There are a lot of ways to ask a vendor or manufacturer about what is in their product. I’ve been doing it on and off, with varying degrees of success, for about 6 years. I don’t have it down pat, but I have definitely learned a thing or two about what hasn’t worked for me. It’s not that there’s really a “right'” way to do this: the right way is the way that gets you good information that you can make safe decisions with. But for me, given the style that I related to people in, there are some things that seem not to work well for me and some that seem to work better.
Less Effective: “Is there any corn in this?”
When I was first diagnosed with a corn allergy, my format for asking this question was something like: “Hi there, I am allergic to corn. Is there any corn in your product?”
That worked for me for a little while. I’d ask, and people would say no, and I’d eat the food and be fine. Until the time I asked that of a famous bratwurst company, and they incredulously replied no, there was no corn in their bratwurst, and I believed them. I reacted, and badly. The customer service representative that answered my email apparently was envisioning whole kernels of corn being added to the meat grinder, and given that image, truthfully answered the question. What he did not realize is that their product contained corn dextrose.
Beyond just corn sugars and ingredients directly made from corn, ingredients that are commonly products of fermentation such as citric acid cause terrible reactions for more sensitive corn allergics because they are grown on a medium containing corn sugar. Customer service representatives will not know exactly how these ingredients are made as they are just reading from a script or information sheet.