Right, not to mention kidney stones: The phosphoric acid binds the calcium and magnesium into crystals, which are too big for the body to use, so it tries to get rid of it in its usual way, through the urinary passage. If the crystals get caught on the way, they'll just sit there, waiting for the next chunk to bind with. So with each sip of soda these rocks grow in size until they become something horribly painful... though made of stuff the body needs but couldn't access.