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Effect of probiotics or prebiotics on thyroid function: A meta-analysis of eight randomized controlled trials.
Shu, Q, Kang, C, Li, J, Hou, Z, Xiong, M, Wang, X, Peng, H
PloS one. 2024;19(1):e0296733
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The gut microbiome is thought to play a role in thyroid disorders, mediated by regulating iodine uptake, degradation and enterohepatic cycling of thyroid hormones, and differences in microbiome composition between patients with thyroid disorders and healthy individuals have been observed. The aim of this systematic review and meta-analysis was to evaluate the effect of pro-, pre- and synbiotics on thyroid function (thyroid stimulating hormone (TSH), free thyroxine (fT4) and free triiodothyronine (fT3) and thyroid stimulating hormone receptor antibody (TRAb)) in patients with and without thyroid disorders. 8 randomised controlled trials including 367 participants were included in the review and meta-analysis. Neither pro-, pre- nor synbiotics had a significant effect on TSH, fT4 or fT3 but pre- and probiotics lead to a significant reduction in TRAb in patients with Graves’ disease.
Abstract
BACKGROUND Microbiome-directed therapies are increasingly utilized to optimize thyroid function in both healthy individuals and those with thyroid disorders. However, recent doubts have been raised regarding the efficacy of probiotics, prebiotics, and synbiotics in improving thyroid function. This systematic review aimed to investigate the potential relationship between probiotics/prebiotics and thyroid function by analyzing the impact on thyroid hormone levels. METHODS We conducted a comprehensive systematic review and meta-analysis of randomized controlled trials that investigated the effects of probiotics, prebiotics, and synbiotics on free triiodothyronine (fT3), free thyroxine (fT4), thyroid stimulating hormone (TSH), and thyroid stimulating hormone receptor antibody (TRAb) levels. We searched for articles from PubMed, Scopus, Web of Science, and Embase up until April 1st, 2023, without any language restriction. Quantitative data analysis was performed using a random-effects model, with standardized mean difference (SMD) and 95% confidence interval as summary statistics. The methods and results were reported according to the PRISMA2020 statement. RESULTS A total of eight articles were included in this review. The meta-analysis showed no significant alterations in TSH (SMD: -0.01, 95% CI: -0.21, 0.20, P = 0.93; I2: 0.00%), fT4 (SMD: 0.04, 95% CI: -0.29, 0.21, P = 0.73; I2: 0.00%) or fT3 (SMD: 0.45, 95% CI: -0.14, 1.03, P = 0.43; I2: 78.00%), while a significant reduction in TRAb levels was observed (SMD: -0.85, 95% CI: -1.54, -0.15, P = 0.02; I2: 18.00%) following probiotics/prebiotics supplementation. No indication of publication bias was found. CONCLUSIONS Probiotics/prebiotics supplementation does not influence thyroid hormone levels, but may modestly reduce TRAb levels in patients with Graves' disease.
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Age-Dependent Relationships Between Disease Risk and Testosterone Levels: Relevance to COVID-19 Disease.
Muehlenbein, M, Gassen, J, Nowak, T, Henderson, A, Morris, B, Weaver, S, Baker, E
American journal of men's health. 2023;17(2):15579883221130195
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A growing body of research finds that in men, testosterone levels may be prognostic of clinical outcomes related to coronavirus disease 2019 (COVID-19 disease). The presence of pre-existing chronic conditions in many patients with COVID-19 disease further complicates the relationship among testosterone and severe outcomes. The aim of this study was to examine whether pre-existing conditions for severe COVID-19 disease were related to serum-free testosterone levels in men who had not been infected with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus. This study obtained data from men (n = 142) who participated in the longitudinal study Waco COVID Survey. All data included in the study was collected as part of the initial intake survey and first laboratory appointment. Results show that serum-free testosterone levels decreased as a function of age. In fact, greater burden of pre-existing conditions for severe COVID-19 disease was related to lower testosterone levels among men younger than 40 years of age. Furthermore, in men older than 40 years of age the decrease in testosterone that accompanies aging attenuated the effect of the clinical risk score on free testosterone levels. Authors conclude that their findings add important insights into the complex role of androgens in chronic and infectious diseases and contribute to the growing body of literature on the relationship between chronic disease and men’s testosterone levels.
