Intestinal permeability and glucagon-like peptide-2 in children with autism: a controlled pilot study.

Doctors compared gut leakiness in kids with autism and typical kids. All children had tummy pain, diarrhea, or constipation. They drank a sweet test drink and gave urine samples. The team also checked blood levels of GLP-2, a hormone that helps fix the gut lining.

The two groups looked the same. Urine tests showed no extra leakiness in the autism group. GLP-2 hormone levels were also identical. In short, the gut barrier was normal in both sets of children.

Marcell et al. (1988) hunted for a different body marker and also came up empty. They measured a brain-fluid chemical and saw no autism–control gap, matching the null gut result here.

Lancioni et al. (2008) ran blood tests for self-attacking antibodies the same year. Again, no group difference, showing a pattern of normal body chemistry in autism.

DWaldron et al. (2023) later gave digestive enzymes to preschoolers with autism and saw calmer behavior. Their positive finding keeps the gut–brain link alive, but it points to enzymes, not a leaky gut, as the useful lever.

You can stop blaming a leaky gut for GI pain in autism. The barrier is intact, so pricey permeability tests or special “sealing” diets lack support. Focus instead on evidence-based GI care: food diaries, fiber, fluids, and medical work-ups when needed. If parents ask about gut theories, show them these data and steer the plan toward symptoms, not unproven markers.