A randomized triple-masked controlled trial on the effects of synbiotics on inflammation markers in overweight children

Effects of probiotics, prebiotics, and synbiotics on cardiometabolic risk factors in children and adolescents with overweight or obesity: a systematic review and Bayesian network meta-analysis

The efficacy of probiotics, prebiotics, or synbiotics in children and adolescents with overweight or obesity remains uncertain. This systematic review evaluates their intervention effects through a network meta-analysis of randomized clinical trials (RCTs). Searches of 4 electronic databases until January 7, 2024, yielded 17 papers reporting on 15 RCTs involving 820 participants. Multiple-strain probiotics (MSP) showed significant efficacy in reducing BMI (Mean Difference (MD) -2.13 kg/m2, 95% credible interval (CrI) [-2.7, -1.57]), waist circumference (MD -1.34 cm, 95% CrI [-2.33, -0.35]), total cholesterol (MD -6.55 mg/dL, 95% CrI [-10.61, -2.45]), triglycerides (MD -3.71 mg/dL, 95% CrI [-5.76, -1.67]), leptin (MD -3.99 ng/mL, 95% CrI [-4.68, -3.3]), and hypersensitive C-reactive protein (Hs-CRP) (MD -1.21 mg/L, 95% CrI [-1.45, -0.97]). Synbiotics were effective in reducing BMI-z score (MD -0.07, 95% CrI [-0.10, -0.04]) and LDL-C (MD -1.54 mg/dL, 95% CrI [-1.98, -1.09]) but led to a slight increase in fasting glucose (MD 1.12 mg/dL, 95% CrI [0.75, 1.49]). Single-ingredient prebiotics and single-strain probiotics also had some beneficial effects on BMI and Hs-CRP, respectively. Moderate to low evidence suggests MSP may be a potential choice for improving BMI and reducing lipids, leptin, and Hs-CRP levels, implying that MSP could aid in managing pediatric obesity and related metabolic issues by modulating the gut microbiota. Although synbiotics show their favorable effects on body metrics and lipid control, their potential impact on blood glucose currently prevents them from being an alternative to MSP for treating pediatric obesity. Further large-scale, well-designed studies are needed to confirm these findings.

Inulin supplementation exhibits increased muscle mass via gut-muscle axis in children with obesity: double evidence from clinical and in vitro studies

Gut microbiota manipulation may reverse metabolic abnormalities in obesity. Our previous studies demonstrated that inulin supplementation significantly promoted Bifidobacterium and fat-free mass in obese children. We aimed to study gut-muscle axis from inulin supplementation in these children. In clinical phase, the plasma samples from 46 participants aged 7-15 years, were analyzed for muscle biomarkers before and after 6-month inulin supplementation. In parallel, the plausible mechanism of muscle production via gut-muscle axis was examined using macrophage cell line. Bifidobacterium was cultured in semi-refined medium with inulin used in the clinical phase. Cell-free supernatant was collected and used in lipopolysaccharide (LPS)-induced macrophage cell line to determine inflammatory and anti-inflammatory gene expression. In clinical phase, IL-15 and creatinine/cystatin C ratio significantly increased from baseline to the 6th month. In vitro study showed that metabolites derived from Bifidobacterium capable of utilizing inulin contained the abundance of SCFAs. In the presence of LPS, treatment from Bifidobacterium + inulin downregulated TNF-α, IL-6, IL-1β, and iNOS, but upregulated FIZZ-1 and TGF-β expression. Inulin supplementation promoted the muscle biomarkers in agreement with fat-free mass gain, elucidating by Bifidobacterium metabolites derived from inulin digestion showed in vitro anti-inflammatory activity and decreased systemic pro-inflammation, thus promoting muscle production via gut-muscle axis response.Clinical Trial Registry number: NCT03968003.

A meta-analysis of the therapeutic effect of probiotic intervention in obese or overweight adolescents

Background & aims

Existing evidence on the possible effects of probiotics on obese or overweight adolescents has not been fully established. Therefore, the aim of this study was to explore the effects of probiotic supplementation on anthropometric indices, inflammatory markers and metabolic indices in obese or overweight adolescents.

