A hundred years ago, when I was younger, my mother took on the responsibilty of raising her nephew's three old son. One day she discovered him eating, yes EATING, the blackened heads off lighted (burned) matches. She took him to a doctor and they figgured out that he craved an important mineral in his diet. I think it might have been magensium, but I'm not sure. As I said, it was a hundred years ago. Bob