As late-night host Jimmy Kimmel so cleverly captured in a recent segment, some people on the gluten-free bandwagon do not know much about gluten, or why, precisely, they should avoid it. (For the record, gluten is a protein found in some cereal grains, including wheat and rye.) Uncertainty about the effects of gluten on people who do not have celiac disease, a serious autoimmune disease, but who ide