Methods

The literature up to March 2023 related to probiotic intervention in obese or overweight adolescents was searched and screened from multiple databases, including the CNKI(China national knowledge infrastructure), CBM(Chinese biomedical literature database), PubMed, EmBase, and Cochrane library databases. All randomized controlled trials using probiotic supplements in obese or overweight adolescents were included in this systematic review and meta-analysis.

Results

A total of 8 studies that met the inclusion criteria were included in this study. There were 201 cases in the experimental group (probiotic treatment) and 190 cases in the control group. Compared to the control group, probiotic intervention in adolescents resulted in a decrease in body mass index, fasting blood glucose and C-reactive protein with WMD(Weighted mean difference) and 95% CI of -2.53 (-4.8 to -0.26) kg/m2, -0.80 (-1.13 to -0.47) mol/L and -0.24 (-0.43 to -0.05) mg/L, respectively. No significant changes were found in weight, waist circumference, waist-to-hip ratio, insulin, Homeostatic Model Assessment of insulin resistance, interleukin 6, tumor necrosis factor alpha and so on; however, an unfavorable elevated effect in total cholesterol, triglycerides, and low-density lipoproteins was detected with WMD and 95% CI of 0.06 (0.02 to 0.09) mmol/L, 0.18 (0.14 to 0.21) mmol/L, and 0.19 (0.18 to 0.20) mmol/L, respectively.

Conclusion

According to our results, probiotic supplementation was beneficial in managing metabolic indicators such as fasting blood glucose, body mass index and inflammation-related C-reactive protein in overweight or obese adolescents. Further large scale studies are warranted to confirm present findings and to identify the effects and mechanisms to provide more precise evidence for clinical intervention.

Systematic review registration

doi: 10.37766/inplasy2024.1.0081, identifier INPLASY202410081.

Effects of Malnutrition on the Immune System and Infection and the Role of Nutritional Strategies Regarding Improvements in Children's Health Status: A Literature Review

Malnutrition refers to a person's status as under- or overnourished, and it is usually associated with an inflammation status, which can subsequently imply a different health status, as the risk of infection is increased, along with a deterioration of the immune system. Children's immune systems are generally more susceptible to problems than adults. In the situation of malnutrition, because malnourished children's immune systems are compromised, they are more likely to die. However, little is known about the underlying mechanism of altered immune functioning and how it relates to starvation. Nutritional interventions have been reported as cost-effective strategies to prevent or treat the development of malnourishment, considering the link between food intake and health, especially in children, and also the susceptibility of this population to diseases and how their health status during childhood might affect their long-term physiological growth. The ingestion of specific nutrients (e.g., vitamins or oligoelements) has been reported to contribute to the proper functioning of children's immune systems. In this review, we aim to describe the basis of malnutrition and how this is linked to the immune system, considering the role of nutrients in the modulation of the immune system and the risk of infection that can occur in these situations in children, as well as to identify nutritional interventions to improve their health.

Probiotic Use in Children and Adolescents with Overweight or Obesity: A Scoping Review

Context: Probiotics have been proposed as a prevention or treatment for pediatric overweight and obesity. Objective: Conduct a scoping review on probiotic use in children and adolescents with overweight or obesity and those with weight-related conditions and to identify knowledge gaps and research priorities. Data Sources: Seven databases using keywords and medical subject heading terms for articles reporting probiotic use in children or adolescents with overweight or obesity published from database conception until initiation of the study. Study Selection: Articles reporting primary data on probiotics use in children or adolescents with overweight or obesity. Data Extraction: We utilized the Arksey and O'Malley framework, PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analysis) guidelines, followed a predetermined study protocol for level-one abstract and level-two full-text screenings, synthesized information into subject-area domains, and identified research gaps. Limitations: Heterogeneity of probiotic interventions, host factors, and genomics. Results: Database search yielded 1356 unique articles with 19 randomized placebo-controlled studies, 945 participants, duration of interventions from 8 weeks to 9 months. Disease indications included Nonalcoholic Fatty Liver Disease, insulin resistance, hypercholesterolemia, Prader-Willi Syndrome, metabolic syndrome, and obesity. Limited and heterogeneous evidence for probiotic use in children and adolescents with weight-related conditions noted. Heterogeneity among published articles in probiotic strains, doses, design, biomarkers, confirmation, and outcomes observed. Conclusions: Despite complex existing and limited data, studies to date of children and adolescents with overweight and obesity demonstrate potential beneficial treatment effects of probiotics on BMI, adiposity, metabolic parameters, inflammatory markers, fatty liver, transaminase levels, and glucose metabolism. Clinical trials to address heterogeneous results are needed.

