John Chrysostom

He calleth Himself, "the bread of life," because He maintaineth our life both which is and which is to be, and saith, "Whosoever shall eat of this bread shall live for ever." By "bread" He meaneth here either His saving doctrines and the faith which is in Him, or His own Body; for both nerve the soul. Yet in another place He said, "If a man hear My saying, he shall never taste of death." And they were offended; here they had no such feeling perhaps, because they yet respected Him on account of the loaves which had been made.

Homily on the Gospel of John 46 ↗

Cyril of Alexandria

For, removing the whole case from His speech, and having taken away (so to say) all that cloaked it. He at length reveals Himself unveiled to them of Israel, saying, I am the Bread of life, that they may now learn that if they would be superior to corruption, and would put off the death which from the transgression fell upon us, they must needs approach to the participation of Him who is mighty to quicken, and destroyeth corruption, and bringeth to nought death: for this verily is a work proper and most fit for that which is by …

Commentary on the Gospel of John, Book 4 ↗

Thomas Aquinas

Having stated his position, he expresses it as, I am the bread of life, which gives life, as clearly follows from the above. We read of this bread: "The bread of Asher will be rich, he will furnish choice morsels," of eternal life, "to kings" (Gn 49:20).

Commentary on John ↗

Bonaventure

"I am the bread of life"; and this for believers, because, as is said in Proverbs three, "she is a tree of life to those who lay hold of her," namely through faith: "and he who holds her fast is blessed," who holds fast through comprehension. And that he is the bread of life, he shows through the effect, because namely he gives the life of grace and the life of glory.

Commentary on John, Chapter 6 ↗