Mika and I were talking about micronutrients and she was mentioning the importance of copper and zinc. I pointed out that pennies have both copper and zinc (although in a 19:1 ratio) and asked her how many pennies I would need to eat to stay healthy. She said 1 or 2 would do.
While I’m not about to start eating pennies, many people do. Eating non-food items after you are a couple years old is pathologic but surprisingly common. It’s often called pica although it has many other names — especially for people that particular types of non-food items (e.g., geophagia for folks who eat dirt, cautopyreiophagia for burnt matches, geomelophagia for raw potatoes, amylophagia for soap, acuphagia for sharp items, etc).
Mika asked me why adults would eat coins. I suggested that it was mental problem. She pointed out it that perhaps it was more of a metal problem.