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Probiotics fortify intestinal barrier function: a systematic review and meta-analysis of randomized trials.
Zheng, Y, Zhang, Z, Tang, P, Wu, Y, Zhang, A, Li, D, Wang, CZ, Wan, JY, Yao, H, Yuan, CS
Frontiers in immunology. 2023;14:1143548
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Plain language summary
Intestinal barrier function is closely related to the pathogenesis of various immune and inflammatory diseases. The intestinal microbiota plays an essential role in maintaining gut homeostasis and functionality in the presence of pro-inflammatory and anti-inflammatory microbes. The aim of this study was to comprehensively evaluate the role of probiotics in contributing to intestinal barrier function, and the related immune function, inflammatory status, and gut microbiota composition. This study was a systematic review of 28 articles (qualitative synthesis), and a meta-analysis of 26 randomised controlled trials. Results showed that probiotics could significantly improve intestinal barrier function according to specific indicators. The meta-analysis also indicated that probiotic supplementation could reduce inflammatory factors. Furthermore, it also demonstrated that probiotics could modulate gut microbiota compositions by elevating the abundances of Bifidobacterium and Lactobacillus. Authors conclude that probiotics could improve intestinal barrier function to some extent, but more high-quality randomised controlled studies are needed to reach a solid conclusion.
Expert Review
Conflicts of interest:
None
Take Home Message:
The probiotics Bifidobacterium and Lactobacillus may be beneficial for health by addressing imbalances in gut bacteria (dysbiosis), reducing inflammation in the gut and improving the integrity and function of the gut barrier
Evidence Category:
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A: Meta-analyses, position-stands, randomized-controlled trials (RCTs)
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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
Probiotics are microorganisms that are considered beneficial to health. The aim of this study was to assess the role of probiotics in protecting intestinal barrier function as well as their effects on the composition of gut microbiota, inflammatory status, and immune function for reducing the risk of related diseases.
Methods
26 randomised controlled trials (RCTs) published between 2005-2021 with a total population of n=1891 (n = 955 Intervention, n = 936 controls)) were included in the meta-analysis. Outcome measures were categorised under indicators relating to intestinal barrier function, inflammatory markers, immune function and microbiota composition. Studies were conducted worldwide with participants being healthcare patients or athletes. Study durations ranged from 3 days to 6 months. Different dosages and forms of probiotics were used. Data was pooled for Bifidobacterium, Lactobacillus, Enterobacteriaceae and Enterococcus species.
Results
Gut barrier function in the probiotic groups was improved as measured by transepithelial resistance (TER) mean difference (MD) 5.27 {95% CI, 3.82 to 6.72, p = < 0.00001], lipopolysaccharide (LPS) standardised mean difference (SMD) -0.47 (95% CI, -0.85 to -0.09, p = 0.02), serum zonulin SMD -1.58 (95% CI,-2.49 to -0.66, p = 0.0007), and endotoxin SMD -3.20 (95% CI, -5.41 to - 0.98, p = 0.005).
The inflammatory markers interleukin 6 (IL-6), C-reactive protein (CRP) and tumour necrosis factor-alpha (TNF-a) were also improved compared to control groups. Lactobacillus (95% CI p=0.02) and Bifidobacterium (95% CI, p=0.01) enhanced microbial composition, however, Enterobacteriaceae and Enterococcus species did not. Immune function as measured by Immunoglobulin A (IgA), Immunoglobulin G IgG and Immunoglobulin M (IgM) were not improved.
Conclusion
The findings of this study suggest that intestinal barrier function and microbial composition could be improved using probiotics. They were also found to help alleviate inflammation. Further studies of high quality are however needed to confirm these results.
No conflicts of interest were reported.
