Background The microbial community of the human gut – the enteric microbiota – plays a critical role in functions that sustain health and is a positive asset in host defenses. In recent years, our ...understanding of this so‐called human ‘super organism’ has advanced, following characterization of fecal metagenomes which identified three core bacterial enterotypes, and based on basic and clinical research into the impact and consequences of microbiota biodiversity and change on gastrointestinal disorders and diseases.
Purpose This article considers current knowledge and future perspectives on the make‐up and function of human gut microbiota, with a particular focus on altered microbiota and gastrointestinal disorders, nutritional influences on the gut microbiota, and the consequences for gastrointestinal health, as well as improved understanding of gut‐microbiota–brain communication.
Summary
Background
Although incrimination of the intestinal microbiota in the pathogenesis of IBD is widely accepted, few data are available about the role of specific bacteria. Potentially, ...Faecalibacterium prausnitzii, bacteria with anti‐inflammatory properties, might be deficient in ulcerative colitis (UC).
Aim
To quantify F. prausnitzii in the faecal microbiota of UC patients in remission and determine its relationship with relapse.
Methods
A cross‐sectional study included 116 UC patients in remission, 29 first‐degree relatives and 31 healthy controls. A subset of eighteen patients, recruited during the first month of remission, underwent a 1‐year follow‐up. Total bacteria and F. prausnitzii were measured by quantitative Real Time PCR (qPCR, copies/g). Calprotectin was determined as inflammatory index (μg/g).
Results
We found that F. prausnitzii was reduced in patients (median, IQR: 1.4 × 108, 5.1 × 107–4.5 × 108) and relatives (1.7 × 108, 9.3 × 107–5.1 × 108) vs. controls (6.5 × 108, 3.7 × 108–1.6 × 109, P < 0.0001). Moreover, low counts of F. prausnitzii were associated with less than 12 months of remission (8.0 × 107, 2.0 × 107–3.5 × 108 vs. 2.1 × 108, 1.0 × 108–7.9 × 108, P < 0.001) and more than 1 relapse/year (8.0 × 107, 3.2 × 107–3.8 × 108 vs. 1.9 × 108, 6.8 × 107–6.0 × 108, P < 0.01). When patients were followed up, F. prausnitzii increased steadily until reaching similar levels to those of controls if remission persisted (2.9 × 108, 9.3 × 106–1.2 × 109; calprotectin: 76, 19–212), whereas it remained low if patients relapsed (2.2 × 108, 1.4 × 106–3.3 × 108; calprotectin: 1760, 844–3662 P < 0.05 vs. controls).
Conclusions
Defective gut colonisation by F. prausnitzii occurred in UC patients during remission and in their unaffected relatives. The recovery of the F. prausnitzii population after relapse is associated with maintenance of clinical remission.
Summary
Background
Prebiotics have been shown to reduce abdominal symptoms in patients with functional gut disorders, despite that they are fermented by colonic bacteria and may induce gas‐related ...symptoms.
Aim
To investigate changes in the metabolic activity of gut microbiota induced by a recognised prebiotic.
Methods
Healthy subjects (n = 20) were given a prebiotic (2.8 g/day HOST‐G904, HOST Therabiomics, Jersey, Channel Islands) for 3 weeks. During 3‐day periods immediately before, at the beginning and at the end of the administration subjects were put on a standard diet (low fibre diet supplemented with one portion of high fibre foods) and the following outcomes were measured: (i) number of daytime gas evacuations for 2 days by means of an event marker; (ii) volume of gas evacuated via a rectal tube during 4 h after a test meal; and (iii) microbiota composition by faecal Illumina MiSeq sequencing.
Results
At the beginning of administration, HOST‐G904 significantly increased the number of daily anal gas evacuations (18 ± 2 vs. 12 ± 1 pre‐administration; P < 0.001) and the volume of gas evacuated after the test meal (236 ± 23 mL vs. 160 ± 17 mL pre‐administration; P = 0.006). However, after 3 weeks of administration, these effects diminished (11 ± 2 daily evacuations, 169 ± 23 mL gas evacuation). At day 21, relative abundance of butyrate producers (Lachnospiraceae) correlated inversely with the volume of gas evacuated (r = −0.52; P = 0.02).
Conclusion
The availability of substrates induces an adaptation of the colonic microbiota activity in bacterial metabolism, which produces less gas and associated issues. Clinical trials.gov NCT02618239.
Linked ContentThis article is linked to Staudacher paper. To view this article visit https://doi.org/10.1111/apt.13976.
There is unequivocal evidence that administration of probiotics could be effective in the treatment of acute infectious diarrhoea in children and the prevention of antibiotic associated diarrhoea and ...nosocomial/community acquired diarrhoea. Encouraging evidence is also emerging for the effectiveness of probiotics in the prevention and management of pouchitis and paediatric atopic diseases, and the prevention of postoperative infections. There is also strong evidence that certain probiotic strains are able to enhance immune function, especially in subjects with less than adequate immune function such as the elderly. Efficacy of probiotics in the prevention of traveller’s diarrhoea, sepsis associated with severe acute pancreatitis, and cancers, the management of ulcerative colitis, and lowering of blood cholesterol remains unproven. In addition to firm evidence of efficacy (for a range of conditions), major gaps exist in our knowledge regarding the mechanisms by which probiotics modulate various physiological functions and the optimum dose, frequency, and duration of treatment for different probiotic strains.
