https://www.sciencedirect.com/science/a ... 7712000928
It came from this article here and is a couple of years old now. https://www.theguardian.com/lifeandstyl ... -happiness
I remembered it because I currently have a sinus infection
So little is known about gut health but there is enough information available to confirm its importance. Good gut health = good health.
Increasing good gut bacteria and decreasing bad gut bacteria has been something I have focused on for several years. Easy and inexpensive to do!
More in depth studies should be done IMHO.