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

Pistachio Allergy Test: Allergen Exposure

The pistachio tree is native to the mountainous regions of central and south-western Asia, but is now cultivated in other parts of the world, particularly in California and Australia. It is related to the mango and cashew nut.

Pistachio nuts are small, green, edible nuts (technically drupes) with a hard whitish shell in two segments. As the nut ripens the shell splits open, sometimes producing an audible popping sound, but enough closure remains that the nut is not released from the shell.

The pistachio shell is sometimes dyed red for commercial sale.

Pistachio nuts are widely used in the catering industry in ice creams, cakes and other confectionery, mortadella (an Italian cooked sausage) and oriental dishes. They are also eaten roasted and salted as a popular snack.

Oil is processed from the seed and may pose a threat to patients with allergy, depending on the method of manufacture and processing.

Pistachio nuts are reported to be highly flammable when stored in large quantities, and are prone to self-heating and spontaneous combustion.

Pistachio Allergy Test: Allergen Description

A number of allergens present in pistachio nut have been isolated, and some characterised, including an albumin, a globulin, a vicilin-like protein and a magnesium superoxide dismutase.

A lipid transfer protein (LTP) may be present.

Pistachio Allergy Test: Potential Cross-Reactivity

The close relationships among the Anacardiaceae suggest cross-reactivity, and this is supported by studies demonstrating cross-reactivity between cashew and pistachio. In a study of 42 children with Cashew allergy, 7 had an associated food allergy to pistachio.

Cross-reactivity was also found between pistachio nut and mango seed, but not mango pulp.

Cross-reactivity has been demonstrated between pistachio, peanut, walnut and sunflower seed.

Cross-reactivity has also been reported to occur among allergens in sesame seed and allergens in other foods, including hazelnut, rye, kiwi, poppy seed, black walnut, cashew, macadamia, pistachio, and peanut.

Cross-reactivity with other lipid transfer protein-containing foods is possible.

Cashew nut, and possibly pistachio nut, allergy may be associated with pectin allergy. The possibility of pectin allergy should be considered in cashew- or pistachio-allergic patients who have unexplained allergic reactions.

Pistachio Allergy Test: Clinical Experience

Pistachio may uncommonly cause symptoms of food allergy in sensitised individuals.

Adverse reactions are similar to those seen with other tree nuts and include symptoms of oral allergy and food allergy, cutaneous manifestations, angioedema and severe anaphylaxis. Most of these reports have concerned small children.

As pistachio nuts, and foods containing them, are introduced into more countries, more reactions are likely to be seen.

Anaphylaxis to pistachio has been described in 3 individuals who were allergic to both mango and pistachio nut.

A 28-year-old man experienced episodes of generalised itching and hives, profuse sweating, abdominal pain, nausea and vomiting immediately after eating peanut, peach, paprika, hazelnut or mango, on different occasions. The patient was found to have skin reactivity to pistachio.

Food-dependent exercise-induced anaphylaxis to pistachio has been described in a 16-year-old boy; it occurred 30 minutes after he began to play football after having ingested pistachio nuts.

Other reactions