They add a lot more than sugar as preservative nowadays. Good luck finding something without preservatives sold in stores.
They even put acids in your food! ACID! The stuff that melts steel beams and makes IE6 crash. Think about that.
The point of preservatives is to prevent biotic life from consuming it. If the food is actively preserved--sugared or salted or what have you--it will be just as cytotoxic if not prepared in a way to dilute or remove the preservative.