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 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.

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.

You can download a Tree Nut Allergy Factsheet from the Allergy Resources Ko-fi Shop for just $0.90 (£0.69 or €0.82). 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.

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