowledge of such mechanisms could lead to better therapeutic manipulation of the human gut microbiota. Full article
(This article belongs to the Special Issue Microbiome and Human Health)
Open AccessArticle Pyrosequencing Analysis Reveals Changes in Intestinal Microbiota of Healthy Adults Who Received a Daily Dose of Immunomodulatory Probiotic Strains
Nutrients 2015, 7(6), 3999-4015; doi:10.3390/nu7063999
Received: 26 January 2015 / Revised: 30 April 2015 / Accepted: 8 May 2015 / Published: 26 May 2015
Cited by 4 | PDF Full-text (921 KB) | HTML Full-text | XML Full-text
Abstract
The colon microbiota plays a crucial role in human gastrointestinal health. Current attempts to manipulate the colon microbiota composition are aimed at finding remedies for various diseases. We have recently described the immunomodulatory effects of three probiotic strains (Lactobacillus rhamnosus CNCM [...] Read more.
The colon microbiota plays a crucial role in human gastrointestinal health. Current attempts to manipulate the colon microbiota composition are aimed at finding remedies for various diseases. We have recently described the immunomodulatory effects of three probiotic strains (Lactobacillus rhamnosus CNCM I-4036, Lactobacillus paracasei CNCM I-4034, and Bifidobacterium breve CNCM I-4035). The goal of the present study was to analyze the compositions of the fecal microbiota of healthy adults who received one of these strains using high-throughput 16S ribosomal RNA gene sequencing. Bacteroides was the most abundant genus in the groups that received L. rhamnosus CNCM I-4036 or L. paracasei CNCM I-4034. The Shannon indices were significantly increased in these two groups. Our results also revealed a significant increase in the Lactobacillus genus after the intervention with L. rhamnosus CNCM I-4036. The initially different colon microbiota became homogeneous in the subjects who received L. rhamnosus CNCM I-4036. While some orders that were initially present disappeared after the administration of L. rhamnosus CNCM I-4036, other orders, such as Sphingobacteriales, Nitrospirales, Desulfobacterales, Thiotrichales, and Synergistetes, were detected after the intervention. In summary, our results show that the intake of these three bacterial strains induced changes in the colon microbiota. Full article
(This article belongs to the Special Issue Microbiome and Human Health)
Open AccessArticle Hypolipidemic Effects and Safety of Lactobacillus Reuteri 263 in a Hamster Model of Hyperlipidemia
Nutrients 2015, 7(5), 3767-3782; doi:10.3390/nu7053767
Received: 11 March 2015 / Revised: 8 April 2015 / Accepted: 12 May 2015 / Published: 15 May 2015
Cited by 5 | PDF Full-text (651 KB) | HTML Full-text | XML Full-text
Abstract
We aimed to verify the beneficial effects of probiotic strain Lactobacillus reuteri 263 (Lr263) on hypolipidemic action in hamsters with hyperlipidemia induced by a 0.2% cholesterol and 10% lard diet (i.e., high-cholesterol diet (HCD)). Male Golden Syrian hamsters were randomly [...] Read more.
