At a Roman Catholic Mass, the consecration of the bread and wine is typically marked by the the elevation of the host and chalice, often accompanied by the ringing of bells..
Additionally, there is often a short period of silence, when the priest no longer saying any words and is simply lifting up the host or chalice for all to see. After each elevation, the priest genuflects.
Should you bow or look up at the elevation at Mass?
After the elevation of the host and chalice were introduced into the Mass in the 13th century, one of the most common responses of the people was to bow their heads in reverence. It was an action to recognize the Real Presence of Jesus in the Eucharist, acknowledging the arrival of the King of kings.
In the 16th century this gesture was prescribed by various councils, and became a standard response.
However, St. Pius X suggested a different response, encouraging the faithful to look up and adore the Eucharistic host or chalice.
St. Pius X issued an indulgence to anyone who said, "My Lord and My God ... with faith, piety, and love, while looking upon the Blessed Sacrament, either during the
Elevation in the Mass, or when exposed on the altar." Many Catholics pray this prayer silently while gazing at the elevated host, and pray "My Jesus, mercy" at the elevation of the chalice. We can bow our heads when the priest genuflects after each elevation.
Both gestures can be done with faith and can lead to an increase in love of God.
There is no "right" gesture, as it depends entirely on the faith of the individual and which gesture best represents their relationship with God.
Whatever you do, consider performing some action of reverence when Jesus becomes present in the consecrated elements.