-
Journal of the International Society of... 2016Fatigue, mood disturbances, under performance and gastrointestinal distress are common among athletes during training and competition. The psychosocial and physical... (Review)
Review
Fatigue, mood disturbances, under performance and gastrointestinal distress are common among athletes during training and competition. The psychosocial and physical demands during intense exercise can initiate a stress response activating the sympathetic-adrenomedullary and hypothalamus-pituitary-adrenal (HPA) axes, resulting in the release of stress and catabolic hormones, inflammatory cytokines and microbial molecules. The gut is home to trillions of microorganisms that have fundamental roles in many aspects of human biology, including metabolism, endocrine, neuronal and immune function. The gut microbiome and its influence on host behavior, intestinal barrier and immune function are believed to be a critical aspect of the brain-gut axis. Recent evidence in murine models shows that there is a high correlation between physical and emotional stress during exercise and changes in gastrointestinal microbiota composition. For instance, induced exercise-stress decreased cecal levels of spp and increased which have well defined roles in intestinal mucus degradation and immune function. Diet is known to dramatically modulate the composition of the gut microbiota. Due to the considerable complexity of stress responses in elite athletes (from leaky gut to increased catabolism and depression), defining standard diet regimes is difficult. However, some preliminary experimental data obtained from studies using probiotics and prebiotics studies show some interesting results, indicating that the microbiota acts like an endocrine organ (e.g. secreting serotonin, dopamine or other neurotransmitters) and may control the HPA axis in athletes. What is troubling is that dietary recommendations for elite athletes are primarily based on a low consumption of plant polysaccharides, which is associated with reduced microbiota diversity and functionality (e.g. less synthesis of byproducts such as short chain fatty acids and neurotransmitters). As more elite athletes suffer from psychological and gastrointestinal conditions that can be linked to the gut, targeting the microbiota therapeutically may need to be incorporated in athletes' diets that take into consideration dietary fiber as well as microbial taxa not currently present in athlete's gut.
Topics: Athletes; Athletic Performance; Brain; Diet; Food; Gastrointestinal Microbiome; Gastrointestinal Tract; Hormones; Humans; Probiotics; Sports Nutritional Physiological Phenomena; Stress, Psychological
PubMed: 27924137
DOI: 10.1186/s12970-016-0155-6 -
The Lancet. Microbe Nov 2022Data from animal models suggest a role of early-life gut microbiota in lung immune development, and in establishing susceptibility to respiratory infections and asthma... (Review)
Review
Data from animal models suggest a role of early-life gut microbiota in lung immune development, and in establishing susceptibility to respiratory infections and asthma in humans. This systematic review summarises the association between infant (ages 0-12 months) gut microbiota composition measured by genomic sequencing, and childhood (ages 0-18 years) respiratory diseases (ie, respiratory infections, wheezing, or asthma). Overall, there was evidence that low α-diversity and relative abundance of particular gut-commensal bacteria genera (Bifidobacterium, Faecalibacterium, Ruminococcus, and Roseburia) are associated with childhood respiratory diseases. However, results were inconsistent and studies had important limitations, including insufficient characterisation of bacterial taxa to species level, heterogeneous outcome definitions, residual confounding, and small sample sizes. Large longitudinal studies with stool sampling during the first month of life and shotgun metagenomic approaches to improve bacterial and fungal taxa resolution are needed. Standardising follow-up times and respiratory disease definitions and optimising causal statistical approaches might identify targets for primary prevention of childhood respiratory diseases.
Topics: Infant; Humans; Infant, Newborn; Child, Preschool; Child; Adolescent; Gastrointestinal Microbiome; RNA, Ribosomal, 16S; Feces; Bacteria; Asthma; Respiration Disorders; Respiratory Tract Infections
PubMed: 35988549
DOI: 10.1016/S2666-5247(22)00184-7 -
Frontiers in Psychiatry 2019Recently discovered relationships between the gastrointestinal microbiome and the brain have implications for psychiatric disorders, including major depressive disorder...
