Macadamia Nut Allergy Test
Latin name: Macadamia spp.
Source material: Shelled nuts
Common names: Macadamia nut, Queensland nut, Australian nut
Macadamia nut is a food which may result in allergy symptoms in sensitised individuals.
Macadamia Nut Allergy Test: Allergen Exposure
Macadamia nuts are the fruit of a large tropical evergreen tree native to Australia but now also grown in Hawaii, in warm Mediterranean regions, in the southern USA and in South Africa. Australia remains the largest global producer of the macadamia nut.
Not a true nut, the macadamia is actually the seed of the tree, with a round whiteish kernel covered by a hard brown shell up to 3mm thick, which is itself contained in a fibrous green husk. The nuts fall naturally from the tree during a season which lasts around half of the year, and are collected by hand before being mechanically processed.
The kernels are generally dry- or oil-roasted before being shipped.
The nuts are richly flavoured and high in protein, with an oil content around 70%, which is notably higher than that of other nuts.
Macadamias can be consumed fresh or roasted and are added to a variety of foods, including snack bars, cereals, and nut mixes. Ground Macadamia meal is becoming an increasingly popular ingredient in baked goods, as is cold pressed Macadamia oil.
Macadamia Nut Allergy Test: Allergen Description
One protein has been identified as an allergen and is present in raw and roasted extracts.
Macadamia Nut Allergy Test: Potential Cross-Reactivity
Partial cross-reactivity has been reported between hazelnut and macadamia nut.
Cross-reactivity was observed between almond and black walnuts, brazil nuts, cashews, hazel nuts, macadamia nuts, pistachios, and sesame seeds.
Macadamia Nut Allergy Test: Clinical Experience
Macadamia nut, although not as common a food as many other tree nuts, may occasionally cause serious allergic reactions in sensitised individuals.
Cases are perhaps becoming more frequent because of the increasing use of macadamia nuts, alone and in other products. In particular, macadamia nut is becoming more frequently available in nut mixes and is being sold in countries which did not previously import it.
In an American study of 115 patients aged 4-19.5 years, moderately severe reactions to macadamia were reported in 13% of individuals, and severe reactions in 4%.
Macadamia nut-induced uvular angioedema, angioedema of the posterior part of the tongue, dysphagia, chest tightness, chest pain, and chest pruritis were described in a 36-year-old man. Symptoms occurred 5 minutes after eating a single chocolate-covered macadamia nut.
Reactions may be severe and result in anaphylaxis. An 18-year-old woman had immediate oral itching when eating flourless orange cake made with Macadamia meal. Within 5 minutes, this reaction had progressed to anaphylaxis. Anaphylaxis following contact with Macadamia nut has also been reported in an infant.
A 42-year-old man developed generalised pruritus, itching of the throat, rhinitis, dyspnoea and dizziness 5 minutes after eating a few roasted Macadamia nuts.
A 23-year-old female with a history of atopic dermatitis, allergic rhinitis, and allergic conjunctivitis reported that in her fourth year of primary school, she ate Macadamia nuts and developed oral discomfort and generalised urticaria.
Occupational dermatitis from Macadamia nut shells was described in 15 nut sorters at a Macadamia nut processing plant. The nature of the allergen was not found but was thought to be confined to the shell, as opposed to the plant leaf or kernel.