>I'm not sure. Remilia often puts it in tea, which is near-boiling
>water and presumably denatures the proteins, but that may be just for
>flavor and not strictly sustenance.

If the point is the proteins rather than the mystical significance of the whole blood consumption thing, the body will not care. In fact, it will likely aid digestion, because as part of the whole digestive process the body denatures long chain proteins so the various enzymes can work at it and chop them into smaller pieces that the body can more easily shuffle around and process as substrate for its own protein sequencing.

And that's before you get into things like prion diseases, where being able to denature proteins is an absolutely critical base function to protect you from them.