Microbiota-targeted interventions for metabolic syndrome-related parameters in adolescents with overweight or obesity: a systematic review and meta-analysis

Abstract Background The prevalence of metabolic syndrome (MetS) is increasing among children and adolescents with obesity, underscoring the urgent need for effective intervention strategies. Gut microbiota-based interventions, including probiotics, prebiotics, synbiotics, and fecal microbiota transplantation, have shown therapeutic potential. However, evidence regarding their efficacy in managing MetS in this population remains limited and inconsistent. Objective This study aimed to evaluate the effects of probiotics, prebiotics, synbiotics, and fecal microbiota transplantation on metabolic parameters (including anthropometric, lipid, glycemic, and inflammatory outcomes) in children and adolescents with overweight or obesity. Methods This systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A comprehensive literature search was performed in PubMed, Embase, Web of Science, Cochrane Library, CNKI, VIP, and Wanfang from database inception to October 31, 2025. Randomized controlled trials (RCTs) evaluating the effects of probiotics, prebiotics, synbiotics, or fecal microbiota transplantation in children and adolescents with obesity aged 7–18 years were eligible for inclusion. The primary outcomes included anthropometric measures, lipid profiles, glycemic parameters, and inflammatory markers. Meta-analyses were conducted using a random-effects model, and the methodological quality of the included studies was assessed using the Cochrane Risk of Bias tool. Results A total of 16 randomized controlled trials involving 974 participants were included. The meta-analysis showed that, compared with placebo, these interventions did not produce significant improvements in BW (MD = -0.91, 95% CI: -2.40 to 0.59), BMI (MD = -0.63, 95% CI: -1.48 to 0.22), lipid profiles, including HDL-C, TG, and TC, or glycemic parameters, including FINS, FPG, and HOMA-IR (all P > 0.05). However, a statistically significant increase in LDL-C was observed in the intervention group compared with placebo (MD = 0.19, 95% CI: 0.18 to 0.19; P < 0.001), alongside a significant reduction in CRP levels (MD = -0.68, 95% CI: -1.25 to -0.12; P = 0.0181). In contrast, no significant effects were found on IL-6 or TNF-α levels. Exploratory subgroup analyses showed that excluding fecal microbiota transplantation trials did not materially alter the primary findings. Similarly, pooling analyses of oral supplements, including probiotics, prebiotics, and synbiotics, yielded consistent null results for anthropometric and metabolic outcomes. Stratification by intervention duration (≤ 12 vs. > 12 weeks) showed that although the long-term subgroup (> 12 weeks) demonstrated a significant reduction in BMI, the between-subgroup difference was not statistically significant ( P = 0.0982), suggesting that treatment duration did not significantly modify the overall effects. Conclusion Current evidence from randomized controlled trials suggests that probiotics, prebiotics, synbiotics, and fecal microbiota transplantation do not consistently improve anthropometric, lipid, or glycemic outcomes in children and adolescents with overweight/obesity. Although a reduction in C-reactive protein was observed, this finding should be interpreted with caution because of substantial heterogeneity. The certainty of evidence was low to very low for most outcomes. Larger, well-designed RCTs with standardized populations, intervention protocols, and outcome reporting are needed to further clarify the efficacy of these gut microbiota-based interventions.