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Key Allergens

Pecans are classified as tree nuts and are in the top 14 allergens which have to be declared on food packaging in Europe. They are in the Juglandaceae family of plants, walnuts are also in this plant family.

There are 3 key allergens associated with pecan allergy, Car i 1, Car i 2 and Car i 4. They are all different types of seed storage proteins.

Car i 1 is a 2S albumin seed storage protein and is considered to be the main allergen linked to allergic reactions. This is why most nuts are grouped together for the purpose of labelling as sufferers of this allergy are most often allergic to multiple types of tree nuts, peanuts and seeds.

Car i 2 is a vicilin like protein also associated with seed storage. These proteins are also known as 7S seed storage proteins.

Car i 4 is a Legumin seed storage protein. These proteins are also known as 11S seed storage proteins.

Though not officially recognised by the WHO (World Health Organization), there is lots of documentary evidence of allergies to the pollen of the pecan tree (also known as hickory). The offending allergen has not yet been identified.

Food Intolerances

Food is low in FODMAP Food is low in histamine Food is low in salicylates

Pecans are a low FODMAP food. FODMAP stands for Fermentable oligosaccharides, disaccharides, monosaccharides and polyols. Foods high in FODMAPs can cause symptoms of food intolerance, affecting the gastro intestinal system and this can be mistaken for a true IgE food allergy.

Pecans are a food low in salicylates, so is suitable for those people who are sensitive to salicylates.

Tree nuts including pecans are considered to be low in histamine, so suitable to eat for those who are eating this type of food.

You can read more about Food Intolerances on the dedicated Food Intolerance Page.

Associated Syndromes

Pecan allergy is not currently associated with any allergic syndromes.

Cross Reactivity

Other food containing 2S albumin seed storage proteins are cashews, peanuts, brazil nuts, mustard seed, rapeseed, turnip, chickpeas, hazelnuts, pistachio, buckwheat, soya, sunflower seeds, walnuts, kiwi, castor beans and sesame seeds.

Other foods containing vicilin like proteins not mentioned in the list above are lupin, lentils, macadamia, peas and mung bean.

Almonds are the only other tree nut containing legumin proteins not mentioned in either of the above cross reactive lists. So if you are additionally allergic to almonds as well as pecans this may be the protein you are reacting to.

You can download a Tree Nut Allergy Factsheet from the Allergy Resources Ko-fi Shop for just $0.50 (£0.40 or €0.45). This has up to date information on which foods contain linked allergens and what foods to avoid if you think you have an allergy to tree nuts.

Please note that the food lists above are not exhaustive, the most up to date information is on the Cross Reactivity Tool.



Allergen Encyclopedia - Pecan

Allergy information for: Pecan (Carya illinoinensis)

AAAAI - Tree Nut Allergy

Anaphylaxis Campaign - Peanut and Tree nut allergies

Scence Direct - Carya Plants

Can You Be Allergic to Just One Type of Tree Nut?

Allergy UK - Tree Nut Allergy

Histamine Food List

ATP Science - Salicylate Food List

Healthline - FODMAP foods

Articles and Journals

Prevalence of tree nut allergy in Europe: A systematic review and meta-analysis, 2024

Oral immunotherapy for food allergy: Translation from studies to clinical practice? 2023

Quantitative In Silico Evaluation of Allergenic Proteins from Anacardium occidentale, Carya illinoinensis, Juglans regia and Pistacia vera and Their Epitopes as Precursors of Bioactive Peptides, 2022

Immunoproteomic identification of allergenic proteins in pecan (Carya illinoinensis) pollen, 2021

Defining challenge-proven coexistent nut and sesame seed allergy: A prospective multicenter European study, 2020

Clinical and Molecular Characterization of Walnut and Pecan Allergy (Nut Cracker Study), 2020

Identification and Characterization of a New Pecan Carya illinoinensis Allergen, Car i 2, 2016

Cloning and characterization of 2S albumin, Car i 1, a major allergen in pecan, 2011

Cloning and characterization of an 11S legumin, Car i 4, a major allergen in pecan, 2011

2S Albumin Storage Proteins: What Makes them Food Allergens?, 2008

Current perspectives on tree nut allergy: a review, 2018

The importance of the pecan tree pollen in allergic manifestations, 1996

Let me know if you found any of these interesting or useful. If you spot an article or research that you think is interesting you can message me or tag me on Facebook or Twitter - links at the bottom of the page.

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