Lauren Mellott
Dr. Cundell
Immunology
27 April 2019
Don’t Buy Me Some Peanuts!
I have two younger brothers, one of which has been allergic to peanuts and tree nuts for
as long as I can remember. Due to his allergy, we grew up eating soy nuts and soy nut butter as
to avoid his severe reaction. My brother, however, is not alone in this allergy: an allergy to
peanuts is the fourth most common food allergy, falling behind cow’s milk, eggs, and tree nuts
(West). Peanut allergies affect around 4–8% of children and 1–2% of adults (West), which may
not seem like much, but it amounts to approximately 5936000 children and 4599787 adults. Just
as having an allergy varies person to person, so does the severity of the reaction to peanuts and
how sensitive one is to the legume in general.
A peanut allergy occurs when the immune system identifies peanut proteins as something
harmful. Direct contact, such as eating peanuts or peanut-containing products, cross-contact – the
unintended introduction of peanuts into a product, or inhalation of dust or aerosols containing
peanuts can all cause the immune system to release symptom-causing chemicals into the
bloodstream. This reaction is strictly an IgE-mediated type I hypersensitivity reaction (AlMuhsen et al. 1279). In such reactions, peanut-specific IgE antibodies bind to high-affinity
receptors on mast cells and basophils. The specific peanut allergens include five proteins
associated with clinical reactions of varying severity: Ara h 1, Ara h 2, Ara h 3, Ara h 8, and Ara
h 9 – the Aha referring to the peanut plant Arachis hypogaea, and the numbers distinguishing
each discrete component (“Peanut Allergy Diagnosis: As Simple as Ara h 1, 2, and 3”). Ara h 1,
2, and 3 are storage proteins that are heat-resistant and present in peanut-allergic persons with
potentially severe reactions. Ara h 9 also is associated with severe symptoms, but it mainly is
identified in southern Europe. Ara h 8 is a pathogenesis-related class 10 (PR-10) protein that is
heat-labile and typically is associated with cross-reactions to pollens; people with it generally
have much milder reactions or no reaction at all to peanut ingestion (“Peanut Allergy Diagnosis:
As Simple as Ara h 1, 2, and 3). A combination of proteins or an individual protein can serve as
the allergen that produces a reaction.
When peanut allergens penetrate mucosal barriers, such as the mouth and nose, cellbound IgE and peanut allergens crosslink, which results in degranulation of preformed allergic
mediators and subsequent cell activation. These cells may then produce a variety of cytokines
and chemokines, which recruit other inflammatory cells and contribute to the IgE-mediated latephase allergic response (Al- Muhsen et al. 1279). The recruitment of inflammatory cells causes
the allergic response associated with most food allergies.
Within minutes of exposure to the peanut allergens, an individual can expect a runny
nose; a skin reaction, such as hives, redness, and swelling; itching or tingling in or around the
mouth and throat; digestive problems, such as diarrhea, stomach cramps, nausea, or vomiting;
tightness of the throat; and shortness of breath or wheezing. Allergic reactions do not always
involve the respiratory and cardiovascular systems, but life-threatening anaphylaxis does.
Treatment of anaphylaxis, which includes constriction of airways, swelling of the throat that
makes it difficult to breathe, a severe drop in blood pressure, rapid pulse, and dizziness,
lightheadedness, or loss of consciousness, requires treatment with epinephrine (Mayo Clinic
Staff). The dose of adrenaline helps to restore blood pressure, increase blood flow, and reduce
swelling in airways (Davis).
Not everyone is subject to peanut allergy, however. Certain risk factors may predispose
individuals to a peanut allergy, which include age, a past allergy to peanuts, having other
allergies, having family members with allergies, and having atopic dermatitis. When it comes to
age, food allergies are most common in children, especially toddlers and infants. As one grows
older, the digestive system matures, and the body is less likely to react to food that triggers
allergies. Additionally, some children with peanut allergy outgrow it. Even so, however, it may
recur. If an individual is allergic to one food, one may be at an increased risk of becoming
allergic to another. Likewise, having another type of allergy, such as hay fever, increases your
risk of having a food allergy. If there is a family history of allergies, especially of food allergies,
then an individual may be at an increased risk of peanut allergies. Finally, some individuals with
atopic dermatitis, better known as eczema, also have a food allergy (Mayo Clinic Staff). Just
because one has one or all of the risk factors does not necessarily mean that s/he will develop an
allergy to peanuts or any allergy at all; however, there are standard ways to diagnose whether or
not someone is presenting with a peanut allergy.
