Effect of Following an “Exclusion Diet” to Modulate the Gut Microbiota of Children with Autism Spectrum Disorder

Abstract

Background: Emerging evidence suggests a link between gut microbiota dysbiosis and the pathogenesis of autism spectrum disorder (ASD). The consumption of food additives, processed foods, trans fats, and high-sugar foods has been linked to gut dysbiosis, potentially affecting the gut-brain axis.Aim: This study aimed to investigate whether the dietary exclusion of these foods would modulate the dysbiotic gut microbiome of children with ASD and ameliorate ASD symptoms.Methods: Twenty Egyptian children with ASD underwent a 3-month dietary intervention that eliminated processed foods, additives, and preservatives. Stool samples were collected pre- and post-intervention for gut microbiome analysis using real-time PCR to quantify the dominant gut microbiome at the phylum, genus, and species levels. Clinical symptoms, including ASD severity, sensory impairment, and gastrointestinal symptoms, were assessed using the Autism Treatment Evaluation Checklist (ATEC), the Short Sensory Profile (SSP), and the 6-item Gastrointestinal Severity Index (6-GSI), respectively.Results: Following 3 months of adopting the exclusion diet, children with ASD significantly improved ATEC, the total SSP, and 6-GSI scores. The sociability and health/physical/behavior subscales of the ATEC showed a significant decline in scores. Notably, the number of cases with definite sensory impairment decreased from 14 to 7 cases, and the number of ASD children with severe GSI scores decreased from 10 to 3 cases. Although the Prevotella/Bacteroides ratio increased threefold for the gut microbiome profile, the difference was insignificant. Overall, there were no significant differences in the gut microbiome profile after three months of following the exclusion diet.