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.
Pecans are a low FODMAP food. FODMAP
stands for F
olyols. 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.
Pecan allergy is not currently associated with any allergic syndromes.
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.
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
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
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