The mind gut connection is sometimes viewed as being a bit " woo woo", but more and more research is coming out to help link the connection between our gut and our brain. Here is an article by Psychology today discussing the Vagus nerve and bottom-up usage of serotonin.
https://www.psychologytoday.com/ie/blog/the-athletes-way/201910/the-vagus-nerve-may-carry-serotonin-along-the-gut-brain-axis?fbclid=IwAR2MXW5yL4Lvg9RT-ZPG4SI4IF126Y8K9ka0Uo5v61_ad82jy3K8zEY-aS8
Early drawing of the Vagus nerve(also known as the wandering nerve) we can see how the gut and brain may be more connected than we thought.