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1.
The potential role of vitamin D supplementation as a gut microbiota modifier in healthy individuals.
Singh, P, Rawat, A, Alwakeel, M, Sharif, E, Al Khodor, S
Scientific reports. 2020;(1):21641
Abstract
Vitamin D deficiency affects approximately 80% of individuals in some countries and has been linked with gut dysbiosis and inflammation. While the benefits of vitamin D supplementation on the gut microbiota have been studied in patients with chronic diseases, its effects on the microbiota of otherwise healthy individuals is unclear. Moreover, whether effects on the microbiota can explain some of the marked inter-individual variation in responsiveness to vitamin D supplementation is unknown. Here, we administered vitamin D to 80 otherwise healthy vitamin D-deficient women, measuring serum 25(OH) D levels in blood and characterizing their gut microbiota pre- and post- supplementation using 16S rRNA gene sequencing. Vitamin D supplementation significantly increased gut microbial diversity. Specifically, the Bacteroidetes to Firmicutes ratio increased, along with the abundance of the health-promoting probiotic taxa Akkermansia and Bifidobacterium. Significant variations in the two-dominant genera, Bacteroides and Prevotella, indicated a variation in enterotypes following supplementation. Comparing supplementation responders and non-responders we found more pronounced changes in abundance of major phyla in responders, and a significant decrease in Bacteroides acidifaciens in non-responders. Altogether, our study highlights the positive impact of vitamin D supplementation on the gut microbiota and the potential for the microbial gut signature to affect vitamin D response.
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2.
Modification of fecal microbiota as a mediator of effective weight loss and metabolic benefits following bariatric surgery.
Oduro-Donkor, D, Turner, MC, Farnaud, S, Renshaw, D, Kyrou, I, Hanson, P, Hattersley, J, Weickert, MO, Menon, V, Randeva, HS, et al
Expert review of endocrinology & metabolism. 2020;(5):363-373
Abstract
INTRODUCTION Bariatric surgery (primarily Laparoscopic Sleeve Gastrectomy [LSG] and Roux-en-Y Gastric Bypass [RYGB]) is an efficacious and durable therapeutic option for weight loss in obesity. The mechanisms that mediate weight loss following bariatric surgery remain incompletely understood. AREAS COVERED Pubmed search of published data on fecal microbiota, metabolic health, LSG, and RYGB. The fecal microbiome plays a key role in the establishment and maintenance of metabolic wellbeing, and may also contribute (through fecal dysbiosis) to metabolic dysfunction. LSG and RYGB both result in characteristic, procedure-specific changes to the fecal microbiota that may mediate at least some of the resultant weight-loss and metabolically beneficial effects, when applied to the management of obesity. EXPERT OPINION The human fecal microbiome, containing around 100 trillion microbes, evolved over millions of years and interacts symbiotically with its human host. Rodent-based studies have provided insights into the complexities of the gut-microbiome-brain axis. This includes the important role of the gut microbiome in the mediation of normal immunological development, inflammatory pathways, metabolic functioning, hypothalamic appetite regulation, and the absorption of essential nutrients as by-products of bacterial metabolism. Fecal transformation is likely to provide an important therapeutic target for future prevention and management of obesity and metabolic dysfunction.
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3.
Clinical nutrition for the gastroenterologist: the physiologic rationale for providing early nutritional therapy to the hospitalized patient.
McClave, SA, Omer, E
Current opinion in gastroenterology. 2020;(2):118-121
Abstract
PURPOSE OF REVIEW Conflicting reports in the literature have been misinterpreted by clinicians, who conclude that nutritional therapy for the hospitalized patient is of marginal value. The true benefit of such therapy is derived from the provision of early enteral nutrition. This article describes the physiologic response to enteral feeding, which accounts for the outcome benefits, and illustrates how use of the gut alters immune responses and the intestinal microbiota. RECENT FINDINGS The provision of early enteral nutrition has been shown to reduce infection and mortality in high-risk hospitalized patients (compared with not providing such therapy). Early feeding maintains gut integrity, reduces permeability, promotes tolerance and appropriate immune responses, and supports commensalism of the intestinal microbiota. Early enteral nutrition influences cross-talk signaling between luminal bacteria and the intestinal epithelium. Failure to utilize the gut in acute illness can amplify the systemic inflammatory response syndrome and worsen disease severity, while at the same time promoting antibiotic resistance and increased septic morbidity. SUMMARY Appropriate nutritional therapy does change outcomes in the hospitalized patient, especially for those who are at risk on the basis of disease severity and/or poor nutritional status. Greatest benefit is seen from those therapeutic regimens that specifically target gut defenses and the intestinal microbiome.
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Beneficial effects of lactitol on the composition of gut microbiota in constipated patients.
