Orthodox can talk about "transubstantiation" occurring, as the Confession of Dositheus does, but we also might say that it does not if one follows the same logic as RINO Tom, identifying it particularly as a confirmation of Aristotelian metaphysics.
In the Orthodox view it is necessary that the Eucharist becomes the Body and Blood of Christ because God enters into us and we partake of His Nature, gaining life because the Blood of He who has Life enters us. Along those lines I find it curious that Roman Catholics affirm transubstantiation but also permit eating animal blood, since the life is in the blood and the ancients believed that having animal life enter you is not spiritually healthy.
Can you elaborate on that last point? I would assume that by "the ancients" you are not referring to the early Christian Church, and if I understand correctly, what you're implying is that veganism would be a necessity to avoid having "animal life enter you." I am also not familiar with any Christian tradition that applies similar logic, of Christ being in His blood, to animal life also being in animal blood.