Link: https://thereader.mitpress.mit.edu/the-invisible-organ-shaping-our-lives-microbiome/
By implication, a great deal of our health and mental wellness can be traced back to diet and lifestyle. Things like smoking, sugar, diet soda, preservatives and antibiotics all negatively affect the gut biome, which in turn affects not only our health but our state of mind.
The good news, you can positively impact it with healthy lifestyle choices and probiotic foods - such as Kombucha, active yogurt, fermented foods, etc.
And, of course - fresh and young fecal transplants. Mmmm. Fecal transplants. I've already called my first unborn grand-childs first dirty diaper, but this could be a long waiting game...at least the kids know I'll be game for baby-sitting.