In Brazil all food manufactures are required to put in the package whether the product contains gluten or not. Isn't that the case in the United States?
It is, but try to go to Safeway and buy a GF powerbar... :)
Jokes aside, we maintain the list mostly for ingredients. Many people, especially "novice", often ask the same questions -- or you may have doubts for strange/unfamiliar foods, for instance if you're traveling in a foreign country.
