Brazil nut is a food which may result in allergy symptoms in sensitised individuals.

Brazil Nut Allergy Test: Allergen Exposure

Not a true nut, the Brazil nut is actually the seed of a giant tree native to the South American rainforest, growing in clusters within large, woody pods. The kernel is white and high in oil, containing about 70% oil and 17% protein.

Brazil nuts were introduced to Europe originally in the 17th century by Dutch and Portugese traders.

In the Amazon region, indigenous people eat the nuts raw, or grate them and mix them into gruels. The plentiful oil is used in cooking. As exported, the nuts are a popular snack food, and their oil is prized. In addition to protein and fat, Brazil nuts are a substantial source of selenium, an important antioxidant.

The tree bark is brewed into tea to treat liver ailments. The husks of the seed pods have also been brewed to treat stomach aches.

The oil extracted from the nuts is commonly used in Peru and other South American countries to manufacture soap, and for lighting, and the empty pods are used as implements and burned to repel insects.

Worldwide, Brazil nut oil is often used in soaps, shampoos, hair conditioning/repair products, and skin moisturisers, and extracts of the pods can be included in insect repellents.

Brazil Nut Allergy Test: Allergen Description

A number of allergenic proteins has been isolated from Brazil nut, including a globulin-like protein and a 2S albumin which is a major allergen and has proved resistant to digestion.

Brazil Nut Allergy Test: Potential Cross-Reactivity

An extensive cross-reactivity within the Lecythidaceae family can be expected.

Brazil nut contains a protein common to many seeds, which displays similarity to those of cotton, cocoa bean, sunflower seed, rape seed, castor bean, english walnut, mustard seed and sesame seed.

Allergenic cross-reactivity has been observed between peanut and Brazil nut.

Walnut-induced anaphylaxis has been reported, with cross-reactivity to hazelnut and Brazil nut described.

Brazil Nut Allergy Test: Clinical Experience

Allergy to Brazil nut is common, frequently has an onset in the first few years of life, generally persists, and accounts for severe and potentially fatal allergic reactions.

The ubiquity of this food in the modern diet makes avoidance difficult, and accidental ingestions, with reactions, are common.

Symptoms include vomiting, diarrhoea and other manifestations associated with food allergy: laryngeal oedema, atopic dermatitis, urticaria and anaphylaxis. Pharyngeal itching, lip swelling, dysphonia, dyspnoea, wheezing, and generalised macular exanthema have been reported.

Anaphylaxis to Brazil nut has been reported, and may occur even with no previous history of ingestion of this nut.

Food allergens have been reported to be present in breast milk. A study also reports on a 20-year-old woman with documented Brazil nut allergy who developed widespread urticaria and mild dyspnoea after intercourse with her boyfriend, who had earlier consumed Brazil nuts.