There is no sin in receiving the Eucharist under the species of bread alone. The Catechism (CCC) explains, “Since Christ is sacramentally present under each of the species, communion under the species of bread alone makes it possible to receive all the fruit of Eucharistic grace” (CCC 1390).
Therefore, the *General Instruction of the Roman Missal * (GIRM) instructs, “Any of the faithful who wish to receive Holy Communion under the species of bread alone should be granted their wish” (GIRM 284).
