I always found that corn was the most difficult ingredient for me to avoid, by far, because it truly is in virtually everything, in one form or another, including many/most vitamin supplements. Most foods seem to contain either corn-based food starch, ascorbic acid, dextrin/dextrose, corn syrup, or HFCS, and if they don't contain one of those, they manage to include some more obscure derivative of corn.
And, of course, if they can't find a reason to put a corn derivative in the product, they'll add a soy derivative, just to make sure that many of us can't use it.
Incidentally, most of us have been taught that in the U. S., the single word "starch", on an ingredient list, always means cornstarch, unless the label states otherwise, with additional details. And this is true, for FDA-regulated products. Please be aware, however, that the FDA does not regulate all foods in this country - the USDA regulates meat products, dairy products, and eggs, and their labeling requirements do not follow the same guidelines as the FDA. The Food Allergen Labeling and Consumer Protection Act, (FALCPA), which went into effect on January 1, 2006, did not apply to USDA regulations - it only applies to FDA regulations. (This is just another example of the incompetent performance of our legislators in this issue).
Therefore, you cannot always rely on the word "starch" on a label of one of these foods, to mean that the source of the starch is corn. Legally, it can also be wheat.
These days, many manufacturers try to also follow FDA conventions on their USDA labeling, but you can't always count on it. When in doubt - ask the manufacturer. Here's a pretty good, down-to-earth, explanation of this possible issue:
http://www.glutenfreedietitian.com/news ... ted-foods/
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