In John Jesus declares that his Body is true food and his Blood true drink. Saint Paul writes in 1 Corinthians:
For I received from the Lord what I also handed on to you, that the Lord Jesus, on the night he was handed over, took bread, and, after he had given thanks, broke it and said, “This is my body that is for you. Do this in remembrance of me.” In the same way also the cup, after supper, saying, “This cup is the new covenant in my blood. Do this, as often as you drink it, in remembrance of me.” For as often as you eat this bread and drink the cup, you proclaim the death of the Lord until he comes. Therefore whoever eats the bread or drinks the cup of the Lord unworthily will have to answer for the body and blood of the Lord. A person should examine himself, and so eat the bread and drink the cup. For anyone who eats and drinks without discerning the body, eats and drinks judgment on himself. That is why many among you are ill and infirm, and a considerable number are dying. If we discerned ourselves, we would not be under judgment; but since we are judged by [the] Lord, we are being disciplined so that we may not be condemned along with the world. Therefore, my brothers, when you come together to eat, wait for one another. If anyone is hungry, he should eat at home, so that your meetings may not result in judgment.Notice the last verse which clearly points out that this is not just a communal meal sharing ones food with others. "If anyone is hungry, he should eat at home." No, this is the partaking in the actual Body and Blood of Jesus. This was the belief and practice the Church from the beginning.
(1 Corinthians 1:23-34)
He also said “The Spirit gives life; the flesh counts for nothing. The words I have spoken to you - they are full of Spirit and life.”