The Relationship of Severity of Autism with Gastrointestinal Symptoms and Serum Zonulin Levels in Autistic Children.

Doctors took blood from 60 autistic kids. They split the kids into mild, moderate, and severe groups. They checked how much zonulin was in each blood sample. Zonulin is a tiny protein that shows if the gut wall is leaky. Parents also filled out a GI symptom checklist.

Severe autism kids had the highest zonulin levels. Their average was almost double the mild group. Higher zonulin matched worse GI pain, diarrhea, and bloating. The link stayed strong even after age and diet were ruled out.

Kaiser et al. (2022) pooled 11 million records and found autistic kids get inflammatory bowel disease 1.5 times more often. Selen’s zonulin result gives one possible reason: a leaky gut may let inflammation start.

Zhou et al. (2018) saw higher stool IgA in autism, another gut immune red flag. Together the papers paint a picture of both barrier damage (zonulin) and immune reaction (IgA).

Cai et al. (2025) used stool microbes to tell autism cases from typical kids with 98 % accuracy. Their microbe signature and Selen’s zonulin signal both come from the gut, but they measure different things; no clash, just more pieces of the same puzzle.

You can’t order zonulin in every clinic yet, but you can act today. Track GI complaints at every visit. Severe autism kids may not report pain with words; watch for new self-harm, food refusal, or night waking. A quick stool log or Bristol chart can catch flare-ups early and guide referrals to GI docs.