Why don't natural anti-freezes cause problems in animals that use them?

Well in fact, many of the natural anti-freeze cryoprotectants are simply sugars and sugar alcohols which we use every day and which are heavily used in the food industry. The problem comes where we use very high quantities of them at the cellular level, then they can become toxic to the cell. Researchers are doing very detailed studies to find out at what exact concentration these cryoprotectants become atoxic.