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The Gut Microbiome in Early Life Stress: A Systematic Review.
Agusti, A, Lamers, F, Tamayo, M, Benito-Amat, C, Molina-Mendoza, GV, Penninx, BWJH, Sanz, Y
Nutrients. 2023;15(11)
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Children exposed to early life stress (ELS) show alterations in brain development and are at increased risk of developing mental illness. This study aims to clarify whether ELS influences the gut microbiome and whether this can be a predictor for the development of mental disorders. 13 articles were included in this systemic review. 4 looked at pre-natal stress and 9 at post-natal stress. Prenatal stress (via maternal stress) may be associated with an increase in Proteobacteria phylum and with a lower abundance of Bifidobacterium and lactic acid bacteria. In the postnatal group, greater microbiome diversity was related to lower depression and anxiety. In boys scores for adaptive skills were higher in those with good levels of Bifidobacterium. A positive association was found between EA (early adversity) experiences and gastrointestinal symptoms and anxiety. This review demonstrates links between ELS and gut microbiome changes. Further research will be necessary to draw more robust conclusions.
Expert Review
Conflicts of interest:
None
Take Home Message:
- This systematic review consolidated and discussed existing evidence on the link between early life stress (ELS) and changes to the human microbiome
- Exposure to ELS, prenatal or postnatal during childhood and adolescence, may impact mental and physical health.
Evidence Category:
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A: Meta-analyses, position-stands, randomized-controlled trials (RCTs)
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X
B: Systematic reviews including RCTs of limited number
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C: Non-randomized trials, observational studies, narrative reviews
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D: Case-reports, evidence-based clinical findings
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E: Opinion piece, other
Summary Review:
Introduction
A systematic review was conducted to consolidate clinical evidence examining the impact of early life stress (ELS) on the human intestinal microbiome.
Method
Thirteen observational studies were included in the review, sourced from Pubmed, Scopus, Web of Science, and EMBASE. Methodological quality was assessed using the Newcastle-Ottawa Assessment Scale (NOS), with most studies scoring seven or eight out of nine stars.
Study designs varied, including prospective prenatal studies, postnatal longitudinal studies, case-control studies, and cross-sectional studies. Four prenatal studies were prospective in design. The other nine postnatal studies included one longitudinal study, five case-control studies, and three cross-sectional studies. All 13 studies were published between 2015 and 2022. Because study designs and outcome assessments varied, the results were presented in a narrative form. Data was extracted by 2 independent authors.
Results
The primary findings from the review were as follows:
- Four longitudinal stress studies indicated that pregnant mothers experiencing psychological stress, increased cortisol levels, HIV, and lack of social support exhibited a lower abundance of beneficial Bifidobacterium and an increased abundance of Enterobacter genus.
- One postnatal stress longitudinal study (n=260) demonstrated lower depression and anxiety and improved internalising behaviour in patients with high microbiome diversity.
- . One postnatal stress case-control study (n=344) showed changes in the microbiome and an abundance of several bacterial taxa in stressed groups, including genera Prevotella, Bacteroides (Bacteroidetes), Coprococcus, Streptococcus, and Escherichia.
- One cross-sectional study of 128 adults without psychiatric conditions revealed that higher stress correlated with increased levels of Bacteroides, Parabacteroides, Rhodococcus, Methanobrevibacter, and Roseburia at the genus level, as well as lower Phascolarcto bacterium and Firmicutes at the phylum level.
- One large prospective study (n=446) found infants exposed to higher cumulative stress exhibited an increased relative abundance of Proteobacteria groups and lower Bifidobacterium.
Conclusion:
Due to the inconsistency of study designs and their results this review failed to find consensus microbiome signatures associated with pre- or postnatal stress, or both.
Clinical practice applications:
- Early life stress, and alterations in the gut microbiome, have been linked to mental health conditions
- Maternal prenatal stress may be linked to emotional, behavioural, and cognitive outcomes in infants.
Considerations for future research:
- Future research should standardise questionnaires, to ensure consistency and comparability across studies
- Additionally, future studies should consider using standard procedures and specific species and strain resolution shotgun metagenomics sequencing
- Consideration should be given to the influence of environmental variables (diet, physical activity, etc.) and sex in gut microbiome analysis.
Abstract
Exposure to early life stress (ELS), prenatal or postnatal during childhood and adolescence, can significantly impact mental and physical health. The role of the intestinal microbiome in human health, and particularly mental health, is becoming increasingly evident. This systematic review aims to summarize the clinical data evaluating the effect of ELS on the human intestinal microbiome. The systematic review (CRD42022351092) was performed following PRISMA guidelines, with ELS considered as exposure to psychological stressors prenatally and during early life (childhood and adolescence). Thirteen articles met all inclusion criteria, and all studies reviewed found a link between ELS and the gut microbiome in both prenatal and postnatal periods. However, we failed to find consensus microbiome signatures associated with pre- or postnatal stress, or both. The inconsistency of results is likely attributed to various factors such as different experimental designs, ages examined, questionnaires, timing of sample collection and analysis methods, small population sizes, and the type of stressors. Additional studies using similar stressors and validated stress measures, as well as higher-resolution microbiome analytical approaches, are needed to draw definitive conclusions about the links between stress and the human gut microbiome.
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Exploring choices of early nutritional support for patients with sepsis based on changes in intestinal microecology.