Effects of Multispecies Synbiotic Supplementation on Anthropometric Measurements, Glucose and Lipid Parameters in Children With Exogenous Obesity: A Randomized, Double Blind, Placebo-Controlled Clinical Trial (Probesity-2 Trial)

Studies on the effects of synbiotics on obesity in children are limited. The objective of this randomized double-blind placebo-controlled trial was to test the effects of a multispecies synbiotic during 12 weeks on anthropometric measurements, glucose metabolism and lipid parameters in 61 children with exogenous obesity. All children were treated with a standard diet and increased physical activity and received once daily a synbiotic supplement (probiotic mixture including Lactobacillus acidophilus, Lacticaseibacillus rhamnosus, Bifidobacterium bifidum, Bifidobacterium longum, Enterococcus faecium and fructo-oligosaccharides) or daily placebo for 12 weeks. At baseline, no statistically significant differences existed in anthropometric measurements, glucose and lipid parameters between both groups. We observed changes for anthropometric measures (% reduction comparing to baseline) in both synbiotic and placebo groups. After 12 weeks; changes (% reduction comparing to baseline) in weight (p < 0.01), BMI (p < 0.05), waist circumference (p < 0.05) and waist circumference to height ratio (p < 0.05) were significantly higher in the children receiving the synbiotic supplement. There is no difference in glucose metabolism, lipid parameters, presence of non-alcoholic fatty liver disease between both groups after 12 weeks. The daily intake of a multispecies synbiotic in addition to diet and increased physical activity did improve anthropometric measurements: body weight, BMI, waist circumference and waist/height ratio. The supplementation of this synbiotic is an efficient weight-loss strategy above diet and exercise in pediatric obesity (Trial identifier: NCT05162209).

Effects of Probiotics and Synbiotics on Weight Loss in Subjects with Overweight or Obesity: A Systematic Review

Intestinal microbiota has been shown to be a potential determining factor in the development of obesity. The objective of this systematic review is to collect and learn, based on the latest available evidence, the effect of the use of probiotics and synbiotics in randomized clinical trials on weight loss in people with overweight and obesity. A search for articles was carried out in PubMed, Web of science and Scopus until September 2021, using search strategies that included the terms “obesity”, “overweight”, “probiotic”, “synbiotic”, “Lactobacillus”, “Bifidobacterium” and “weight loss”. Of the 185 articles found, only 27 complied with the selection criteria and were analyzed in the review, of which 23 observed positive effects on weight loss. The intake of probiotics or synbiotics could lead to significant weight reductions, either maintaining habitual lifestyle habits or in combination with energy restriction and/or increased physical activity for an average of 12 weeks. Specific strains belonging to the genus Lactobacillus and Bifidobacterium were the most used and those that showed the best results in reducing body weight. Both probiotics and synbiotics have the potential to help in weight loss in overweight and obese populations.

