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Potential role of microbiome in Chronic Fatigue Syndrome/Myalgic Encephalomyelits (CFS/ME).
Lupo, GFD, Rocchetti, G, Lucini, L, Lorusso, L, Manara, E, Bertelli, M, Puglisi, E, Capelli, E
Scientific reports. 2021;11(1):7043
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Chronic Fatigue Syndrome/Myalgic Encephalomyelits (CFS/ME) is a severe multisystemic disease. The main symptom is persistent unexplained fatigue, it has inflammatory symptoms, is characterized by an abnormal immune response and dysfunction of energy metabolism. Recent studies suggest strong correlations between dysbiosis and other conditions such as intestinal disorders, autoimmune conditions, cancer and several neurological disorders. In the case of CFS/ME, some studies have shown an altered composition of the gut and oral microbiomes. In this study the oral and intestinal bacterial composition of CFS/ME patients were analysed and compared to a group of relatives and to a control population outside the families. This was to identify a possible effect of lifestyle habits and a microbial profile of CFS/ME syndrome. The study showed significant variations in both the intestinal and oral bacteria composition between CFS/ME patients, their relatives and external controls. There is a lot of interesting detail about the levels of specific bacteria in each group. Further studies are needed to better understand if the microbial composition changes are cause or consequence of the onset of CFS/ME and if they are related to any of the several secondary symptoms.
Abstract
Chronic Fatigue Syndrome/Myalgic Encephalomyelitis (CFS/ME) is a severe multisystemic disease characterized by immunological abnormalities and dysfunction of energy metabolism. Recent evidences suggest strong correlations between dysbiosis and pathological condition. The present research explored the composition of the intestinal and oral microbiota in CFS/ME patients as compared to healthy controls. The fecal metabolomic profile of a subgroup of CFS/ME patients was also compared with the one of healthy controls. The fecal and salivary bacterial composition in CFS/ME patients was investigated by Illumina sequencing of 16S rRNA gene amplicons. The metabolomic analysis was performed by an UHPLC-MS. The fecal microbiota of CFS/ME patients showed a reduction of Lachnospiraceae, particularly Anaerostipes, and an increased abundance of genera Bacteroides and Phascolarctobacterium compared to the non-CFS/ME groups. The oral microbiota of CFS/ME patients showed an increase of Rothia dentocariosa. The fecal metabolomic profile of CFS/ME patients revealed high levels of glutamic acid and argininosuccinic acid, together with a decrease of alpha-tocopherol. Our results reveal microbial signatures of dysbiosis in the intestinal microbiota of CFS/ME patients. Further studies are needed to better understand if the microbial composition changes are cause or consequence of the onset of CFS/ME and if they are related to any of the several secondary symptoms.
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Effects of Microbiota Imbalance in Anxiety and Eating Disorders: Probiotics as Novel Therapeutic Approaches.
Navarro-Tapia, E, Almeida-Toledano, L, Sebastiani, G, Serra-Delgado, M, García-Algar, Ó, Andreu-Fernández, V
International journal of molecular sciences. 2021;22(5)
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The interest in mental health has increased recently. Anxiety and mood disorders are associated with many disabilities and there is a close relationship between eating disorders and anxiety. Although current medical treatments for anxiety disorders are safer than a few decades ago; the effectiveness in some of them has not improved, they have side effects and can cause addiction. Therefore, the development of new tools to restore mental health without the undesired effects is necessary. Recent studies indicate that patients with generalized anxiety or eating disorders (anorexia nervosa, bulimia nervosa, and binge-eating disorders) show a specific gut microbiota profile, and this imbalance can be partially restored after a single or multi-strain probiotic supplementation. The purpose of this review is to look at the main microbial patterns seen in patients with generalized anxiety and/or eating disorders as well as the importance of probiotics as a preventive or a therapeutic tool in these pathologies. The studies reviewed showed an imbalance of microbial communities in patients with anxiety and with eating disorders. The effect of probiotics in reducing anxiety seems to be more effective the higher the baseline anxiety level of the individual. For eating disorders, the correction of dysbiosis may be associated with the physical and emotional well-being of these subjects. Further study of the intestinal microbiota will enable progress in the study of therapeutic approaches of these areas.
