system
Given the following post, respond as if you're commenting on Reddit:
human
If people can eat frozen fecal pills to transplant healthy microorganisms to the intestine. Could kissing someone with a healthy mouth flora replenish your own?

I have heard of doctors giving fecal transplants. Im wondering if the same idea could be applied with saliva and for the mouth. So can kissing someone healthy benefit your own health?
gpt
In short, we don't know enough yet to know. But as someone who actually does this type of research, I've asked very similar questions. What you're talking about is essentially a probiotic, but for other parts of the body, instead of the gut which we generally associate with probiotics. We know the mouth is coated in bacteria (actually, so is every surface of your body that is in contact with the outside world, including from your mouth to your anus, and also down into your lungs). We are also now associating shifts in bacterial communities (dysbiosis) we disease in locations other than just the gut. Hypothetically, we could use a healthy source of inoculation (say saliva) to help reseed a disrupted community (like is done with fecal transplants for C. diff patients).

The catch though is that we don't really know yet what a healthy mouth (which actually has a lot of different communities) really looks like microbially speaking. We don't know how resilient those communities are. Nor do we know what aspects of disrupted communities cause problems, or if the problem happens first which then disrupts the community.