Probiotics for the Treatment of Overweight and Obesity in Humans-A Review of Clinical Trials

The World Health Organization (WHO) reports that 400 million people are obese, and over 1.6 billion adults are overweight worldwide. Annually, over 2.8 million people die from obesity-related diseases. The incidence of overweight and obesity is steadily increasing, and this phenomenon is referred to as a 21st-century pandemic. The main reason for this phenomenon is an easy access to high-energy, processed foods, and a low-activity lifestyle. These changes lead to an energy imbalance and, as a consequence, to the development of body fat. Weight gain contributes to the development of heart diseases, skeletal system disorders, metabolic disorders such as diabetes, and certain types of cancer. In recent years, there have been many works linking obesity with intestinal microbiota. Experiments on germ-free animals (GFs) have provided much evidence for the contribution of bacteria to obesity. The composition of the gut microbiota (GM) changes in obese people. These changes affect the degree of energy obtained from food, the composition and secretory functions of adipose tissue, carbohydrate, and lipid metabolism in the liver, and the activity of centers in the brain. The study aimed to present the current state of knowledge about the role of intestinal microbiota in the development of obesity and the impact of supplementation with probiotic bacteria on the health of overweight and obese patients.

The Effects of Synbiotic Supplementation on Metabolic Status in Diabetic Patients Undergoing Hemodialysis: a Randomized, Double-Blinded, Placebo-Controlled Trial

This study was conducted to evaluate the effects of synbiotic supplementation on metabolic profiles in diabetic patients undergoing hemodialysis (HD). This randomized, double-blinded, placebo-controlled clinical trial was performed in 60 diabetic HD patients. Participants were randomly assigned into two groups to receive either synbiotic capsule, containing Lactobacillus acidophilus, Lactobacillus casei, and Bifidobacterium bifidum (2 × 10⁹ CFU/g each), plus 0.8 g/day of inulin (n = 30) or placebo (n = 30) for 12 weeks. Synbiotic supplementation significantly decreased fasting plasma glucose (β - 13.56 mg/dL; 95% CI, - 23.82, - 3.30; P = 0.01), insulin levels (β - 5.49 μIU/mL; 95% CI, - 6.92, - 4.05; P < 0.001), and insulin resistance (β - 2.25; 95% CI, - 3.02, - 1.48; P < 0.001), while increased the quantitative insulin sensitivity check index (β 0.02; 95% CI, 0.01, 0.02; P < 0.001) compared with the placebo. Additionally, synbiotic intake resulted in a significant reduction in high-sensitivity C-reactive protein (β - 2930.48 ng/mL; 95% CI, - 3741.15, - 2119.80; P < 0.001) and malondialdehyde levels (β - 0.60 μmol/L; 95% CI, - 0.99, - 0.20; P = 0.003). Moreover, we found a significant increase in total antioxidant capacity (β 142.99 mmol/L; 95% CI, 61.72, 224.25; P = 0.001) and total glutathione levels (β 131.11 μmol/L; 95% CI, 89.35, 172.87; P < 0.001) in the synbiotic group compared with the placebo group. Overall, synbiotic supplementation for 12 weeks had beneficial effects on glycemic control, biomarkers of inflammation, and oxidative stress in diabetic patients under HD. This study was registered in the Iranian website (www.irct.ir) for registration of clinical trials (http://www.irct.ir: IRCT2017090133941N17). http://www.irct.ir: IRCT2017090133941N17.

The food-gut axis: lactic acid bacteria and their link to food, the gut microbiome and human health

Lactic acid bacteria (LAB) are present in foods, the environment and the animal gut, although fermented foods (FFs) are recognized as the primary niche of LAB activity. Several LAB strains have been studied for their health-promoting properties and are employed as probiotics. FFs are recognized for their potential beneficial effects, which we review in this article. They are also an important source of LAB, which are ingested daily upon FF consumption. In this review, we describe the diversity of LAB and their occurrence in food as well as the gut microbiome. We discuss the opportunities to study LAB diversity and functional properties by considering the availability of both genomic and metagenomic data in public repositories, as well as the different latest computational tools for data analysis. In addition, we discuss the role of LAB as potential probiotics by reporting the prevalence of key genomic features in public genomes and by surveying the outcomes of LAB use in clinical trials involving human subjects. Finally, we highlight the need for further studies aimed at improving our knowledge of the link between LAB-fermented foods and the human gut from the perspective of health promotion.

