The two proteins that
control your gut - lining permeability — occludin and
zonulin — also
control your blood - brain barrier permeability, and when they are elevated, it can lead to both leaky gut and leaky brain.
For example, a close look at the data from one study finds that only 42 percent of the patients with type 1 diabetes had an elevated serum
zonulin level (defined as 2 standard deviations above the
control group mean)(13).