Abstract
Anxiety and eating disorders produce a physiological imbalance that triggers alterations in the abundance and composition of gut microbiota. Moreover, the gut-brain axis can be altered by several factors such as diet, lifestyle, infections, and antibiotic treatment. Diet alterations generate gut dysbiosis, which affects immune system responses, inflammation mechanisms, the intestinal permeability, as well as the production of short chain fatty acids and neurotransmitters by gut microbiota, which are essential to the correct function of neurological processes. Recent studies indicated that patients with generalized anxiety or eating disorders (anorexia nervosa, bulimia nervosa, and binge-eating disorders) show a specific profile of gut microbiota, and this imbalance can be partially restored after a single or multi-strain probiotic supplementation. Following the PRISMA methodology, the current review addresses the main microbial signatures observed in patients with generalized anxiety and/or eating disorders as well as the importance of probiotics as a preventive or a therapeutic tool in these pathologies.
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Probiotic Supplementation Improves Cognitive Function and Mood with Changes in Gut Microbiota in Community-Dwelling Older Adults: A Randomized, Double-Blind, Placebo-Controlled, Multicenter Trial.
Kim, CS, Cha, L, Sim, M, Jung, S, Chun, WY, Baik, HW, Shin, DM
The journals of gerontology. Series A, Biological sciences and medical sciences. 2021;76(1):32-40
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Aging is characterized by progressive decline in biological functions of the organism. Diet is one of the critical lifestyle factors for physical and mental well-being throughout the life span, including later life. The aim of this study was to investigate the effects of probiotics consumption on intestinal and brain health in elders over the age of 65. This study is a randomised, double-blind, placebo-controlled, multicentre trial. All participants, study coordinators, and researchers were blinded throughout the entire study. Sixty-three participants were randomized, with 31 and 32 subjects in the placebo and probiotics group, respectively. Results demonstrate that probiotics have system-wide effects on the gut–brain axis in healthy community-dwelling older adults by promoting cognitive and mental health and changing the gut microbial composition. Authors conclude that their findings provide evidence that probiotics have health-promoting properties as part of a healthy diet in the general population of independently living older adults.
Abstract
Probiotics have been proposed to ameliorate cognitive impairment and depressive disorder via the gut-brain axis in patients and experimental animal models. However, the beneficial role of probiotics in brain functions of healthy older adults remains unclear. Therefore, a randomized, double-blind, and placebo-controlled multicenter trial was conducted to determine the effects of probiotics on cognition and mood in community-dwelling older adults. Sixty-three healthy elders (≥65 years) consumed either placebo or probiotics containing Bifidobacterium bifidum BGN4 and Bifidobacterium longum BORI for 12 weeks. The gut microbiota was analyzed using 16S rRNA sequencing and bioinformatics. Brain functions were measured using the Consortium to Establish a Registry for Alzheimer's disease, Satisfaction with life scale, stress questionnaire, Geriatric depression scale, and Positive affect and negative affect schedule. Blood brain-derived neurotrophic factor (BDNF) was determined using enzyme-linked immunosorbent assay. Relative abundance of inflammation-causing gut bacteria was significantly reduced at Week 12 in the probiotics group (p < .05). The probiotics group showed greater improvement in mental flexibility test and stress score than the placebo group (p < .05). Contrary to placebo, probiotics significantly increased serum BDNF level (p < .05). Notably, the gut microbes significantly shifted by probiotics (Eubacterium and Clostridiales) showed significant negative correlation with serum BDNF level only in the probiotics group (RS = -0.37, RS = -0.39, p < .05). In conclusion, probiotics promote mental flexibility and alleviate stress in healthy older adults, along with causing changes in gut microbiota. These results provide evidence supporting health-promoting properties of probiotics as a part of healthy diet in the older adults.
