St. Thomas Aquinas
“As to the effect, considered in each of the partakers. For, as Ambrose (Mag. Sent. iv, D, xi) says on 1 Cor. 11:20, this sacrament ‘avails for the defense of soul and body’; and therefore ‘Christ’s body is offered’ under the species of bread ‘for the health of the body, and the blood’ under the species of wine ‘for the health of the soul,’ according to Lev. 17:14: ‘The life of the animal [Vulg.: ‘of all flesh’] is in the blood.'”
Source: St. Thomas Aquinas, Summa Theologica