Children are much less likely to develop peanut allergies if they are frequently fed peanuts, according to a new study published this week in the New England Journal of Medicine.
The findings are part of a shifting understanding of what causes peanut allergies — one that's pointing away from avoiding nuts while young.
It's estimated that two million children in the US are allergic to peanuts. Peanut allergies have more than doubled over the last decade in the UK and North America, and researchers haven't been certain about why — or how to stop it.
"There's been a huge question about why there's an increase in peanut allergy and what we can do to try to stem that increase," Scott Sicherer, an advisor on allergies to the American Academy of Pediatrics said in an interview with NPR. "This is a major study — really what we would call a landmark study."
This is a major finding about how peanut allergies really might develop
Researchers at King's College London looked at 640 British infants at high risk of developing peanut allergies and found that those who ate the equivalent of 4 big teaspoons of peanut butter every week were 80 percent less likely than others to develop a peanut allergy by the time they were five.
The trial looked at two groups of children — those who were determined to be mildly sensitive to peanuts through a skin prick test, and those who didn't show sensitivity.
Parents of half of the children in each group were asked to feed them foods with peanuts in them at least three times a week, starting between four months and eleven months old. (They were given peanut products, not whole peanuts, which aren't safe for small children to eat.) The other parents were asked to keep their children from eating all peanut products until they turned five.
The results were remarkable. Seventeen percent of the children who had avoided peanuts developed peanut allergies. But only three percent of children who were fed peanuts developed peanut allergies.
It's part of a greater shift in advice about peanuts
Peanut allergies generally cause symptoms like hives and a scratchy throat, but in some children peanuts can lead to life-threatening anaphylaxis or other serious problems with breathing. Peanut allergies can be hard to manage — trace amounts of nuts are found all over.
Avoiding peanuts is clearly part of the solution for someone who has an allergy, but in the past it has also been recommended for preventing allergies from developing in the first place. Starting in 2000, the American Academy of Pediatrics recommended that parents not give their children peanuts and tree nuts until they were three years old to prevent allergies. But in 2008, with the recommendations in place for nearly a decade and peanut allergies still on the rise, the AAP clarified that the evidence just wasn't strong enough to support the guidelines — and so changed them to say that though solid foods shouldn't be introduced into a baby's diet before four to six months, there isn't any evidence to say delaying certain solid foods (like peanuts) at that point is dangerous. The new findings published this week are part of that turnaround in the approach to preventing food allergies.