Autism-related dietary preferences mediate autism-gut microbiome associations.

This Australian study of 247 people found that autistic people don't have different gut bacteria because of their autism itself. Instead, autistic people often have restricted food preferences, which leads to less variety in their diet. This limited diet then affects their gut bacteria and bowel movements. The research suggests that gut bacteria differences in autism are likely due to food choices, not autism directly causing gut problems.

This large Australian study (n=247) investigated the relationship between autism and gut microbiome composition using stool metagenomics. Contrary to expectations, researchers found negligible direct associations between autism diagnosis and gut microbiome differences. Instead, the data revealed that autism-related restricted interests lead to less diverse diets, which in turn cause reduced microbial diversity and looser stool consistency. The study was well-powered to detect microbiome associations with age, dietary intake, and stool consistency, but not direct autism-microbiome links.

The findings suggest that previously reported microbiome differences in autism may be mediated by dietary preferences related to diagnostic features rather than representing a causal pathway.

Results suggest that interventions should focus on expanding dietary variety rather than directly targeting the microbiome. Clinicians should assess and address restricted eating patterns in autistic clients. Caution warranted regarding microbiome-based treatments for autism symptoms.

Study design not fully specified in abstract. Cross-sectional design cannot establish causality. Sample may not represent all autistic individuals. Dietary assessment methods not detailed. Potential confounding factors beyond those measured may still exist.

There is increasing interest in the potential contribution of the gut microbiome to autism spectrum disorder (ASD). However, previous studies have been underpowered and have not been designed to address potential confounding factors in a comprehensive way. We performed a large autism stool metagenomics study (n = 247) based on participants from the Australian Autism Biobank and the Queensland Twin Adolescent Brain project. We found negligible direct associations between ASD diagnosis and the gut microbiome.

Instead, our data support a model whereby ASD-related restricted interests are associated with less-diverse diet, and in turn reduced microbial taxonomic diversity and looser stool consistency. In contrast to ASD diagnosis, our dataset was well powered to detect microbiome associations with traits such as age, dietary intake, and stool consistency. Overall, microbiome differences in ASD may reflect dietary preferences that relate to diagnostic features, and we caution against claims that the microbiome has a driving role in ASD.