Clinical practice applications:
The use of the probiotics Bifidobacterium and Lactobacillus may be beneficial for:
- supporting the integrity of gut barrier function
- improving the composition of gut microbiota
- lowering inflammation
Considerations for future research:
High heterogeneity between studies may affect the applicability of the results. Future research development should focus on the following areas:
- testing methods
- study durations
- measuring indicators
- the type and dose of probiotics
Abstract
BACKGROUND Probiotics play a vital role in treating immune and inflammatory diseases by improving intestinal barrier function; however, a comprehensive evaluation is missing. The present study aimed to explore the impact of probiotics on the intestinal barrier and related immune function, inflammation, and microbiota composition. A systematic review and meta-analyses were conducted. METHODS Four major databases (PubMed, Science Citation Index Expanded, CENTRAL, and Embase) were thoroughly searched. Weighted mean differences were calculated for continuous outcomes with corresponding 95% confidence intervals (CIs), heterogeneity among studies was evaluated utilizing I2 statistic (Chi-Square test), and data were pooled using random effects meta-analyses. RESULTS Meta-analysis of data from a total of 26 RCTs (n = 1891) indicated that probiotics significantly improved gut barrier function measured by levels of TER (MD, 5.27, 95% CI, 3.82 to 6.72, P < 0.00001), serum zonulin (SMD, -1.58, 95% CI, -2.49 to -0.66, P = 0.0007), endotoxin (SMD, -3.20, 95% CI, -5.41 to -0.98, P = 0.005), and LPS (SMD, -0.47, 95% CI, -0.85 to -0.09, P = 0.02). Furthermore, probiotic groups demonstrated better efficacy over control groups in reducing inflammatory factors, including CRP, TNF-α, and IL-6. Probiotics can also modulate the gut microbiota structure by boosting the enrichment of Bifidobacterium and Lactobacillus. CONCLUSION The present work revealed that probiotics could improve intestinal barrier function, and alleviate inflammation and microbial dysbiosis. Further high-quality RCTs are warranted to achieve a more definitive conclusion. CLINICAL TRIAL REGISTRATION https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=281822, identifier CRD42021281822.
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Association of gestational diabetes mellitus with overall and type specific cardiovascular and cerebrovascular diseases: systematic review and meta-analysis.
Xie, W, Wang, Y, Xiao, S, Qiu, L, Yu, Y, Zhang, Z
BMJ (Clinical research ed.). 2022;378:e070244
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Gestational diabetes mellitus, defined as glucose intolerance with first onset during pregnancy, usually resolves after birth, however, a growing number of long-term observational studies suggest that the impact persists over time. The increased cardiovascular risk in women with gestational diabetes mellitus has been increasingly recognised. The aim of this study was to quantify the risks of overall and type specific cardiovascular and cerebrovascular diseases in women with gestational diabetes mellitus. This study is a systematic review and meta-analysis of fifteen studies. The study included almost nine million women. Results show that participants with a history of gestational diabetes mellitus were at significantly increased risks of cardiovascular and cerebrovascular diseases in general and at variable risks for most common types of cardiovascular and cerebrovascular diseases. Authors conclude that their findings highlight the need for early intervention in women at high risk of gestational diabetes mellitus, and for continuous monitoring of women with a history of gestational diabetes mellitus after pregnancy.
Abstract
OBJECTIVE To quantify the risk of overall and type specific cardiovascular and cerebrovascular diseases as well as venous thromboembolism in women with a history of gestational diabetes mellitus. DESIGN Systematic review and meta-analyses. DATA SOURCES PubMed, Embase, and the Cochrane Library from inception to 1 November 2021 and updated on 26 May 2022. REVIEW METHODS Observational studies reporting the association between gestational diabetes mellitus and incident cardiovascular and cerebrovascular diseases were eligible. Data, pooled by random effects models, are presented as risk ratios (95% confidence intervals). Certainty of evidence was appraised by the Grading of Recommendations, Assessment, Development, and Evaluations. RESULTS 15 studies rated as moderate or serious risk of bias were included. Of 513 324 women with gestational diabetes mellitus, 9507 had cardiovascular and cerebrovascular disease. Of more than eight million control women without gestational diabetes, 78 895 had cardiovascular and cerebrovascular disease. Compared with women without gestational diabetes mellitus, women with a