This is a metastudy based on Chinese studies regarding their high natural levels of fluoride - much higher than is used for artificially fluoridated water. Like most things the dose makes the poison, and you cannot assume that just because excessive consumption of salt is bad for your health that the healthiest amount is zero.
Another problem is that naturally occurring fluoride tends to be in remote mountain areas where everyone is going to be dumber from poverty and cultural isolation.
There are many counties in the US that do not have fluoride and they're right next to counties that do, so you could easily study those locations. But that won't get the answer you want.
This is a metastudy based on Chinese studies regarding their high natural levels of fluoride - much higher than is used for artificially fluoridated water. Like most things the dose makes the poison, and you cannot assume that just because excessive consumption of salt is bad for your health that the healthiest amount is zero.
Another problem is that naturally occurring fluoride tends to be in remote mountain areas where everyone is going to be dumber from poverty and cultural isolation.
There are many counties in the US that do not have fluoride and they're right next to counties that do, so you could easily study those locations. But that won't get the answer you want.
Which is kinda the opposite of the problem we have over in the States.