We aimed to verify the beneficial effects of probiotic strain Lactobacillus reuteri 263 (Lr263) on hypolipidemic action in hamsters with hyperlipidemia induced by a 0.2% cholesterol and 10% lard diet (i.e., high-cholesterol diet (HCD)). Male Golden Syrian hamsters were randomly divided into two groups: normal (n = 8), standard diet (control), and experimental (n = 32), a HCD. After a two-week induction followed by a six-week supplementation with Lr263, the 32 hyperlipidemic hamsters were divided into four groups (n = 8 per group) to receive vehicle or Lr263 by oral gavage at 2.1, 4.2, or 10.5 × 109 cells/kg/day for 6 weeks, designated the HCD, 1X, 2X and 5X groups, respectively. The efficacy and safety of Lr263 supplementation were evaluated by lipid profiles of serum, liver and feces and by clinical biochemistry and histopathology. HCD significantly increased serum levels of total cholesterol (TC), triacylglycerol (TG) cholesterol, high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C), LDL-C/HDL-C ratio, hepatic and fetal TC and TG levels, and degree of fatty liver as compared with controls. Lr263 supplementation dose dependently increased serum HDL-C level and decreased serum TC, TG, LDL-C levels, LDL-C/HDL-C ratio, hepatic TC and TG levels, and fecal TG level. In addition, Lr263 supplementation had few subchronic toxic effects. Lr263 could be a potential agent with a hypolipidemic pharmacological effect. Full article
(This article belongs to the Special Issue Microbiome and Human Health)
Open AccessArticle Phylum Level Change in the Cecal and Fecal Gut Communities of Rats Fed Diets Containing Different Fermentable Substrates Supports a Role for Nitrogen as a Factor Contributing to Community Structure
Nutrients 2015, 7(5), 3279-3299; doi:10.3390/nu7053279
Received: 3 February 2015 / Revised: 31 March 2015 / Accepted: 22 April 2015 / Published: 6 May 2015
Cited by 2 | PDF Full-text (478 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Fermentation differs between the proximal and distal gut but little is known regarding how the bacterial communities differ or how they are influenced by diet. In order to investigate this, we compared community diversity in the cecum and feces of rats by [...] Read more.
Fermentation differs between the proximal and distal gut but little is known regarding how the bacterial communities differ or how they are influenced by diet. In order to investigate this, we compared community diversity in the cecum and feces of rats by 16S rRNA gene content and DNA shot gun metagenomics after feeding purified diets containing different fermentable substrates. Gut community composition was dependent on the source of fermentable substrate included in the diet. Cecal communities were dominated by Firmicutes, and contained a higher abundance of Lachnospiraceae compared to feces. In feces, community structure was shifted by varying degrees depending on diet towards the Bacteroidetes, although this change was not always evident from 16S rRNA gene data. Multi-dimensional scaling analysis (PCoA) comparing cecal and fecal metagenomes grouped by location within the gut rather than by diet, suggesting that factors in addition to substrate were important for community change in the distal gut. Differentially abundant genes in each environment supported this shift away from the Firmicutes in the cecum (e.g., motility) towards the Bacteroidetes in feces (e.g., Bacteroidales transposons). We suggest that this phylum level change reflects a shift to ammonia as the primary source of nitrogen used to support continued microbial growth in the distal gut. Full article
(This article belongs to the Special Issue Microbiome and Human Health)
Open AccessArticle Hydrolysis of the Rutinose-Conjugates Flavonoids Rutin and Hesperidin by the Gut Microbiota and Bifidobacteria
Nutrients 2015, 7(4), 2788-2800; doi:10.3390/nu7042788
Received: 26 February 2015 / Revised: 1 April 2015 / Accepted: 7 April 2015 / Published: 14 April 2015
Cited by 4 | PDF Full-text (309 KB) | HTML Full-text | XML Full-text
Abstract
Flavonols and flavanones are polyphenols exerting many healthy biological activities. They are often glycosylated by rutinose, which hampers absorption in the small intestine. Therefore they require the gut microbiota to release the aglycone and enable colonic absorption. The role of the gut [...] Read more.
Flavonols and flavanones are polyphenols exerting many healthy biological activities. They are often glycosylated by rutinose, which hampers absorption in the small intestine. Therefore they require the gut microbiota to release the aglycone and enable colonic absorption. The role of the gut microbiota and bifidobacteria in the release of the aglycones from two major rutinosides, hesperidin and rutin, was investigated. In bioconversion experiments, the microbiota removed rutinose from both rutin and hesperidin, even though complete hydrolysis was not obtained. To investigate whether bifidobacteria can participate to the hydrolysis of rutinosides, 33 strains were screened. Rutin was resistant to hydrolysis by all the strains. Among six tested species, mostly Bifidobacterium catenulatum and Bifidobacterium pseudocatenultum were able to hydrolyze hesperidin, by means of a cell-associated activity. This result is in agreement with the presence of a putative α-l-rhamnosidase in the genome of B. pseudocatenulatum, while most of the available genome sequences of bifidobacteria aside from this species do not bear this sequence. Even though B. pseudocatenulatum may contribute to the release of the aglycone from certain rutinose-conjugated polyphenols, such as hesperidin, it remains to be clarified whether this species may exert a role in affecting the bioavailability of the rutinoside in vivo. Full article
(This article belongs to the Special Issue Microbiome and Human Health)
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Open AccessCommunication Detection of Sialic Acid-Utilising Bacteria in a Caecal Community Batch Culture Using RNA-Based Stable Isotope Probing
Nutrients 2015, 7(4), 2109-2124; doi:10.3390/nu7042109
Received: 30 January 2015 / Accepted: 18 March 2015 / Published: 25 March 2015
Cited by 1 | PDF Full-text (804 KB) | HTML Full-text | XML Full-text
Abstract
Sialic acids are monosaccharides typically found on cell surfaces and attached to soluble proteins, or as essential components of ganglioside structures that play a critical role in brain development and neural transmission. Human milk also contains sialic acid conjugated to oligosaccharides, glycolipids, [...] Read more.
