I’m not the original poster, but there is definitely increasing evidence in modern health research that gut bacteria is directly linked to mental health: https://www.science.org/content/article/meet-psychobiome-gut...

Agree (in terms of the kind of formal evidence I imagine you would accept). However it doesn't need to be "true" in any objective sense, to provide relief or improve wellbeing.

Is an interesting thought, would love to see clinical trials of various spiritual and traditional medicine practices.

The combo of say, CBT and (dubiously effective) antidepressants doesn't seem wildly different, except traditional practices are often better "socially integrated" and have less stigma.