Recently discovered relationships between the gastrointestinal microbiome and the brain have implications for psychiatric disorders, including major depressive disorder (MDD). Bacterial transplantation from MDD patients to rodents produces depression-like behaviors. In humans, case-control studies have examined the gut microbiome in healthy and affected individuals. We systematically reviewed existing studies comparing gut microbial composition in MDD and healthy volunteers. A PubMed literature search combined the terms "depression," "depressive disorder," "stool," "fecal," "gut," and "microbiome" to identify human case-control studies that investigated relationships between MDD and microbiota quantified from stool. We evaluated the resulting studies, focusing on bacterial taxa that were different between MDD and healthy controls. Six eligible studies were found in which 50 taxa exhibited differences ( < 0.05) between patients with MDD and controls. Patient characteristics and methodologies varied widely between studies. Five phyla-, and -were represented; however, divergent results occurred across studies for all phyla. The largest number of differentiating taxa were within phylum , in which nine families and 12 genera differentiated the diagnostic groups. The majority of these families and genera were found to be statistically different between the two groups in two identified studies. Family differentiated the diagnostic groups in four studies (with an even split in directionality). Across all five phyla, nine genera were higher in MDD (, and ), six were lower (, and ), and six were divergent (, and ). We highlight mechanisms and products of bacterial metabolism as they may relate to the etiology of depression. No consensus has emerged from existing human studies of depression and gut microbiome concerning which bacterial taxa are most relevant to depression. This may in part be due to differences in study design. Given that bacterial functions are conserved across taxonomic groups, we propose that studying microbial functioning may be more productive than a purely taxonomic approach to understanding the gut microbiome in depression.
PubMed: 30804820
DOI: 10.3389/fpsyt.2019.00034 -
CNS Neuroscience & Therapeutics Jan 2023Recent advances have highlighted the relationships between gut dysbiosis and Parkinson's disease (PD). Microbiota transplantation from PD patients to mice can induce... (Review)
Review
INTRODUCTION
Recent advances have highlighted the relationships between gut dysbiosis and Parkinson's disease (PD). Microbiota transplantation from PD patients to mice can induce increased alpha-synuclein-mediated motor deficits. Human studies have identified differences in the gut microbiota of PD patients compared to healthy controls. We undertook a systematic review to evaluate the available evidence for the involvement of gut bacteria in the etiology of PD.
METHODS
The PubMed databank, the China National Knowledge Infrastructure databank, and Wanfang Data were searched from inception until June 2021 to identify human case-control studies that investigated relationships between PD and microbiota quantified from feces. We evaluated the resulting studies focusing on bacterial taxa that were different between PD patients and healthy controls.
RESULTS
Twenty-six studies were found in which 53 microbial families and 98 genera exhibited differences between patients with PD and healthy controls. The genera identified by more than two studies as increased in PD were Bifidobacterium, Alistipes, Christensenella, Enterococcus, Oscillospira, Bilophila, Desulfovibrio, Escherichia/Shigella, and Akkermansia, while Prevotella, Blautia, Faecalibacterium, Fusicatenibacter, and Haemophilus had three or more reports of being lower in PD patients. More than one report demonstrated that Bacteroides, Odoribacter, Parabacteroides, Butyricicoccus, Butyrivibrio, Clostridium, Coprococcus, Lachnospira, Lactobacillus, Megasphaera, Phascolarctobacterium, Roseburia, Ruminococcus, Streptococcus, and Klebsiella were altered in both directions.
CONCLUSION
Our review shows that the involvement of the gut microbiome in the etiology of PD may involve alterations of short-chain fatty acids (SCFAs)-producing bacteria and an increase in putative gut pathobionts. SCFAs-producing bacteria may vary above or below an "optimal range," causing imbalances. Considering that Bifidobacterium, Lactobacillus, and Akkermansia are beneficial for human health, increased Bifidobacterium and Lactobacillus in the PD gut microbiome may be associated with PD medications, especially COMT inhibitors, while a high level of Akkermansia may be associated with aging.
