Study debunks autism–gut microbiome link

A study by Australian researchers has found changes in the gut microbiome of people on the autism spectrum appear to be due to “fussy eating”, which is more common among autistic children due to sensory sensitivities or restricted and repetitive interests.

First-author Chloe Yap from Mater Research and The University of Queensland said, “While it’s a popular idea that the microbiome affects behaviour, our findings flip that causality on its head.”

Yap and fellow researchers examined genetic material from stool samples of 247 children, including 99 children diagnosed with autism. “We found that children with an autism diagnosis tended to be pickier eaters, which led them to have a less diverse microbiome. This in turn was linked to more-watery stools. So, our data suggests that behaviour and dietary preferences affect the microbiome, rather than the other way around,” Yap said.

The findings of the Autism CRC study, led by Mater Research and The University of Queensland, are being published in the scientific journal Cell.

Senior study investigator and head of Mater Research’s Cognitive Health Genomics Group Dr Jake Gratten said that out of more than 600 bacterial species identified in the gut microbiomes of study participants, only one was associated with a diagnosis of ASD.

“There’s been a lot of hype around the gut microbiome in autism in recent years, driven by reports that autistic children have high rates of gut problems. But that hype has outstripped the evidence,” Dr Gratten said.

“We are already seeing early clinical trials involving faecal microbiota transplants from non-autistic donors to autistic people, despite not actually having evidence that the microbiome drives autism. Our results suggest that these studies are premature.”

Autism CRC Research Strategy Director Professor Andrew Whitehouse from the Telethon Kids Institute and University of Western Australia said the findings provide impressive clarity to an area that has been shrouded in mystery and controversy.

“Families are desperately seeking new ways to support their child’s development and wellbeing. Sometimes that strong desire can lead them to diet or biological therapies that have no basis in scientific evidence,” Professor Whitehouse said.

“The findings of this study provide clear evidence that we need to help support families at mealtimes, rather than trying fad diets. This is a hugely important finding.”

Professor Valsamma Eapen, Chair of Infant, Child and Adolescent Psychiatry at UNSW Sydney, said the study used a comprehensive dataset with other clinical and biological measures.

“This allowed us to examine the complex relationships of the microbiome with dietary preferences, clinical data and genetics,” she said.

Brisbane autistic woman Trudy Bartlett said the research findings provided an important step forward for the autism community.

“I have found that many autistics have gut issues, which I thought may be linked to the fact that many of us — including myself — have restrictive diets so we may not get all the nutrients we should. Wanting to know more about it is like walking through a minefield trying to filter fact from fiction,” she said.

“Having evidence-based research like this study will help members of the autism community to navigate this space and not spend copious amounts of money and time on fads that claim to improve the quality of life for an autistic person.”

The study claims to be one of the largest to date to examine what organisms are in the stool microbiome and what those organisms have the potential to do. The stool samples and dietary information of the 247 children were sourced from the Australian Autism Biobank and the Queensland Twin Adolescent Brain Project.

Image credit: ©stock.adobe.com/au/9dreamstudio