It's definitely a thing. I know one person that is seriously allergic to corn. She carries several EpiPens because corn is in almost everything and the reaction

It's definitely a thing. I know one person that is seriously allergic to corn. She carries several EpiPens because corn is in almost everything and the reaction is pretty severe. She can't even consume meat from animals that were fed corn. Thankfully grass-fed beef is becoming more common, but chicken and pork are generally off limits.