Leaky Gut: Real Mechanism, Broken Test, Fake Syndrome

Summary

Intestinal permeability is a **real, measurable property of the gut barrier** whose pathological increase is genuinely documented in coeliac disease and IBD (Tier 1 for the phenomenon) — but **"leaky gut syndrome,"** the marketed claim that a porous bowel is the hidden root cause of fatigue, autoimmunity, migraine, and autism and is fixed by glutamine/collagen/"gut repair" blends and open-ended elimination diets, is **medically unrecognised, sold on a broken biomarker (the commercial zonulin test), and unsupported by evidence** (Tier 3/4 for the syndrome). The honest middle is small: support t