I am installing an upflush toilet. When installing the vent pipe, must I go straight up through the roof or can I put a bend in it?

I am installing an upflush toliet. When installing the vent pipe, must I go straight up through the roof or can I put a bend in it?
You may put as many bends as you wish in a vent. Just make sure it has pitch back to the drain. Regards, Tom