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Effects of Probiotic NVP-1704 on Mental Health and Sleep in Healthy Adults: An 8-Week Randomized, Double-Blind, Placebo-Controlled Trial.
Lee, HJ, Hong, JK, Kim, JK, Kim, DH, Jang, SW, Han, SW, Yoon, IY
Nutrients. 2021;13(8)
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Dietary changes directly alter the gut microbiome composition. A diversified gut microbiome may have therapeutic implications for mental health, and specific strains of probiotics have shown the potential to treat depression and anxiety. Several preclinical trials have found the probiotic mixture NVP-1704 to alleviate depression and anxiety in mice through modulating the gut-brain-microbiome axis. The aim of this randomised, double-blind, placebo-controlled, parallel study was to examine the efficacy and safety of NVP-1704 for the management of depression, anxiety and insomnia in healthy adults. A total of 156 healthy adults with subclinical depression, anxiety and insomnia were randomised to receive either NVP-1704 or placebo for eight weeks. Participants completed various questionnaires and biomarkers of stress and inflammation were assessed. After eight weeks, this study found that NVP-1704 to be a safe and well-tolerated probiotic with beneficial effects on depression, sleep quality, inflammation and gut microbiome composition in healthy adults. Based on this study, the authors conclude the therapeutic effects of NVP-1704 previously found in preclinical mice trials may now be translated to clinical trials. The authors suggest large, highly controlled, longitudinal human studies be conducted in the future to further confirm the benefits of probiotics on mental health and sleep.
Abstract
The human gut microbiome is closely linked to mental health and sleep. We aimed to verify the efficacy and safety of probiotic NVP-1704, a mixture of Lactobacillus reuteri NK33 and Bifidobacterium adolescentis NK98, in improving stress, depression, anxiety, and sleep disturbances, along with the measurement of some blood biomarkers. A total of 156 healthy adults with subclinical symptoms of depression, anxiety, and insomnia were retrospectively registered and randomly assigned to receive either NVP-1704 (n = 78) or a placebo (n = 78) for eight weeks. Participants completed the Stress Response Inventory, Beck's Depression and Anxiety Inventory, Pittsburg Sleep Quality Index, and Insomnia Severity Index at baseline, at four and eight weeks of treatment. Pre- and post-treatment blood tests for biomarkers were conducted. After intervention, gut microbiota composition was quantified by pyrosequencing the bacterial 16S rRNA gene. The NVP-1704 group had a more significant reduction in depressive symptoms at four and eight weeks of treatment, and anxiety symptoms at four weeks compared to the placebo group. Those receiving NVP-1704 also experienced an improvement in sleep quality. NVP-1704 treatment led to a decrease in serum interleukin-6 levels. Furthermore, NVP-1704 increased Bifidobacteriaceae and Lactobacillacea, whereas it decreased Enterobacteriaceae in the gut microbiota composition. Our findings suggest that probiotic NVP-1704 could be beneficial for mental health and sleep.
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Characterization of the Oral and Gut Microbiota in Patients with Psoriatic Diseases: A Systematic Review.
Todberg, T, Kaiser, H, Zachariae, C, Egeberg, A, Halling, AS, Skov, L
Acta dermato-venereologica. 2021;101(7):adv00512
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Psoriasis is a common inflammatory skin disease that results in patches of dry, scaly skin that can be itchy or sore. Psoriatic arthritis is an inflammatory arthritis that affects up to 30% of psoriasis patients. There is growing interest in the association between the microbiome and inflammatory conditions. This systematic review examined the role of the oral and gut microbiota and the effect of probiotics in patients with psoriasis and/or psoriatic arthritis. 23 studies were included in the analysis. Studies examined the microbiota using culture or 16S ribosomal RNA gene sequencing analysis. The results showed an increased presence of Candida in the mouth, and an altered gut microbiota in patients with psoriatic disease compared with healthy controls. Probiotics were associated with a significant decrease in psoriasis severity, but the microbiota was unchanged. The study authors concluded that further research is required into the role of the microbiome in patients with psoriasis.