Sialic acids are monosaccharides typically found on cell surfaces and attached to soluble proteins, or as essential components of ganglioside structures that play a critical role in brain development and neural transmission. Human milk also contains sialic acid conjugated to oligosaccharides, glycolipids, and glycoproteins. These nutrients can reach the large bowel where they may be metabolised by the microbiota. However, little is known about the members of the microbiota involved in this function. To identify intestinal bacteria that utilise sialic acid within a complex intestinal community, we cultured the caecal microbiota from piglets in the presence of 13C-labelled sialic acid. Using RNA-based stable isotope probing, we identified bacteria that consumed 13C-sialic acid by fractionating total RNA in isopycnic buoyant density gradients followed by 16S rRNA gene analysis. Addition of sialic acid caused significant microbial community changes. A relative rise in Prevotella and Lactobacillus species was accompanied by a corresponding reduction in the genera Escherichia/Shigella, Ruminococcus and Eubacterium. Inspection of isotopically labelled RNA sequences suggests that the labelled sialic acid was consumed by a wide range of bacteria. However, species affiliated with the genus Prevotella were clearly identified as the most prolific users, as solely their RNA showed significantly higher relative shares among the most labelled RNA species. Given the relevance of sialic acid in nutrition, this study contributes to a better understanding of their microbial transformation in the intestinal tract with potential implications for human health. Full article
(This article belongs to the Special Issue Microbiome and Human Health)
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Open AccessArticle Changes in Composition of Caecal Microbiota Associated with Increased Colon Inflammation in Interleukin-10 Gene-Deficient Mice Inoculated with Enterococcus Species
Nutrients 2015, 7(3), 1798-1816; doi:10.3390/nu7031798
Received: 22 December 2014 / Revised: 10 February 2015 / Accepted: 2 March 2015 / Published: 11 March 2015
Cited by 6 | PDF Full-text (707 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Human inflammatory bowel disease (IBD) is a chronic intestinal disease where the resident microbiota contributes to disease development, yet the specific mechanisms remain unclear. Interleukin-10 gene-deficient (Il10-/-) mice develop inflammation similar to IBD, due in part to an inappropriate [...] Read more.
