For instance, some researchers found that the microbiota of autistic children lacked the beneficial strains of bacteria Bifidobacteria and Prevotella, while other studies found “a significant increase in the Firmicutes/Bacteroidetes ratio” and higher levels of the bacterial taxa Escherichia/Shigella and Clostridium cluster XVIII.
Also, autistic children tend to experience gastrointestinal issues such as constipation, diarrhea, and abdominal pain.