Abstract
Advances in technology have led to an increased number of studies investigating the microbiome in patients with psoriasis. This systematic review examined data regarding the oral and gut microbiota in patients with psoriasis and/or psoriatic arthritis and the effect of probiotics on the microbiota and severity of psoriasis. Of 1,643 studies, 23 were included (22 observational, 1 interventional). Studies examined the microbiota using culture or 16S rRNA gene sequencing analysis. All culture-based studies identified an increased presence of oral Candida in patients with psoriasis, whereas small variations in the oral microbiota were found in a 16S rRNA gene-based study. All 16S rRNA gene sequencing based studies agreed that the gut microbiota of patients with psoriatic disease differed from that of healthy controls, but the results were heterogeneous. Probiotics were associated with a significant improvement in the severity of psoriasis, but did not change microbiota. Overall, studies lacked relevant inclusion criteria and baseline information. In conclusion, the role of the microbiota in patients with psoriasis requires further investigation using more robust methods.
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Effect of Lactobacillus casei on lipid metabolism and intestinal microflora in patients with alcoholic liver injury.
Li, X, Liu, Y, Guo, X, Ma, Y, Zhang, H, Liang, H
European journal of clinical nutrition. 2021;75(8):1227-1236
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Alcoholic liver disease (ALD) is a series of liver diseases caused by long-term heavy drinking. Lipid metabolism disorder often occurs in people with alcoholic liver injury. Treatment is mainly a combination of alcohol abstinence, improving nutrition, treating the liver injury, and preventing or reversing the progress of liver fibrosis or promoting liver regeneration. The aim of this study was to investigate the effect of Lactobacillus casei on lipid metabolism and intestinal microflora in patients with alcoholic liver injury. This study was a randomised, double-blind, placebo-controlled trial. A total of 181 ALD patients were recruited and randomly assigned to one of the three groups; low-dose group, high-dose group and positive control group (+ there was another group of 20 healthy people which served as normal control group). Results showed disorder of lipid metabolism, intestinal flora imbalance and inflammation in patients with alcoholic liver injury. Furthermore, after supplementation of Lactobacillus casei, there was a significant increase in the amount of Lactobacillus and Bifidobacterium. Authors conclude that Lactobacillus casei supplementation can improve lipid metabolism and regulate intestinal flora disorders in patients with alcoholic liver injury.
Abstract
BACKGROUND The present study aims to investigate the effect of Lactobacillus casei on lipid metabolism and intestinal microflora in patients with alcoholic liver injury. METHODS In a double-blind randomized controlled trial, 158 recruited alcoholic liver injury patients were randomized to three treatments for 60 days: low-dose group (LP, n = 58, 100 ml of Lactobacillus casei strain Shirota (LcS)), high-dose group (HP, n = 54, 200 ml of LcS), and positive control group (PC, n = 46, 100 ml of special drinks without active Lactobacillus casei). Another group of 20 healthy people was served as normal control group (NC). RESULTS The serum levels of TG and LDLC in the HP group were significantly decreased by 26.56% and 23.83%, respectively than those in the PC group (P < 0.05). After supplementation of Lactobacillus casei, there was a significant increase in the amount of Lactobacillus and Bifidobacterium when compared with the PC group (P < 0.05). CONCLUSIONS Supplementation of Lactobacillus casei can improve lipid metabolism and regulate intestinal flora disorders in patients with alcoholic liver injury.
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Efficacy of probiotics on digestive disorders and acute respiratory infections: a controlled clinical trial in young Vietnamese children.
