The Mayo Clinic: Peanut allergies have increased significantly

DEAR MAYO CLINIC: Why is it that so many kids these days have peanut allergies? I don’t remember it being an issue even 20 years ago. Is it something most kids will grow out of? I have heard of children doing a peanut allergy study to “cure” them of their allergy. What does that involve?

ANSWER: You’re correct that the number of children with peanut allergies has increased significantly in the last several decades. Although researchers have many theories, at this time there’s no definitive explanation for the increase. A variety of studies are underway to better understand peanut allergies and to help find more effective ways of treating them.

While the reasons behind the dramatic increase in peanut allergies are unclear, lifestyle, diet choices and genetics all seem to play a role.

For example, one theory, called the hygiene hypothesis, highlights how living in developed countries may have an effect on childhood allergies, including peanut allergies. Babies born in developing countries have a lower incidence of allergies than those in developed countries. But if a family moves to a more developed country, their children’s incidence of childhood allergies increases. So simply being in the environment of a developed country seems to change things.

The hygiene hypothesis suggests that children who have more exposure to germs and certain infections at a very early age develop immune systems that are better suited to differentiating harmless substances from harmful substances. In this theory, exposure to certain germs teaches the immune system not to overreact.

It would also explain why children who grow up on farms or have certain types of pets are less likely to develop allergies than other children. But much more research is needed to understand exactly how childhood germ exposure might help prevent allergies.

In about 20% of people who develop a peanut allergy when they are young, the allergy goes away over time. The remaining 80% have some sensitivity to peanuts throughout their lives, although the severity of symptoms varies widely from one person to another.

Of note, peanuts are actually legumes and not related to other nuts, known as tree nuts. Unfortunately, many children with a peanut allergy go on to develop a tree nut allergy. In addition, tree nuts can be cross-contaminated or confused with peanuts, so for these reasons, we often ask children with a peanut allergy to avoid tree nuts as well.

A variety of research studies are looking at possible ways to treat peanut allergies. A number of them involve giving a small amount of peanut protein to children with peanut allergies, increasing the amount over time. In some of these studies, children eat the peanut proteins, while in others a patch on the skin is used to deliver them.

The goal is to make children less sensitive to peanuts so that if they have a small exposure, it won’t result in anaphylaxis — a potentially life-threatening allergic reaction that causes blood pressure to drop and airways to narrow and restrict breathing.

Some success has been achieved, but these studies come with risks. In addition to the possibility of anaphylaxis, some study participants have developed eosinophilic esophagitis. This is the result of certain white blood cells called eosinophils building up in the lining of the esophagus, damaging the esophageal tissue and making it hard to swallow. Because of these risks, children in these studies need to be carefully monitored.

At this time, the most effective way to manage a peanut allergy is to strictly avoid peanuts and to always carry an injectable dose of the medication epinephrine to use for emergency treatment in the event of accidental peanut exposure.

If you have a child who is allergic to peanuts, or you suspect a peanut allergy in your infant or toddler, consult a pediatric allergist. These specialists can provide a thorough evaluation and offer a comprehensive education on how to best deal with the allergy. — Dr. Martha Hartz, pediatric allergy and immunolog , Mayo Clinic, Rochester, Minn.

The MAYO CLINIC Q&A is an educational resource and doesn’t replace regular medical care. Email questions to MayoClinicQ&[email protected]. For more information, visit mayoclinic.org.