Abstract
Testosterone levels in men appear to be prognostic of a number of disease outcomes, including severe COVID-19 disease. Testosterone levels naturally decline with age and are lower in individuals with a number of comorbidities and chronic conditions. Low testosterone may therefore be both a cause and a consequence of illness, including COVID-19 disease. The present project examines whether preexisting conditions for severe COVID-19 disease were themselves related to serum-free testosterone levels in men who had not been infected with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus. A clinical risk score for severe COVID-19 disease was computed based on the results of previously published meta-analyses and cohort studies, and relationships between this score and testosterone levels were tested in 142 men ages 19 to 82 years. Greater burden of preexisting conditions for severe COVID-19 disease was related to lower testosterone levels among men younger than 40 years of age. In older men, the decrease in testosterone that accompanies aging attenuated the effect of the clinical risk score on free testosterone levels. Given that older age itself is a predictor of COVID-19 disease severity, these results together suggest that the presence of preexisting conditions may confound the relationship between testosterone levels and COVID-19 disease outcomes in men. Future research examining relationships among testosterone and outcomes related to infectious and chronic diseases should consider potential confounds, such as the role of preexisting conditions.
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The efficacy of N-acetylcysteine in chronic obstructive pulmonary disease patients: a meta-analysis.
Huang, C, Kuo, S, Lin, L, Yang, Y
Therapeutic advances in respiratory disease. 2023;17:17534666231158563
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Chronic obstructive pulmonary disease (COPD) is characterised by reduced airflow, excess mucus secretion and shortness of breath. During exacerbations, excessive free radicals are formed leading to reduced levels of the body’s glutathione (GSH) antioxidant system. N-acetylcysteine (NAC) is a precursor to GSH and also a well-known mucolytic agent. The aim of this meta-analysis, which included 9 randomised, placebo-controlled trials with 2137 COPD patients, was to evaluate the effectiveness of NAC supplementation. Outcome measures were number of patients with no acute exacerbations, change in forced expiratory volume at 1s (FEV1), change in forced vital capacity (FVC), St George’s Respiratory Questionnaire, change in glutathione levels and adverse events. There was no statistically significant difference between the NAC and the placebo group in any of the outcomes. This was regardless of dose, which ranged from 600 mg every 24 hours to 1800 every 12 hours. Limitations of this meta-analysis, as listed by the authors, include the small number and sizes of studies and the heterogeneity of study designs.
Abstract
BACKGROUND N-acetylcysteine (NAC) may reduce acute exacerbations of chronic obstructive pulmonary disease through an antioxidant effect. Due to the heterogeneity in studies, the currently available data do not confirm the efficacy of oral NAC therapy in chronic obstructive pulmonary disease patients. We hypothesize that chronic obstructive pulmonary disease patients receiving regular oral NAC therapy do not achieve improved clinical outcomes. OBJECTIVES The purpose of this meta-analysis was to determine the efficacy of long-term oral NAC therapy in chronic obstructive pulmonary disease patients. DATA SOURCES AND METHODS The literature search was performed using the PubMed, Web of Science, and Cochrane Library databases to identify all included clinical studies. Studies were eligible for inclusion only if they directly compared the outcomes of NAC versus placebo in adults with chronic obstructive pulmonary disease between 1 January 2000 and 30 May 2022. All studies were included if they reported one or more of the following outcomes: number of patients with no acute exacerbations, forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), St George's Respiratory Questionnaire score, glutathione level, and adverse events. RESULTS Nine randomized controlled trials were included in the meta-analysis. There were 1061 patients in the NAC group and 1076 patients in the placebo group. The current meta-analysis provides evidence that the number of patients with no acute exacerbations (965 patients receiving NAC therapy, 979 control group patients), change in FEV1 (433 patients receiving NAC therapy, 447 control group patients), change in FVC (177 patients receiving NAC therapy, 180 control group patients), change in St George's Respiratory Questionnaire score (128 patients receiving NAC therapy, 131 control group patients), change in glutathione levels (38 patients receiving NAC therapy, 40 control group patients), and adverse events (832 patients receiving NAC therapy, 846 control group patients) were not significantly different between the two groups. CONCLUSION NAC did not reduce the risk of acute exacerbation or ameliorate the decline in lung volume in chronic obstructive pulmonary disease patients.
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Effect of supplementation with probiotics or synbiotics on cardiovascular risk factors in patients with metabolic syndrome: a systematic review and meta-analysis of randomized clinical trials.
