Gluten (from Latin gluten, "glue") is a protein composite found in foods processed from wheat and related grain species, including barley and rye. It gives elasticity to dough, helping it to rise and to keep its shape, and often giving the final product a chewy texture. ... Worldwide, gluten is a source of protein, both in foods prepared directly from sources containing it, and as an additive to foods otherwise low in protein.Below is a wonderfully detailed but long list of grains, flours, seeds, etc. that we absolutely, positively CANNOT have. I like to Google some of the listed items at various times to find out in more detail why they're on the list. Take meringue, for example: I missed it on the list the first time I read it, and only now noticed it!