Yang, XJ, Wang, XH, Yang, MY, Ren, HY, Chen, H, Zhang, XY, Liu, QF, Yang, G, Yang, Y, Yang, XJ
World journal of gastroenterology. 2023;29(13):2034-2049
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Sepsis is a condition brought about by infection and results in organ dysfunction and gut microbiota imbalance. Nutrition plays a large part in recovery from sepsis, however it is unclear as to the optimal diet for gut microbial balance in individuals with sepsis. This randomised control trial of 30 individuals with sepsis aimed to determine the optimal delivery of nutrition for gut microbial health either through a gastric tube (TEN), through the jugular vein (TPN), or a mixture of the two modes (SPN). The results showed differences in gut microbiota composition between the different modes of nutrition. Enterococcus increased in TEN, Campylobacter decreased in TPN, and Dialister decreased in SPN groups. Fermentation products produced by gut microbiota also changed depending on the mode of nutrition, with the TEN group showing improvements amongst the most fermentation products. Individuals in the TEN group also showed improved immune system function alongside those in the SPN group. It was concluded that based upon improvements to the immune system and gut microbiota, TEN is the most suitable mode for nutrition in individuals with sepsis. This study could be used by healthcare professionals to understand that nutrition methods for individuals with sepsis aren’t equally effective and recovery may be faster if individuals receive nutrition through a gastric tube.
Abstract
BACKGROUND Sepsis exacerbates intestinal microecological disorders leading to poor prognosis. Proper modalities of nutritional support can improve nutrition, immunity, and intestinal microecology. AIM: To identify the optimal modality of early nutritional support for patients with sepsis from the perspective of intestinal microecology. METHODS Thirty patients with sepsis admitted to the intensive care unit of the General Hospital of Ningxia Medical University, China, between 2019 and 2021 with indications for nutritional support, were randomly assigned to one of three different modalities of nutritional support for a total of 5 d: Total enteral nutrition (TEN group), total parenteral nutrition (TPN group), and supplemental parenteral nutrition (SPN group). Blood and stool specimens were collected before and after nutritional support, and changes in gut microbiota, short-chain fatty acids (SCFAs), and immune and nutritional indicators were detected and compared among the three groups. RESULTS In comparison with before nutritional support, the three groups after nutritional support presented: (1) Differences in the gut bacteria (Enterococcus increased in the TEN group, Campylobacter decreased in the TPN group, and Dialister decreased in the SPN group; all P < 0.05); (2) different trends in SCFAs (the TEN group showed improvement except for Caproic acid, the TPN group showed improvement only for acetic and propionic acid, and the SPN group showed a decreasing trend); (3) significant improvement of the nutritional and immunological indicators in the TEN and SPN groups, while only immunoglobulin G improved in the TPN group (all P < 0.05); and (4) a significant correlation was found between the gut bacteria, SCFAs, and nutritional and immunological indicators (all P < 0.05). CONCLUSION TEN is recommended as the preferred mode of early nutritional support in sepsis based on clinical nutritional and immunological indicators, as well as changes in intestinal microecology.
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Randomised trial of safety and efficacy of immediate postoperative enteral feeding in patients undergoing gastrointestinal resection.
Carr, CS, Ling, KD, Boulos, P, Singer, M
BMJ (Clinical research ed.). 1996;312(7035):869-71
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Malnutrition predisposes patients to postoperative complications such as infection and a prolonged hospital stay. Postoperative gastric stasis causes nausea and vomiting thus inhibiting oral intake, but it has been shown that small bowel function continues. This randomised trial of 28 patients assessed the safely and efficacy of immediate post-operative enteral feeding in patients who had undergone gastrointestinal resection, compared to conventional intravenous fluids. The study found that the average caloric intake was significantly higher in enterally fed patients compared to those on intravenous fluids. Urinary nitrogen balance, a marker of nutritional status, was negative on the first postoperative day in those on intravenous fluids but positive in all 14 enterally fed patients. There was no change in gut mucosal permeability in the enterally fed group (assessed by lactulose:mannitol absorption ratio) but a significant increase from the test ratios seen before the operation in those on intravenous fluids. There were also fewer postoperative complications in the enterally fed group. Immediate postoperative enteral feeding in patients undergoing intestinal resection seems to be safe, prevents an increase in gut mucosal permeability, and produces a positive nitrogen balance. Postoperative enteral feeding may reduce the need for total parenteral nutrition and reduce expenditure and complications.
Abstract
OBJECTIVES To assess whether immediate post-operative enteral feeding in patients who have undergone gastrointestinal resection is safe and effective. DESIGN Randomised trial of immediate post-operative enteral feeding through a nasojejunal tube v conventional postoperative intravenous fluids until the reintroduction of normal diet. SETTING Teaching hospitals in London. SUBJECTS 30 patients under the care of the participating consultant surgeon who were undergoing elective laparotomies with a view to gastrointestinal resection for quiescent, chronic gastrointestinal disease. Two patients did not proceed to resection. MAIN OUTCOME MEASURES Nutritional state, nutritional intake and nitrogen balance, gut mucosal permeability measured by lactulose-mannitol differential sugar absorption test, complications, and outcome. RESULTS Successful immediate enteral feeding was established in all 14 patients with a mean (SD) daily intake of 6.78 (1.57)MJ (1622 (375) kcal before reintroduction of oral diet compared with 1.58 (0.14) MJ (377 (34) kcal) for those on intravenous fluids (P < 0.0001). Urinary nitrogen balance on the first postoperative day was negative in those on intravenous fluids but positive in all 14 enterally fed patients (mean (SD) - 13.2 (11.6) g v 5.3 (2.7) g; P < 0.005). There was no difference by day 5. There was no change in gut mucosal permeability in the enterally fed group but a significant increase from the test ratios seen before the operation in those on intravenous fluids (0.11(0.06) v 0.15 (0.12); P < 0.005). There were also fewer postoperative complications in the enterally fed group (P < 0.005). CONCLUSIONS Immediate postoperative enteral feeding in patients undergoing intestinal resection seems to be safe, prevents an increase in gut mucosal permeability, and produces a positive nitrogen balance.