Chen, T, Wang, J, Liu, Z, Gao, F
Frontiers in endocrinology. 2023;14:1282699
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Metabolic syndrome (metS) is characterised by insulin resistance, dyslipidaemia, central obesity and/or high blood pressure and is a significant risk factor for cardiovascular disease and type 2 diabetes mellitus. MetS is associated with an imbalanced microbiome and some but not all studies have shown benefits of supplementation with probiotics. The aim of this systematic review and meta-analysis of randomised controlled trials was to evaluate the effects of pro- or synbiotics on cardiovascular risk factors (body mass index, LDL cholesterol, fasting blood glucose and systolic blood pressure) in patients with metS. 11 studies were included in the review of which 7 were judged to have a low risk of bias, whilst risk of bias was unclear in 4 articles. The meta-analysis found that pro- or synbiotics have a positive effect on body mass index, LDL cholesterol and fasting blood glucose but not on systolic blood pressure. Subgroup analysis of pro- and synbiotics separately also found no effects on systolic blood pressure.
Abstract
PURPOSE The effectiveness of probiotics or synbiotics in adults with metabolic syndromes (MetS) remains controversial, this meta-analysis will further analyze the effects of probiotics or synbiotics on cardiovascular factors in adults with MetS. METHODS We searched Web of Science, PubMed, Embase, Cochrane Library and other databases for randomized controlled trials (RCTs) on the effects of probiotics or synbiotics on MetS in adults up to July 2023, and used RevMan 5.4.0 software for statistical analysis. RESULTS This analysis included eleven RCTs (n = 608 participants), and the results showed that compared with the control group, supplementation with probiotics or synbiotics reduced body mass index (weighted mean difference, WMD = -0.83, 95% CI = [-1.21, -0.44], P <0.0001, n = 9), low-density lipoprotein (LDL-c) (standard mean difference, SMD = -0.24, 95% CI = [-0.41, -0.08], P = 0.004, n = 10), fasting blood glucose (FBG)(SMD = -0.17, 95% CI = [-0.33, -0.01], P = 0.03, n = 11), but had no beneficial effect on systolic blood pressure (SBP) (WMD = 1.24, 95% CI = [-2.06, 4.54], P = 0.46, n = 8) in MetS patients. CONCLUSION Supplementation with probiotics or synbiotics can reduce BMI, LDL-c, FBG in patients with MetS, but our findings did not demonstrate a favorable effect on reducing SBP. Future studies with larger samples and longer intervention periods are needed.
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Effects of prebiotics, probiotics and synbiotics on serum creatinine in non-dialysis patients: a meta-analysis of randomized controlled trials.
Liu, F, Liu, Y, Lv, X, Lun, H
Renal failure. 2023;45(1):2152693
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Creatinine is a biomarker of kidney function and is used to diagnose chronic kidney disease. The aim of this meta-analysis of randomised controlled trials was to evaluate the effect of supplementation with prebiotics, probiotics and synbiotics on serum creatinine levels in patients not receiving dialysis. 12 RCTs were included in the meta-analysis of which seven were judged to have a low risk of bias whilst 1 was judged to have a high risk of bias. Overall, there was no significant effect of supplementation on serum creatinine levels. The following three subgroup analyses also showed no significant effects on creatinine levels: 1) by probiotics, prebiotics and synbiotics separately; 2) by duration: two months or less or longer than two months, 3) subgroup of 7 studies which included patients with non-dialysis kidney disease. The authors concluded that probiotics, prebiotics and synbiotics do not decrease serum creatinine levels.
Abstract
OBJECTIVE Serum creatinine level are influenced by many factors. Although accumulated data suggested that prebiotics, probiotics and synbiotics supplements could affect serum creatinine level, the results remained controversial. The aim of the present paper was to evaluate the effects of prebiotics, probiotics and synbiotics on serum creatinine in non-dialysis patients. METHODS PubMed, EMBASE (Excerpta Medica Database) and the Cochrane Library databases were searched for eligible randomized, controlled trials (RCTs) which were limited to English language studies until 30 September 2022. A random-effects model was performed to analyze the impact of pooled trials. RESULT Twelve randomized, controlled trial studies were included in the meta-analysis. Prebiotics, probiotics or synbiotics supplementation did not significantly decrease the serum creatinine levels in non-dialysis patients compared to placebo [standardized mean difference (SMD) = 0.05; 95% confidence interval (CI): (-0.21, 0.31); p = 0.72; I2 = 61%]. CONCLUSION The present meta-analysis indicated that supplementation with prebiotics, probiotics and synbiotics could not act as promising adjuvant therapies to decrease the serum creatinine levels in non-dialysis patients.
