The use of probiotics in the treatment of Autism Spectrum Disorder: a narrative review

Gastrointestinal symptoms affect approximately 70% of individuals with Autism Spectrum Disorder (ASD), suggesting a strong interaction between gut physiology and behavioral manifestations (McElhanon, 2014). Considering the relevance of the gut–brain axis, numerous studies have investigated the potential therapeutic role of probiotics in ASD. This narrative review aims to analyze clinical findings on probiotic supplementation in children and adolescents with ASD. A literature search was conducted in PubMed, SciELO, and Google Scholar, identifying 137 studies; 18 met the inclusion criteria. Results indicate that probiotic supplementation—particularly strains such as Lactobacillus plantarum, Lactobacillus reuteri, Bifidobacterium longum, and multistrain formulations—consistently improves gastrointestinal symptoms, including constipation, abdominal pain, diarrhea, and dysbiosis (Liu et al., 2019; Santocchi et al., 2020). Several studies also reported secondary behavioral improvements (e.g., reduced irritability, enhanced attention, lower hyperactivity) associated with improved gastrointestinal function (Hsiao et al., 2013; Sanctuary et al., 2019). However, heterogeneity in study design, supplementation protocols, dosage, and ASD severity limits definitive conclusions. Overall, probiotics appear to be a safe and promising complementary therapy for gastrointestinal symptoms in ASD, although further randomized clinical trials with standardized methodologies are needed.