Peanut and Other Legume Allergies

If you are allergic to peanuts, which is a legume, you may also be allergic to other legumes.

Boiled peanuts close up
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Peanuts Are a Legume

Peanuts are similar to other legumes that grow underground—such as soybeans, lentils, peas, and beans. Foods classified as legumes have a protein profile which could cross-react with peanuts.

Common legumes include:

  • Soy and soybeans
  • Beans
  • Peas
  • Lentils
  • Lupin

Peanut Allergy and Legumes

Having a co-existing allergy to another legume is similar to the risk of having any type of food allergy along with a peanut allergy. In fact, most people with a peanut allergy are able to eat other legumes without a problem.

Then why are so many people told to avoid legumes? The answer is cross-sensitization.

Cross-Sensitization Between Peanuts and Other Legumes on Blood Tests

Allergy tests often show a positive result to more than one legume. This is a result of cross-sensitization, which occurs when proteins found in legumes bind to the same allergic antibodies that are directed against similar peanut proteins.

Studies examining the incidence of cross-reactivity on blood tests or prick tests show that approximately 35% of people with peanut allergies have positive allergy tests to all beans, and up to 60% of people with peanut allergies have positive allergy tests to soy.

Yet only 5% of those who are allergic to peanuts experience allergic symptoms from exposure to other leptins. This is the same percentage of people with peanut allergies who also have another food allergy that's unrelated to the peanut allergy—such as a milk allergy.

The only way to know if you have a true allergy to another legume is through an oral food challenge.

Lupin

Lupin is becoming much more of a problem for those with food allergies. Lupin is a legume commonly ground into flour or eaten whole in European countries. There is some level of cross-reactivity between peanuts and legumes—studies have shown that 11 to 63% of people with a peanut allergy experience allergic reactions after eating lupin.

It's uncommon to find lupin in the grocery store in the U.S., but it is fairly common in some European countries. Those who live outside the U.S. or who travel to Europe should keep this in mind. Apparently, the use of lupin (for example, as a substitute for wheat) is becoming more common in the U.S. as well, especially in packaged foods.

What Should You Do About Legumes If You're Allergic to Peanuts?

If you are told that you have positive allergy tests to multiple legumes, you should check with your doctor before eating any of these foods.

The likelihood of having multiple life-threatening legume allergies is low, but if there is a concern, your doctor may perform an oral food challenge to any legume you are interested in eating to determine whether you are not allergic.

During an oral food challenge, you would eat a specific food that could cause an allergic reaction—with medical supervision. Your medical team would observe you for symptoms and would initiate treatment if you develop effects that require medical intervention.

Coping With Peanut Allergy

Peanut allergies can vary in severity and in degree of sensitivity. These allergies can cause reactions ranging from stomach upset to anaphylaxis. Some people will only have a reaction after eating a lot of peanuts, while others experience allergic symptoms from eating or smelling peanuts. And some people have a reaction after consuming foods that were prepared using equipment that came into contact with peanuts.

Peanut allergy has increased drastically in the past century and now affects approximately 1% of the western population. Since this phenomenon is occurring in some regions around the world, but not others, it's been suggested that the way in which peanuts are processed may underlie some of this increase.

According to some researchers, boiled peanuts may offer an approach to overcoming the allergy. While this is interesting, you shouldn't try this method without close supervision by your physician.

Avoiding peanuts (and other foods that your allergist advises could be dangerous) is the only surefire way to escape the reactions that may occur with these allergies.

While legumes are not usually a problem, it's important that you know that roughly 20 to 60% of people with a peanut allergy also have a tree nut allergy. Tree nuts include cashews, almonds, and walnuts which grow on trees.

Medication

Palforzia, a prescription treatment, is an oral immunotherapy indicated for the mitigation of allergic reactions, including anaphylaxis, that may occur with accidental exposure to peanuts. This medication is approved for adults and children age 4 and over who have a confirmed diagnosis of peanut allergy. Palforzia is to be used in conjunction with a peanut-avoidant diet.

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