yes, vampires can eat and drink human food, but they don't cause they find it hideous... if you read twilight, you could read that Edward took a bite from Bella's pizza when she challenged him... they don't digest it (human food and drinks), they just cough it out later

PC#7 on Lexicon (Q answered by SM herself):
Q. What happened to the piece of pizza Bella dared Edward to eat? Would it be stuck in his system for the rest of eternity? Vampires don’t, um, go to the bathroom. Would he just have pizza floating in his stomach for the rest of his life? Ew…

A: Ew, yes. He’d have to cough it up later to get rid of it. Not the most pleasant thing, which is why the vampires only eat food when they absolutely have to in order to blend in.

well yeah, but it dont really 'go' with their non human state aha, and they dont like the taste and stuff. they have to hurl it back up later dont theyyy. (: x