They can eat from 180-300 kg of food a day, and 40% of that will pass through undigested. They eat a big variety of foods, from trees to grass, including soil and sometimes dung from other Elephants to replace enzymes they need to digest their food.
They have two rows of teeth on the top of the mouth, and on the lower part, which will be replaced 6 times in the Elephants life time, the last set of teeth being the biggest, comes at a age of about 35, and will last till the Elephant dies, due to the teeth wearing done.