Why does the Church use unleavened bread and wine for the Eucharist?

The Church uses bread and wine because Jesus chose them at the Last Supper and commanded the apostles to celebrate the Eucharist in His memory. The Latin Church uses unleavened wheat bread, while many Eastern Catholic Churches validly use leavened wheat bread.

Why bread and wine. Bread and wine were part of Israel’s worship and daily life. Melchizedek brought out bread and wine and blessed Abraham (Gen 14:18). At the Last Supper, Jesus took bread and said, “This is my body,” then took the cup and identified it with His blood of the covenant (Mt 26:26-28). The Church has no authority to replace these elements with rice cakes, beer, grape juice, or other foods and drinks. The essential signs are wheat bread and natural grape wine (CCC 1333, 1412; Canon 924).

Why the Latin Church uses unleavened bread. The Synoptic Gospels place the Last Supper in the setting of the Jewish feast of Unleavened Bread (Mt 26:17; Mk 14:12). The Roman rite preserves this biblical and ancient connection by requiring unleavened bread (Canon 926). It also recalls St. Paul’s words: “Christ, our paschal lamb, has been sacrificed. Therefore, let us celebrate the feast” with sincerity and truth (1 Cor 5:7-8).

What Eastern Catholics use. Several Eastern Catholic traditions use leavened wheat bread. The leavened loaf often symbolizes the risen Christ and the life of the Holy Spirit in the Church. Both leavened and unleavened wheat bread are valid matter for the Eucharist. This difference is a matter of liturgical discipline and tradition, not a disagreement about the Eucharist. The Council of Florence explicitly recognized both practices.

Why wine is mixed with water. In the Latin liturgy, a little water is added to the wine. This is an ancient Christian practice. It recalls the blood and water that flowed from Christ’s pierced side (Jn 19:34) and symbolizes the union of Christ with His people. The Eucharistic wine itself must be natural wine made from grapes and must not be spoiled (Canon 924).

What happens at consecration. The bread and wine do not remain ordinary food and drink. By Christ’s words and the action of the Holy Spirit, their whole substance becomes the Body and Blood of Christ, while the appearances of bread and wine remain. The Church calls this change transubstantiation (CCC 1376). At Mass, look beyond the humble signs and adore the Lord who chose them to give Himself completely to us.