Psychological stress worsens gut permeability. Speaking in public does it, with transient effects

It is worth noting that psychological stress worsens gut permeability. Speaking in public does it, with transient effects (Vanuytsel et al., 2014), and early maternal deprivation does it too, with long-term ones (demonstrated in rats: Barreau et al., 2004). Interestingly, psychological stress also worsens gut inflammation (for a brief review, see Daulatzai, 2015), exacerbates immune-related diseases (Dhabhar, 2009), and predicts the onset and severity of mental disorders (Kendler et al., 1999; Carr et al., 2013). Some common spices (Jensen-Jarolim et al., 1998) and food components (e.g., Bischoff et al., 2014) modulate gut permeability too, either increasing it (like fructose, widely used to sweeten commercial beverages) or decreasing it (like the flavonoid quercetin, found in onions and tea). Probably because it is mistaken for a microbial molecule (Fasano et al., 2015), gluten stimulates zonulin release and hence features prominently in the former group (Hollon et al., 2015). Ingestion of an inhibitor of zonulin prevents gluten from raising gut permeability, and a gluten-free diet reduces both zonulin levels and gut permeability (Fasano, 2011). In all of us, zonulin increases the permeability not only of the intestinal wall, but also of other no less interesting barriers—notably the blood-brain one. A toxin mimicking zonulin is actually being studied for its ability to enhance delivery to the brain of drugs such as anticancer agents (Karyekar et al., 2003).

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4809873/