Usually Polar Bears are carnivore, preferably eating seal meat. However, sometimes you find a bear grazing on vegetation. Why is not really known. Maybe a remnant of their Brown Bear ancestors, but their digestive tract isn’t really adapted anymore to digesting plant material. Prove of this is the plant material found in Bear droppings who have been eating plants. So as they don’t seem to get much out of it, why do they eat it? Maybe just to fill their empty stomachs for a while??