I am sorry if this sounds disgusting but I noticed my stools were the color of spinach, kind of like a blackish green. It really startled me since I have never seen this before, and then I had a thought.. I had , had birthday cake with navy blue icing, and I assume it is the dye from the icing that has caused this discoloration ? Can food coloring do this? It probably is the cause, but I wanted to make sure , and see if anyone else has had this happen. Thanks.Jeanne.