The Effect of Probiotics and Synbiotics on Risk Factors Associated with Cardiometabolic Diseases in Healthy People-A Systematic Review and Meta-Analysis with Meta-Regression of Randomized Controlled Trials

The effects of prebiotic, probiotic or synbiotic supplementation on overweight/obesity indicators: an umbrella review of the trials' meta-analyses

Background

There is controversial data on the effects of prebiotic, probiotic, or synbiotic supplementations on overweight/obesity indicators. Thus, we aimed to clarify this role of biotics through an umbrella review of the trials' meta-analyses.

Methods

All meta-analyses of the clinical trials conducted on the impact of biotics on overweight/obesity indicators in general populations, pregnant women, and infants published until June 2023 in PubMed, Web of Sciences, Scopus, Embase, and Cochrane Library web databases included. The meta-analysis of observational and systematic review studies without meta-analysis were excluded. We reported the results by implementing the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) flowchart. The Assessment of Multiple Systematic Reviews-2 (AMSTAR2) and Grading of Recommendations Assessment, Development, and Evaluation (GRADE) systems were used to assess the methodological quality and quality of evidence.

Results

Overall, 97 meta-analysis studies were included. Most studies were conducted on the effect of probiotics in both genders. Consumption of prebiotic: 8-66 g/day, probiotic: 104 -1.35×1015 colony-forming unit (CFU)/day, and synbiotic: 106-1.5×1011 CFU/day and 0.5-300 g/day for 2 to 104 weeks showed a favorable effect on the overweight/obesity indicators. Moreover, an inverse association was observed between biotics consumption and overweight/obesity risk in adults in most of the studies. Biotics did not show any beneficial effect on weight and body mass index (BMI) in pregnant women by 6.6×105-1010 CFU/day of probiotics during 1-25 weeks and 1×109-112.5×109 CFU/capsule of synbiotics during 4-8 weeks. The effect of biotics on weight and BMI in infants is predominantly non-significant. Prebiotics and probiotics used in infancy were from 0.15 to 0.8 g/dL and 2×106-6×109 CFU/day for 2-24 weeks, respectively.

Conclusion

It seems biotics consumption can result in favorable impacts on some anthropometric indices of overweight/obesity (body weight, BMI, waist circumference) in the general population, without any significant effects on birth weight or weight gain during pregnancy and infancy. So, it is recommended to intake the biotics as complementary medications for reducing anthropometric indices of overweight/obese adults. However, more well-designed trials are needed to elucidate the anti-obesity effects of specific strains of probiotics.

Anti-obesity properties of probiotics; a considerable medical nutrition intervention: Findings from an umbrella meta-analysis

Although several studies have indicated that consumption of probiotics is effective in the treatment of obesity, the results in this regard have yielded controversial findings. The current umbrella meta-analysis was performed to evaluate the effects of probiotics supplementation on obesity indices in adults. Scopus, PubMed, Web of Science, Embase and Google Scholar were searched for relevant studies published till November 2021. Meta-analysis was conducted using the random-effects model. Sensitivity and subgroup analyses were performed. In total, 29 meta-analyses with 14,366 participants, including 112, 78, and 38 unique trials for body mass index (BMI), body weight (BW), and waist circumference (WC), were included in the study, respectively. The findings demonstrated that the probiotics supplementation was significantly effective on decreasing of BMI (ES = -0.21; 95% CI: -0.30, -0.13, p < 0.001; I² = 83.0%, p < 0.001), BW (ES = -0.38, 95% CI: -0.60, -0.16; p < 0.001; I² = 81.8%, p < 0.001), and WC (ES = -0.60; 95% CI: -0.89, -0.31; p < 0.001; I² = 89.1%, p < 0.001). Greater effects on BW were observed when intervention duration was >8 weeks and on obese individuals. BMI was also greatly modified in participants with metabolic syndrome and when intervention duration lasted for ≥12 weeks. The methodological quality (AMSTAR2) was moderate in 83%, low in 10%, and critically low in 7% of included studies. The current umbrella meta-analysis indicated that supplementation of probiotics in adults led to a meaningful reduction in BW, BMI, and WC. Therefore, our findings strongly recommend supplementation with probiotics as a potent intervention in the management of obesity.

Treatment With Multi-Species Probiotics Changes the Functions, Not the Composition of Gut Microbiota in Postmenopausal Women With Obesity: A Randomized, Double-Blind, Placebo-Controlled Study

Probiotics are known to regulate host metabolism. In randomized controlled trial we aimed to assess whether interventions with probiotic containing following strains: Bifidobacterium bifidum W23, Bifidobacterium lactis W51, Bifidobacterium lactis W52, Lactobacillus acidophilus W37, Levilactobacillus brevis W63, Lacticaseibacillus casei W56, Ligilactobacillus salivarius W24, Lactococcus lactis W19, and Lactococcus lactis W58 affect gut microbiota to promote metabolic effects. By 16S rRNA sequencing we analyzed the fecal microbiota of 56 obese, postmenopausal women randomized into three groups: (1) probiotic dose 2.5 × 10⁹ CFU/day (n = 18), (2) 1 × 10¹⁰ CFU/day (n = 18), or (3) placebo (n = 20). In the set of linear mixed-effects models, the interaction between pre- or post-treatment bacterial abundance and time on cardiometabolic parameters was significantly (FDR-adjusted) modified by type of intervention (26 and 19 three-way interactions for the pre-treatment and post-treatment abundance, respectively), indicating the modification of the bio-physiological role of microbiota by probiotics. For example, the unfavorable effects of Erysipelotrichi, Erysipelotrichales, and Erysipelotrichaceae on BMI might be reversed, but the beneficial effect of Betaproteobacteria on BMI was diminished by probiotic treatment. Proinflammatory effect of Bacteroidaceae was alleviated by probiotic administration. However, probiotics did not affect the microbiota composition, and none of the baseline microbiota-related features could predict therapeutic response as defined by cluster analysis. Conclusions: Probiotic intervention alters the influence of microbiota on biochemical, physiological and immunological parameters, but it does not affect diversity and taxonomic composition. Baseline microbiota is not a predictor of therapeutic response to a multispecies probiotic. Further multi-omic and mechanistic studies performed on the bigger cohort of patients are needed to elucidate the cardiometabolic effect of investigated probiotics in postmenopausal obesity.

