An interesting citation
Many pagan religions profaned blood by the way they used it. For instance it has been the view of many in occultic religions in both ancient and modern times that if you would eat animal, or even human, flesh while it was still living you would receive in yourself the strength, or life force, of the thing being eaten. This was the reason why God placed such a restriction on Noah and Israel.
from here: http://www.watchman.org/jw/blood.htm