My s/o acts like medicinals I order are silly, useless and won't consider any of them.Why?

My s/o , when learning I have purchased any sort of herbal
preparations, vitamins of any type or the latest patented
formula says , “keep that stuff away from me” or, “I want nothing
to do with it; it’s ridiculous.” Why is he so rude and rejecting
and not open-minded? Why won’t he even read about them?
If it’s nutritious (veggies, fruits, exercise) he acts like it’s BS
and for other less “informed” mortals. It is so irritating and
infuriating. If anyone ever needed to at least try any of these
things it’s he. His lifestyle , attitude and diet are dreadful and
have , imo, been disastrous to his health. Is it just plain stubborn?