Let's try rewriting that: "For my food is real flesh, and my drink is real blood." That's more in line with what one would expect if Christ were arguing the communion was transumuted. But it is the exact opposite. A physically literal interpretation would suggest that Christ's veins coursed with beverage and His epidermis was composited of flour and leavening agent... unlikely what He was talking about, to say the least. Now, the verse is indeed literal, but it's not
physical (which is hardly surprising...eternality isn't physical either). Christ is talking of spiritual food and spiritual drink. As it says in John 6:63 "The Spirit gives life; the flesh counts for nothing." So when Jesus says He is the bread of life, he is talking about something spiritual, not something flesh-like.
Furthermore, the Bible tells us in the New Testament in Acts 15:29 to 'abstain from blood.' So do you really mean to tell me that the council of Jerusalem issued an edict to the Syrian church, etc., which would have forbid them from partaking of communion? I think it's pretty clear that the idea of transmutation had not even come up at that point.
My whole point is that Protestants will take certain verses of the Bible and tell us they are "literal" and not open to interpretation, and then turn around and take other verses and interpret them and say "What it REALLY means is...."
You can't have it both ways - either the Bible is literal or its not. You can't pick and choose which parts you want to take literally and which parts you want to interpret.
I am NOT a literalist - but most Fundamentalists are (except when it comes to a verse they don't like).