CCC 1355 In the communion, preceded by the Lord’s prayer and the breaking of the bread, the faithful receive “the bread of heaven” and “the cup of salvation,” the body and blood of Christ who offered himself “for the life of the world”:1
Because this bread and wine have been made Eucharist (“eucharisted,” according to an ancient expression), “we call this food Eucharist, and no one may take part in it unless he believes that what we teach is true, has received baptism for the forgiveness of sins and new birth, and lives in keeping with what Christ taught.”2
1 Jn 6:51.
2 St. Justin, Apol. 1, 66,1-2: PG 6, 428.