I had a medical doctor explain to me the difference between taking blood into the body as a transfusion as opposed to eating blood.
A friend of mine received blood transfusions for hemorrhaging esophageal varices. While he was recovering, several days later, he was behaving strangely (in the doctor's words - "loopy").
The doctor explained his behavior to me:
"When a person gets a blood transfusion, their body does not usually have a problem accepting the blood. However, when a person digests their own blood, and that is what happened to your friend - it does something funny to their brain and they behave as though they are drunk - "loopy". It takes a few days for the blood to be completely digested and after that, they will return to their normal behavior. We don't know why this happens but it does."
After being told this, I got to thinking about the bible verses that dealt with god's prohibition on "drinking the blood of your enemies" and getting "drunk" on that blood.
Eating blood does very different things to your body than what accepting a blood transfusion will.