It is possible to be allergic to cashews but not peanuts, or vice versa. Both are common food allergens, but they belong to distinct botanical families. This means the allergenic proteins that trigger reactions are different, allowing for separate immune responses.
The Distinct Nature of Cashews and Peanuts
Peanuts are legumes, in the same family as peas, beans, and lentils. Unlike tree nuts, peanuts grow underground. Cashews are tree nuts, originating from the cashew tree. This botanical distinction explains why an allergy to one does not automatically imply an allergy to the other.
The immune system identifies specific proteins within foods, leading to an allergic reaction. Peanuts contain several allergenic proteins, with Ara h 1, Ara h 2, and Ara h 3 being considered major allergens. Research also highlights Ara h 2 and Ara h 6 as potent elicitors of anaphylaxis in peanuts. Cashews have their own distinct major allergenic proteins, primarily Ana o 1, Ana o 2, and Ana o 3.
Since peanut and cashew allergens have different protein structures, an individual’s immune system can react to the specific proteins in cashews without reacting to those in peanuts, and vice versa. This difference in protein composition is the primary reason why separate allergies are possible.
Understanding Allergic Reactions
An allergy occurs when the immune system overreacts to a typically harmless substance, known as an allergen. Upon initial exposure, the immune system becomes sensitized and produces specific immunoglobulin E (IgE) antibodies. These IgE antibodies attach to immune cells, such as mast cells.
When re-exposed to the allergen, IgE antibodies bind to it, triggering the release of chemicals, including histamine, from immune cells. This chemical release leads to allergic reaction symptoms, which can range from mild to severe.
Mild symptoms include skin reactions like hives, itching, or flushing, and swelling of the lips, face, or eyes. Gastrointestinal issues such as abdominal pain, nausea, vomiting, or diarrhea can also occur. More severe reactions, known as anaphylaxis, can develop rapidly and affect multiple body systems. Anaphylaxis symptoms include difficulty breathing, wheezing, throat tightness, a sudden drop in blood pressure, dizziness, or fainting. Even a past mild reaction does not guarantee future reactions will be mild.
Navigating Diagnosis and Management
Accurate diagnosis of food allergies requires consultation with an allergist. Common diagnostic methods include skin prick tests, where a small amount of allergen extract is placed on the skin to observe for a reaction. Blood tests, also known as allergen-specific IgE tests, measure IgE antibodies to specific foods. While these tests indicate sensitization, a positive result does not always confirm a clinical allergy, as false positives can occur.
The “gold standard” for confirming a food allergy is often an oral food challenge, performed under strict medical supervision. During this test, increasing amounts of the suspected food are given to the patient, who is closely monitored for reactions. This procedure helps determine if a true allergy exists or if an allergy has been outgrown.
A diagnosis of an allergy to cashews but not peanuts, or vice versa, means dietary avoidance should be specific to the identified allergen. While cashews and peanuts are distinct, cross-reactivity can occur between cashews and other tree nuts like pistachios due to similar protein structures. Co-sensitization, where an individual develops multiple distinct allergies over time, is also possible. Careful diagnosis is important to differentiate between actual allergies and potential cross-sensitivities.
Management strategies center on strict avoidance of the identified allergen. This involves carefully reading food labels and informing others, such as restaurant staff, about the allergy. For individuals at risk of severe reactions, carrying emergency medication like an epinephrine auto-injector is essential. Epinephrine is the primary treatment for anaphylaxis and should be administered immediately if severe symptoms occur. Regular follow-up with an allergist helps ensure appropriate management.