Is it safe to fill a plaster table base with cement to hold a granite table top?

I have a plaster table base that has a opening on the bottom. I guess it's used for if you need to fill it with something? I was wondering If I filled it with cement to make it more heavy to hold the granite table top. I have kids and I don't want it to tip over. I was also thinking of filling it with plaster. Not sure what to do. Please help if anyone knows.. Thank You!!