The origins of the Eucharist are found in the Last Supper that Jesus shared with his Apostles. The use of bread and wine in worship is found in the early history of God’s people. In the Old Testament, bread and wine are seen as gifts from God, to whom praise and thanks are given in return for these blessings and for other manifestations of his care and grace... When Jesus instituted the Eucharist he gave a final meaning to the blessing of the bread and the wine and the sacrifice of the lamb. The Gospels narrate events that anticipated the Eucharist. The miracle of the loaves and fish, prefigured the unique abundance of the Eucharist. The miracle of changing water into wine at the wedding feast in Cana manifested the divine glory of Jesus and the heavenly wedding feast in which we share at every Eucharist.
“I am the living bread that came down from heaven... Unless you eat the flesh of the Son of Man and drink his blood, you do not have life within you” (Jn 6:51, 53)
~ from the United States Catholic Catechism for Adults