An olive is not always quite what you think.

Here I was happily adding sliced black olives from a can to various things: quesadillas, pizza, casseroles, salads, etc. Now I find out that black olives are not really black olives. Let me go back a bit in my story. I was perusing a sample magazine sent to me by Cook's Illustrated and saw a recipe for Provencal pizzaladiére which is made with black olives, anchovies, fresh thyme leaves and caramelized onions. This is something I would really like to try. In a side bar the author discussed various types of black olives. Niçoise olives were recommended but are hard to find, especially in the small city where I live. Kalamata olives are recommended for a substitute. California black olives were  not. It seems that they are really green olives with a chemical additive to make them black. This bit of info sent me to the kitchen cupboard to look at the label on a can of sliced California black olives. Yes, they had an additive, ferrous glutamate. Ferrous glutamate is often given as an iron supplement for certain conditions.  Having worked in various medical settings for most of my working life I know that one of it's side effects is turning one's stools a jet black color, which can be a little unsettling to a patient who does not realize that this is going to happen. I suppose one would really have to eat a lot of the olives before this took effect, but it's useful to know what exactly is in one's food.