Everything You Need to Know About Peanut Allergy
Peanut allergy is one of the eight most common food allergies, affecting approximately 1-2% of the U.S. population. Peanuts grow underground and are considered legumes. Most individuals with peanut allergy can tolerate other legumes, such as peas, soya beans, lentils, and chickpeas. Fewer than 5-10% of peanut allergic people have an allergy to other legumes. The majority of individuals with peanut allergy are also able to tolerate tree nuts (almond, Brazil nut, cashew, hazelnut, pecan, pistachio, walnut). About 30% of people with peanut allergy also have a tree nut allergy.
Most allergic reactions to peanuts are mediated by immunoglobulin-E (IgE) antibodies, causing immediate symptoms that can range from mild reactions to severe anaphylaxis. Anaphylaxis, a very serious allergic reaction, can be life-threatening. Management of peanut allergy requires avoidance of peanut, and this involves reading ingredient labels and clearly communicating with anyone involved in preparing foods for the individual with peanut allergy. The U.S. Food and Drug Administration (FDA) requires that in food containing peanut as an ingredient or containing protein from a peanut, that this be declared on package labels. Individuals with peanut allergy should also have epinephrine autoinjectors available at all times because accidental exposures are relatively common. With proper education, individuals with peanut allergy can maintain a broad and nutritionally adequate diet and a good quality of life.
Peanut allergy typically starts in childhood and persists throughout life. Approximately 20% of individuals may outgrow peanut allergy over time. Based on results of repeat allergy testing, a supervised oral food challenge in an allergist’s office can be considered if there is a favorable likelihood that the allergy has been outgrown or if the diagnosis is in doubt.
Food challenges may be considered if patients have small skin prick test reactions on allergy testing or low serum peanut specific IgE in the blood, suggesting a low likelihood of clinical peanut allergy. Several allergenic proteins have been identified that play a role in IgE-mediated peanut allergy. The proteins Ara h 1, Ara h 2 and Ara h 3 are the dominant allergens. Ara h 8 has high similarity with a birch tree pollen allergen and is most often associated with a less severe form of allergy called pollen-food allergy syndrome. Serum IgE testing to allergenic peanut protein components can help identify individuals who may have favorable food challenges outcomes. All food challenges should be performed in a medical facility equipped to recognize and treat allergic reactions, with supervision by an allergist.
In 2020, an oral immunotherapy medication for peanut allergy was approved by the FDA. This treatment helps reduce the risk of anaphylaxis associated with accidental peanut exposure and involves slowly increasing the dose of the medication, at times in the allergist’s office, over the course of several months. Individuals on treatment should continue to avoid peanuts and always have epinephrine autoinjectors readily available as severe reactions may occur.
Infants with severe eczema and/or egg allergy have a higher risk of being allergic to peanuts, but it is now known that earlier introduction of peanut-containing foods reduces the subsequent risk of developing a peanut allergy. Based on these findings, guidelines for peanut introduction were published in 2017 by the National Institute of Allergy and Infectious Diseases. Infants with severe eczema and/or egg allergy should be strongly considered for peanut allergy screening around 4-6 months of age. Infants with mild or moderate eczema do not need testing for peanut allergy and introduction of peanut in age-appropriate forms should begin around 6 months of age. Infants with eczema or egg allergy can introduce peanut based on the family’s preferences and cultural practices.
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