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Effects of Vitamin D Supplementation During Pregnancy on Birth Size: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.
Maugeri, A, Barchitta, M, Blanco, I, Agodi, A
Nutrients. 2019;11(2)
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Vitamin D deficiency may affect mother and neonatal outcomes, increasing the risk of pregnancy complications, preterm birth, low birth weight (LBW), small for gestational age (SGA), and poor offspring health. This systematic review and meta-analysis evaluates the effects of oral vitamin D supplementation during pregnancy on foetal growth and incidence of LBW and SGA births. 13 randomised controlled trials (RCTs), published between 1980 and 2016, were included in the meta-analysis, including in total 2016 newborns (1184 from mothers in the intervention groups and 832 from controls). Dosages ranged from 200-4000 IU for daily intakes and 35000 IU to 600000 IU for single or intermittent administration. Whilst there was no evidence for publication bias (e.g. an over-reporting of positive outcomes), overall, the quality of the reviewed studies varied from very low (head circumference) to moderate (birth weight, birth length, LBW, and SGA). All studies evaluating the effect of vitamin D supplementation on blood 25-hydroxyvitamin D (OHD) levels showed that intervention significantly increased 25-OHD concentration in both mothers and infants. The meta-analysis showed that vitamin D supplementation significantly increased birth weight and length, independent of dosage and whether vitamin D was administered daily or in single/intermittent high dosages. Head circumference was increased in a non-dose dependent way with daily but not with single/intermittent vitamin D supplementation. Effects on all three parameters were seen when vitamin D was supplemented alone, but not in combination with other nutrients. Both, risk of LBW and SGA, were also significantly reduced with vitamin D supplementation.
Abstract
During pregnancy, vitamin D supplementation may be a feasible strategy to help prevent low birthweight (LBW) and small for gestational age (SGA) births. However, evidence from randomized controlled trials (RCTs) is inconclusive, probably due to heterogeneity in study design and type of intervention. A systematic literature search in the PubMed-Medline, EMBASE, and Cochrane Central Register of Controlled Trials databases was carried out to evaluate the effects of oral vitamin D supplementation during pregnancy on birthweight, birth length, head circumference, LBW, and SGA. The fixed-effects or random-effects models were used to calculate mean difference (MD), risk ratio (RR), and 95% Confidence Interval (CI). On a total of 13 RCTs, maternal vitamin D supplementation had a positive effect on birthweight (12 RCTs; MD = 103.17 g, 95% CI 62.29⁻144.04 g), length (6 RCTs; MD = 0.22 cm, 95% CI 0.11⁻0.33 cm), and head circumference (6 RCTs; MD:0.19 cm, 95% CI 0.13⁻0.24 cm). In line with these findings, we also demonstrated that maternal vitamin D supplementation reduced the risk of LBW (3 RCTs; RR = 0.40, 95% CI 0.22⁻0.74) and SGA (5 RCTS; RR = 0.69, 95% CI 0.51⁻0.92). The present systematic review and meta-analysis confirmed the well-established effect of maternal vitamin D supplementation on birth size. However, further research is required to better define risks and benefits associated with such interventions and the potential implications for public health.
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Probiotic monotherapy and Helicobacter pylori eradication: A systematic review with pooled-data analysis.
Losurdo, G, Cubisino, R, Barone, M, Principi, M, Leandro, G, Ierardi, E, Di Leo, A
World journal of gastroenterology. 2018;24(1):139-149
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Helicobacter pylori (H-pylori) is a parasite that resides in the human stomach and is associated with the development of stomach ulcers, amongst other conditions. Conventional treatment relies on a combination of antibiotics and stomach acid suppressants, however failure rates for standard treatments have been rising and alternatives are required. Probiotics (live bacteria that provide health benefits to their host) have been used alongside antibiotic treatment for H-pylori in some cases to reduce medication side effects. This systematic review of 11 studies including 517 H-pylori infected patients, aimed to assess the effects of probiotic therapy alone on H-pylori status. The study found that the eradication rate of H-pylori with a variety of probiotic strains was 12-16%, compared to a 0% success rate in the placebo groups. Clinically, this rate is low, however the authors conclude that probiotics may have a role to play in a multi-therapy approach for the eradication of H-pylori.
