alt Hacker NewsSerotonin produced in the gut doesn’t get into your brain.
This factoid is repeated everywhere but it’s misleading without knowing that gut serotonin is a different pool than brain serotonin and they have different functions.
The brain synthesizes its serotonin locally within the brain.
Serotonin from the gut affects vagal neurons. They carry that signal directly to the brain. That has a significant effect on up and down regulation of mood and arousal.