There's still an economic incentive for the highest level of FDA approval: Medicare and insurance companies have to cover it and doctors can prescribe it. That

There's still an economic incentive for the highest level of FDA approval: Medicare and insurance companies have to cover it and doctors can prescribe it. That ensures a high and consistent level of usage across the whole country, not just among people with more money than sense (usually IMHO; it's possible that they're just smarter & savvier than the notoriously conservative FDA, who knows, this is a big reason why taking away choice is bad on principle). I don't think the lack of credible evidence of efficacy in the supplement market is for lack of trying. If an alternative medicine is actually effective, it just becomes medicine that the majority of people can trust and use.