"I am the living bread that came down from heaven. If anyone eats of this bread he will live forever. The bread that I will give for the life of the world is My flesh" (John 6:51 HCSB).
Eucharist-"The name given to the Blessed Sacrament of the Altar in its twofold aspect of sacrament and Sacrifice of Mass, and in which Jesus Christ is truly present under the appearances of bread and wine" (Catholic Encyclopedia).
Leon Morris presents some excellent objections to viewing John 6:51ff as eucharistic. He explains: "The objections already urged [against a eucharistic interpretation] remain. The very strength of the language is against it. The eating and drinking spoken of are the means of bringing eternal life (v. 54), and they are absolutely unqualified. Are we to say that the one thing necessary for life is to receive the sacrament? Again, 'flesh' is not commonly used with reference to the sacrament. In every other New Testament passage referring to 'flesh,' the Scriptures use the word 'body'" (John, 376-377).
Morris thus concludes: "I am not contending that there is no application to the sacrament. But I very strongly doubt whether this is the primary meaning. It seems much better to think of the words as meaning first of all the appropriation of Christ" (Morris, Leon. John [The New ICC], 377).
He continues to point out in footnote 122 (on page 377) that other scholars see the terminology "flesh and blood" as applicable to "the demand for faith in [the enfleshed] Christ" and the words may further apply to his death. A suggestion I would also make is that its quite possible the wilderness motif (found in Exodus) is applicable in John 6:51ff too. A symbolic "feeding" and "drinking" would be quite appropriate in that case. For instance, the apostle Paul wrote: "our forefathers were all under the cloud and all passed through the sea and all got baptized into Moses by means of the cloud and of the sea; and all ate the same spiritual food and all drank the same spiritual drink. For they used to drink from the spiritual rock-mass that followed them, and that rock-mass meant the Christ" (1 Cor. 10:1-4). Cf. John 6:31-34, 41-51.
If you will forgive my saying that does, to me at least, seem a eucharistic formula. So I would suggest that the Greek does indicate that the eucharist is under consideration as is confirmed by the question in verse 52. Jesus answer is that truly his flesh and blood are food and drink, and where else is this association found? Only in the eucharist I would suggest.
I think you're missing a very important point here. Jesus is clearly using metaphorical language here as we see by the words: "I am the living bread that came down from heaven . . . the bread that I shall give is my flesh in behalf of the life of the world" (John 6:51).
Jesus was not literal bread and he was not going to offer up literal or physical bread as he plainly demonstrated by his utterance in 6:51. Notice too that Jesus uses SARX in this account whereas in Matthew 26:26 and other related discourses, he employs SWMA. Jesus' use of SARX in 6:51 undoubtedly points back to John 1:14 where John tells us the Word became flesh (SARX) and dwelled among us. The evidence for a eucharistic interpretation seems to be lacking.
G. R. B. Murray writes in his "Theology in the Fourth Gospel" concerning John 6:51-58:
"The concept of Jesus as the Bread of Life can be related not alone to Jewish thought but to other cultures of the nearer and remoter East. The most remarkable parallel to John 6, however, is found in an utterance of Rabbi Hillel, son of Gamaliel III . . . He astonished his contemporaries by saying, 'there shall be no Messiah for Israel, for they have already eaten him in the days of Hezekiah' " (See Page 98).
Interestingly, as Murray points out, Jewish translations of the Talmud into English render the language for "have eaten" as "enjoy." So John 6:51-58 must be viewed in the proper context to be rightly understood.
I conclude with an observation from Johannine scholar Gerald Borchert:
"The means to life, accordingly, is not eating and drinking communion elements, but believing is the means of inwardly accepting the suffering death of the Passover Lamb who gave his life for the sin of the world" (Borchert, John 1-11, 272).
For additional information, see http://fosterheologicalreflections.blogspot.com/2015/04/john-656-57-eucharist-and-sons-present.html