I've been trying to make at least a few phone calls per day to manufacturers of food or medicine to try to find information about the corn content of various foods and medications.
Even picking just the things that seem likely after scrutinizing the ingredients and researching on the web, I end up with maybe 1 out of every 5-10 attempts being actually confirmed as something that's probably safe.
One recent conversation was a pretty good example of a typical interaction: I called a company to ask about the xanthan gum and cellulose fiber in their brown rice bread. That one was a bit of a stretch, I knew, but I was hoping that they might have made an effort to make this special gluten-free supposedly-hypoallergenic bread without any of the more common allergens.
"Our xanthan gum does not have any corn in it," the customer service representative said with confidence. "It's not made from corn."
"Are you sure? Because xanthan gum is usually manufactured using corn derivatives."
"Xanthan gum isn't a corn product. I'm certain our xanthan gum does not contain any corn."
"Really?" I asked, "Xanthan gum isn't actually a corn product, but it's usually grown on corn syrup."
"Our xanthan gum is not grown on corn syrup."
"Wow, that's great. It must be grown on molasses or something like that, then? I know it can be grown on molasses, but it's not very common. I'm so glad--It's hard to find xanthan gum that's grown on something besides corn."
"It has to be grown on something? Isn't it just . . . gum from a xanthan tree or something?"
"No, it's an organism kind of similar to yeast, in a way." [Actually, it's a bacteria called Xanthonomonas campestris, usually responsible for the black mold on things like cauliflower, that creates a gummy substance in its external cell structure. But I didn't go into that much detail.] "It has to be grown on some kind of syrup, and then they separate it from the growth medium and dry it. But even after purification it will still have some traces of the corn syrup or whatever it was grown on."
I heard computer keys tapping.
"Uh. Um," she said. "This says it's also known as corn sugar gum."
"Yes, it is. That's because it's usually grown on corn sugar. But not always."
"Well, then I would think you probably shouldn't eat it, if it's called corn sugar gum. I wouldn't risk it if I were you."
"Uh, yeah. Thanks."
"What was the other thing you were wondering about? Cellulose fiber? Let me see what I can find out about that."
"Hmmm," she said, "My computer says that our cellulose fiber is made from fibrous plants. But it doesn't say what kind. Corn could definitely be a fibrous plant, couldn't it?"
"Yes, it certainly could. Is that all the information you're able to get on those ingredients?"
"Yes, that's all I can tell you. We buy these ingredients from suppliers, and we don't know what's in them. The suppliers may change, so it may even be different from one batch to another."
"Okay. Well, thanks anyway."
Without accurate labeling and with no requirement for manufacturers to know the ingredients of ingredients in foods, it really is almost impossible to find out which foods are truly corn-free.