Background
We have shown that a galactooligosaccharide prebiotic administration (HOST‐G904) initially increased intestinal gas production and this increase declined back to baseline after 2 week ...administration. Our aim was to determine the mechanism of microbiota adaptation; i.e., to determine whether the net reduction is due to decreased overall production or increased gas consumption.
Methods
In 10 healthy subjects, intestinal gas production and intraluminal disposal was measured before, at the beginning and after 2 week of HOST‐G904 prebiotic administration. Anal gas was collected for 4 hour after a probe meal. Paired studies were performed without and with high‐rate infusion of exogenous gas (24 mL/min) into the jejunum to wash‐out the endogenous gas produced by bacterial fermentation. The exogenous gas infused was labeled (5% SF6) to calculate the proportion of endogenous gas evacuated.
Key Results
The volume of intestinal gas produced i.e., endogenous gas washed‐out, increased by 37% at the beginning of HOST‐G904 administration (P=.049 vs preadministration) and decreased down to preadministration level after 2 week administration (P=.030 vs early administration). The proportion of gas eliminated from the lumen before reaching the anus tended to increase after 2‐week administration (87±3% vs 78±5% preadministration; P=.098).
Conclusions & Inferences
Adaptation to regular consumption of HOST‐G904 prebiotic involves a shift in microbiota metabolism toward low‐gas producing pathways, with a non‐significant increase in gas‐consuming activity. Hence, regular consumption of HOST‐G904 regulates intestinal gas metabolism: less gas is produced and a somewhat larger proportion of it is consumed.
Effect of HOST‐G904 administration on the volume of gas evacuated. Anal evacuation of endogenous gas (produced by bacterial fermentation) 2‐4 hours after a probe meal with and without gaseous wash‐out measured before, at the beginning and after 2 week administration (n=10). With gaseous wash‐out, most endogenous gas produced by colonic fermentation was flushed out and evacuated per anus: gas production increased in the early administration phase and returned back to baseline. Without wash‐out, a large proportion of the gas produced by bacterial fermentation was eliminated from the lumen before reaching the anus and the proportion tended to increase during HOST‐G904 administration.
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The intestine is an extremely complex living system that participates in the protection of the host through a strong defense against aggressions from the external environment. This defensive task is ...based on 3 constituents that are in permanent contact and dialog with each other: the microflora, mucosal barrier, and local immune system. We review herein current knowledge about these important functions. The gut microflora play a major role against exogenous bacteria through colonization resistance, but the mechanism of action is not yet established, although it is linked to the bacteria colonizing the gut. This colonization involves bacteria-bacteria dialog, bacteria-mucins interactions, and bacteria-colonocytes cross-talk associated with environmental factors. The intestinal mucosa is a cellular barrier and the main site of interaction with foreign substances and exogenous microorganisms. It is a complex physicochemical structure consisting of a mucous layer linked to cellular and stromal components that participate in the defense of the host through mucosal blood flow, mucosal secretions, epithelial cell functionals, surface hydrophobicity, and defensin production. The intestine is the primary immune organ of the body represented by the gut-associated lymphoid tissue through innate and acquired immunity. This immune system can tolerate dietary antigens and the gut-colonizing bacteria and recognizes and rejects enteropathogenic microorganisms that may challenge the body's defenses. In cooperation with these endogenous barriers, some in-transit bacteria, such as probiotics, can act as partners of the defense system of the intestine.
Inflammation is a stereotypical physiological response to infections and tissue injury; it initiates pathogen killing as well as tissue repair processes and helps to restore homeostasis at infected ...or damaged sites. Acute inflammatory reactions are usually self-limiting and resolve rapidly, due to the involvement of negative feedback mechanisms. Thus, regulated inflammatory responses are essential to remain healthy and maintain homeostasis. However, inflammatory responses that fail to regulate themselves can become chronic and contribute to the perpetuation and progression of disease. Characteristics typical of chronic inflammatory responses underlying the pathophysiology of several disorders include loss of barrier function, responsiveness to a normally benign stimulus, infiltration of inflammatory cells into compartments where they are not normally found in such high numbers, and overproduction of oxidants, cytokines, chemokines, eicosanoids and matrix metalloproteinases. The levels of these mediators amplify the inflammatory response, are destructive and contribute to the clinical symptoms. Various dietary components including long chain ω-3 fatty acids, antioxidant vitamins, plant flavonoids, prebiotics and probiotics have the potential to modulate predisposition to chronic inflammatory conditions and may have a role in their therapy. These components act through a variety of mechanisms including decreasing inflammatory mediator production through effects on cell signaling and gene expression (ω-3 fatty acids, vitamin E, plant flavonoids), reducing the production of damaging oxidants (vitamin E and other antioxidants), and promoting gut barrier function and anti-inflammatory responses (prebiotics and probiotics). However, in general really strong evidence of benefit to human health through anti-inflammatory actions is lacking for most of these dietary components. Thus, further studies addressing efficacy in humans linked to studies providing greater understanding of the mechanisms of action involved are required.