Human inflammatory bowel disease (IBD) is a chronic intestinal disease where the resident microbiota contributes to disease development, yet the specific mechanisms remain unclear. Interleukin-10 gene-deficient (Il10-/-) mice develop inflammation similar to IBD, due in part to an inappropriate response to commensal bacteria. We have previously reported changes in intestinal morphology and colonic gene expression in Il10-/- mice in response to oral bacterial inoculation. In this study, we aimed to identify specific changes in the caecal microbiota associated with colonic inflammation in these mice. The microbiota was evaluated using pyrotag sequencing, denaturing gradient gel electrophoresis (DGGE) and quantitative real-time PCR. Microbiota profiles were influenced by genotype of the mice and by bacterial inoculation, and a strong correlation was observed between the microbiota and colonic inflammation scores. Although un-inoculated Il10-/- and C57 mice had similar microbiota communities, bacterial inoculation resulted in different changes to the microbiota in Il10-/- and C57 mice. Inoculated Il10-/- mice had significantly less total bacteria than un-inoculated Il10-/- mice, with a strong negative correlation between total bacterial numbers, relative abundance of Escherichia/Shigella, microbiota diversity, and colonic inflammation score. Our results show a putative causative role for the microbiota in the development of IBD, with potentially key roles for Akkermansia, or for Bacteroides, Helicobacter, Parabacteroides, and Alistipes, depending on the composition of the bacterial inoculum. These data support the use of bacterially-inoculated Il10-/- mice as an appropriate model to investigate human IBD. Full article
(This article belongs to the Special Issue Microbiome and Human Health)
Open AccessArticle Pilot Dietary Intervention with Heat-Stabilized Rice Bran Modulates Stool Microbiota and Metabolites in Healthy Adults
Nutrients 2015, 7(2), 1282-1300; doi:10.3390/nu7021282
Received: 11 November 2014 / Accepted: 15 January 2015 / Published: 16 February 2015
Cited by 3 | PDF Full-text (1960 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Heat-stabilized rice bran (SRB) has been shown to regulate blood lipids and glucose, modulate gut mucosal immunity and inhibit colorectal cancer in animal and human studies. However, SRB’s effects on gut microbial composition and metabolism and the resulting implications for health remain [...] Read more.
Heat-stabilized rice bran (SRB) has been shown to regulate blood lipids and glucose, modulate gut mucosal immunity and inhibit colorectal cancer in animal and human studies. However, SRB’s effects on gut microbial composition and metabolism and the resulting implications for health remain largely unknown. A pilot, randomized-controlled trial was developed to investigate the effects of eating 30 g/day SRB on the stool microbiome and metabolome. Seven healthy participants consumed a study meal and snack daily for 28 days. The microbiome and metabolome were characterized using 454 pyrosequencing and gas chromatography-mass spectrometry (GC-MS) at baseline, two and four weeks post-intervention. Increases in eight operational taxonomic units (OTUs), including three from Bifidobacterium and Ruminococcus genera, were observed after two and four weeks of SRB consumption (p < 0.01). Branched chain fatty acids, secondary bile acids and eleven other putative microbial metabolites were significantly elevated in the SRB group after four weeks. The largest metabolite change was a rice bran component, indole-2-carboxylic acid, which showed a mean 12% increase with SRB consumption. These data support the feasibility of dietary SRB intervention in adults and support that SRB consumption can affect gut microbial metabolism. These findings warrant future investigations of larger cohorts evaluating SRB’s effects on intestinal health. Full article
(This article belongs to the Special Issue Microbiome and Human Health)
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Open AccessArticle Association of Polyphenols from Oranges and Apples with Specific Intestinal Microorganisms in Systemic Lupus Erythematosus Patients
Nutrients 2015, 7(2), 1301-1317; doi:10.3390/nu7021301
Received: 18 December 2014 / Revised: 4 February 2015 / Accepted: 11 February 2015 / Published: 16 February 2015
Cited by 9 | PDF Full-text (411 KB) | HTML Full-text | XML Full-text
Abstract
Our group has recently shown the existence of a gut microbial dysbiosis in systemic lupus erythematosus (SLE), supporting previous evidence involving intestinal bacteria in the initiation and amplification of autoimmune diseases. While several studies have addressed the use of dietary fibres to [...] Read more.