Topics: Humans; Animals; Mice; Parkinson Disease; Gastrointestinal Microbiome; Bacteria; Feces; Fatty Acids, Volatile
PubMed: 36284437
DOI: 10.1111/cns.13990 -
Cureus Oct 2022Hypertension (HTN) is one of the most prevalent and dangerous cardiovascular diseases worldwide. Recently, its direct or indirect association with gut dysbiosis has been... (Review)
Review
Hypertension (HTN) is one of the most prevalent and dangerous cardiovascular diseases worldwide. Recently, its direct or indirect association with gut dysbiosis has been an interest of study for many. It also includes the metabolomic and functional gene changes in hypertensives compared with healthy individuals. This systematic review aims to study quantitative and qualitative interactions between the two and re-defining the heart-gut axis. We have strictly followed the (PRISMA), 2020, guidelines. We conducted an in-depth search of databases such as PubMed, PubMed Central (PMC), Medline, and ScienceDirect to find relevant studies for our topic of interest. After the final quality check, we included eight articles in the systematic review. A significant difference in richness and diversity in gut microbiota was observed in hypertensive patients compared with healthy controls. There was an increased abundance of many bacteria such as , , , Enterobacteriaceae, , , , , and , while a decreased abundance of , , spp., and . Alteration of the composition also varied based on diet, age, ethnicity, and severity of HTN. Short-chain fatty acids (SCFAs)-producing bacteria are found to be on the lower side in hypertensives owing to the protective property of SCFAs against inflammation, especially butyric acid. From the perspective of metabolomic changes, harmful metabolites for cardiovascular health such as intestinal fatty acid binding protein (I-FABP), lipopolysaccharides (LPSs), zonulin, sphingomyelins, acylcarnitines, and trimethylamine -oxide (TMAO) were found to be increased in hypertensives. Changes in these biomarkers further establish the relation between gut epithelial health and high blood pressure (BP). Participants affected by diseases have an overall lower rate of acquiring new genes, which results in a low richness of genes in them compared with healthy individuals. There is increased expression of the choline utilization () gene and reduced expression of genes associated with biosynthesis and transport of amino acids in high-BP participants. The unique changes in the composition of the microbiota, functional changes in genes, and metabolome collectively help for a better understanding of the pathogenesis of HTN and also suggest the gut as a promising new therapeutic target for HTN. To establish a further causal relationship between the two, more research is required.
PubMed: 36381851
DOI: 10.7759/cureus.29927 -
Lipids in Health and Disease Feb 2021Although imbalanced intestinal flora contributes to the pathogenesis of nonalcoholic fatty liver disease (NAFLD), conflicting results have been obtained for... (Meta-Analysis)
Meta-Analysis
BACKGROUND
Although imbalanced intestinal flora contributes to the pathogenesis of nonalcoholic fatty liver disease (NAFLD), conflicting results have been obtained for patient-derived microbiome composition analyses. A meta-analysis was performed to summarize the characteristics of intestinal microbiota at the species level in NAFLD patients.
METHODS
Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) Statement, a completed search (last update: December 30, 2020) of databases was performed to identify eligible case-control studies detecting gut microbiota in NAFLD patients. The meta-analysis results are presented as the standard mean difference (SMD) and 95% confidence interval (CI). Bias controls were evaluated with the Newcastle-Ottawa Scale (NOS), funnel plot analysis, and Egger's and Begg's tests.
RESULTS
Fifteen studies (NOS score range: 6-8) that detected the gut microbiota in the stools of 1265 individuals (577 NAFLD patients and 688 controls) were included. It was found that Escherichia, Prevotella and Streptococcus (SMD = 1.55 [95% CI: 0.57, 2.54], 1.89 [95% CI: 0.02, 3.76] and 1.33 [95% CI: 0.62, 2.05], respectively) exhibited increased abundance while Coprococcus, Faecalibacterium and Ruminococcus (SMD = - 1.75 [95% CI: - 3.13, - 0.37], - 9.84 [95% CI: - 13.21, - 6.47] and - 1.84 [95% CI, - 2.41, - 1.27], respectively) exhibited decreased abundance in the NAFLD patients compared with healthy controls. No differences in the abundance of Bacteroides, Bifidobacterium, Blautia, Clostridium, Dorea, Lactobacillus, Parabacteroides or Roseburia were confirmed between the NAFLD patients and healthy controls.
CONCLUSIONS
This meta-analysis revealed that changes in the abundance of Escherichia, Prevotella, Streptococcus, Coprococcus, Faecalibacterium and Ruminococcus were the universal intestinal bacterial signature of NAFLD.
