Well... [She's never went without food so she doesn't have first hand experience.]
I could probably just survive off of blood. But we get hungry for food, too. So I think it's probably important... yeah...
[Sorry, she's such a novice vampire, even if she was born as one.]
I've never really thought deeply about it. I think it helps sustain us, and keep us full. If we went without, the need for blood would probably increase. And if we had neither, I think it would probably be painful. At Kurosu Academy we were still served regular food.