Was talking to someone online recently about supplements, medications and he was talking about how his doctor had prescribed him some weight-loss drug that was working incredibly well for him and he'd lost loads of weight over the course of a couple months, and that he didn't understand why stuff like it wasn't more freely available/widely prescribed.

With that said I've lately been wondering - what simple, over-the-counter/easily available stuff is there that people could take which could noticably improve their life?

I've been aware of Vit D and fish oil for years, but it's got me wondering if there's other things that come with benefits, which you'd think would be used by everyone, everyday, but just aren't.