Effect of Lactobacillus paracasei N1115 and fructooligosaccharides in nonalcoholic fatty liver disease

INTRODUCTION

Nonalcoholic fatty liver disease (NAFLD) is a growing health concern worldwide. Administration of probiotics and prebiotics has been proposed as a convenient and effective treatment. Our study aims to evaluate the therapeutic benefits of Lactobacillus paracasei N1115 (N1115) and fructooligosaccharides (FOS) by examining the histopathogenesis and underlying molecular events of NAFLD.

MATERIAL AND METHODS

An NAFLD mouse model was established by feeding C57BL/6 mice with a high-fat diet (HFD). N1115, FOS and synbiotics were administered for 16 weeks.

RESULTS

N1115, FOS and synbiotics alleviated HFD-induced hepatic steato-sis and release of tumor necrosis factor-α, and slowed the progression of cirrhosis. Compared to the HFD group, these dietary supplements reduced serum total triglyceride and cholesterol, and appeared to decrease the fasting blood glucose and insulin. Intraperitoneal glucose tolerance tests, homeostatic model assessment of insulin resistance and real-time PCR showed that the regimens could overcome insulin resistance. These findings were associated with the transcriptional repression of inflammatory factors such as lipopolysaccharides, Toll-like receptor 4 and nuclear factor-κB. Lastly, N1115, FOS, and synbiotics improved the intestinal barrier functions and histologic integrity. This was accompanied by the restoration of the p38 MAPK pathway and in-creased expression of the tight junction components occludin-1 and claudin-1.

CONCLUSIONS

N1115, FOS and synbiotics are effective in the prevention and treatment of NAFLD. Our data support the translation of these agents into clinical evaluation in human subjects with NAFLD and/or associated risk factors.

The Effects of Synbiotic Supplementation on Pregnancy Outcomes in Gestational Diabetes

Synbiotics are known to exert multiple beneficial effects, including anti-inflammatory and antioxidative actions. This study was designed to evaluate the effects of synbiotic administration on biomarkers of inflammation, oxidative stress, and pregnancy outcomes among gestational diabetic (GDM) women. This randomized, double-blind, placebo-controlled clinical trial was carried out among 60 subjects with GDM who were not on oral hypoglycemic agents. Patients were randomly assigned to consume either one synbiotic capsule containing Lactobacillus acidophilus strain T16 (IBRC-M10785), L. casei strain T2 (IBRC-M10783), and Bifidobacterium bifidum strain T1 (IBRC-M10771) (2 × 10⁹ CFU/g each) plus 800 mg inulin (HPX) (n = 30) or placebo (n = 30) for 6 weeks. Compared with the placebo, synbiotic supplementation significantly decreased serum high-sensitivity C-reactive protein (hs-CRP) (- 1.9 ± 4.2 vs. +1.1 ± 3.5 mg/L, P = 0.004), plasma malondialdehyde (MDA) (- 0.1 ± 0.6 vs. + 0.3 ± 0.7 μmol/L, P = 0.02), and significantly increased total antioxidant capacity (TAC) (+ 70.1 ± 130.9 vs. - 19.7 ± 124.6 mmol/L, P = 0.009) and total glutathione (GSH) levels (+ 28.7 ± 61.5 vs. - 14.9 ± 85.3 μmol/L, P = 0.02). Supplementation with synbiotic had a significant decrease in cesarean section rate (16.7 vs. 40.0%, P = 0.04), lower incidence of hyperbilirubinemic newborns (3.3 vs. 30.0%, P = 0.006), and newborns' hospitalization (3.3 vs. 30.0%, P = 0.006) compared with the placebo. Synbiotic supplementation did not affect plasma nitric oxide (NO) levels and other pregnancy outcomes. Overall, synbiotic supplementation among GDM women for 6 weeks had beneficial effects on serum hs-CRP, plasma TAC, GSH, and MDA; cesarean section; incidence of newborn's hyperbilirubinemia; and newborns' hospitalization but did not affect plasma NO levels and other pregnancy outcomes. http://www.irct.ir : www.irct.ir : IRCT201704205623N108.

