Evidence check: Leaky Gut Test in the context of Sport

The concept of 'leaky gut' (increased intestinal permeability) is often discussed in sports contexts regarding performance, inflammation, or GI distress. However, the evidence for commercial leaky gut tests (e.g., zonulin, occludin, LPS-binding) is weak. Most markers are not well-validated, show high intra-individual variability, and are influenced by diet, exercise, stress, and time of day. Fecal or serum zonulin does not reliably correlate with actual permeability measured by the gold-standard lactulose/mannitol test. In elite sports, some studies show transient permeability increases after intense exercise, but translating this to at-home test kits is problematic. Without medical supervision and functional diagnostics, results can be misleading. MyBody-X advises caution: these tests should not drive supplement or diet changes alone. Evidence: mostly mechanistic/animal, few robust human trials on the specific markers offered.