If you want to find more on this topic then the relevant search words would be the Gut-brain Axis or Gut-brain connection.
Wikipedia has a starting point: https://en.wikipedia.org/wiki/Gut–brain_axis
Studies have confirmed that gut microbiome contribute to range of brain functions controlled by the hippocampus, prefrontal cortex and amygdala (responsible for emotions and motivation) and act as a key node in the gut-brain behavioral axis.[9]
I’ve suspected this, but source?
Edit: Oh, metabolomics
If you want to find more on this topic then the relevant search words would be the Gut-brain Axis or Gut-brain connection.
Wikipedia has a starting point:
https://en.wikipedia.org/wiki/Gut–brain_axis
Here’s the 9th reference on a site that doesn’t require a login:
https://www.researchgate.net/publication/321136378_Gutsy_Moves_The_Amygdala_as_a_Critical_Node_in_Microbiota_to_Brain_Signaling
Honestly I don’t have one at hand, but I remember it quite distinctly as it’s tied into research into neurodivergence.