Gut microbiota and pediatric obesity/non-alcoholic fatty liver disease

Huge amount microorganisms resides in human intestine, and many contribute to the maturation and homeostasis of immune system. The diversity of gut ecology are affected by the gestational age, delivery type, feeding sources, and antibiotics use in neonates. Recent studies pointed out that disturbance of gut microbiota, so called dysbiosis, could result in several pediatric diseases including obesity, non-alcoholic fatty liver disease (NAFLD), metabolic syndromes, allergic diseases, and inflammatory bowel diseases. However, there are no single species can be proven to play a key factor in pediatric obesity and NAFLD at present. Various probiotics may confer benefit to these gut microbiota-related pediatric diseases. The clinical application is still limited. This review article aimed to elucidate evidently the relationship between gut microbiota and pediatric obesity/NAFLD and to discuss the potential probiotics use in pediatric obesity and NAFLD.

Characterization of the Stool Microbiome in Hispanic Preschool Children by Weight Status and Time

BACKGROUND

Variations in gut microbiota composition and diversity have been associated with childhood adiposity, although most studies describing this have been cross-sectional in nature. Our objective was to evaluate associations between body weight and the gut microbiota over time in obese preschool-age children.

METHODS

Obese, preschool-age, Hispanic children provided stool samples at baseline and following a 6-month behavioral intervention. Normal-weight (NW) children also provided stool samples. Stool microbial community composition was characterized using 16S rRNA gene sequencing. Estimates of within-sample diversity were calculated on operational taxonomic unit (OTU) count data, and the Firmicutes:Bacteroidetes (F:B) ratio was determined on per-sample basis. Estimates of between-sample diversity were generated using the weighted Unifrac metric, differential abundances were evaluated using Wilcoxon rank-sum tests, and associations of microbiome features with clinical data were quantified using Spearman rank correlations.

RESULTS

For the 30 obese children sampled preintervention and postintervention, a decrease in body mass index (BMI) z-score from 2.55 to 2.34 (p = 0.004, paired t-test) was observed. Bacteroides massiliensis was significantly enriched in obese children, while B. plebius was significantly enriched in NW controls. We identified significant correlations between multiple Bacteroides-like OTUs and BMI z-score, but neither F:B ratios nor OTU-level abundances were altered in conjunction with weight change in the obese children. Rather, highly individualized OTU-level responses were observed.

CONCLUSIONS

Although differences exist between the gut microbiota of obese and NW children, we detected highly individualized responses of the gut microbiota of obese children over time and following weight loss.

Short-chain fatty acids, prebiotics, synbiotics, and systemic inflammation: a systematic review and meta-analysis

BACKGROUND

Prebiotic soluble fibers are fermented by beneficial bacteria in the colon to produce short-chain fatty acids (SCFAs), which are proposed to have systemic anti-inflammatory effects.

OBJECTIVE

This review examines the effect of SCFAs, prebiotics, and pre- and probiotic combinations (synbiotics) on systemic inflammation.

DESIGN

Relevant English language studies from 1947 to May 2017 were identified with the use of online databases. Studies were considered eligible if they examined the effects of SCFAs, prebiotics, or synbiotics; were delivered orally, intravenously, or per rectum; were on biomarkers of systemic inflammation in humans; and performed meta-analysis where possible.

RESULTS

Sixty-eight studies were included. Fourteen of 29 prebiotic studies and 13 of 26 synbiotic studies reported a significant decrease in ≥1 marker of systemic inflammation. Eight studies compared prebiotic and synbiotic supplementation, 2 of which reported a decrease in inflammation with synbiotics only, with 1 reporting a greater anti-inflammatory effect with synbiotics than with prebiotics alone. Meta-analyses indicated that prebiotics reduce C-reactive protein (CRP) [standardized mean difference (SMD): -0.60; 95% CI: -0.98, -0.23], and synbiotics reduce CRP (SMD: -0.40; 95% CI: -0.73, -0.06) and tumor necrosis factor-α (SMD -0.90; 95% CI: -1.50, -0.30).

