One study, a follow-up to landmark research published last year, suggests that the early prevention strategy leads to persistent, long-lasting results in children at risk for food allergies. It found that allergy protection lasted at least through age 5 and didn't wane even when kids stopped eating peanut-containing foods for a year.

That means at-risk kids who don't want to eat peanut butter on a weekly basis can safely take a break, at least for a year.

The second new study suggests that the early strategy could also work with eggs, another food that can cause allergies in young children. It found that allergies to peanuts and eggs were less common in young children who started eating those foods at 3 months of age than in kids who as infants received only breast milk.