John 6:63 It is the spirit that quickeneth; the flesh profiteth nothing: the words that I speak unto you, they are spirit, and they are life.
2 Corinthians 3:6 Who also hath made us able ministers of the new testament; not of the letter, but of the spirit: for the letter killeth, but the spirit giveth life.
The word of our Lord Jesus Christ is spiritual. There are two types of bread in the Bible, one is physical and the other is spiritual bread. Just like the eat that can perish and eat that are everlasting according to:
St. John 6:27 Labour not for the meat which perisheth, but for that meat which endureth unto everlasting life, which the Son of man shall give unto you: for him hath God the Father sealed.
St. John 6:50 This is the bread which cometh down from heaven, that a man may eat thereof, and not die.
Jesus was talking about the bread that comes down from heaven. Good things which can not perish comes down from heaven.
James 1:17 Every good gift and every perfect gift is from above, and cometh down from the Father of lights, with whom is no variableness, neither shadow of turning.