Interesting thread- there was an article a couple of years ago about a woman who left her church, catholic, as I recall because she was violently allergic to wheat, and they wouldn't substitute anything just for her. My pastor pointed out that they made bread out of all kinds of grains in bible times - the feeding of the 5000, remember, it was fish and barley loaves. So we don't honestly even know that the bread at the Last Supper was wheat-based. but for me, as with the others, the tiny amounts don't seem cause for worry.