The pathogenesis of enteritis after abdominal radiotherapy (RT) is unknown, although changes in fecal microbiota may be involved. Prebiotics stimulate the proliferation of Lactobacillus spp and ...Bifidobacterium spp, and this may have positive effects on the intestinal mucosa during abdominal RT.
We performed a randomized, double-blind, placebo-controlled trial involving patients with gynecological cancer who received abdominal RT after surgery. Patients were randomized to receive prebiotics or placebo. The prebiotic group received a mixture of fiber (50 inulin and 50% fructo-oligosaccharide), and the placebo group received 6 g of maltodextrin twice daily from 1 week before to 3 weeks after RT. The number of bowel movements and stool consistency was recorded daily. Diarrhea was evaluated according to the Common Toxicity Criteria of the National Cancer Institute. Stool consistency was assessed using the 7-point Bristol scale. Patients' quality-of-life was evaluated at baseline and at completion of RT using the EORTC-QLQ-C30 (European Organization for Research and Treatment of Cancer quality-of-life Questionnaire C30) test.
Thirty-eight women with a mean age of 60.3±11.8 years participated in the study. Both groups (prebiotic (n=20) and placebo (n=18)) were comparable in their baseline characteristics. The number of bowel movements per month increased in both groups during RT. The number of bowel movements per day increased in both groups. The number of days with watery stool (Bristol score 7) was lower in the prebiotic group (3.3±4.4 to 2.2±1.6) than in the placebo group (P=0.08). With respect to quality-of-life, the symptoms with the highest score in the placebo group were insomnia at baseline and diarrhea toward the end of the treatment. In the prebiotic group, insomnia was the symptom with the highest score at both assessments, although the differences were not statistically significant.
Prebiotics can improve the consistency of stools in gynecologic cancer patients on RT. This finding could have important implications in the quality-of-life of these patients during treatment.
Summary
Background Inulin and oligofructose promote selective growth of saccharolytic bacteria with low inflammatory potential.
Objective To test the effect of oligofructose‐enriched inulin in ...patients with active ulcerative colitis.
Design Prospective, randomized, placebo controlled pilot trial. Eligible patients had been previously in remission with mesalazine as maintenance therapy or no drug, and presented with a relapse of mild to moderate activity. They were treated with mesalazine (3 g/day) and randomly allocated to receive either oligofructose‐enriched inulin (12 g/day, p.o., n = 10) or placebo (12 g/day of maltodextrin, p.o., n = 9) for 2 week. Primary endpoint was the anti‐inflammatory effect as determined by reduction of calprotectin and human DNA in faeces.
Results Rachmilewitz score decreased in both groups, reaching statistical significance at day 14 (P < 0.05). Oligofructose‐enriched inulin was well‐tolerated and dyspeptic symptoms scale decreased significantly with active treatment but not with placebo. At day 7, an early significant reduction of calprotectin was observed in the group receiving oligofructose‐enriched inulin (day 0: 4377 ± 659 µg/g; day 7: 1033 ± 393 µg/g, P < 0.05) but not in the placebo group (day 0: 5834 ± 1563 µg/g; day 7: 4084 ± 1395 µg/g, n.s.). Changes in faecal concentration of human DNA were not significant.
Conclusion In active ulcerative colitis, dietary supplementation with oligofructose‐enriched inulin is well tolerated and is associated with early reduction in faecal calprotectin.
This study aimed to systematically evaluate safety of probiotics and synbiotics in immune compromised adults (≥18 years). Safety was analysed using the Common Terminology Clinical Adverse Events ...(CTCAE version 4.0) classification, thereby providing an update on previous reports using the most recent available clinical data (2008-2013). Safety aspects are represented and related to number of participants per probiotic strain/culture, study duration, dosage, clinical condition and selected afflictions. Analysis of 57 clinical studies indicates that probiotic and/or synbiotic administration in immune compromised adults is safe with regard to the current evaluated probiotic strains, dosages and duration. Individuals were considered immune compromised if HIV-infected, critically ill, underwent surgery or had an organ- or an autoimmune disease. There were no major safety concerns in the study, as none of the serious adverse events (AE)s were related, or suspected to be related, to the probiotic or synbiotic product and the study products were well tolerated. Overall, AEs occurred less frequent in immune compromised subjects receiving probiotics and/or synbiotics compared to the control group. In addition, the results demonstrated a flaw in precise reporting and classification of AE in most studies. Furthermore, generalisability of conclusions are greatly limited by the inconsistent, imprecise and potentially incomplete reporting as well as the variation in probiotic strains, dosages, administration regimes, study populations and reported outcomes. We argue that standardised reporting on adverse events (CTCAE) in ‘food’ studies should be obligatory, thereby improving reliability of data and re-enforcing the safety profile of probiotics.
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