Our group has recently shown the existence of a gut microbial dysbiosis in systemic lupus erythematosus (SLE), supporting previous evidence involving intestinal bacteria in the initiation and amplification of autoimmune diseases. While several studies have addressed the use of dietary fibres to modify intestinal microbiota, information about other correlated components, such as polyphenols, is scarce. The aim of this work was to identify dietary components able to influence this altered microbiota in 20 SLE women and 20 age-matched controls. Food intake was recorded by means of a food frequency questionnaire. The intake of fibres was calculated from Marlett tables, and Phenol-Explorer was used for polyphenol consumption. Results showed positive associations between flavone intake and Blautia, flavanones and Lactobacillus, and dihydrochalcones and Bifidobacterium in the SLE group. Regarding the controls, dihydroflavonols were directly associated with Faecalibacterium, whereas flavonol intake was inversely associated with Bifidobacterium. From the food sources of these polyphenols related to microbiota, orange intake was directly associated with Lactobacillus and apple with Bifidobacterium in SLE, whilst red wine was the best contributor to Faecalibacterium variation. The association between common foods and particular microbial genera, reported to be decreased in SLE, could be of great importance for these patients. Full article
(This article belongs to the Special Issue Microbiome and Human Health)
Open AccessArticle Intestinal Microbial Dysbiosis and Colonic Epithelial Cell Hyperproliferation by Dietary α-Mangostin is Independent of Mouse Strain
Nutrients 2015, 7(2), 764-784; doi:10.3390/nu7020764
Received: 10 October 2014 / Revised: 14 January 2015 / Accepted: 15 January 2015 / Published: 22 January 2015
Cited by 1 | PDF Full-text (991 KB) | HTML Full-text | XML Full-text
Abstract
Beverages and supplements prepared from mangosteen fruit are claimed to support gut health and immunity, despite the absence of supporting evidence from clinical trials. We recently reported that α-mangostin (α-MG), the most abundant xanthone in mangosteen fruit, altered the intestinal microbiome, promoted [...] Read more.
Beverages and supplements prepared from mangosteen fruit are claimed to support gut health and immunity, despite the absence of supporting evidence from clinical trials. We recently reported that α-mangostin (α-MG), the most abundant xanthone in mangosteen fruit, altered the intestinal microbiome, promoted dysbiosis, and exacerbated colitis in C57BL/6J mice. The objective of this study was to determine whether induction of dysbiosis by dietary α-MG is limited to the C57BL/6J strain or represents a more generic response to chronic intake of the xanthone on the gut microbiota of mice. C3H, Balb/c, Nude FoxN1nu, and C57BL/6J mice, each demonstrating unique microbiomes, were fed standard diet or diet containing 0.1% α-MG for four weeks. Dietary α-MG significantly altered the cecal and colonic microbiota in all four strains of mice, promoting a reduction in generally assumed beneficial bacterial groups while increasing the abundance of pathogenic bacteria. Consumption of α-MG was associated with reduced abundance of Firmicutes and increased abundance of Proteobacteria. The abundance of Lachnospiraceae, Ruminococcaceae, and Lactobacillaceae was reduced in α-MG-fed mice, while that of Enterobacteriaceae and Enterococcaceae was increased. Dietary α-MG also was associated with increased proliferation of colonic epithelial cells, infiltration of immune cells, infiltration of immune cells and increased fluid content in stool. These results suggest that ingestion of pharmacologic doses of xanthones in mangosteen-containing supplements may adversely alter the gut microbiota and should be used with caution. Full article
(This article belongs to the Special Issue Microbiome and Human Health)

Review

Jump to: Research

Open AccessReview The Role of Microbial Amino Acid Metabolism in Host Metabolism
Nutrients 2015, 7(4), 2930-2946; doi:10.3390/nu7042930
Received: 20 February 2015 / Revised: 21 March 2015 / Accepted: 1 April 2015 / Published: 16 April 2015
Cited by 12 | PDF Full-text (162 KB) | HTML Full-text | XML Full-text
Abstract
Disruptions in gut microbiota composition and function are increasingly implicated in the pathogenesis of obesity, insulin resistance, and type 2 diabetes mellitus. The functional output of the gut microbiota, including short-chain fatty acids and amino acids, are thought to be important modulators [...] Read more.
