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ASD is a neurodevelopment disorder that influences the social behavior and communication of afflicted individuals throughout their lifetime [241, 242], where ASD severity is linked to the intestinal microbiota and gastrointestinal symptoms [238, 243]. Studies on isolated fecal bacteria from ASD patients revealed microbial dysbiosis resulting in the enrichment of Clostridium, Lactobacillus, and Desulfovibrio species; and decreased Bacteroidetes/Firmicutes ratio [244–247]. Carbohydrate‐degrading bacteria from the Prevotella, Coprococcus, and unclassified Veillonellaceae genera showed lower abundance than healthy people [248]. Despite this observation, the fluctuations of specific bacterial species from different studies are inconsistent, thus proving a challenge to determine the role of bacteria dysbiosis in the pathogenesis of ASD [238]. Clinical research using specialized diet to alleviate ASD symptoms has been studied to perturb these microbiota populations. Gluten‐ and casein‐free (GFCF) diet is currently widely prescribed to children with ASD, designed to reduce leaky gut‐causing proteins and facilitate symptom remission [249]. However, there are some inconsistencies in treatment in some small clinical trials [250–252]. Alternatively, the ketogenic diet was found to improve ASD symptoms both in an animal model and small‐sized clinical experiment despite potentially causing ketosis. This is due to the ketogenic diet to compensate the lower Firmicutes to Bacteroidetes ratio and increase A. muciniphila in mice of ASD [253]. While showing much success in mice, the detailed mechanism linking in a ketogenic diet, gut microbiota, and ASD remains unclear due to the lack of appropriate animal models that mimics the human BGM [254]. In addition to altering dietary composition, probiotics, such as Lactobacillus and Bifidobacterium, have been found to improve ASD behavior while treating the ASD‐linked gastrointestinal symptoms [255, 256].