Probiotics as a Treatment for "Metabolic Depression"? A Rationale for Future Studies

Depression and metabolic diseases often coexist, having several features in common, e.g., chronic low-grade inflammation and intestinal dysbiosis. Different microbiota interventions have been proposed to be used as a treatment for these disorders. In the paper, we review the efficacy of probiotics in depressive disorders, obesity, metabolic syndrome and its liver equivalent based on the published experimental studies, clinical trials and meta-analyses. Probiotics seem to be effective in reducing depressive symptoms when administered in addition to antidepressants. Additionally, probiotics intake may ameliorate some of the clinical components of metabolic diseases. However, standardized methodology regarding probiotics use in clinical trials has not been established yet. In this narrative review, we discuss current knowledge on the recently used methodology with its strengths and limitations and propose criteria that may be implemented to create a new study of the effectiveness of probiotics in depressive disorders comorbid with metabolic abnormalities. We put across our choice on type of study population, probiotics genus, strains, dosages and formulations, intervention period, as well as primary and secondary outcome measures.

Link between microbiota and hypertension: Focus on LPS/TLR4 pathway in endothelial dysfunction and vascular inflammation, and therapeutic implication of probiotics

High blood pressure (BP) presents a significant public health challenge. Recent findings suggest that altered microbiota can exert a hypertensive effect on the host. One of the possible mechanisms involved is the chronic translocation of its components, mainly lipopolysaccharides (LPS) into systemic circulation leading to metabolic endotoxemia. In animal models, LPS has been commonly used to induce endothelial dysfunction and vascular inflammation. In human studies, plasma LPS concentration has been positively correlated with hypertension, however, the mechanistic link has not been fully elucidated. It is hypothesised here that the LPS-induced direct alterations to the vascular endothelium and resulting hypertension are possible targets for probiotic intervention. The methodology of this review involved a systematic search of the literature with critical appraisal of papers. Three tranches of search were performed: 1) existing review papers; 2) primary mechanistic animal, in vitro and human studies; and 3) primary intervention studies. A total of 70 peer-reviewed papers were included across the three tranches and critically appraised using SIGN50 for human studies and the ARRIVE guidelines for animal studies. The extracted information was coded into key themes and summarized in a narrative analysis. Results highlight the role of LPS in the activation of endothelial toll-like receptor 4 (TLR4) initiating a cascade of interrelated signalling pathways including: 1) Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase/ Reactive oxygen species (ROS)/ Endothelial nitric oxide synthase (eNOS) pathway leading to endothelial dysfunction; and 2) Mitogen-Activated Protein Kinase (MAPK) and Nuclear factor kappa B (NF-κB) pathways leading to vascular inflammation. Findings from animal intervention studies suggest an improvement in vasorelaxation, vascular inflammation and hypertension following probiotic supplementation, which was mediated by downregulation of LPS-induced pathways. Randomised controlled trials (RCTs) and systematic reviews provided some evidence for the anti-inflammatory effect of probiotics with statistically significant antihypertensive effect in clinical samples and may offer a viable intervention for the management of hypertension.

Nrf2-interacting nutrients and COVID-19: time for research to develop adaptation strategies

There are large between- and within-country variations in COVID-19 death rates. Some very low death rate settings such as Eastern Asia, Central Europe, the Balkans and Africa have a common feature of eating large quantities of fermented foods whose intake is associated with the activation of the Nrf2 (Nuclear factor (erythroid-derived 2)-like 2) anti-oxidant transcription factor. There are many Nrf2-interacting nutrients (berberine, curcumin, epigallocatechin gallate, genistein, quercetin, resveratrol, sulforaphane) that all act similarly to reduce insulin resistance, endothelial damage, lung injury and cytokine storm. They also act on the same mechanisms (mTOR: Mammalian target of rapamycin, PPARγ:Peroxisome proliferator-activated receptor, NFκB: Nuclear factor kappa B, ERK: Extracellular signal-regulated kinases and eIF2α:Elongation initiation factor 2α). They may as a result be important in mitigating the severity of COVID-19, acting through the endoplasmic reticulum stress or ACE-Angiotensin-II-AT₁R axis (AT₁R) pathway. Many Nrf2-interacting nutrients are also interacting with TRPA1 and/or TRPV1. Interestingly, geographical areas with very low COVID-19 mortality are those with the lowest prevalence of obesity (Sub-Saharan Africa and Asia). It is tempting to propose that Nrf2-interacting foods and nutrients can re-balance insulin resistance and have a significant effect on COVID-19 severity. It is therefore possible that the intake of these foods may restore an optimal natural balance for the Nrf2 pathway and may be of interest in the mitigation of COVID-19 severity.