The Gospel of Matthew, Mark and Luke tell us how Jesus broke the bread
and gave it to His disciples:

"While they were eating, Jesus took bread, gave thanks and broke it, and
gave it to His disciples, saying, 'Take and eat; this is my body.'"
Matthew 26:26

Afterwards, Jesus took the cup:

"Then He took the cup, gave thanks and offered it to them, saying,
'Drink from it, all of you. This is my blood of the covenant, which is
poured out for many for the forgiveness of sins.'" Matthew 26:27-28

Does this mean that the cup and bread literally became His blood and
body?Some teach this, however this is not what Jesus meant. He was using
a metaphor.The bread and cup were symbols of His body and blood.Jesus
asked that we observe the Lord's Supper for two reasons:

He wanted us to remember the punishment that He endured and the blood
that He shed for our sins. The death of Jesus is central to the
Christian faith. Only through His death could there be forgiveness for
our sins. Jesus wants us never to forget what He did for us. Jesus also
wants us to observe the Lord's Supper in anticipation of His return.He
says in Matthew 26:29:

"I tell you, I will not drink of this fruit of the vine from now on
until the day when I drink it anew with you in my Father's kingdom."

Every time we partake of the bread and cup we are declaring that Jesus
will soon return to partake with us again. Only people who are saved
should partake in this observance. That is what Paul is referring to in
1 Corinthians 11:27 when he says that some partake in an unworthy
manner. Many Christians with sensitive hearts that have sinned feel like
this may be referring to them. Remember that the Lord's Supper is to
remind us about the cleansing of the cross. If you have sinned, ask
forgiveness from the Lord and partake of the elements. The Lord wants
you to enjoy His communion.

http://www.prophecytalk.com/index.php?topic=564.0

Brandon