It is generally assumed that the Eucharistic species of bread remains for about 15 minutes after reception. This is based on simple biology and reflects the Catechism’s statement that the presence of Christ “endures as long as the Eucharistic species subsist.”

This is why many saints have recommended offering 15 minutes of prayer after receiving the Eucharist as a thanksgiving to God. This allows the soul to savor the presence of God and have a true “heart-to-heart” with Jesus.