I learned something interesting about taking calcium supplements from my dentist. My teeth have been staining awfully in the last year. This also coincides with beginning to take supplemental calcium. I was told that when some of the non-absorbed calcuim ends up in your saliva, it attaches to your teeth. Before that happens, though, it also clings to food particles in your mouth. I counldn't figure out why my teeth were so brown after just 6 months. I don't smoke or drink coffee. I'm deficient, so I must continue taking it. Now I use my sonicare with baking soda once a week. It seems to be working.