Food allergies have risen in the United States over the last few decades. Research suggests that 40 years ago the actual prevalence of food allergies was less than 1%. But this year, the Centers for Disease Control and Prevention (CDC) released data showing that almost 6% of U.S. adults and children have a food allergy. But this trend is not present in all countries — and what people are allergic to varies globally. Today, we dive into the complex world of food allergies with Dr. Waheeda Samady. She's the Director of Clinical Research at Northwestern University's Center for Food Allergy and Asthma Research.Have a science question? Email us at shortwave@npr.org.