Abstract
AIM: To define probiotic monotherapy effect on Helicobacter pylori (H. pylori) status by performing a systematic review. METHODS Methods of analysis and inclusion criteria were based on PRISMA recommendations. Relevant publications were identified by searching PubMed, MEDLINE, Science Direct, and EMBASE. The end-point was to estimate eradication rate and urea breath test delta value before and after probiotic monotherapy across all studies and, overall, with a pooled data analysis. Adverse events of probiotic therapy were evaluated. The data were expressed as proportions/percentages, and 95%CIs were calculated. For continuous variables, we evaluated the weighted mean difference. Odd ratios (ORs) were calculated according to the Peto method for the comparison of eradication rates between probiotics and placebo. RESULTS Eleven studies were selected. Probiotics eradicated H. pylori in 50 out of 403 cases. The mean weighted eradication rate was 14% (95%CI: 2%-25%, P = 0.02). Lactobacilli eradicated the bacterium in 30 out of 235 patients, with a mean weighted rate of 16% (95%CI: 1%-31%). Saccharomyces boulardii achieved eradication in 6 out of 63 patients, with a pooled eradication rate of 12% (95%CI: 0%-29%). Multistrain combinations were effective in 14 out of 105 patients, with a pooled eradication rate of 14% (95%CI: 0%-43%). In the comparison of probiotics vs placebo, we found an OR of 7.91 in favor of probiotics (95%CI: 2.97-21.05, P < 0.001). Probiotics induced a mean reduction in delta values higher than placebo (8.61% with a 95%CI: 5.88-11.34, vs 0.19% for placebo, P < 0.001). Finally, no significant difference in adverse events was found between probiotics and placebo (OR = 1, 95%CI: 0.06-18.08). CONCLUSION Probiotics alone show a minimal effect on H. pylori clearance, thus suggesting a likely direct role.
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The Effect of Bifidobacterium animalis ssp. lactis HN019 on Cellular Immune Function in Healthy Elderly Subjects: Systematic Review and Meta-Analysis.
Miller, LE, Lehtoranta, L, Lehtinen, MJ
Nutrients. 2017;9(3)
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Elderly individuals are more susceptible to infections and cancer, due to lowered immune system function. The gut bacteria play a key role in human immune system function and there is an interest in a potential role for probiotics in strengthening the immune system through manipulation of the microbiome. This systematic review and meta-analysis of 4 randomised controlled trials aimed to examine the efficacy of Bifidobacterium animalis lactis HN019 on the cellular immune activity of healthy elderly adults age 60-70 years. The authors concluded that supplementation with this bacterial strain at a range of potencies for 3-6 weeks duration had a significant positive impact on the part of the immune system that is responsible for removing pathogens and cell debris (phagocytosis) and a lesser but nevertheless significant impact on natural killer cells responsible for tumour destruction.
Abstract
Elderly people have increased susceptibility to infections and cancer that are associated with decline in cellular immune function. The objective of this work was to determine the efficacy of Bifidobacterium (B.) animalis ssp. lactis HN019 (HN019) supplementation on cellular immune activity in healthy elderly subjects. We conducted a systematic review of Medline and Embase for controlled trials that reported polymorphonuclear (PMN) cell phagocytic capacity or natural killer (NK) cell tumoricidal activity following B. lactis HN019 consumption in the elderly. A random effects meta-analysis was performed with standardized mean difference (SMD) and 95% confidence interval between probiotic and control groups for each outcome. A total of four clinical trials were included in this analysis. B. lactis HN019 supplementation was highly efficacious in increasing PMN phagocytic capacity with an SMD of 0.74 (95% confidence interval: 0.38 to 1.11, p < 0.001) and moderately efficacious in increasing NK cell tumoricidal activity with an SMD of 0.43 (95% confidence interval: 0.08 to 0.78, p = 0.02). The main limitations of this research were the small number of included studies, short-term follow-up, and assessment of a single probiotic strain. In conclusion, daily consumption of B. lactis HN019 enhances NK cell and PMN function in healthy elderly adults.
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Impact of Probiotic Administration on Serum C-Reactive Protein Concentrations: Systematic Review and Meta-Analysis of Randomized Control Trials.
