Night World by L.J. Smith

So I'm reading a new book (Night world), and the first (of three) stories is called Secret vampire, and is, obviously, about vampires.

At one point they kind of explain why vampires need to drink human blood to survive, and I thought that it made a lot of sense, so I'm going to use it for my vampires.

"Vampire blood destroy hemoglobin-the red cells-in human blood. Once it destroys enough of the red cells, you stop getting the oxygen you need to live"..."We take a little and that carries oxygen through our system until our own blood destroys it."

Doesn't that make a lot of sense?

So that and for other mystical reasons is why my vampires need human blood to survive.