Disruptions in gut microbiota composition and function are increasingly implicated in the pathogenesis of obesity, insulin resistance, and type 2 diabetes mellitus. The functional output of the gut microbiota, including short-chain fatty acids and amino acids, are thought to be important modulators underlying the development of these disorders. Gut bacteria can alter the bioavailability of amino acids by utilization of several amino acids originating from both alimentary and endogenous proteins. In turn, gut bacteria also provide amino acids to the host. This could have significant implications in the context of insulin resistance and type 2 diabetes mellitus, conditions associated with elevated systemic concentrations of certain amino acids, in particular the aromatic and branched-chain amino acids. Moreover, several amino acids released by gut bacteria can serve as precursors for the synthesis of short-chain fatty acids, which also play a role in the development of obesity. In this review, we aim to compile the available evidence on the contribution of microbial amino acids to host amino acid homeostasis, and to assess the role of the gut microbiota as a determinant of amino acid and short-chain fatty acid perturbations in human obesity and type 2 diabetes mellitus. Full article
(This article belongs to the Special Issue Microbiome and Human Health)
Open AccessReview The Queuine Micronutrient: Charting a Course from Microbe to Man
Nutrients 2015, 7(4), 2897-2929; doi:10.3390/nu7042897
Received: 30 January 2015 / Accepted: 25 March 2015 / Published: 15 April 2015
Cited by 7 | PDF Full-text (1280 KB) | HTML Full-text | XML Full-text
Abstract
Micronutrients from the diet and gut microbiota are essential to human health and wellbeing. Arguably, among the most intriguing and enigmatic of these micronutrients is queuine, an elaborate 7-deazaguanine derivative made exclusively by eubacteria and salvaged by animal, plant and fungal species. [...] Read more.
Micronutrients from the diet and gut microbiota are essential to human health and wellbeing. Arguably, among the most intriguing and enigmatic of these micronutrients is queuine, an elaborate 7-deazaguanine derivative made exclusively by eubacteria and salvaged by animal, plant and fungal species. In eubacteria and eukaryotes, queuine is found as the sugar nucleotide queuosine within the anticodon loop of transfer RNA isoacceptors for the amino acids tyrosine, asparagine, aspartic acid and histidine. The physiological requirement for the ancient queuine molecule and queuosine modified transfer RNA has been the subject of varied scientific interrogations for over four decades, establishing relationships to development, proliferation, metabolism, cancer, and tyrosine biosynthesis in eukaryotes and to invasion and proliferation in pathogenic bacteria, in addition to ribosomal frameshifting in viruses. These varied effects may be rationalized by an important, if ill-defined, contribution to protein translation or may manifest from other presently unidentified mechanisms. This article will examine the current understanding of queuine uptake, tRNA incorporation and salvage by eukaryotic organisms and consider some of the physiological consequence arising from deficiency in this elusive and lesser-recognized micronutrient. Full article
(This article belongs to the Special Issue Microbiome and Human Health)
Open AccessReview Dietary Gut Microbial Metabolites, Short-chain Fatty Acids, and Host Metabolic Regulation
Nutrients 2015, 7(4), 2839-2849; doi:10.3390/nu7042839
Received: 14 January 2015 / Revised: 29 March 2015 / Accepted: 2 April 2015 / Published: 14 April 2015
Cited by 27 | PDF Full-text (265 KB) | HTML Full-text | XML Full-text
Abstract
During feeding, the gut microbiota contributes to the host energy acquisition and metabolic regulation thereby influencing the development of metabolic disorders such as obesity and diabetes. Short-chain fatty acids (SCFAs) such as acetate, butyrate, and propionate, which are produced by gut microbial [...] Read more.
During feeding, the gut microbiota contributes to the host energy acquisition and metabolic regulation thereby influencing the development of metabolic disorders such as obesity and diabetes. Short-chain fatty acids (SCFAs) such as acetate, butyrate, and propionate, which are produced by gut microbial fermentation of dietary fiber, are recognized as essential host energy sources and act as signal transduction molecules via G-protein coupled receptors (FFAR2, FFAR3, OLFR78, GPR109A) and as epigenetic regulators of gene expression by the inhibition of histone deacetylase (HDAC). Recent evidence suggests that dietary fiber and the gut microbial-derived SCFAs exert multiple beneficial effects on the host energy metabolism not only by improving the intestinal environment, but also by directly affecting various host peripheral tissues. In this review, we summarize the roles of gut microbial SCFAs in the host energy regulation and present an overview of the current understanding of its physiological functions. Full article
(This article belongs to the Special Issue Microbiome and Human Health)
Open AccessReview The Infant Gut Microbiome: Evidence for Obesity Risk and Dietary Intervention
Nutrients 2015, 7(4), 2237-2260; doi:10.3390/nu7042237
Received: 30 January 2015 / Revised: 4 March 2015 / Accepted: 18 March 2015 / Published: 31 March 2015
Cited by 7 | PDF Full-text (258 KB) | HTML Full-text | XML Full-text
Abstract
Increasing globally, particularly in children, obesity is a serious public health issue and risk factor for overweight and metabolic disease in later life. Both in experimental animal and human studies, advances in gene sequencing technologies have yielded intriguing possibilities for the role [...] Read more.