Mazidi, M, Rezaie, P, Ferns, GA, Vatanparast, H
Nutrients. 2017;9(1)
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C-reactive protein (CRP) is a blood marker of inflammation and is frequently elevated in chronic conditions such as heart disease, obesity and Type 2 diabetes. Some strains of probiotics (bacteria that exert health benefits) are thought to act as anti-inflammatory agents through various mechanisms. This systematic review and meta-analysis of 20 randomised controlled trials (RCTs) aimed to investigate the effects of probiotic supplementation on CRP levels as one measure of inflammation. The meta-analysis indicates that probiotic supplementation with various strains of bacteria has a significant impact on serum CRP levels, with a weighted mean difference of -1.35mg/l. Whilst positive impacts were also seen for interleukin-10 and tumour necrosis factor-alpha (other markers of inflammation) with probiotics, these did not reach significance. The authors of this study point out that the results need to be interpreted with caution owing to the wide variety of study types, study size, probiotic strains and health outcomes measured in the included RCTs. However, Nutrition Practitioners working with clients with raised CRP levels may want to investigate the use of certain probiotic strains as part of an anti-inflammatory protocol.
Abstract
We conducted this systematic review and meta-analysis of prospective studies to determine the effect of probiotic administration on serum C-reactive protein (CRP) concentrations. We searched PubMed-Medline, Web of Science, the Cochrane, and Google Scholar databases (until May 2016) to identify prospective studies evaluating the impact of probiotic administration on CRP. We used a random effects models and generic inverse variance methods to synthesize quantitative data, followed by a leave-one-out method for sensitivity analysis. The systematic review registration number was: CRD42016039457. From a total of 425 entries identified via searches, 20 studies were included in the final analysis. The meta-analysis indicated a significant reduction in serum CRP following probiotic administration with a weighted mean difference (WMD) of -1.35 mg/L, (95% confidence interval (CI) -2.15 to -0.55, I² 65.1%). The WMDs for interleukin 10 (IL10) was -1.65 pg/dL, (95% CI -3.45 to 0.14, I² 3.1%), and -0.45 pg/mL, (95% CI -1.38 to 0.48, I² 10.2%) for tumor necrosis factor alpha (TNF-α). These findings were robust in sensitivity analyses. This meta-analysis suggests that probiotic administration may significantly reduce serum CRP while having no significant effect on serum IL10 and TNF-α.
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Effects of Probiotics and Synbiotics on Obesity, Insulin Resistance Syndrome, Type 2 Diabetes and Non-Alcoholic Fatty Liver Disease: A Review of Human Clinical Trials.
Sáez-Lara, MJ, Robles-Sanchez, C, Ruiz-Ojeda, FJ, Plaza-Diaz, J, Gil, A
International journal of molecular sciences. 2016;17(6)
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The microbiome influences human physiology and affects metabolism. The aim of this review was to investigate the effectiveness of probiotics and synbiotics (a combination of probiotics and prebiotics) in the prevention and treatment of obesity, metabolic syndrome, type 2 diabetes mellitus (T2DM) and non-alcoholic liver disease (NAFLD) in human clinical trials. Supplementation of selected probiotics was found to have beneficial effects on body mass index (BMI), waist circumference, visceral (abdominal) fat and hip circumference in overweight or obese people. Some probiotic strains also appear to have positive effects on glucose metabolism and insulin sensitivity in patients with metabolic syndrome, obesity and/or T2DM. Increased antioxidant status, reduced inflammation and improved lipid metabolism were observed in these patient groups. Specific pro- and synbiotics also led to improvements in NAFLD. However, there were also studies which showed no benefits of probiotic/synbiotic supplementation. The authors state that this may be due to study design, choice of probiotic strains or too small number of trial subjects, and call for more research.
Abstract
The use of probiotics and synbiotics in the prevention and treatment of different disorders has dramatically increased over the last decade. Both probiotics and synbiotics are well known ingredients of functional foods and nutraceuticals and may provide beneficial health effects because they can influence the intestinal microbial ecology and immunity. The present study reviews the effects of probiotics and synbiotics on obesity, insulin resistance syndrome (IRS), type 2 diabetes (T2D) and non-alcoholic fatty liver disease (NAFLD) in human randomized clinical trials. Select probiotics and synbiotics provided beneficial effects in patients with obesity, mainly affecting the body mass index and fat mass. Some probiotics had beneficial effects on IRS, decreasing the cell adhesion molecule-1 levels, and the synbiotics decreased the insulin resistance and plasma lipid levels. Moreover, select probiotics improved the carbohydrate metabolism, fasting blood glucose, insulin sensitivity and antioxidant status and also reduced metabolic stress in subjects with T2D. Some probiotics and synbiotics improved the liver and metabolic parameters in patients with NAFLD. The oral intake of probiotics and synbiotics as co-adjuvants for the prevention and treatment of obesity, IRS, T2D and NAFLD is partially supported by the data shown in the present review. However, further studies are required to understand the precise mechanism of how probiotics and synbiotics affect these metabolic disorders.