It is well known that stress can cause a stomach ache, but the relationship works both ways, says a pediatrician.
Researchers are starting to show that a bacterial imbalance in the gut can cause mental health problems, says Dr Leila Masson, who specialises in treating children on the autistic spectrum.
Although an imbalance does not cause autism, getting the balance right can help reduce some of the anguish.
"I have repeatedly seen autistic children become more settled and less anxious when this imbalance is resolved," says the New Zealand pediatrician, who is a speaker at the MINDD international conference in Sydney on June 14.
"We are not talking about curing autism. It is about treating some of the problems that come with it."