Increasing globally, particularly in children, obesity is a serious public health issue and risk factor for overweight and metabolic disease in later life. Both in experimental animal and human studies, advances in gene sequencing technologies have yielded intriguing possibilities for the role of the gut microbiome in later development of overweight status. Before translating study findings into practice, we must first reconcile inconsistencies between animal experimentation, and human adult and infant studies. Recent evidence for associations with gut microbiota and infant weight gain or child weight status, implicate Bacteroides and Lactobacillus species. Dietary manipulation with human milk and pre/probiotic formulations holds promise for preventing obesity. Full article
(This article belongs to the Special Issue Microbiome and Human Health)
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Open AccessReview The Controversial Role of Food Allergy in Infantile Colic: Evidence and Clinical Management
Nutrients 2015, 7(3), 2015-2025; doi:10.3390/nu7032015
Received: 18 December 2014 / Revised: 16 February 2015 / Accepted: 11 March 2015 / Published: 19 March 2015
Cited by 3 | PDF Full-text (431 KB) | HTML Full-text | XML Full-text
Abstract
Food allergies (FAs) are an increasing problem in Western countries, affecting up to 10% of young children. FAs are frequently associated with gastrointestinal manifestations. The role of FAs as a potential causative factor for infantile colic (IC) is still controversial. We report [...] Read more.
Food allergies (FAs) are an increasing problem in Western countries, affecting up to 10% of young children. FAs are frequently associated with gastrointestinal manifestations. The role of FAs as a potential causative factor for infantile colic (IC) is still controversial. We report the most recent evidence on the pathogenesis, clinical and diagnostic aspects of FA-induced infantile colic (IC) and suggest a stepwise diagnostic approach. We selected articles on clinical and immunologic features, pathogenesis and management of FAs and IC from of 1981 to 2015. Original and review articles were identified through selective searches performed on PubMed, using the following terms: colic, infantile colic, food allergy and infantile colic, infantile colic treatment. The possible relationship between FAs and IC derives from the presence of dysmotility with visceral hypersensitivity and dysbiosis, demonstrated in both conditions, and the clinical response to dietary interventions. Unfortunately, the design of the studies, poor characterization of atopy and different dietary approaches limit the understanding of the importance of FAs in subjects with IC. The role of FAs in IC subjects without other symptoms of atopy remains controversial. However, where there is a suspicion of FAs, a short trial with an extensively hydrolyzed cow’s proteins formula or, if breast fed, with maternal elimination diet may be considered a reasonable option. Full article
(This article belongs to the Special Issue Microbiome and Human Health)
Open AccessReview The Impact of Diet and Lifestyle on Gut Microbiota and Human Health
Nutrients 2015, 7(1), 17-44; doi:10.3390/nu7010017
Received: 17 September 2014 / Accepted: 9 December 2014 / Published: 24 December 2014
Cited by 36 | PDF Full-text (237 KB) | HTML Full-text | XML Full-text
Abstract
There is growing recognition of the role of diet and other environmental factors in modulating the composition and metabolic activity of the human gut microbiota, which in turn can impact health. This narrative review explores the relevant contemporary scientific literature to provide [...] Read more.
