The Effect of Probiotics Supplementation on Mental Health Outcomes Among Children and Adolescents: A Systematic Review and Meta-Analysis of randomized controlled trials

Background Interest is growing in microbiota-targeted approaches to support mental health in children and adolescents. Probiotics may influence brain function through the microbiota–gut–brain axis, but evidence in pediatric populations remains limited, and prior reviews often include non-RCT data, weakening conclusions. So, this study aimed to evaluate the effects of probiotic supplementation on mental health outcomes in children and adolescents using randomized controlled trials only. Methods This systematic review and meta-analysis followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 guidelines. Comprehensive searches of PubMed/MEDLINE, Embase, Cochrane CENTRAL, and ClinicalTrials.gov. Eligible studies included participants aged ≤ 18 years, compared probiotics with placebo or non-probiotic controls, and reported validated mental health outcomes. Risk of bias was assessed using the Cochrane Risk of bias 2 tool. Meta-analysis was conducted using standardized mean differences with 95% confidence intervals. Results Of 51 records identified, seven trials met inclusion criteria, focusing on attention deficit hyperactivity disorder (three studies), autism spectrum disorder (two studies), and depression or anxiety (two studies). Overall risk of bias was rated as having some concerns. Three trials (n = 215) were sufficiently comparable for meta-analysis. Probiotic supplementation was associated with a statistically significant improvement in mental health outcomes (pooled mean difference − 0.4; 95% CI − 0.69 to − 0.01), indicating a moderate reduction in symptom severity across anxiety, depressive symptoms, attention deficit hyperactivity disorder -related difficulties, stress, and behavioral problems. Conclusions Probiotic supplementation has beneficial effects on mental health outcomes in children and adolescents. However, the limited number of randomized controlled trials warrant cautious interpretation. Larger, well-designed trials with standardized outcomes are needed to clarify clinical relevance and long-term effects.