One of the worst parts about feeding a child is getting easier, says a new study.

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Parents are constantly reminded about food allergies. Whether it’s the sign on the day care window saying that the building is a nut-free space, or someone regaling you at a birthday party about all of the foods their child can’t eat, you can’t go for more than a day or two without thinking about allergic reactions. It’s just one more worry to add to the giant pile of things that you have at the back of your mind every day.

But according to a new study published in the journal of the American Academy of Pediatrics, there’s good news in the realm of nuts. Peanut allergies have fallen precipitously, with rates dropping by 30 percent or more since 2013. It’s great news for anxious parents, for community spaces where children eat, and for all the kids who deserve to know the simple bliss of a peanut butter and jelly sandwich. Let’s look at the data the study is drawing from and at what has happened over the past few decades.

Peanut allergies were for a long time something of a source of academic disagreement. In the ’80s, ’90s, and ’00s we saw a sharp increase in the number of children with allergies to a variety of foods. We still aren’t entirely clear on whether this was due to better measurement of disease, better testing, or some environmental trigger that could’ve impacted children’s health.

The advice at the time was that the best strategy was avoidance for those at high risk of developing an allergy, determined by a combination of family history, other allergies, and having eczema, which can indicate allergy issues. If you’re never exposed to an allergen, you can’t develop an allergy, and this would result in fewer allergies in the community, the theory went. However, this advice did not seem to stem the rising tide of allergies, and in 2008 the American Academy of Pediatrics officially changed the recommendations to say that there was no benefit to avoiding foods.

This is where the story gets really interesting. A group of researchers noticed that peanut allergies were 10 times more common in the U.K. than in Israel. While there are many differences between the two countries, they hypothesized that this could be because Israeli children are exposed to peanuts early and often through a range of peanut-based snacks. U.K. children, on the other hand, have a much lower exposure to peanuts in their early years.

This led to a truly fascinating randomized trial published in 2015. Researchers took a large group of infants aged 4–11 months who were at a very high risk of getting a peanut allergy—either they already had severe eczema, an egg allergy, or both. These kids were then randomly allocated to either get peanuts regularly until they were 5 years old, or have no exposure to peanuts at all.

The results were, in a word, startling: 1 in 7 of the children in the no-peanuts group developed an allergy by age 5, compared to just 1 in 50 in the peanut group. Early peanut exposure reduced a child’s risk of developing an allergy to peanuts by a little over seven times.

The study immediately changed recommendations. Rather than the previous advice—which at that point was that we didn’t really know whether exposure made a difference or not—pediatricians started to advise that kids should be exposed to potential food allergens early and often. At the very least, every baby should get peanuts before they turned 1. It’s the advice I was given when my daughter was born in 2023, and it’s probably very familiar to new parents everywhere.

The new research that’s just hit the headlines shows that this advice appears to be working. The Pediatrics journal study is an observational paper looking at trends in peanut allergies in a cohort of children in the United States. The authors took kids aged 0–3 from 2013–2015, before the new advice came out, and compared them to a cohort from 2015–2019. They used a variety of statistical models to examine what happened with respect to peanut allergies and eczema over the course of two years for the children in each of these groups.

Overall, there was a reduction of around 30 percent in peanut allergies. In absolute terms, around 1 in 100 kids had a diagnosed peanut allergy before the guidelines changed, and around 1 in 300 had an allergy in the years after.

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There are always caveats to this sort of research. While the authors did use a type of statistical modeling called an interrupted time series, which in theory allows us to make causal claims here, in practice it’s a bit more complicated. We can’t be entirely sure that this decline is driven by the guideline change. On the other hand, it’s hard to see what else could be happening here. We know that introducing peanuts early reduces peanut allergies, so the fact that they fell after the new guidelines is exactly what we’d expect.

This whole story is a great example of science working exactly as intended. It’s messy, and a bit painful, but through rigorous experimentation we came to the right conclusion. We had a theory that didn’t pan out. We then came up with another theory, which proved to be true. We changed the guidelines to reflect this, and are now preventing tens of thousands of kids from developing allergies every year. In a time when science is under relentless attack, it’s a heartening reminder that the whole process can work well. We just have to let it.

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