In the first major cross-canada poll about the prevalence of food allergies, researchers found 3.2 percent of Canadians may be allergic to at least one of the foods in our chart. Those food allergies are lifelong and cause the most severe reactions. Not sure if you’re allergic? ‘If you have hives or itchy, red eyes after eating a certain food, talk to your doctor,’ says Dr. Ann Clarke of McGill University, a researcher involved in compiling the data. She adds that you should get to the ER if you experience swelling lips or tongue, trouble breathing or swallowing, abdominal pain or vomiting.