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Thanks to all who answered my question.  It seems that the thing to do is
go for the straight gluten.  Most people suggested seitan, a gluten
product which can be put into casseroles, stir-frys, etc, and is mostly
protein.  People also mentioned deliberately avoiding gluten-free
products, although I don't want to stock up too much, in case I have to
switch over.

I sincerely hope I never need this group, but if my testing is positive, I
may see y'all in a few weeks.  :-(

Laura