Mai, TT, Thi Thu, P, Thi Hang, H, Trang, TTT, Yui, S, Shigehisa, A, Tien, VT, Dung, TV, Nga, PB, Hung, NT, et al
European journal of clinical nutrition. 2021;75(3):513-520
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The World Health Organization (WHO) reported that acute respiratory infection (ARI) is the leading cause of death in children followed by diarrhoea and constipation. In Vietnam, despite many achievements in malnutrition prevention, the rate of malnutrition is elevated. Malnutrition results in ARI, diarrhoea, and physical and mental retardation in children The aim of this study was to investigate the effects of a probiotic fermented milk product containing Lactobacillus casei strain Shirota (LcS) on gastrointestinal symptoms, respiratory infections, and the nutrition status of children from Vietnam. This study was a community based, controlled open trial and it was conducted over a period of 18 weeks consisting of 2-week screening/pre-observational period; 12-week intervention period; and 4-week postintervention period. A total of 1036 children (518 children in the Control group and 518 children in the Probiotic group) were enrolled in this study. Results showed a significant reduction in the incidence of constipation and beneficial effects to prevent infectious diseases in Vietnamese children. Furthermore, while LcS did not affect the duration of diarrhoea, the incidence of diarrhoea tended to be improved after 12 weeks of intervention. Authors conclude that habitual consumption of fermented milk containing LcS prevented constipation and ARI in Vietnamese children, and it may be useful for treating diarrhoea and improving nutritional status, thus conferring remarkable health benefits to children in Vietnam.
Abstract
OBJECTIVES To evaluate the efficacy of fermented milk containing Lactobacillus casei strain Shirota (LcS) on the incidence of constipation, diarrhea, acute respiratory infections (ARI), and nutritional status of young Vietnamese children. METHODS A controlled field trial was conducted with 1003 children (3-5 years old) in Thanh Hoa province in Vietnam. The probiotic group (n = 510) consumed fermented milk 65 mL/day containing 108 CFU/mL of LcS for the 12-week intervention period, whereas the control group (n = 493) was not given any. The incidence of constipation, diarrhea, ARI, and anthropometry in children was determined at baseline, after 4, 8, and 12-week intervention, and after the 4-week follow-up period. RESULTS Probiotic drink decreased the incidence of constipation after the 12-week intervention period (12.0% vs. 32.0%, OR = 0.28 (95% CI: 0.21-0.40), p < 0.001), tended to decrease the incidence of diarrhea (4.9% vs. 7.9%, OR = 0.60 (95% CI: 0.35-1.01), p = 0.068), and prevented the occurrence of ARI (15.9% vs. 24.5%, OR = 0.58 (95% CI: 0.42-0.79), p < 0.001), when compared with the control group. In contrast, no probiotic effects were observed for the duration of diarrhea or ARI. Weight gain was higher in the probiotic group than in the control group after 4, 8, and 12-week intervention and after the 4-week follow-up period (p < 0.05). CONCLUSIONS Daily intake of fermented milk containing LcS strongly prevented the incidence of constipation and ARI in Vietnamese children. This study also revealed the potential effects of the use of a probiotic drink on diarrhea prevention as well as nutritional status improvement.
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Naturalization of the microbiota developmental trajectory of Cesarean-born neonates after vaginal seeding.
Song, SJ, Wang, J, Martino, C, Jiang, L, Thompson, WK, Shenhav, L, McDonald, D, Marotz, C, Harris, PR, Hernandez, CD, et al
Med (New York, N.Y.). 2021;2(8):951-964.e5
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Studies on model organisms show that foetal development can be modulated by microbial products from the pregnant mother’s microbiota, and early colonisation is critical for immune system development. However, natural transmission and colonisation of maternal microbes is impaired by caesarean section (CS) delivery. The aim of this study was to determine the effect of restoring exposure to maternal vaginal fluids after CS birth. This study is a large observational study of 177 infants born to 174 mothers. Physicians assessed healthy mothers who were set to deliver vaginally or by scheduled CS. Results demonstrate that microbial differences associated with delivery mode can be reduced by exposure to a vaginal microbial source at birth. In fact, birth mode significantly differentiated infant gut and skin microbiome development, and that seeding worked to adjust the trajectory of CS-delivered infants through partial restoration of microbiome features associated with a vaginal delivery. Authors conclude that restoring natural exposures at birth may be one way to reduce the risk of CS-associated diseases such as obesity, asthma, allergies, and immune disfunctions. However, randomised clinical trials on large cohorts are needed to gain conclusive evidence for microbial restoration at birth improving health outcomes.
