Cashew (Anacardium occidentale)

Botanical Characteristics of Cashew (Anacardium occidentale)

• Scientific Name: Anacardium occidentale
• Family: Anacardiaceae (Same family as poison ivy, mango, and pistachio)
• Common Names: Cashew nut, Marañón
• Native Region: Brazil (now widely cultivated in India, Vietnam, and Africa)

Tree and Fruit Description

• The cashew tree is an evergreen tropical tree that grows 10–12 meters (33–40 feet) tall.
• The cashew nut is actually the seed of the cashew apple, growing at the bottom of the fleshy fruit.
• The seed is encased in a hard shell containing cardol and anacardic acid, which can cause skin irritation (similar to poison ivy).

Cashew as a Food Allergen

Cashews are classified as a major food allergen by the U.S. FDA, requiring mandatory labeling.

Allergenic Proteins in Cashews

Allergen Name	Protein Family	Molecular Weight (kDa)	Function	Cross-Reactivity
Ana o 1	7S Vicilin	~50 kDa	Seed storage protein	Cross-reactive with peanuts and tree nuts (almonds, walnuts)
Ana o 2	11S Globulin (Legumin)	~32-36 kDa	Storage protein	Common in tree nuts (walnut, pistachio, pecan)
Ana o 3	2S Albumin	~9 kDa	Seed storage protein	Highly stable allergen, linked to severe reactions
Ana o 4	Profilin	~15 kDa	Actin-binding protein	Cross-reactive with pollen allergens
Ana o 5	LTP (Lipid Transfer Protein)	~9 kDa	Defense protein	Cross-reactive with peach, apple, and other Rosaceae fruits

Molecular and Clinical Properties of Cashew Allergens

Ana o 1 (7S Vicilin)

• Structure:
  • Large glycoprotein involved in nutrient storage.
• Clinical Significance:
  • Major cause of severe IgE-mediated reactions.
• Cross-Reactivity:
  • Similar to peanut (Ara h 1) and almond proteins.

Ana o 2 (11S Globulin – Legumin)

• Structure:
  • Hexameric globulin with multiple IgE-binding epitopes.
• Clinical Significance:
  • Triggers systemic allergic reactions in sensitized individuals.
• Cross-Reactivity:
  • Common in walnuts, pecans, and pistachios.

Ana o 3 (2S Albumin)

• Structure:
  • Small, compact, and disulfide-stabilized, making it highly resistant to heat and digestion.
• Clinical Significance:
  • Most potent cashew allergen.
  • Linked to anaphylactic reactions.
• Cross-Reactivity:
  • Found in peanuts, Brazil nuts, and hazelnuts.

Ana o 4 (Profilin)

• Structure:
  • Cytoskeletal actin-binding protein.
• Clinical Significance:
  • Causes milder reactions like oral allergy syndrome (OAS).
• Cross-Reactivity:
  • Similar to birch pollen (Bet v 2).

Ana o 5 (Lipid Transfer Protein – LTP)

• Structure:
  • Lipid-stabilizing protein involved in defense mechanisms.
• Clinical Significance:
  • Can trigger severe allergic responses.
• Cross-Reactivity:
  • Linked to peach, apple, and other Rosaceae fruit allergies.

Stability of Cashew Allergens

Factor	Ana o 1 (7S Vicilin)	Ana o 2 (11S Globulin)	Ana o 3 (2S Albumin)	Ana o 4 (Profilin)	Ana o 5 (LTP)
Heat Resistance	Medium	High	High	Low	High
Gastric Stability	Medium	High	High	Low	High
Cross-Reactivity	Tree nuts, peanuts	Tree nuts	Peanuts, tree nuts	Pollen	Rosaceae fruits

• Cashew allergens are highly stable → Cooking or roasting does not eliminate allergenicity.
• Small traces of cashew proteins can trigger severe reactions.

Symptoms of Cashew Allergy

Symptoms appear within minutes to an hour after ingestion.

Mild to Moderate Reactions

• Oral Allergy Syndrome (OAS) (Itchy mouth, swelling)
• Hives (Urticaria)
• Nausea, Vomiting, Diarrhea
• Facial Swelling (Angioedema)

Severe Reactions (Anaphylaxis)   Epinephrine (EpiPen®) is the first-line treatment for anaphylaxis.

• Drop in Blood Pressure (Hypotension)
• Severe Bronchoconstriction (Wheezing, Asthma)
• Throat Swelling (Laryngeal Edema)
• Cardiovascular Collapse (Anaphylactic Shock)

Cross-Reactivity of Cashews

Cashews share IgE-binding epitopes with other tree nuts, peanuts, and even pollen.

Cross-Reactive Allergen Source	Similar Protein in Cashews	Potential Symptoms
Peanuts (Ara h 1, Ara h 2)	Ana o 1, Ana o 3	Systemic allergic reactions
Pistachios (Pis v 1, Pis v 2)	Ana o 2 (Legumin)	Severe anaphylaxis
Walnuts, Almonds, Pecans	Ana o 1, Ana o 2	Severe reactions
Birch Pollen (Bet v 2 – Profilin)	Ana o 4 (Profilin)	Mild oral allergy symptoms
Peach, Apple, Cherry	Ana o 5 (LTP)	Cross-reactive fruit allergy

Diagnosis of Cashew Allergy

Skin Prick Test (SPT)

• Detects IgE-mediated hypersensitivity to cashew extract.

Serum IgE Testing

• Measures specific IgE antibodies against Ana o 1, Ana o 2, Ana o 3.

Oral Food Challenge (OFC)

• Gold standard for diagnosing food allergy.
• Performed under medical supervision.

Management of Cashew Allergy

Avoidance Strategies

• Read Labels: Cashews are found in trail mixes, nut butters, vegan cheeses.
• Cross-Contamination: Often processed with pistachios and almonds.

Emergency Treatment

• Epinephrine Auto-Injector (EpiPen®) for severe reactions.
• Antihistamines for mild symptoms.
• Corticosteroids for prolonged allergic reactions.

Immunotherapy (OIT)

• Experimental desensitization therapy is being researched.

Conclusion

• Cashews contain potent allergens (Ana o 1, Ana o 2, Ana o 3), causing severe IgE-mediated reactions.
• Cross-reactivity is high with pistachios, peanuts, and walnuts.
• Cooking does not reduce allergenicity.
• Anaphylaxis risk → Patients must carry epinephrine.