[metmom]

Since this was done at the Passover, where eating the lamb was essential to the ritual under the Old Covenant, and since Jesus was the Lamb about to be sacrificed (He carried his cross at the same hour as the lambs were being slaughtered all over Jerusalem.) it makes perfect sense that eating the Lamb would be an essential part of the ritual in the New Covenant. St. John in particular emphasizes that Jesus is replacing the old Passover with a new Passover, the old lamb with the Lamb of God (himself), the old sacrament with a new sacrament.

But the blood of the Passover Lamb was NEVER consumed.

[Arthur McGowan]

Consuming the blood of the Passover lamb would have been disgusting.

Since Jesus makes it possible to consume his blood without being horrified, there is no problem.