Abstract
BACKGROUND Early microbiota perturbations are associated with disorders that involve immunological underpinnings. Cesarean section (CS)-born babies show altered microbiota development in relation to babies born vaginally. Here we present the first statistically powered longitudinal study to determine the effect of restoring exposure to maternal vaginal fluids after CS birth. METHODS Using 16S rRNA gene sequencing, we followed the microbial trajectories of multiple body sites in 177 babies over the first year of life; 98 were born vaginally, and 79 were born by CS, of whom 30 were swabbed with a maternal vaginal gauze right after birth. FINDINGS Compositional tensor factorization analysis confirmed that microbiota trajectories of exposed CS-born babies aligned more closely with that of vaginally born babies. Interestingly, the majority of amplicon sequence variants from maternal vaginal microbiomes on the day of birth were shared with other maternal sites, in contrast to non-pregnant women from the Human Microbiome Project (HMP) study. CONCLUSIONS The results of this observational study prompt urgent randomized clinical trials to test whether microbial restoration reduces the increased disease risk associated with CS birth and the underlying mechanisms. It also provides evidence of the pluripotential nature of maternal vaginal fluids to provide pioneer bacterial colonizers for the newborn body sites. This is the first study showing long-term naturalization of the microbiota of CS-born infants by restoring microbial exposure at birth. FUNDING C&D, Emch Fund, CIFAR, Chilean CONICYT and SOCHIPE, Norwegian Institute of Public Health, Emerald Foundation, NIH, National Institute of Justice, Janssen.
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Gluten and FODMAPs Relationship with Mental Disorders: Systematic Review.
Aranburu, E, Matias, S, Simón, E, Larretxi, I, Martínez, O, Bustamante, MÁ, Fernández-Gil, MDP, Miranda, J
Nutrients. 2021;13(6)
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There is growing evidence that gluten and FODMAPs, such as fermentable oligosaccharides, disaccharides, monosaccharides and polyols, can cause gastrointestinal symptoms, inflammation, and immune responses in patients with celiac disease and irritable bowel syndrome. In addition, a high intake of gluten and FODMAPs may also be associated with neurological and psychiatric disorders. Thirteen studies were included in this systematic review to examine the relationship between gluten and FODMAP consumption and illnesses affecting the central nervous system. In addition, the studies examined the effects of potential dietary strategies that consider gluten and FODMAP intake on mental disorders, anxiety, depression, schizophrenia, Alzheimer’s disease, and autism spectrum disorders. Several possible mechanisms identified in this systematic review could contribute to neurological and psychiatric disorders, including the release of proinflammatory cytokines, immune responses, gut dysbiosis, intestinal permeability, and interactions between the gut-brain axis. In patients with fibromyalgia, celiac disease, and irritable bowel syndrome, avoiding or limiting gluten may reduce depression, anxiety, and cognitive impairment. However, the effects of a low-FODMAP diet on the central nervous system are inconclusive. There is some evidence that gluten-free diets can improve cognition in schizophrenia patients. In addition, those with autism spectrum disorders may benefit from a gluten-free diet and a low-FODMAP diet. Further robust research is required to evaluate the beneficial effects of interventions that avoid or restrict the consumption of foods high in FODMAPs and gluten. However, healthcare professionals can use the results of this systematic review to understand the potential benefits of therapeutic interventions that consider the intake of FODMAPs and gluten on illnesses affecting the central nervous system and their possible mechanisms of action.
