Gut Microbiota and Autism: Unlocking Connections

Background: Autism Spectrum Disorder (ASD) is a multifactorial neurodevelopmental condition in which genetic predisposition interacts with environmental factors. Among these, the gut microbiota has emerged as a crucial modulator of the microbiota–gut–brain axis (MGBA), influencing neuroinflammation, neurotransmission, and behavior. This review aims to provide an updated and integrative overview of the relationship between gut microbiota, diet, and neurodevelopment in ASD. Methods: A comprehensive search was conducted in PubMed, Scopus, and Web of Science for articles published between 2010 and 2025. Original studies, systematic reviews, and meta-analyses in English were included. Results: Evidence from human and animal studies supports a strong association between gut dysbiosis and ASD-related behaviors. Alterations in microbial composition, characterized by reduced Bifidobacterium and Prevotella and increased Clostridium spp., have been linked to impaired intestinal barrier function, chronic inflammation, and altered production of microbial metabolites such as short-chain fatty acids and tryptophan derivatives. Discussion: Maternal dysbiosis, nutritional imbalances, and perinatal stressors may further modulate fetal neurodevelopment through immune and epigenetic pathways. Emerging data suggest that dietary modulation, targeted nutritional interventions, functional foods, prebiotics, probiotics, and postbiotics could help restore microbial balance and improve neurobehavioral outcomes. Conclusions: The gut microbiota represents a key biological interface between environment, metabolism, and neurodevelopment. It is, therefore, necessary to transform current knowledge about the microbiota and neurodevelopment into clinical, social, and health actions that offer real solutions to people with ASD and their families. From this perspective, focusing on prevention, promoting healthy lifestyles, and integrating new technologies represent the true tools for building a more sustainable and inclusive healthcare system.