Brazil Nut (Bertholletia excelsa)

Botanical Characteristics of Brazil Nut (Bertholletia excelsa)

• Scientific Name: Bertholletia excelsa
• Family: Lecythidaceae
• Common Names: Brazil nut, Pará nut
• Native Region: Amazon Rainforest (Brazil, Bolivia, Peru, Venezuela, Colombia)

Tree and Fruit Description

• The Brazil nut tree is a large tropical tree, reaching 50 meters (160 feet) in height.
• The fruit is a woody capsule (similar to a coconut), containing 10–25 seeds (Brazil nuts).
• The seeds are high in oil content (~67% fat), making them nutritionally dense.

Brazil Nut as a Food Allergen

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

Allergenic Proteins in Brazil Nuts

Allergen Name	Protein Family	Molecular Weight (kDa)	Function	Cross-Reactivity
Ber e 1	2S Albumin	~9-12 kDa	Seed storage protein	Highly cross-reactive with peanuts, walnuts, cashews
Ber e 2	11S Globulin (Legumin)	~34 kDa	Storage protein	Cross-reacts with tree nuts (walnuts, almonds)
Ber e 3	7S Vicilin	~47 kDa	Storage protein	Found in peanuts and soy
Ber e 4	Hevein-like Protein	~4.5 kDa	Defense protein	Cross-reacts with latex (Latex-Fruit Syndrome)

Molecular and Clinical Properties of Brazil Nut Allergens

Ber e 1 (2S Albumin)

• Structure:
  • Small, highly stable seed storage protein.
  • Resistant to heat, enzymatic digestion, and pH changes.
• Clinical Significance:
  • Major cause of systemic allergic reactions.
  • Highly potent, requiring only trace amounts to trigger anaphylaxis.
• Cross-Reactivity:
  • Found in peanuts, cashews, walnuts, and almonds.

Ber e 2 (11S Globulin – Legumin)

• Structure:
  • Forms hexameric complexes, making it a large and stable allergen.
• Clinical Significance:
  • Triggers severe reactions in IgE-sensitized individuals.
• Cross-Reactivity:
  • Common in walnuts, almonds, and pecans.

Ber e 3 (7S Vicilin)

• Structure:
  • Glycoprotein with multiple IgE-binding epitopes.
• Clinical Significance:
  • May contribute to delayed allergic reactions.
• Cross-Reactivity:
  • Similar to peanut (Ara h 1) and soy (Gly m 5).

Ber e 4 (Hevein-like Protein)

• Structure:
  • Similar to latex proteins, leading to Latex-Fruit Syndrome.
• Clinical Significance:
  • May cause cross-reactivity with latex allergies.
• Cross-Reactivity:
  • Strongly linked to latex allergy (similar to avocado, banana, and chestnut allergies).

Stability of Brazil Nut Allergens

Factor	Ber e 1 (2S Albumin)	Ber e 2 (11S Globulin)	Ber e 3 (7S Vicilin)	Ber e 4 (Hevein-like Protein)
Heat Resistance	High	High	Medium	High
Gastric Stability	High	High	Low	High
Cross-Reactivity	Tree nuts, peanuts	Tree nuts	Peanuts, soy	Latex, fruits

• Highly stable allergens, meaning cooked, roasted, or processed Brazil nuts remain allergenic.
• Small traces of Brazil nut proteins can trigger severe reactions.

Symptoms of Brazil Nut Allergy

Symptoms can range from mild to severe, appearing minutes to an hour after ingestion.

Mild to Moderate Reactions

• Oral Allergy Syndrome (OAS) (Itching, tingling in the mouth)
• Hives (Urticaria)
• Nausea, Vomiting, Stomach Cramps
• Swelling of Lips, Face, or Throat

Severe Reactions (Anaphylaxis)

• Drop in Blood Pressure (Hypotension)
• Severe Bronchoconstriction (Difficulty Breathing)
• Laryngeal Edema (Throat Swelling)
• Cardiovascular Collapse (Anaphylactic Shock)

Epinephrine (EpiPen®) is required for anaphylactic reactions.

Cross-Reactivity of Brazil Nuts

Brazil nuts share IgE-binding epitopes with other tree nuts, peanuts, and even latex.

Cross-Reactive Allergen Source	Similar Protein in Brazil Nuts	Potential Symptoms
Peanuts (Ara h 1, Ara h 2)	Ber e 1 (2S Albumin), Ber e 3 (7S Vicilin)	Systemic allergic reactions
Almonds, Walnuts, Cashews	Ber e 2 (11S Globulin)	Severe anaphylaxis
Soy (Gly m 5)	Ber e 3 (7S Vicilin)	Mild to moderate reactions
Latex (Rubber Tree Sap)	Ber e 4 (Hevein-like Protein)	Latex-Fruit Syndrome (Swelling, rash, wheezing)

Diagnosis of Brazil Nut Allergy

Skin Prick Test (SPT)

• Measures IgE reaction to Brazil nut extract.
• Positive test suggests sensitization.

Serum IgE Testing

• Specific IgE antibodies against Ber e 1, Ber e 2, Ber e 3.

Oral Food Challenge (OFC)

• Gold standard for confirming allergy.
• Conducted under medical supervision.

Management of Brazil Nut Allergy

Avoidance Strategies

• Read Food Labels: Brazil nuts are found in trail mixes, chocolates, nut butters.
• Cross-Contamination Risks: Processed with walnuts, almonds, cashews.

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 studied.

Conclusion

• Brazil nuts contain potent allergens (Ber e 1, Ber e 2, etc.), causing IgE-mediated reactions.
• Highly stable allergens → Remain allergenic even after processing.
• Cross-reactivity with peanuts, tree nuts, and latex.
• Anaphylaxis risk → Patients must carry epinephrine.