This is the first of the "I Am" statements found in John 6:35 made by Jesus. This statement takes place after the feeding of the five thousand and Jesus is rebuking the crowd saying you are just following Me because I gave you a free meal. Sounds like a lot of folks today who follow Jesus simply for what they can get, be it food, money, healing, etc. instead of asking what can I give to Jesus. Jesus is trying to get them to think outside the box to spiritual things not just physical food and work. One thing we must remember is that bread=life, after water this was the most essential element to sustain life, if you had no bread you died. It was a staple of life and comfort since the Garden of Eden. (Gen. 3:19) Another thing it symbolized was fellowship(Gen. 14:18) so much so that in the Jewish mindset when you sat down to eat with someone you actually became one with them. That is why they had such beef with eating with gentiles who were unclean, in doing so they became unclean.
In light of the O.T. bread played a significant part in Jewish life. There are 3 key pictures that come to mind from the O.T. 1) The unleavened bread of the Passover meal. 2) the Manna God provided in the wilderness that was later placed in the Ark as a reminder of His provision. 3) The Table of Shewbread in the Tabernacle. All three relate to God's faithfulness, provision, and deliverance. In this "I Am" statement Jesus is comparing the Manna which sustained their physical life to His body(symbolically) which would give them eternal life, Jesus is illustrating a picture here not endorsing cannibalism, just as He did at the Last Supper when he compared the bread to His body. What Jesus is saying in true Messianic language is when you believe on Me you become one with Me and escape death and are given everlasting life. We symbolically identify with His death and resurrection by faith in the Bread of Life.
A Messianic passage that foreshadows this bread and the eventual destruction of all death and all mourning comes out of Isaiah 25:6-8. In vs. 8 "He will destroy death forever, and God will wipe away the tears from every face." Jesus as the Messiah, the Bread of Life has won victory over death and sin and we look forward to that day when finally there will be no more death, mourning, or pain when He comes back as conquering King.
On a personal note I have found true life in this Bread. For years I was searching for the purpose and meaning in life in so many destructive behaviors, but now know it's only found in a relationship with Jesus the Bread of Life. I believe today more than ever this "I AM" statement rings out to our nation. Stop trying to satisfy yourselves with entertainment, sports, porn, alcohol, drugs, and whatever else and come to Me and I will quench your thirst and fill your life and the cost is free. (Isaiah 55:1-2) All those other things will not fulfill you only the True Bread of Jesus will.