Topics: Bacteroides; Bifidobacterium; Case-Control Studies; Clostridium; Dysbiosis; Escherichia; Feces; Gastrointestinal Microbiome; Humans; Lactobacillus; Liver; Non-alcoholic Fatty Liver Disease; Prevotella; Streptococcus
PubMed: 33637088
DOI: 10.1186/s12944-021-01440-w -
PloS One 2022Respiratory tract infections (RTIs) are extremely common and can cause gastrointestinal tract symptoms and changes to the gut microbiota, yet these effects are poorly... (Meta-Analysis)
Meta-Analysis
Respiratory tract infections (RTIs) are extremely common and can cause gastrointestinal tract symptoms and changes to the gut microbiota, yet these effects are poorly understood. We conducted a systematic review to evaluate the reported evidence of gut microbiome alterations in patients with a RTI compared to healthy controls (PROSPERO: CRD42019138853). We systematically searched Medline, Embase, Web of Science, Cochrane and the Clinical Trial Database for studies published between January 2015 and June 2021. Studies were eligible for inclusion if they were human cohorts describing the gut microbiome in patients with an RTI compared to healthy controls and the infection was caused by a viral or bacterial pathogen. Dual data screening and extraction with narrative synthesis was performed. We identified 1,593 articles and assessed 11 full texts for inclusion. Included studies (some nested) reported gut microbiome changes in the context of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) (n = 5), influenza (H1N1 and H7N9) (n = 2), Tuberculosis (TB) (n = 4), Community-Acquired Pneumonia CAP (n = 2) and recurrent RTIs (rRTI) (n = 1) infections. We found studies of patients with an RTI compared to controls reported a decrease in gut microbiome diversity (Shannon) of 1.45 units (95% CI, 0.15-2.50 [p, <0.0001]) and a lower abundance of taxa (p, 0.0086). Meta-analysis of the Shannon value showed considerable heterogeneity between studies (I2, 94.42). Unbiased analysis displayed as a funnel plot revealed a depletion of Lachnospiraceae, Ruminococcaceae and Ruminococcus and enrichment of Enterococcus. There was an important absence in the lack of cohort studies reporting gut microbiome changes and high heterogeneity between studies may be explained by variations in microbiome methods and confounder effects. Further human cohort studies are needed to understand RTI-induced gut microbiome changes to better understand interplay between microbes and respiratory health.
Topics: Animals; Bacteria; Gastrointestinal Microbiome; Gastrointestinal Tract; Humans; Respiratory Tract Infections
PubMed: 35025938
DOI: 10.1371/journal.pone.0262057 -
Genes & Nutrition Jan 2022Previous observational studies have demonstrated inconsistent and inconclusive results of changes in the intestinal microbiota in patients with obesity and metabolic... (Review)
Review
BACKGROUND
Previous observational studies have demonstrated inconsistent and inconclusive results of changes in the intestinal microbiota in patients with obesity and metabolic disorders. We performed a systematic review to explore evidence for this association across different geography and populations.
METHODS
We performed a systematic search of MEDLINE (OvidSP) and Embase (OvidSP) of articles published from Sept 1, 2010, to July 10, 2021, for case-control studies comparing intestinal microbiome of individuals with obesity and metabolic disorders with the microbiome of non-obese, metabolically healthy individuals (controls). The primary outcome was bacterial taxonomic changes in patients with obesity and metabolic disorders as compared to controls. Taxa were defined as "lean-associated" if they were depleted in patients with obesity and metabolic disorders or negatively associated with abnormal metabolic parameters. Taxa were defined as "obesity-associated" if they were enriched in patients with obesity and metabolic disorders or positively associated with abnormal metabolic parameters.
RESULTS
Among 2390 reports screened, we identified 110 full-text articles and 60 studies were included. Proteobacteria was the most consistently reported obesity-associated phylum. Thirteen, nine, and ten studies, respectively, reported Faecalibacterium, Akkermansia, and Alistipes as lean-associated genera. Prevotella and Ruminococcus were obesity-associated genera in studies from the West but lean-associated in the East. Roseburia and Bifidobacterium were lean-associated genera only in the East, whereas Lactobacillus was an obesity-associated genus in the West.
