I have been closely following the gut microbiome for a few years. The gut microbiome is the colony of hundreds of thousands of types of bacteria that lives in your large intestine. A lot of research is going on showing that shows a direct connection between your got microbiome and your health.
There are studies showing transplanting fecal matter from skinny rats to fat rats and the fat rats get skinny with NO change in diet. (in rats no studies in people)
There are studies showing connections between the gut microbiome and IBS.
And now a study, very preliminary, showing a connection between the gut microbiome and brain condition as we age.
Again this is all very preliminary and not enough evidence yet to go try and do anything.
But there is more and more evidence from around the world showing many connections. One I have always been interested in is antibiotics and weight gain. I don't know how many of you are aware but one of the early uses that antibiotics were (and still are) sold for, was to farmers. It was found that livestock put on weight faster if the livestock were given antibiotics.
A known side effect of antibiotics is it thoroughly disrupts your gut microbiome. And many people put on weight which they find very hard to loos after major surgery - where they get a follow regimen of antibiotics. Not all but some people.
Now this study:
Nature Microbiota from young mice counteracts age-associated behavioral definicts
Interesting times we are living in.