history of gestational diabetes mellitus showed a 45% increased risk of overall cardiovascular and cerebrovascular diseases (risk ratio 1.45, 95% confidence interval 1.36 to 1.53), 72% for cardiovascular diseases (1.72, 1.40 to 2.11), and 40% for cerebrovascular diseases (1.40, 1.29 to 1.51). Women with gestational diabetes mellitus showed increased risks of incident coronary artery diseases (1.40, 1.18 to 1.65), myocardial infarction (1.74, 1.37 to 2.20), heart failure (1.62, 1.29 to 2.05), angina pectoris (2.27, 1.79 to 2.87), cardiovascular procedures (1.87, 1.34 to 2.62), stroke (1.45, 1.29 to 1.63), and ischaemic stroke (1.49, 1.29 to 1.71). The risk of venous thromboembolism was observed to increase by 28% in women with previous gestational diabetes mellitus (1.28, 1.13 to 1.46). Subgroup analyses of cardiovascular and cerebrovascular disease outcomes stratified by study characteristics and adjustments showed significant differences by region (P=0.078), study design (P=0.02), source of data (P=0.005), and study quality (P=0.04), adjustment for smoking (P=0.03), body mass index (P=0.01), and socioeconomic status (P=0.006), and comorbidities (P=0.05). The risk of cardiovascular and cerebrovascular diseases was, however, attenuated but remained significant when restricted to women who did not develop subsequent overt diabetes (all gestational diabetes mellitus: 1.45, 1.33 to 1.59, gestational diabetes mellitus without subsequent diabetes: 1.09, 1.06 to 1.13). Certainty of evidence was judged as low or very low quality. CONCLUSIONS Gestational diabetes mellitus is associated with increased risks of overall and type specific cardiovascular and cerebrovascular diseases that cannot be solely attributed to conventional cardiovascular risk factors or subsequent diabetes.
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Consumption of ultra-processed foods and health outcomes: a systematic review of epidemiological studies.
Chen, X, Zhang, Z, Yang, H, Qiu, P, Wang, H, Wang, F, Zhao, Q, Fang, J, Nie, J
Nutrition journal. 2020;19(1):86
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Unhealthy diets are recognized as a major determinant of the occurrence of non-communicable diseases (NCDs). The aim of this study was to summarize the evidence for the association between ultra-processed food (UPFs) consumption and health outcomes. This study is a systemic review of 20 published epidemiological studies (12 cohort and 8 cross-sectional studies), with a total of 334,114 participants and 10 diseases. Results indicate a positive association between UPFs consumption and risk of all-cause mortality, overall cardiovascular diseases, coronary heart diseases, cerebrovascular diseases, hypertension, metabolic syndrome, overweight and obesity, depression, irritable bowel syndrome, overall cancer, postmenopausal breast cancer, gestational obesity, adolescent asthma and wheezing, and frailty. However, on the contrary, there was not an obvious association with cardiovascular disease mortality, prostate and colorectal cancer, gestational diabetes mellitus and gestational overweight. Authors conclude that their findings encouraged a decrease in UPFs consumption and an increase in the proportion of unprocessed or minimally processed foods, such as fruits and vegetables.
Abstract
BACKGROUND Consumption of ultra-processed foods (UPFs) plays a potential role in the development of obesity and other diet-related noncommunicable diseases (NCDs), but no studies have systematically focused on this. This study aimed to summarize the evidence for the association between UPFs consumption and health outcomes. METHODS A comprehensive search was conducted in PubMed, Embase, and Web of Science to identify all relevant studies. Epidemiological studies were included, and identified studies were evaluated for risk of bias.A narrative review of the synthesized findings was provided to assess the association between UPFs consumption and health outcomes. RESULTS 20 studies (12 cohort and 8 cross-sectional studies) were included in the analysis, with a total of 334,114 participants and 10 health outcomes. In a narrative review, high UPFs consumption was obviously associated with an increased risk of all-cause mortality, overall cardiovascular diseases, coronary heart diseases, cerebrovascular diseases, hypertension, metabolic syndrome, overweight and obesity, depression, irritable bowel syndrome, overall cancer, postmenopausal breast cancer, gestational obesity, adolescent asthma and wheezing, and frailty. It showed no significant association with cardiovascular disease mortality, prostate and colorectal cancers, gestational diabetes mellitus and gestational overweight. CONCLUSIONS This study indicated a positive association between UPFs consumption and risk of several health outcomes. Large-scale prospective designed studies are needed to confirm our findings.