Effects of Probiotic and Synbiotic Supplementation on Body Composition and Glucose Metabolism in Children and Adolescents with Overweight or Obesity: A Systematic Review and Meta-Analysis.

Abstract

Childhood and adolescent overweight and obesity are associated with adverse body composition and impaired glucose metabolism. Probiotic and synbiotic supplementation may modulate the gut microbiota and has been proposed as a potential adjunctive strategy for obesity management. This systematic review and meta-analysis aimed to evaluate the effects of probiotic and synbiotic supplementation on body composition and glucose metabolism in children and adolescents with overweight or obesity. This review was conducted according to the PRISMA 2020 statement. PubMed, Embase, Web of Science, the Cochrane Library, and CNKI were searched from inception to 5 May 2026. Randomized controlled trials evaluating probiotic or synbiotic supplementation in children and adolescents with overweight or obesity were included. Outcomes included BMI z-score, BMI, waist circumference, body fat percentage, fasting glucose, fasting insulin, and HOMA-IR. Random-effects meta-analyses, sensitivity analyses, and subgroup analyses according to intervention type (probiotic versus synbiotic supplementation) were performed using mean differences (MDs) and 95% confidence intervals (CIs). Risk of bias was assessed using RoB 2, and certainty of evidence was evaluated using GRADE. Sixteen randomized controlled trials were included. Probiotic or synbiotic supplementation did not significantly reduce BMI z-score (MD = -0.03, 95% CI -0.11 to 0.05), waist circumference (MD = 0.60 cm, 95% CI -1.57 to 2.77), or body fat percentage (MD = -0.29 percentage points, 95% CI -1.64 to 1.06). A modest reduction in BMI was observed (MD = -0.91 kg/m2, 95% CI -1.81 to -0.01), although this finding should be interpreted cautiously because no significant improvement was observed in BMI z-score. No significant effects were found for fasting glucose, fasting insulin, or HOMA-IR. Subgroup analyses showed no significant differences between probiotic and synbiotic supplementation for BMI, BMI z-score, or waist circumference, whereas a significant subgroup difference was observed for fasting glucose. Probiotic or synbiotic supplementation may be associated with a modest reduction in BMI; however, the certainty of this evidence was low, which limits confidence in its clinical implications. Current evidence does not support clear benefits for BMI z-score, waist circumference, body fat percentage, or glucose metabolism. The subgroup findings, particularly for fasting glucose, should be interpreted cautiously because they were based on a limited number of studies. Further high-quality randomized controlled trials are warranted.