Note 1 at 1Co 10:16: Here, Paul used the observance of the Lord's Supper as an illustration. The physical elements that we use in communion aren't literally the body and blood of Jesus. They simply represent them. Yet, when we eat these elements, we are communing with the Lord over His death and resurrection. These elements provoke thoughts and emotions with great significance and dire consequences if done unworthily (1Co 11:27-30).

Likewise, there is real meaning to those who offer food unto idols, although nothing technically happens to the food. Therefore, in the same way that it would be offensive to us for an idolater to partake of communion, we should be repulsed at the thought of eating food sacrificed to idols.