It just is not a medically recognized disorder/disease/syndrome. There’s no ICD-10 code. To borrow from Wikipedia which does a better job at explaining the dif

It just is not a medically recognized disorder/disease/syndrome. There’s no ICD-10 code. To borrow from Wikipedia which does a better job at explaining the difference in simpler terms (and is accurate in this case): > “Leaky gut syndrome is a hypothetical, medically unrecognized condition. Unlike the scientific phenomenon of increased intestinal permeability ("leaky gut"), claims for the existence of "leaky gut syndrome" as a distinct medical condition come mostly from nutritionists and practitioners of alternative medicine. Proponents claim that a "leaky gut" causes chronic inflammation throughout the body that results in a wide range of conditions, including chronic fatigue syndrome, rheumatoid arthritis, lupus, migraines, multiple sclerosis, and autism. There is little evidence to support this hypothesis.” > “Increased intestinal permeability is a factor in several diseases, such as Crohn's disease, celiac disease … allergic diseases among others. In the majority of cases, increased permeability develops prior to disease, but the cause–effect relationship between increased intestinal permeability in most of these diseases is not clear.” It is at best right now a finding of uncertain clinical significance. What is being called a disease is pseudoscience pushed by quacks. > To say that there is no need to treat epithelial permeability is just blinding yourself to possible treatments of immune disorders. That’s exactly the point. From your first link: “It is still unproven that restoring barrier function can ameliorate clinical manifestations in GI or systemic diseases.“ Because some researcher measured some values in a model or small observational study it doesn’t mean clinicians should recognize it as a disorder and consider treating it outside of a clinical trial.