Vitamin L.

People think I'm gross, because I eat lice out of my hair, but what people don't realize is lice have a vitamin, called vitamin L, that isn't found anywhere else, though it is essential to the body.  In the days before shampoo and stuff, everybody had lice, and everybody ate them.  Now they generally put it into multivitamins, but they don't tell people where it came from.  It's also added to sugar in the same way iodine is added to salt, so people can get it just by eating normally.