For more than a decade, doctors told new parents to keep their children away from peanuts and peanut-related food until they were at least three years old. Now, scientists are telling people the exact opposite-that earlier exposure might prevent them from becoming allergic.

Dr. Anthony Fauci leads the National Institute of Allergy and Infectious Diseases. He joins Morning Shift to explain the theories and studies that ultimately led to a brand-new set of guidelines for parents and pediatricians. We also talk about the recent increase in American children with nut allergies, and how the science around allergies has changed.