Assess the effect of a casein-free and gluten-free diet on gastrointestinal symptoms, clinical variables, and the composition of the intestinal microbiota in Mexican children with autism spectrum disorder.

The objective of this quasi-experimental pre-post study with time series is to evaluate the effect of a casein-free and gluten-free diet on gastrointestinal symptoms, clinical variables, and the composition of the intestinal microbiota in Mexican children with autism spectrum disorder. The main question it aims to answer is:

Does a casein free and gluten free diet promote a reduction in gastrointestinal symptoms, an improvement in clinical variables, and a state of eubiosis in the composition of the intestinal microbiota in Mexican children with autism spectrum disorder?

Participants will undergo:

An intervention of a casein-free and gluten-free diet for 3 months. Sample collection before and after the nutritional intervention. Clinical evaluations.

Inclusion Criteria:

Children between 4-10 years old diagnosed with autism spectrum disorder using the criteria established in the ADOS scale and the CARS.

Exclusion Criteria:

Children who have received:

• Antibiotics
• Antimycotics
• Probiotic supplements
• Prebiotic supplements
• Any medication that may alter the microbial composition of the patient, minimum one month prior to sampling.
• Children on a strict dietary regimen other than a casein-free and gluten-free diet.
• Children with celiac disease or who present any gluten-related disorder.
• Children with allergy to dairy products.