Does supplementation with prebiotics, probiotics, and postbiotics improve behavioral symptoms in Autism Spectrum Disorder (ASD) through gut microbiota modulation?

Introduction Autism Spectrum Disorder (ASD) is a neurodevelopmental condition characterized by social communication challenges and restricted behavioral patterns. Recently, the literature has highlighted the influence of the gut-brain axis and intestinal dysbiosis on the disorder's symptomatology. Alterations in the microbiota, increased intestinal permeability, and the presence of pathogenic microorganisms appear to modulate behavioral phenotypes. In this context, interventions with prebiotics, probiotics, and postbiotics emerge as promising strategies to restore intestinal homeostasis and mitigate symptoms. Given the absence of standardized clinical protocols, this study aims to map the scientific literature regarding the effects of biotic supplementation on the microbiota and behavioral symptoms of individuals with ASD. Methodology This is a scoping review conducted according to the Joanna Briggs Institute (JBI) methodology and the PRISMA-ScR checklist. The research was structured using the PCC mnemonic: Population (People with ASD), Concept (Microbiota modulation via prebiotic, probiotic, and postbiotic supplementation), and Context (Gut-brain axis and behavioral symptoms). The study seeks to determine the breadth of the literature on the topic and investigate whether interventions such as microbiota transplantation influence behavior. Searches were conducted in January 2026 across the PubMed, Scopus, Cochrane Library, VHL (BVS), and Web of Science databases. Selection criteria include grey literature and articles in Portuguese, English, and Spanish, with no time restriction. The search strategy utilized controlled descriptors (MeSH/DeCS) related to "Autism Spectrum Disorder", "Gastrointestinal Microbiome", and "Gut-Brain axis", with the exclusion of animal models.