Li, XQ, Zhang, XM, Wu, X, Lan, Y, Xu, L, Meng, XC, Li, JN
Journal of digestive diseases. 2020;(8):445-453
Abstract
OBJECTIVE To explore the changes in microbial composition and the corresponding impact after lactitol treatment in constipated patients. METHODS Altogether 29 consecutive outpatients diagnosed with chronic constipation from three centers were recruited and stratified based on their history of diabetes mellitus. All patients were administered with oral lactitol for 2 weeks, and a symptoms diary of constipation was recorded. Fecal samples were collected before and after lactitol treatment, and were analyzed by 16S rRNA sequencing and real-time polymerase chain reaction (PCR) to detect gut microbiota. RESULTS Twenty patients with diabetes mellitus and nine without, all with chronic constipation, were enrolled in this study. After 2-week administration of lactitol, their subscale scores and constipation symptoms significantly decreased (P < 0.05). An analysis of fecal flora using 16S rRNA sequencing found an increasing trend of abundance of Bifidobacterium in the post-lactitol group (P = 0.08). Actinobacteria, Actinobacteria, Bifidobacteriales, Bifidobacteriaceae and Bifidobacterium were significantly more abundant after lactitol administration. Real-time PCR showed significantly high DNA copy numbers of Bifidobacterium after lactitol treatment (1.39 × 1010 vs 2.74 × 109 copies/μL, P = 0.01). The results of 16S rRNA sequencing and real-time PCR illustrated an increasing trend of Bifidobacterium in both patients with and without diabetes. In addition, Bifidobacterium was negatively correlated with constipation subscale scores. CONCLUSIONS Alterations in fecal flora composition after lactitol supplementation, especially in terms of an increasing trend of Bifidobacterium, alleviated constipation symptoms. Lactitol may be a promising prebiotic candidate for patients with constipation, regardless of diabetes mellitus.
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Metagenomics reveals impact of geography and acute diarrheal disease on the Central Indian human gut microbiome.
Monaghan, TM, Sloan, TJ, Stockdale, SR, Blanchard, AM, Emes, RD, Wilcox, M, Biswas, R, Nashine, R, Manke, S, Gandhi, J, et al
Gut microbes. 2020;(1):1752605
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Abstract
BACKGROUND The Central Indian gut microbiome remains grossly understudied. Herein, we sought to investigate the burden of antimicrobial resistance and diarrheal diseases, particularly Clostridioides difficile, in rural-agricultural and urban populations in Central India, where there is widespread unregulated antibiotic use. We utilized shotgun metagenomics to comprehensively characterize the bacterial and viral fractions of the gut microbiome and their encoded functions in 105 participants. RESULTS We observed distinct rural-urban differences in bacterial and viral populations, with geography exhibiting a greater influence than diarrheal status. Clostridioides difficile disease was more commonly observed in urban subjects, and their microbiomes were enriched in metabolic pathways relating to the metabolism of industrial compounds and genes encoding resistance to 3rd generation cephalosporins and carbapenems. By linking phages present in the microbiome to their bacterial hosts through CRISPR spacers, phage variation could be directly related to shifts in bacterial populations, with the auxiliary metabolic potential of rural-associated phages enriched for carbon and amino acid energy metabolism. CONCLUSIONS We report distinct differences in antimicrobial resistance gene profiles, enrichment of metabolic pathways and phage composition between rural and urban populations, as well as a higher burden of Clostridioides difficile disease in the urban population. Our results reveal that geography is the key driver of variation in urban and rural Indian microbiomes, with acute diarrheal disease, including C. difficile disease exerting a lesser impact. Future studies will be required to understand the potential role of dietary, cultural, and genetic factors in contributing to microbiome differences between rural and urban populations.
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Emerging science on benefits of whole grain oat and barley and their soluble dietary fibers for heart health, glycemic response, and gut microbiota.
Tosh, SM, Bordenave, N
Nutrition reviews. 2020;(Suppl 1):13-20
Abstract
The aim of this work is to review the major mechanisms by which consumption of whole grain oats and barley, and β-glucans, reduces the risk of coronary heart disease, type 2 diabetes, and other noncommunicable chronic conditions. These effects have been predominantly explained by the role of soluble dietary fibers and smaller bioactive compounds, such as phenolic compounds, in oats and barley. These help to reduce the level of serum low-density lipoprotein cholesterol, decreasing postprandial blood glucose and modulating gut microbiota. In the present review, the role of viscosity development of the intestinal content by β-glucans in these mechanisms is discussed, as well as the impact of processing conditions altering the composition or the physicochemical characteristics of β-glucans.
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The effects of inulin on gut microbial composition: a systematic review of evidence from human studies.
