But you definitely can eat it, and it's good at cleaning out your system. Also great for pool or aquarium filters.
I have a 10lb bag of food grade diatomaceous earth in the kitchen. I mix a teaspoon in with my dog food a couple times a month as a worm preventative. I also rub a little into their hair after a bath to keep fleas and ticks at bay.
I dust garden plants with it or spread it on the ground for snails and slugs.
I discovered it years ago when I worked for Dawn foods and saw them putting it in cake mix as an anti caking agent.