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

Pecan Nut Allergy Test: Allergen Exposure

Pecan nuts are native to North America, where they provided a food source for indigenous peoples for thousands of years. Today, North America remains the main producer, with the USA producing around 250 million pounds of pecan nuts annually, the largest part of which comes from Texas. Pecan nut cultivation has also been exported to many of the world’s warmer temperate zones and subtropical regions.

The pecan nut itself is deep brown in color, with a smooth shell and mild flavour described as similar to that of the walnut.

Over 100 varieties are commercially available and they are used whole or crushed. Oil from the nuts is an ingredient in processed foods, is used in the manufacture of cosmetics and soap, and is a drying agent in paints.

Pecan Nut Allergy Test: Allergen Description

Only one allergen present in pecan nut has been characterised to date, an albumin known as napin.

The allergen profile may change as the pecan nut matures, is stored or heated. Maillard-type reactions may be responsible for the change in allergenicity of the protein.

Pecan nut allergens in small quantities may result in severe reactions.

Pecan Nut Allergy Test: Potential Cross-Reactivity

Pecan appears to be highly cross-reactive with walnut at even the lowest concentrations used, and this correlates with clinical reports of cross-reactivity in the patients in question.

Some degree of cross-reactivity between peanut and pecan nut has been observed, as well as with brazil nut.

Pecan Nut Allergy Test: Clinical Experience

Allergy to foods containing pecan nuts is common. Nine percent of self-reporting tree nut-allergic patients list pecan as an allergen.

Pecan nut allergy frequently has an onset in the first few years of life and generally persists, accounting for severe and potentially fatal allergic reactions.

Pecan nut allergens may be absent in fresh pecan nuts, which become allergenic as the pecan nut protein matures during aging, or during the heating process for roasting Pecan nuts.

These neoallergens have been identified as the cause in anaphylaxis in a child who experienced this condition after eating cookies containing these nuts.

In a group of 122 children who had experienced acute reactions to nuts, 68 reacted to peanut alone, 20 only to tree nuts, and 34 to both. Of those reacting to tree nuts, the most common were walnut, almond, and pecan.

Initial reactions usually occurred at home and were thought to result from a first exposure in 72% of cases. Eighty-nine percent of the reactions involved the skin (urticaria, angioedema), 52% the respiratory tract (wheezing, throat tightness, repetitive coughing, dyspnoea), and 32% the gastrointestinal tract (vomiting, diarrhoea). Two organ systems were affected in 31% of initial reactions, and all 3 in 21% of reactions.

Other reactions

Commercial products may contain peanuts that have been deflavoured and reflavoured and coloured to resemble walnuts, pecans, or almonds. This may result in anaphylaxis in peanut-sensitive individuals.

Protein contact dermatitis from pecan nut has been reported.

Acute vesicular cutaneous reaction after prolonged contact with pecans has been reported.