Hi, Paul,
Magical hemoglobin, eh?

Well… let’s see what we have here…
We do not accept the Eucharist and see the Lord’s Supper as symbolic of His flesh and blood. In fact, I personally, am even more heretical. To me, the blood is just a symbol of His life on this earth which He gave up. I.e., there are no magical qualities to the hemoglobin of Christ.
What, if I may ask, is the basis for you seeing the Lord’s Supper - the Eurcharist - as smbolic? Catholics see the Lord’s Supper as really being Christ, hidden under the appearance of common bread and wine (no hemoglobin which is not a property of either common bread or wine) We Catholic believe this way for the following reasons:
John 6:32-71 This is a lenghty section that I will summarize in part: The previous day Christ had just fed 5,000 men by multiplying a few loaves and fishes, the Jews attempt to make him their earthly king and Jesus leaves the area. The Jews find him and demand another sign - (obviously feeding 5,000 was not enough…!) Christ then sets the foundation for the Eucharistic Discourse and identifies that if they do not eat His Flesh and drink His Blood they will not have life in them.
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I am the bread of life.
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Your ancestors ate the manna in the desert, but they died;
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this is the bread that comes down from heaven so that one may eat it and not die.
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**I am the living bread that came down from heaven; whoever eats this bread will live forever; and the bread that I will give is my flesh for the life of the world." **52
**The Jews quarreled among themselves, saying, “How can this man give us (his) flesh to eat?”
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Jesus said to them, “Amen, amen, I say to you, unless you eat the flesh of the Son of Man and drink his blood, you do not have life within you.
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Whoever eats my flesh and drinks my blood has eternal life, and I will raise him on the last day. **55
For my flesh is true food, and my blood is true drink.
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Whoever eats my flesh and drinks my blood remains in me and I in him.
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Just as the living Father sent me and I have life because of the Father, so also the one who feeds on me will have life because of me.
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This is the bread that came down from heaven. Unlike your ancestors who ate and still died, whoever eats this bread will live forever.”
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These things he said while teaching in the synagogue in Capernaum.
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**Then many of his disciples who were listening said, “This saying is hard; who can accept it?”
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Since Jesus knew that his disciples were murmuring about this, he said to them, “Does this shock you?
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What if you were to see the Son of Man ascending to where he was before?
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It is the spirit that gives life, while the flesh is of no avail. The words I have spoken to you are spirit and life.
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But there are some of you who do not believe.” Jesus knew from the beginning the ones who would not believe and the one who would betray him.
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And he said, “For this reason I have told you that no one can come to me unless it is granted him by my Father.”
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As a result of this, many (of) his disciples returned to their former way of life and no longer accompanied him. **
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Jesus then said to the Twelve, “Do you also want to leave?”
As a personal note, I have always been amazed at the statement that Jesus really did not mean what he said, or this statement was just an analogy or just an illustration. Just like the Jews listening to Our Lord - these modern individuals ask, “How can this man give us his flesh to eat?” Remember, Christ was here to save souls - and here is a group who are not arguing about not observing the Sabbath, or paying taxes, or not properly washing - this is a group arguing about a doctrine specific to Christ. If ever there was a time when the arugment about Christ’s statement not being taken literally was true - this would have been it. And, then you would read about Christ jumping in front of the group about to leave and say something like,
“Wait, you have misunderstood me. Let me use another example. You did not become upset when I compared myself to a door, or a vine, or shepherd.” But, this did not happen. These Jews walked (except for Judas who also did not believe) and Jesus did not call them back. Surely those actions should tell you that everyone was being serious and clearly understanding one another: Christ said something and the Jews (and, now the Protestants) refused to believe it. The Real Presence has been believed by the Catholic Chruch since 33AD to this very day.
Matt 26:26-29 This is an account from one of the Synoptics. You can look to Mark and Luke for other versions of the same event. Remember, in less then 24-hours Christ will be dead - and He knows this. These are the last words of Christ to His Apostles in a friendly setting of a meal - in a couple of hours He will begin His Passion. Don’t you think He wants to be clearly understood?
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While they were eating, Jesus took bread, said the blessing, broke it, and giving it to his disciples said, “Take and eat; this is my body.”
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Then he took a cup, gave thanks, and gave it to them, saying, "Drink from it, all of you,
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for this is my blood of the covenant, which will be shed on behalf of many for the forgiveness of sins.
**1 Cor. 10:15-17
**
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I am speaking as to sensible people; judge for yourselves what I am saying.
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The cup of blessing that we bless, is it not a participation in the blood of Christ? The bread that we break, is it not a participation in the body of Christ?
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Because the loaf of bread is one, we, though many, are one body, for we all partake of the one loaf.
St. Paul is quite clearn in this matter. (For an additional Pauline reference go to 1Cor 11:23-29). Another item I personally find amazing is for any group that will swear that the world was created in six 24-hour or calendar days because “the Bible says so” - even though it only appears once in Genesis, and yet refuse to Believe the Word of God who repeats this over and over again… well… that is really difficult to understand.
Here is a link you may want to read:
catholic.com/library/Seventh_Day_Adventism.asp
God bless