I can't get my family to do everything I think is good for them either. Sometimes you just have to give up on the idea of "helping" them, and realize we each have our own path. I try to respect and trust them (and God) enough to let them live their life without co-opting it and trying to do it better than they can.
God loves my husband no matter how big an idiot he is and allows him to make mistakes. I try to follow His example.
Now, to show you what hypocrites we southern women are - here's a suggestion. You might consider giving up on the pills, smile sweetly at him, and put Lugols drops in his food. You can hide a good deal of Lugols in pancake batter :)
OR, pull out his life insurance papers and make a point of thoroughly going over them.
But a wise woman would just drop the whole subject out of love and respect because he is an adult and capable of making his own choice. A man NEEDS respect and trust. They HATE being told what to do like a child.