Pretzels and Lent

A friend of mine and I talk about food, the culture of food, and the history of food quite a bit. He is suspicious of food history, because much of it seems to be nothing more than urban legends, repeated until they are accepted.

I tend to agree with him, but I want to read real food history, as I see the culture of the table as vitally significant to understanding the general culture.

So, what I want to know is: on several blogs I have read about the Lenten origin of pretzels, how they are simple Lenten breads (no fat, meat, etc.), bent into the shape of arms in prayer. Sure, it sounds good, and some folks even suggest a century, but I want to know: what is the source of this tidbit? Even a good secondary source would be good, as I can follow the footnotes to see where this comes from.

So, if you have any information on this, please let me know, as I am curious as to whether or not this is just another urban legend passing as food history, or if it was at least noted somewhere in some document near to the alleged source.

Sorry to be a spoilsport!