One of the methods of diagnosing a peanut allergy is a food diary – logging what an
individual eats and describing any symptoms that one experiences a result of eating (Mayo Clinic
Staff). This method enables physicians to match symptoms with the consumption of certain
foods, and narrow down the possible list of allergens that could be causing a reaction. Another
way of diagnosis is the elimination diet, which asks patients to refrain from including suspected
allergens from the diet for at least one week (Mayo Clinic Staff). Then, the foods can be
reincorporated into the diet, one by one, so that it is more easily shown which foods cause
symptoms and which do not. The final two tests a diagnostician may use include the skin test, in
which a small amount of food is placed on your skin and pricked with a needle, and the blood
test, in which levels of IgE are measured (Mayo Clinic Staff). Once an allergen is determined
using one or multiple of the diagnostic criteria, a physician can then discuss how best to avoid
the allergens to prevent reaction and anaphylaxis.
No definitive treatment for peanut allergy exists, but researchers are actively studying
oral immunotherapy, which allows the immune system to become desensitized to the allergen.
Long-term safety of such a therapy is still unknown, which prevents the United States Food and
Drug Administration (FDA) from approving the therapy (Mayo Clinic Staff). With no approved
treatment, the only viable way to ensure that a reaction is not life-threatening is to safeguard
patients from a potential response. Avoiding peanuts is vital for patients with an allergy, but for
those with severe reactions, carrying an epinephrine autoinjector (EpiPen, Auvi-Q, Twinject)
could help sustain life until an emergency room can be reached (Mayo Clinic Staff). As
researchers continue to test possible desensitization, the hope is that fewer individuals will be
reliant upon epinephrine doses and will be able to eat their allergens in small doses without
severe reactions.
Allergies are more common now than they were in the past, and there are multiple
theories as to why such a trend is occurring. One of those is the high sugar, low fiber diet
common in Western societies. Much of the conventionally grown produce is genetically
modified and laden with pesticides and herbicides. Additionally, farm animals are pumped full of
drugs and antibiotics. All of these processes can have a severe impact on the human microbiome
— the mini-ecosystem in the gut that is the basis of good health and immunity over our lifetime.
Breakdown of the microbiome can lead to food allergies (Sinatra). Another theory is the hygiene
hypothesis, which states that the cleanliness associated with modern societies is increasing the
susceptibility of developing allergies (Sinatra). The final approach is termed early exposure, in
which children are not exposed to common allergens, such as peanuts, early enough to avoid
developing an allergy (Sinatra). Overall, therefore, it is essential for individuals to be exposed to
allergens early in their life to avoid reactions to them later in life.
Avoiding allergens may not be as difficult in the future as it is now: researcher Kit
McQuiston, CEO of Alrgn Bio, is currently working to develop an allergen-free peanut. He
believes that a ninety-eight percent allergen-free peanut is attainable within the next two years.
The company has accomplished the feat by soaking shelled-peanuts in a food-grade enzyme
solution (Manning). While McQuiston recognizes that all jars of peanut butter are not able to be
replaced, he does hope that parents may feel more at ease when it comes to exposing their
children to peanuts and peanut-based products for the first time (Manning). Because there is no
genetic modification, the technology is much more accepted among the scientific community and
is providing hope to those with severe peanut allergies.
Works Cited
Al-Muhsen, Saleh et al. “Peanut allergy: an overview” CMAJ : Canadian Medical Association
journal = journal de l'Association medicale canadienne vol. 168,10 (2003): 1279-85.
Davis, Caitlin Q. “Why Is Epinephrine Used during an Allergic Reaction?” SCIENCELINE,
Arthur L. Carter Journalism, 9 Feb. 2013, scienceline.org/2013/02/why-is-epinephrineused-during-an-allergic-reaction/.
Manning, Kay. “Will Allergy-Free Peanut Be a Reality Soon?” Chicago Tribune, 26 Apr. 2017,
www.chicagotribune.com/lifestyles/health/sc-peanut-allergy-health-0510-20170425story.html.
Mayo Clinic Staff. “Peanut Allergy.” Mayo Clinic, Mayo Foundation for Medical Education and
Research, 13 Nov. 2018, www.mayoclinic.org/diseases-conditions/peanutallergy/symptoms-causes/syc-20376175.
“Peanut Allergy Diagnosis: As Simple as Ara h 1, 2, and 3.” Consultant, vol. 12, no. 8, Aug.
2013, www.consultant360.com/articles/peanut-allergy-diagnosis-simple-ara-h-1-2-and-30.
Sinatra, Stephen. “Food Allergies So Common Now - Why?” Heart MD Institute, Heart MD
Institute, 14 Aug. 2018, heartmdinstitute.com/health-and-wellness/food-allergies-socommon-why/.
West, Helen. “The 8 Most Common Food Allergies.” Healthline, Healthline Media, 15 Jan.
2017, www.healthline.com/nutrition/common-food-allergies.