But it is my experience that RCs cannot deal objectively with the evidence so as to even allow the allegorical as a possibility, so i will leave you to your choice.
Actually, the non Catholic position is the premise that must be proved, as it is the rejection of what the universal Church has held as firm belief since the beginning.
First, there is no evidence that Jesus ate of the bread which He gave to the Apostles or that He drank of the wine in the cup which He gave them.
Second, we must take into account ALL the words Jesus spoke regarding this subject, all of which are unflinchingly supportive of the Catholic belief in the actuality of Christ’s body and blood in the Eucharist.
Third, we must consider the story of Ezekiel and the eating of the scroll which the Lord gave him. The story is similar to what Jesus says of His flesh, that those who ate of it would never be hungry.
Fourth, we see that the first Christians regularly shared in the breaking of the bread and that bread was not just ordinary food. Some of it was reserved and taken to those who were not present.
So we see that there is abundant support for the Catholic belief from the OT, the NT and the early writings of the those who learned from the Apostles themselves.