I can't speak for chiropractic as that's out of scope for the FDA and I have no knowledge of the regulatory process there. Homeopathy and supplements are class

I can't speak for chiropractic as that's out of scope for the FDA and I have no knowledge of the regulatory process there. Homeopathy and supplements are classified as food, not medicine. Therefore, they're not required to seek FDA approval. (They still have to meet food safety standards, of course.) If they could do anything meaningful, they'd be required to reclassify as medicine and undergo approval. So you get this fun situation where anything useful is locked up and can only make very specific claims about what it can cure. The things that can't cure anything can make weasel-worded claims about anything.