CONCLUSIONS

There is significant heterogeneity of outcomes in studies examining the effect of prebiotics and synbiotics on systemic inflammation. Approximately 50% of included studies reported a decrease in ≥1 inflammatory biomarker. The inconsistency in reported outcomes may be due to heterogeneity in study design, supplement formulation, dosage, duration, and subject population. Nonetheless, meta-analyses provide evidence to support the systemic anti-inflammatory effects of prebiotic and synbiotic supplementation.

Gut microbiota in health and disease: an overview focused on metabolic inflammation

In concern to the continuously rising global prevalence of obesity, diabetes and associated diseases, novel preventive and therapeutic approaches are urgently required. However, to explore and develop such innovative strategies, a meticulous comprehension of the biological basis of these diseases is extremely important. Past decade has witnessed an enormous amount of research investigation and advancement in the field of obesity, diabetes and metabolic syndrome, with the gut microbiota receiving a special focus in the triangle of nutrition, health and diseases. In particular, the role of gut microbiota in health and diseases has been one of the most vigorous and intriguing field of recent research; however, much still remains to be elucidated about its precise role in host metabolism and immune functions and its implication in the onset, progression as well as in the amelioration of metabolic ailments. Recent investigations have suggested a significant contribution of the gut microbiota in the regulation and impairment of energy homeostasis, thereby causing metabolic disorders, such as metabolic endotoxemia, insulin resistance and type 2 diabetes. Numerous inflammatory biomarkers have been found to be associated with obesity, diabetes and risk of other associated adverse outcomes, thereby suggesting that a persistent low-grade inflammatory response is a potential risk factor. In this milieu, this review intends to discuss potential evidences supporting the disturbance of the gut microbiota balance and the intestinal barrier permeability as a potential triggering factor for systemic inflammation in the onset and progression of obesity, type 2 diabetes and metabolic syndrome.

Impacts of gut bacteria on human health and diseases

Gut bacteria are an important component of the microbiota ecosystem in the human gut, which is colonized by 10¹⁴ microbes, ten times more than the human cells. Gut bacteria play an important role in human health, such as supplying essential nutrients, synthesizing vitamin K, aiding in the digestion of cellulose, and promoting angiogenesis and enteric nerve function. However, they can also be potentially harmful due to the change of their composition when the gut ecosystem undergoes abnormal changes in the light of the use of antibiotics, illness, stress, aging, bad dietary habits, and lifestyle. Dysbiosis of the gut bacteria communities can cause many chronic diseases, such as inflammatory bowel disease, obesity, cancer, and autism. This review summarizes and discusses the roles and potential mechanisms of gut bacteria in human health and diseases.

Childhood obesity: immune response and nutritional approaches

Childhood obesity is characterized by a low-grade inflammation status depending on the multicellular release of cytokines, adipokines, and reactive oxygen species. In particular, the imbalance between anti-inflammatory T regulatory cells and inflammatory T helper 17 cells seems to sustain such a phlogistic condition. Alterations of gut microbiota since childhood also contribute to the maintenance of inflammation. Therefore, besides preventive measures and caloric restrictions, dietary intake of natural products endowed with anti-oxidant and anti-inflammatory activities may represent a valid interventional approach for preventing and/or attenuating the pathological consequences of obesity. In this regard, the use of prebiotics, probiotics, polyphenols, polyunsaturated fatty acids, vitamins, and melatonin in human clinical trials will be described.

Gut microbioma population: an indicator really sensible to any change in age, diet, metabolic syndrome, and life-style

Obesity has become a pandemic threat in the latest 30 years. The trend of the prevalence of overweight and obesity has got an overall increase in every part of the world, regardless of ethnicity, life-style and social ties. High food intake, genetic, and sedentary have been related to obesity; it has been also hypothesized that gut microbiota could have an impact on the complex mechanism underlying the weight gain. This review aims to illustrate the actual literature about gut microbiota and its relation with obesity and to analyze the possible implications of factors such as diet and life-style onto the composition of gut microbiota, that can lead to overweight/obesity condition.