Good question.
I have also posted this on the other autism thread, in hopes it can be of some help.
Check out autism researcher Dr. Derrick MacFabe (has several Youtubes).
His theory centers on short chain fatty acids (SCFA) and microbiome disruption. ASD is associated with overproduction of propionic acid (propionates) from dietary and bacterial sources.
Children with developing microbiome are susceptible to disruption from several contributing factors — C-section delivery, lack of breast feeding, vaccines, antibiotics, diet etc. Bacteria that overproduce propionates proliferate.
Propionates are overused as natural food preservatives, especially in wheat and grain products. Adults can tolerate much higher amounts than children with developing neural systems.
Dr. Jacob Wilson in his book “The Ketogenic Bible” suggests that MCT oil or exogenous ketones may help. This would make sense because another SCFA (butyrate) would balance off the propionate.
Dr. MacFabe also recommends limiting dietary sugar and including more fibrous foods. This would favor gut bacteria that generate more butyrate over propionate.
There is a vidio First Do No Harm with Meryl Streep that deals with treating a child with ketogenic diet. And the medical profession swooped down on the mother of this child and removed him from her care. Even though the child was getting much better. The movie made me sooo angry ! Its an older movie but deals with similar issues as being discussed here.