In the Lord's Prayer, to what does "daily bread" refer? I am taught that in the Lord's Prayer (Matthew 6:9-13) all petitions concern matters of our souls upon which we should meditate, except the fourth, "Give us today our daily bread" which petitions for an earthly concern, namely, and literally, bread. In Luther's Small Catechism, it states: 


  The Fourth Petition.
  
  Give us this day our daily bread...
  
  What is meant by daily bread?--Answer.
  
  Everything that belongs to the support and wants of the body, such as
  meat, drink, clothing, shoes, house, homestead, field, cattle, money,
  goods, a pious spouse, pious children, pious servants, pious and
  faithful magistrates, good government, good weather, peace, health,
  discipline, honor, good friends, faithful neighbors, and the like. 


But in John 6:31-35:  


  31 Our ancestors ate the manna in the wilderness; as it is written:
  ‘He gave them bread from heaven to eat.’”
  
  32 Jesus said to them, “Very truly I tell you, it is not Moses who has
  given you the bread from heaven, but it is my Father who gives you the
  true bread from heaven. 33 For the bread of God is the bread that
  comes down from heaven and gives life to the world.”
  
  34 “Sir,” they said, “always give us this bread.”
  
  35 Then Jesus declared, “I am the bread of life. Whoever comes to me
  will never go hungry, and whoever believes in me will never be
  thirsty..


And in Matthew 4:4: 


  Jesus answered, “It is written: ‘Man shall not live on bread alone,
  but on every word that comes from the mouth of God.’”


And since John 1:1 says:


  In the beginning was the Word, and the Word was with God, and the Word
  was God.


And since the Passover bread is symbolic of Jesus Christ as well, on what basis am I to believe that the bread in the Lord's Prayer is food (etc.), and not Jesus Himself?
Martin Luther once participated in a debate with Ulrich Zwingli’s over whether the Lords Supper was actually the body of Christ or simply a remembrance of it.  It is reported that Martin Luther walked into the debate, went up to the board and took a piece of chalk and wrote “This Is my Body” then left the debate without looking back.

The translation of the Lords supper is a curious one, first off Christ says,  “Give us each day, our Daily bread” this is strange in itself as he could of said if what he meant was our substance to survive.  “Give us each day our bread” It would have been enough, but he did not just say that, in fact, he said something almost unexplainable.

To fully understand this we have to go to the Greek text and look at the actual translation by the inspired authors.   The word translated to “Daily Bread” Is the Greek word  “επιούσιος  “ or more easily read “Epiousios” The word epiousios is only found in the two versions of the Lord’s Prayer in Mathew and Luke, not appearing anywhere else in known classical ‘Greek Literature.  It is as if when translating Christ words from Aramaic to Greek,  the inspired Authors had to make up a word to explain what was being said.

The term is a Hapax Legomanon, a Greek phrase meaning a word only used once.

In the Lutheran Church the term “Consubstantiation” is used to describe what happens to the bread and wine when the mass is celebrated.  The ideas are that all of a sudden Christ is present with the bread and the wine together.   This however is not what the lord stated while initiating the New Covenant.  He said, “This is my Body” as Luther so boldly wrote on the board during his debate, he did not say,  “This contains my body”.  

The Catholic Church however has a different term, that being “Transubstantiation” in Greek “μετουσίωσις” again more easily “metousiosis”.  The term with out getting to technical refers to the fact that the bread and wine ceases to be and becomes only the body and blood of our lord.

When you break down the word “Epiousios” you end up with two separate words in Greek  “Epi” meaning “Super” and “ousios” meaning “substance”.  It is the tradition of the Church that these words refer not specifically to food for our stomachs but to the bread, which came down from heaven, the Manna, which was provided by the father to the people in the wilderness before crossing the Jordon.

The Church takes the word “Epiousios” used in the Lords Prayer and alters it but not changes it to explain the process by which the bread and wine do in fact change during the consecration of the mass.  “This is my Body”,  “This is the bread that came down from heaven” “This is the Manna of the New Covenant”  “This is the New Covenant, do this in memory of me”  "this is the supersubstantion (transubstantial) bread"

"Give us each day our super substantial bread" or "Give us the Eucharist, give us the true manna that came down from heaven, give us you Lord Jesus Christ"

IN Response:

“am I to believe that the bread in the Lord's Prayer is food (etc.), and not Jesus Himself?”

By no means Should you believe such a thing, it is in every way Jesus Christ our Lord and Savior, Body Blood Soul and Divinity.  This is The Second Person in the trinity, present and real, worthy of worship and adoration.   To believe this is to believe the Gospel, to believe this is to be part of the body of Christ and to Share table with Abraham Isaac and Jacob.   This is the bread that is our super substance while in this vale of tears, before we cross the river Jordon into the promises revealed by Christ.