Vitamins: mostly harmless and very profitable
The lead character in The Hitchhiker’s Guide to the Galaxy, Arthur Dent, is incredulous upon reading the book’s description of planet Earth as “harmless”.
“Is that all it’s got to say? Harmless! One word?” he exclaims.
To which his friend, Ford Prefect, replies: “I managed to transmit a new entry off to the editor. He had to trim it a bit, but it's still an improvement."
Arthur: "And what does it say now?"
Ford: “Mostly harmless.”
This is what pops into my head when I think about vitamin D. Sure