There is growing recognition of the role of diet and other environmental factors in modulating the composition and metabolic activity of the human gut microbiota, which in turn can impact health. This narrative review explores the relevant contemporary scientific literature to provide a general perspective of this broad area. Molecular technologies have greatly advanced our understanding of the complexity and diversity of the gut microbial communities within and between individuals. Diet, particularly macronutrients, has a major role in shaping the composition and activity of these complex populations. Despite the body of knowledge that exists on the effects of carbohydrates there are still many unanswered questions. The impacts of dietary fats and protein on the gut microbiota are less well defined. Both short- and long-term dietary change can influence the microbial profiles, and infant nutrition may have life-long consequences through microbial modulation of the immune system. The impact of environmental factors, including aspects of lifestyle, on the microbiota is particularly poorly understood but some of these factors are described. We also discuss the use and potential benefits of prebiotics and probiotics to modify microbial populations. A description of some areas that should be addressed in future research is also presented. Full article
(This article belongs to the Special Issue Microbiome and Human Health)
Open AccessReview Understanding How Commensal Obligate Anaerobic Bacteria Regulate Immune Functions in the Large Intestine
Nutrients 2015, 7(1), 45-73; doi:10.3390/nu7010045
Received: 7 October 2014 / Accepted: 9 December 2014 / Published: 24 December 2014
Cited by 5 | PDF Full-text (634 KB) | HTML Full-text | XML Full-text
Abstract
The human gastrointestinal tract is colonised by trillions of commensal bacteria, most of which are obligate anaerobes residing in the large intestine. Appropriate bacterial colonisation is generally known to be critical for human health. In particular, the development and function of the [...] Read more.
The human gastrointestinal tract is colonised by trillions of commensal bacteria, most of which are obligate anaerobes residing in the large intestine. Appropriate bacterial colonisation is generally known to be critical for human health. In particular, the development and function of the immune system depends on microbial colonisation, and a regulated cross-talk between commensal bacteria, intestinal epithelial cells and immune cells is required to maintain mucosal immune homeostasis. This homeostasis is disturbed in various inflammatory disorders, such as inflammatory bowel diseases. Several in vitro and in vivo studies indicate a role for Faecalibacterium prausnitzii, Bacteroides thetaiotaomicron, Bacteroides fragilis, Akkermansia muciniphila and segmented filamentous bacteria in maintaining intestinal immune homeostasis. These obligate anaerobes are abundant in the healthy intestine but reduced in several inflammatory diseases, suggesting an association with protective effects on human health. However, knowledge of the mechanisms underlying the effects of obligate anaerobic intestinal bacteria remains limited, in part due to the difficulty of co-culturing obligate anaerobes together with oxygen-requiring human epithelial cells. By using novel dual-environment co-culture models, it will be possible to investigate the effects of the unstudied majority of intestinal microorganisms on the human epithelia. This knowledge will provide opportunities for improving human health and reducing the risk of inflammatory diseases. Full article
(This article belongs to the Special Issue Microbiome and Human Health)
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Open AccessReview Dysbiotic Events in Gut Microbiota: Impact on Human Health
Nutrients 2014, 6(12), 5786-5805; doi:10.3390/nu6125786
Received: 14 May 2014 / Revised: 22 July 2014 / Accepted: 19 November 2014 / Published: 11 December 2014
Cited by 17 | PDF Full-text (242 KB) | HTML Full-text | XML Full-text
Abstract
The human body is colonized by a large number of microbes coexisting peacefully with their host. The most colonized site is the gastrointestinal tract (GIT). More than 70% of all the microbes in the human body are in the colon. The microorganism [...] Read more.
The human body is colonized by a large number of microbes coexisting peacefully with their host. The most colonized site is the gastrointestinal tract (GIT). More than 70% of all the microbes in the human body are in the colon. The microorganism population is 10 times larger of the total number of our somatic and germ cells. Two bacterial phyla, accounting for more than 90% of the bacterial cells, dominate the healthy adult intestine: Firmicutes and Bacteroidetes. Considerable variability in the microbiota compositions between people is found when we look at the taxonomic level of species, and strains within species. It is possible to assert that the human microbiota could be compared to a fingerprint. The microbiota acts as a barrier from pathogens, exerts important metabolic functions, and regulates inflammatory response by stimulating the immune system. Gut microbial imbalance (dysbiosis), has been linked to important human diseases such as inflammation related disorders. The present review summarizes our knowledge on the gut microbiota in a healthy context, and examines intestinal dysbiosis in inflammatory bowel disease (IBD) patients; the most frequently reported disease proven to be associated with changes in the gut microbiota. Full article
(This article belongs to the Special Issue Microbiome and Human Health)
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