Albert Barnes Commentary John 6:51

"I am the living bread which came down out of heaven: if any man eat of this bread, he shall live for ever: yea and the bread which I will give is my flesh, for the life of the world." — John 6:51 (ASV)

The bread that I will give is my flesh. That is, his body would be offered as a sacrifice for sin, according to his declaration when he instituted the Supper: This is my body which is broken for you, (1 Corinthians 11:24).

Life of the world. That sinners might, by his atoning sacrifice, be recovered from spiritual death and be brought to eternal life. The use of the word world here shows that the sacrifice of Christ was full, free, ample, and designed for all people, as it is said in 1 John 2:2, He is the propitiation for our sins, and not for ours only, but also for the sins of the whole world.

In this verse, Jesus introduces the subject of his death and atonement. It may be remarked that in the language he used, the transition from bread to his flesh would appear easier than it does in our language. The same word that in Hebrew means bread also means flesh in Syriac and Arabic.

the life of the world (John 3:16).