Ask Scientists

Question: Why are so many people allergic to peanuts?

I admit it: I have a love affair with peanut butter. It’s smooth and creamy — or pleasantly crunchy — super rich and satisfying, can be put on just about anything carb-ey, and a heck of a lot cheaper than other nut butters, which is a win-win-win in my book.

So, whenever I think about the people that can’t have peanut butter — or just peanut products in general — I’m a little devastated. They have to miss out on all of this! And to make matters worse, if their allergy is severe enough, they have to be cautious even being around peanuts.

So one day, in the midst of my completely unnecessarily guilty and over thoughtful brain, I decided to see why peanuts, specifically, cause allergies in so many people. And boy, did I go down a rabbit-hole.

It turns out, there’s quite an interesting origin story of how the peanut allergy rose in children and the general science around how food allergies evolve in children. Surprise number one to me, children are not innately born with this allergy.

The peanut allergy is developed early in life (usually found within 12-24 months of birth), is rarely outgrown and is an abnormal response to an otherwise harmless food that triggers an inflammatory reaction in the body’s immune system. The immune system misidentifies the peanut protein as something harmful to the body, triggering an immune response.

Antibodies — such as immunoglobulin E (IgE) — are then made specifically for peanut protein, thus generating an allergic reaction. The peanut allergy is often regarded as one of the most harmful because it usually elicits some of the worst, life-threatening reactions like anaphylactic shock. Research has shown that doses as low as 100 ug of peanut protein can trigger symptoms in highly sensitized individuals. For perspective, one peanut contains around 200 mg of protein. That means 0.05% of one peanut can cause allergic reactions!

This problem seemed to only be getting worse, too! In the early 2000s, researchers noticed that there was an insane increase in the number of children being diagnosed with a peanut allergy over the past decade — more than quadrupling in the US from 0.4% in the late 1990s to almost 2% in 2010.

This allergy became of specific interest to Gideon Lack from King’s College London. He, along with other researchers, met with health authorities to discuss their theories of how this “epidemic” arose and if there were any ways to prevent children from developing it in the future.

Through their meetings, they concluded expectant or lactating mothers and children (especially at genetically high risk) under the age of three should steer clear of any peanut-containing foods. Subsequently, the American Academy of Pediatrics (AAP) and Committee on Toxicity in the UK made similar recommendations in order to help prevent peanut allergies in children.

Many parents listened, and soon enough, it was commonplace for pregnant women and young children to avoid peanuts. This went on for years, but the peanut allergy still continued to rise in children.

Researchers, including Lack, became suspicious of their recommendations, so Lack decided to look into it further and realized the sharp increase in peanut allergies was mainly concentrated in western countries. He connected the dots when he went to a conference in Israel and, to his surprise, met with numerous Israeli doctors who had not recalled having seen a case of a peanut allergy in the last year — something very commonplace in western countries. He figured that something in their lifestyle had to be different.

Then he found Bamba.

Bamba is not just a funny-sounding word, it’s a funny little puffed peanut snack — kind of like a peanut-flavored Cheeto puff — wildly popular in Israel. Little kids were chowing down on this easy-to-eat snack, but they weren’t developing peanut allergies. This made him consider that maybe this snack could be helping protect kids against the mighty peanut allergy.

He decided to test his hypothesis out at home. He and his team conducted the now, landmark Learning Early About Peanut (LEAP) study published in 2015, where they randomly assigned infants to either avoid peanuts entirely or were fed six grams of peanut protein per week mainly in the form of — you guessed it — Bamba. They stayed the course until these children reached five years of age. Sure enough, he was right. He found that kids who ate peanuts regularly were around five times less likely to develop peanut allergies.

Today, scientists have been able to use this practice for other allergies too. When used for other kinds of allergies, this practice is called immunotherapy.

Our perspective has changed a lot since that study. In 2017, the AAP released a new set of guidelines that completely overhauled previous guidelines: Introduce peanut-containing foods to children, and introduce them early.

As recent as late last year, the FDA even approved a new peanut allergy treatment that — you guessed it — contains peanuts. It’s based on the immunotherapy idea that you can build a sort of tolerance to something by slowly introducing it over time. Kind of like a flu shot in a pill. It’s crazy just how far the science around this has come. It has literally taken a 180 and jumped on the peanut train.

All of this makes me eat my spoonful of peanut butter with a bit of scientific retrospect for just how weird and beautiful science is.

So while there will always be those who inevitably develop a peanut allergy, hopefully, with good, honest science in the future, more and more children will be able to enjoy the delightful satisfaction of a good-ole PB&J.

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