A study that upended medical practice by recommending feeding babies peanut products early to prevent allergies has had a big effect in the real world. A new study in the medical journal Pediatrics found that peanut allergies in children ages 0 to 3 declined by more than 27% after guidance was first issued, and by more than 40% after it was expanded in 2017. For decades, doctors had recommended delaying feeding children peanuts and other foods likely to trigger allergies until age 3. The approach has helped 60,000 children avoid food allergies, including 40,000 children who otherwise would have developed peanut allergies.