A new study in Pediatrics has a brief but useful summary of the evidence linking autism and digestive problems. Here’s one study. Here’s a review, with this abstract:
Recent publications describing upper gastrointestinal abnormalities and ileocolitis have focused attention on gastrointestinal function and morphology in [autistic] children. High prevalence of histologic abnormalities in the esophagus, stomach, small intestine and colon, and dysfunction of liver conjugation capacity and intestinal permeability were reported. Three surveys conducted in the United States described high prevalence of gastrointestinal symptoms in children with autistic disorder.
I believe that few people in America eat enough bacteria — in practice, this means not enough fermented food — and that this causes digestive and immune problems. A vast number of people will say, “of course, good food is really important, bad food causes X, Y, and Z” — where X, Y, and Z can be practically anything. The difference between my views and theirs is the prescription: They inevitably think that people should eat more fresh unprocessed food. (Usually fruits and vegetables, for some curious reason.) Fermented food, of course, is not fresh and not unprocessed.