CONCLUSIONS
We identified specific bacteria associated with obesity and metabolic disorders in western and eastern populations. Mechanistic studies are required to determine whether these microbes are a cause or product of obesity and metabolic disorders.
PubMed: 35093025
DOI: 10.1186/s12263-021-00703-6 -
Medicine Sep 2023Accumulating evidence has indicated a possible connection between post-stroke cognitive impairment (PSCI) and gut microbiota imbalance. To further investigate this... (Meta-Analysis)
Meta-Analysis
BACKGROUND
Accumulating evidence has indicated a possible connection between post-stroke cognitive impairment (PSCI) and gut microbiota imbalance. To further investigate this association, the present work was designed to systematically assess the dissimilarity of gut microbiota between PSCI and healthy individuals or stroke patients.
METHODS
A meta-analysis and systematic review was conducted by searching various databases including PubMed, Web of Science, Embase, VIP, CNKI, and Wangfang for relevant studies. The pooled outcomes were used to estimate the combined dissimilarity of gut microbiota composition between PSCI and healthy individuals or patients with stroke.
RESULTS
Nine eligible studies were included in this meta-analysis. The results showed that there were no significant changes in observed richness indexes (Chao1 and ACE) and Shannon index. Notably, a significant decrease in Simpson index was observed in PSCI patients in comparison to the healthy individuals (-0.31, 95% CI: -0.62 to -0.01, P = 0.04). Moreover, the microbiota composition at the phylum level (increased abundance of Proteobacteria), family level (increased abundance of Bacteroidaceae, Lachnospiraceae, and Veillonellaceae; decreased abundance of Enterobacteriaceae), and genus level (increased abundance of Bacteroides, Clostridium XIVa, and Parabacteroides; decreased abundance of Prevotella and Ruminococcus) was found to be significantly different between PSCI and controls.
CONCLUSION
This meta-analysis suggests a significant shift of observed species and microbiota composition in PSCI compared to healthy individuals or patients with stroke.
Topics: Humans; Gastrointestinal Microbiome; Microbiota; Bacteroides; Clostridiales; Cognitive Dysfunction; Stroke
PubMed: 37657030
DOI: 10.1097/MD.0000000000034764 -
Brain and Behavior Jun 2023Bipolar disorder (BD) is a mood disorder that affects millions worldwide. Up to half of the diagnosed patients are reported to not receive adequate treatment. This study... (Review)
Review
BACKGROUND
Bipolar disorder (BD) is a mood disorder that affects millions worldwide. Up to half of the diagnosed patients are reported to not receive adequate treatment. This study aims to assess the relationship between the gut-brain axis and BD and to discuss and compare the efficacy of varying methods of balancing gut microbiotas in BD.
METHODS
Using PubMed, Embase, and Google Scholar from November 2021 to February 2022, we found 5310 studies on gut microbiota and its relation to BD. Using our inclusion criteria, 5283 studies were excluded. A total of 27 full-text articles were assessed for eligibility. Also, 12 articles that met our criteria and eligibility criteria reported on 613 BD patients.
RESULTS
Most studies analyzed found an overall difference in gut microbiota composition in bipolar patients compared to healthy controls, though the alterations found were not consistent. Differences in Lactobacillus, Faecalibacterium, and Ruminococcus abundance in BD compared to controls were found to be the most consistent across a few of the studies, but their effects on the gut-brain axis conflicted. Probiotic supplementation was found to lower patient rehospitalizations and significantly improve depressive symptoms and cognitive impairments among patients with BD.
CONCLUSIONS
Multiple studies included in this review point toward a possible link between BD and the gut microbiota. Probiotic supplements and other gut-balancing therapies could serve as effective adjunctive methods for the treatment of BD. Notable limitations of the studies included for analysis were small sample sizes and majority observational study designs. Furthermore, the microbiota aberrations found in patients with BD were not consistent across multiple studies. Despite these limitations, our findings demonstrate the need for further research regarding the relationship between aberrant gut microbiota profiles and BD, as well as the effectiveness of gut balancing methods as adjunctive treatments.
Topics: Humans; Bipolar Disorder; Gastrointestinal Microbiome; Brain-Gut Axis; Observational Studies as Topic
PubMed: 37127945
DOI: 10.1002/brb3.3037