Abstract
Nowadays, gluten and FODMAP food components (fermentable oligosaccharides, disaccharides, monosaccharides and polyols) are increasingly studied due to their possible relation with extraintestinal-associated conditions. In recent years, gluten-free diets (GFD) and low-FODMAP diets (LFD) are becoming more popular not only in order to avoid the food components that cause intolerances or allergies in some people, but also due to the direct influence of marketing movements or diet trends on feeding habits. Likewise, neurological and psychiatric diseases are currently of increasing importance in developed countries. For this reason, a bibliographic systematic review has been carried out to analyse whether there is a pathophysiological relationship between the dietary intake of gluten or FODMAPs with mental disorders. This review collects 13 clinical and randomized controlled trials, based on the PRISMA statement, which have been published in the last ten years. Based on these results, limiting or ruling out gluten or FODMAPs in the diet might be beneficial for symptoms such as depression, anxiety (7 out of 7 articles found any positive effect), or cognition deficiency (improvements in several cognition test measurements in one trial), and to a lesser extent for schizophrenia and the autism spectrum. Nevertheless, further studies are needed to obtain completely reliable conclusions.
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Avocado Consumption Alters Gastrointestinal Bacteria Abundance and Microbial Metabolite Concentrations among Adults with Overweight or Obesity: A Randomized Controlled Trial.
Thompson, SV, Bailey, MA, Taylor, AM, Kaczmarek, JL, Mysonhimer, AR, Edwards, CG, Reeser, GE, Burd, NA, Khan, NA, Holscher, HD
The Journal of nutrition. 2021;151(4):753-762
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Conflicting reports exist on the role of gastrointestinal microorganisms in the development of obesity. The consumption of avocados has been associated with lower body weight, increased feelings of being full and lower blood lipid concentrations. This randomised controlled trial of 163 adults aimed to determine the effect of 12 weeks of daily avocado intake on the gut microbiota and the by-products they produce. The results showed that the regular consumption of avocados resulted in greater abundances of gut bacteria capable of fibre fermentation and altered the by-products produced. Faecalibacterium, Lachnospira and Alistipes bacteria were all increased. However it should be noted that the individuals in the avocado group were also given a meal plan higher in fibre. It was concluded that avocados can alter gut microbiota composition and metabolic function of the gut. This study could be used by healthcare professionals to understand that nutrient dense foods may have the ability to alter metabolic functions in the gut, however further research is needed to determine whether avocado consumption is of benefit to those with obesity.
Abstract
BACKGROUND Avocados are rich in dietary fiber and monounsaturated fatty acids (MUFAs), nutrients that have been independently connected to metabolic health benefits and the gastrointestinal microbiota. OBJECTIVES We aimed to evaluate the impact of avocado consumption on the gastrointestinal microbiota and microbial metabolites, secondary outcomes of the Persea americana for Total Health (PATH) study, and conduct exploratory analyses to assess relations between the fecal microbiota, fecal metabolites, and health markers. METHODS Adults [n = 163, 25-45 y, BMI (kg/m2) ≥ 25.0] were enrolled in the PATH study, a 12-wk investigator-blinded trial where participants were batch randomized to match the 2 groups by age, sex, visceral adiposity, and fasting glucose concentrations. Participants consumed isocaloric meals with or without avocado (175 g, men; 140 g, women) once daily for 12 wk. The fecal microbiota was assessed with 16S ribosomal RNA gene (V4 region) sequencing and analysis using DADA2 and QIIME2. Fecal fatty acid and bile acid concentrations were quantified using GC and LC-MS. Per-protocol (≥80% meal consumption) and intent-to-treat analyses were conducted using univariate ANOVA and Mann-Whitney U tests. Bivariate correlations were conducted between fecal microbiota, fecal metabolites, and health measures. RESULTS The avocado treatment increased ɑ diversity and enriched Faecalibacterium, Lachnospira, and Alistipes between 26% and 65% compared with the control group. The avocado group had 18% greater fecal acetate, 70% greater stearic acid, and 98% greater palmitic acid concentrations than the control group, while the concentrations of the bile acids cholic and chenodeoxycholic acid were 91% and 57% lower, respectively. CONCLUSIONS Daily avocado consumption resulted in lower fecal bile acid concentrations, greater fecal fatty acid and SCFAs, and greater relative abundances of bacteria capable of fiber fermentation, providing evidence that this nutrient-dense food affects digestive physiology, as well as the composition and metabolic functions of the intestinal microbiota. This trial was registered at www.clinicaltrials.gov as NCT02740439.