The Catholic Eucharist is the Body and Blood of Jesus according to Scripture and the Church Fathers.

Scripture affirms that the Eucharist is truly the Body and Blood of Jesus. Jesus Himself spoke of the time when the Apostles would eat His flesh and drink His blood in John 6:53-55, which says: "Jesus said to them, 'Truly, truly, I say to you, unless you eat the flesh of the Son of Man and drink his blood, you have no life in you. Whoever feeds on my flesh and drinks my blood has eternal life, and I will raise him up on the last day. For my flesh is true food, and my blood is true drink.' " 1 Corinthians 10:16 confirms that the words spoken by Jesus in John 6 apply to the Eucharist as St. Paul said: "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?" The early Church Fathers also teach that the Eucharist is truly the Body and Blood of Jesus, as the following quotes from the second century demonstrate: "Take note of those who hold heterodox opinions on the grace of Jesus Christ which has come to us, and see how contrary their opinions are to the mind of God. . . . They abstain from the Eucharist and from prayer because they do not confess that the Eucharist is the flesh of our Savior Jesus Christ, flesh which suffered for our sins and which that Father, in his goodness, raised up again. They who deny the gift of God are perishing in their disputes" (Ignatius of Antioch, Letter to the Smyrnaeans 6:2"7:1 [A.D. 110]). ""We call this food Eucharist, and no one else is permitted to partake of it, except one who believes our teaching to be true and who has been washed in the washing which is for the remission of sins and for regeneration [i.e., has received baptism] and is thereby living as Christ enjoined. For not as common bread nor common drink do we receive these; but since Jesus Christ our Savior was made incarnate by the word of God and had both flesh and blood for our salvation, so too, as we have been taught, the food which has been made into the Eucharist by the Eucharistic prayer set down by him, and by the change of which our blood and flesh is nurtured, is both the flesh and the blood of that incarnated Jesus" (St. Justin Martyr, First Apology 66 [A.D. 151]). "If the Lord were from other than the Father, how could he rightly take bread, which is of the same creation as our own, and confess it to be his body and affirm that the mixture in the cup is his blood?" (St. Irenaeus, Against Heresies 4:33"32 [A.D. 189]). "He has declared the cup, a part of creation, to be his own blood, from which he causes our blood to flow; and the bread, a part of creation, he has established as his own body, from which he gives increase unto our bodies. When, therefore, the mixed cup [wine and water] and the baked bread receives the Word of God and becomes the Eucharist, the body of Christ, and from these the substance of our flesh is increased and supported, how can they say that the flesh is not capable of receiving the gift of God, which is eternal life"flesh which is nourished by the body and blood of the Lord, and is in fact a member of him?" (ibid., 5:2).