V(om)itamins

Why do vitamins smell so damned putrid?
What is that?
I’m not talkin’ Chocks Chewables. Or purple Freds or pink Dinos, with or without that little iron coating that I used to scrape off when I was an enterprising, crafty youngster oh so many moons ago.
I’m talkin’ regular vitamins. Good old-fashioned horse-pill sized vitamins with a new-fangled “vegetarian” twist (no gelatin, sugar, or starch). Multi-vitamins. Chock full of goodness and chock full of nauseating malodorous vomitatiousness.
What’s the deal? Why the big stink?