A generation ago, peanut allergies seemed to be a rare occurrence. Today, they’re getting much more attention in the news — with stories popping up all the time of children with severe and life-threatening reactions to peanuts.
Why are peanut allergies on the rise?
So what’s going on here?
Meanwhile, scientists have recently done a surprising flip on what they think causes peanut allergies. Up until recently, many medical experts thought that exposure to peanuts in the womb or in early life was the trigger. Now, they're not so sure and have some evidence that a lack of exposure to peanuts might cause allergies. Here's a guide to what researchers know so far on the topic:
Peanut allergies are on the rise — but so are lots of allergies
Trends in Allergic Conditions Among Children: United States, 1997-2011 (CDC)
The overall increase in allergies is still a big mystery in epidemiology. One of the leading explanations is the hygiene hypothesis, which posits that society has become too clean and hygienic. Essentially, children aren’t exposed to enough bacteria, viruses, and possible allergens early on, which in turn inhibits the development of their immune system. That leads to more problems later on, including allergies and asthma. Researchers are still trying to figure out if this hypothesis is true.
As for peanut allergies specifically, another new hypothesis is that Americans tend to eat their peanuts dry roasted — and something about the roasting process introduces problematic molecules. A recent study published in the Journal of Allergy and Clinical Immunology found that dry-roasted peanuts cause more allergies in lab mice. But this is still far from conclusive. Many effects found in lab mice turn out to not translate to people.
Meanwhile, there’s been a long debate about what actually causes peanut allergies to form in individual people. Allergies arise from a combination of genetic and environmental factors — and both of these are still being researched.
Experts are trying to figure out what early life experiences with peanuts then cause allergies
(Shutterstock)
Until recently, most experts recommended that pregnant and nursing mothers should avoid eating peanuts altogether. They assumed that exposure to peanuts early in life was what was causing peanut allergies.
Parents followed the advice — but peanut allergies continued to rise in the United States anyway. So, in 2008 the American Academy of Pediatrics released a report stating that there wasn’t any evidence to support restricting mothers’ and babies’ diets.
Since then, there’s been more research on the topic. In 2014, a study came out in the Journal of the American Medical Association that observed a correlation between mothers eating more nuts being less likely to have children with peanut and tree-nut allergies. The study was quite large, involving 8,205 children, 140 of whom had nut allergies.
But this was just a correlational observation, not a controlled experiment. A newer, ongoing study led by Gideon Lack of King’s College London should provide better answers. The experiment enrolled 640 children at high risk of developing peanut allergies and randomly assigned some of them to eat peanuts three times a week and some of them to never eat peanuts at all for their first three years of life. The researchers will then look at which kids develop peanut allergies by age five.
Lack is also leading a separate study of 1,303 families to test out what happens when babies are exposed to several foods while they’re still being breastfed.
It could turn out that peanut allergies develop in utero, through breast milk, or by eating peanuts. These studies should help find out.
Another possible culprit? Peanut dust. Peanuts are such a fundamental part of many Americans’ diets that peanut dust is found in our homes, and there’s evidence that some children with a specific genetic profile are susceptible to developing peanut allergies through skin exposure.
If researchers can figure out what causes peanut allergies, then they may be able to give parents better advice to prevent more children from developing them in the first place.
Peanut allergy treatments are also getting better
Metaphorical peanut-allergy treatment (Shutterstock)
But what about those who are already allergic? Are they doomed to a peanut-butter-free-existence for the rest of their lives?
Maybe not. Right now, the best advice for those with peanut allergies is to avoid foods with peanuts and to be trained how to use an adrenaline pen in the rare case of an anaphylactic shock.
But scientists are also developing treatments that might reduce how allergic children are. In the past decade or so, researchers started compiling good evidence that by very carefully exposing children to tiny bits of peanut, they could very slowly work up children’s tolerance.
Patients eat tiny doses of peanut or use a peanut patch worn on the skin, and medical professionals stand ready to jump in with an adrenaline shot in case of a severe reaction. Over time, as the dose increases, the body learns that the peanut is not the enemy.
One small 2014 study in The Lancet showed encouraging results. In a randomized, controlled trial of 39 patients, the researchers got 54 percent to tolerate the equivalent of roughly 10 peanuts. If you want to read more about this technique, Carlyn Kolker wrote an essay in The New York Times about her son participating in a similar study.
Experts are fairly optimistic about this type of treatment. “I think the new studies show that maybe in a few years we’ll have a treatment,” says Burks. But the treatment is still in experimental stages right now and not ready for the general public. And it’s certainly not perfect.
One current issue is that it doesn’t work for everyone. About half the kids that get treated are still allergic a year later, whereas another half can eat peanuts just fine. (It’s possible that studying these two groups may give us better insight into how peanut allergies work.) And researchers still don’t know how long the treatment lasts. It could wear off over time.
But experts do insist on one thing: Don’t try this at home. “It really does hold promise, but it’s not there yet,” says Burks. This treatment is experimental and should only be done by a medical professional. Allergic reactions can be very risky, and no one should try to hack this on their own.
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