Autism Spectrum Disorder (ASD) is a severe neurological/neurodegenerative syndrome that results in cognitive and communication disorders. The degree of dysbiosis is related to the severity of ASD signs. The gut is conferred with a variety of sensory receptors that cooperate with effector systems including the endocrine, nervous and gut immune systems of the intestine. Gut dysbiosis causes amplified inflammation, the launch of the HPA axis, changed levels of neurotransmitters and bacterial metabolites; these may donate to abnormal signaling throughout the Vagus nerve in ASD. Decreased integrity of the gastrointestinal barrier led to extreme leakage of substances as of the intestine in early life and inflammation followed by disruption of BBB integrity maybe increase the risk of ASD. Microbiota, by controlling the barrier permeability, regulate the quantity and types of bioactive materials that are transferred from the intestine to the brain. Exposure to metabolites and microbial products regulate significant procedures in the CNS, including glial cell role, myelination, synaptic pruning, and play a role in neurobehavioral, neurodegenerative, psychiatric, and metabolic syndrome. CLICK TO REVIEW