Bread and Wine symbolize the body and blood of Christ which represent all that encompasses the new covenant. John the baptist was a forerunner to Christ but part of the old covenant. Hence Jesus words, "The least in the kingdom of God is greater than John the baptist."
The fact that John ate no bread or drank no wine was "a picture" of the dispensation he represented. Another way to say this would be, "John did not partake of communion (the body and blood of Christ)."
Pictures in the bible are prophetic words painted by God. To this end they operate according to 2 Peter 1:20 "But know this first of all that no prophecy of scripture is a matter of ones own interpretation, for no prophecy was ever made by an act of human will, but men moved by the Holy Spirit spoke from God."
Pictures painted by God in the Bible are like parables. Given to illustrate a point. For example, most people can clearly see and understand how the baker and wine bearer who were in prison with Joseph (Genesis) represented the body and blood of Christ. The baker lost his head and the wine bearer was restored to his position. Joseph was a "type" of Christ. Joseph provided bread to the world, Christ was the bread of the world.
These pictures painted by God are not limited to the old testament. While Jesus was teaching and providing examples of the Kingdom of God on earth there was in His actions a prophetic picture being painted of the ministry He came to set up. For example, when He told Peter to cast out into the deep and Peter pulled in a huge number of fish such that he had to call for the other boat to help...This was a prophetic picture of Peters calling, "I will make you a fisher of men."
When Jesus fed the multitude (twice) and had the disciples pick up the scraps. The baskets collected (12 once and 7 the second time) represented the gospel (broken bread) handed out and the harvest (scraps picked up so that nothing was lost).
Pictures painted by God are only understood in hindsight. God uses this effect at times to "time release" the message behind the message. Secondly, they are only understood in hindsight to prevent any man from claiming to "cause" the event.
These pictures painted by God are a Language of God. 1 Corinthians 14:10 "There are perhaps a great many kinds of Language in the world, and no kind of language is without meaning." This text does not say that there are many languages it says there are many KINDS of languages. I personally walk in this language so speak from experience (although I am growing in understanding).
Psalm 19: The heavens are telling of the glory of God; and their expanse is declaring the work of His hands. Day to day pours forth speech, and night to night reveals knowledge. There is no speech, nor are there words; there voice is not heard.
This verse describes what I am saying. God paints His message in all of creation (without a word) and He illustrates specific messages in the lives of men. What I am saying raises dozens of additional points and questions but hopefully I have made my point regarding why John the baptist did not eat bread of drink wine.