Le Bastard, Q, Chapelet, G, Javaudin, F, Lepelletier, D, Batard, E, Montassier, E
European journal of clinical microbiology & infectious diseases : official publication of the European Society of Clinical Microbiology. 2020;(3):403-413
Abstract
BACKGROUND Inulin, consisting of repetitive fructosyl units linked by β(2,1) bonds, is a readily fermentable fiber by intestinal bacteria that generates large quantities of short-chain fatty acids (SCFA). In individuals with constipation, it was reported that inulin ingestion was associated with a significant increase in stool frequency, suggesting a potential impact of inulin on human gut microbiota composition. Progress in high-throughput technologies allow assessment of human-associated microbiomes in terms of diversity and taxonomic or functional composition, and can identify changes in response to a specific supplementation. Hence, to understand the effects of inulin on the human gut microbiome is pivotal to gain insight into their mechanisms of action. METHODS Here, we conducted a systematic review of human studies in adult individuals showing the effects of inulin on the gut microbiome. We searched in MEDLINE, EMBASE, Web of Science, and Scopus databases for articles in English published in peer-reviewed journals and indexed up until March 2019. We used multiple search terms capturing gut microbiome, gut microflora, intestinal microbiota, intestinal flora, gut microbiota, gut flora, microbial gut community, gut microbial composition, and inulin. RESULTS Overall, nine original articles reported the effects of inulin on microbiome composition in adult humans, most of them being randomized, double-blind, placebo-controlled trials (n = 7). Studies varied significantly in design (3 studies associated inulin and oligofructose), supplementation protocols (from 5 to 20 gr per day of inulin consumed) and in microbiome assessment methods (16S sequencing, n = 7). The most consistent change was an increase in Bifidobacterium. Other concordant results included an increase in relative abundance of Anaerostipes, Faecalibacterium, and Lactobacillus, and a decrease in relative abundance of Bacteroides after inulin supplementation. CONCLUSIONS Our systematic review assessed the evidence for the effects of inulin supplementation on the human gut microbiome. However, these in vivo studies did not confirm in vitro experiments as the taxonomic alterations were not associated with increase in short-chain fatty acids levels.
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Epithelial Toll-like receptors and their role in gut homeostasis and disease.
Burgueño, JF, Abreu, MT
Nature reviews. Gastroenterology & hepatology. 2020;(5):263-278
Abstract
The human gastrointestinal tract is colonized by trillions of microorganisms that interact with the host to maintain structural and functional homeostasis. Acting as the interface between the site of the highest microbial burden in the human body and the richest immune compartment, a single layer of intestinal epithelial cells specializes in nutrient absorption, stratifies microorganisms to limit colonization of tissues and shapes the responses of the subepithelial immune cells. In this Review, we focus on the expression, regulation and functions of Toll-like receptors (TLRs) in the different intestinal epithelial lineages to analyse how epithelial recognition of bacteria participates in establishing homeostasis in the gut. In particular, we elaborate on the involvement of epithelial TLR signalling in controlling crypt dynamics, enhancing epithelial barrier integrity and promoting immune tolerance towards the gut microbiota. Furthermore, we comment on the regulatory mechanisms that fine-tune TLR-driven immune responses towards pathogens and revisit the role of TLRs in epithelial repair after injury. Finally, we discuss how dysregulation of epithelial TLRs can lead to the generation of dysbiosis, thereby increasing susceptibility to colitis and tumorigenesis.
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Antidiabetic Effects of Flavan-3-ols and Their Microbial Metabolites.
Márquez Campos, E, Jakobs, L, Simon, MC
Nutrients. 2020;(6)
Abstract
Diet is one of the pillars in the prevention and management of diabetes mellitus. Particularly, eating patterns characterized by a high consumption of foods such as fruits or vegetables and beverages such as coffee and tea could influence the development and progression of type 2 diabetes. Flavonoids, whose intake has been inversely associated with numerous negative health outcomes in the last few years, are a common constituent of these food items. Therefore, they could contribute to the observed positive effects of certain dietary habits in individuals with type 2 diabetes. Of all the different flavonoid subclasses, flavan-3-ols are consumed the most in the European region. However, a large proportion of the ingested flavan-3-ols is not absorbed. Therefore, the flavan-3-ols enter the large intestine where they become available to the colonic bacteria and are metabolized by the microbiota. For this reason, in addition to the parent compounds, the colonic metabolites of flavan-3-ols could take part in the prevention and management of diabetes. The aim of this review is to present the available literature on the effect of both the parent flavan-3-ol compounds found in different food sources as well as the specific microbial metabolites of diabetes in order to better understand their potential role in the prevention and treatment of the disease.
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Iron Supplementation Influence on the Gut Microbiota and Probiotic Intake Effect in Iron Deficiency-A Literature-Based Review.
Rusu, IG, Suharoschi, R, Vodnar, DC, Pop, CR, Socaci, SA, Vulturar, R, Istrati, M, Moroșan, I, Fărcaș, AC, Kerezsi, AD, et al
Nutrients. 2020;(7)
Abstract
Iron deficiency in the human body is a global issue with an impact on more than two billion individuals worldwide. The most important functions ensured by adequate amounts of iron in the body are related to transport and storage of oxygen, electron transfer, mediation of oxidation-reduction reactions, synthesis of hormones, the replication of DNA, cell cycle restoration and control, fixation of nitrogen, and antioxidant effects. In the case of iron deficiency, even marginal insufficiencies may impair the proper functionality of the human body. On the other hand, an excess in iron concentration has a major impact on the gut microbiota composition. There are several non-genetic causes that lead to iron deficiencies, and thus, several approaches in their treatment. The most common methods are related to food fortifications and supplements. In this review, following a summary of iron metabolism and its health implications, we analyzed the scientific literature for the influence of iron fortification and supplementation on the gut microbiome and the effect of probiotics, prebiotics, and/or synbiotics in iron absorption and availability for the organism.