Actually, the passage in John and the Lord’s Supper have nothing in common in the context of the Lord’s Supper, but since Scripture is consistent with itself we can look at John 6:63 and show that indeed He did tell everyone the manner in which He spoke.
6:63
"It is the Spirit who gives life; the flesh profits nothing; the words that I have spoken to you are spirit and are life. — Can Jesus make it or rephrase it for you to make it any clearer?
Then, Paul in 1 Co. 11, way after the Lord’s Supper, gives even more detail into the actual meaning, which of course is symbolic of the fleah and blood shed on the cross of Calvary.
23 For I received from the Lord that which I also delivered to you: that the Lord Jesus on the same night in which He was betrayed took bread; 24and when He had given thanks, He broke it and said, "Take, eat; this is My body which is broken for you; do this in remembrance of Me." 25In the same manner He also took the cup after supper, saying, “This cup is the new covenant in My blood. This do, as often as you drink it, in remembrance of Me.”
26For as often as you eat this bread and drink this cup, you proclaim the Lord’s death till He comes
What could be the reason you do not understand the plain reading of these?