← Back to all studies
gut microbiome diet
Effects of Probiotic Supplementation on Core Symptoms of Autism Spectrum Disorder in Children
31 March 2026
Chan MX, Hoh CY, Teh YY, Toh XY, Ismail NAS.
Summary
Plain-Language Summary
This review analyzed 14 studies to determine if probiotic supplements can improve core symptoms of autism in children and adolescents. The findings suggest that certain probiotics, particularly the strain Lactobacillus reuteri, may help improve social and communication skills when taken consistently for several months.
Key Findings
- Social Improvement: Over half of the studies (8 out of 14) reported significant improvements in core ASD symptoms, specifically in the social and communication domains.
- Strain Specificity: The probiotic Lactobacillus reuteri was the most effective and consistent strain for enhancing social behavior.
- Duration Matters: Benefits were most frequently observed when supplementation lasted for at least three months.
- Limited Impact on Other Areas: There was less consistent evidence regarding probiotics' ability to reduce repetitive behaviors or other non-social ASD symptoms.
Practical Takeaways
- Prioritize Specific Strains: Probiotic benefits are "strain-specific." For neurological or behavioral support, look for products containing L. reuteri rather than generic "multi-strain" blends.
- Play the Long Game: Gut-brain axis interventions require patience; do not evaluate the effectiveness of a probiotic until it has been used consistently for at least 90 days.
- Microbiome-Brain Link: This study reinforces that gut health is a critical pillar of cognitive and behavioral health at any age.
Study Limitations
The evidence is currently limited by high "methodological heterogeneity," meaning studies used different doses and measurement tools, making broad conclusions difficult. More large-scale, standardized clinical trials are required to confirm these therapeutic effects.
Abstract
<b>Background/Objectives</b>: Increasing evidence implicates the microbiome-gut-brain axis in Autism Spectrum Disorder (ASD) pathophysiology, prompting interest in probiotics as a therapeutic strategy, although findings remain inconsistent. This systematic review aimed to evaluate the clinical efficacy of probiotic supplementation on core ASD symptoms, examine the outcome measures used, and provide insights into optimal probiotic interventions. <b>Methods</b>: This review was conducted in accordance with PRISMA 2020 guidelines. PubMed, Scopus, Web of Science, Ovid, ProQuest, and Wiley Online Library were searched for studies published between January 2015 and July 2025. Randomized, non-randomized, and open-label clinical studies evaluating oral probiotic supplementation in children and adolescents with ASD were included. Outcomes assessed core symptom domains using validated instruments. Study selection, data extraction, and risk-of-bias assessment (RoB 2 and ROBINS-I) were performed independently by multiple reviewers. Due to methodological heterogeneity, the findings were synthesized narratively. <b>Results</b>: Fourteen studies involving 924 children and adolescents with ASD across seven countries or regions were included, of which ten were randomized controlled trials. Eight studies reported significant improvement in core ASD symptoms, predominantly within the social and communication domain. The most frequently used assessment tools were the Social Responsiveness Scale (SRS), Autism Treatment Evaluation Checklist (ATEC), and Autism Diagnostic Observation Schedule (ADOS). <i>Lactobacillus reuteri</i> supplementation for at least three months was consistently associated with improvement in social behavior. <b>Conclusions</b>: <i>L. reuteri</i> supplementation possibly improves social and communication function in children with ASD. However, there is limited high-quality evidence on this. Evidence for other core domains remains limited and inconsistent, highlighting the need for well-designed, multicenter trials using standardized outcome measures and strain-specific hypotheses.