Peanuts (also known as groundnuts and monkey nuts) are legumes rather than tree nuts and grow underground. They are in the Fabaceae family of plants which also includes peas, lentils, lupin, soya and other beans, pulses and legumes.

There are 18 allergens recognised by the World Health Organisation (WHO) associated with peanut allergy.

These allergens include 2S seed storage proteins, commonly found in other nuts, seeds and legumes. Peanuts also contain 7S seed stoage proteins, also known as vicilin and 11S seed storage proteins, also known as legumin, which are also found in many seeds and legumes.

Peanuts also contain plant profilin proteins, Lipid Transfer Proteins (LTP) and Bet v 1 proteins which are associated with Pollen Food Syndrome. These proteins are all considered to be panallergens - having the potential to cause allergic reactions across multiple groups of foods.

Plant defensin proteins have been identified in peanuts and have the potential to cause food allergy. They are peptides in the plant used to defend against fungal attack.

More recently there is interest in oleosin proteins, which are found in the oils of certain nuts and seeds and are not denatured by heating. There are 4 oleosin proteins in peanuts which have been shown to cause allergic reactions.

Peanuts 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.

Peanuts are high in salicylates. Salicylates have the potential to cause worsening of asthma, swelling, itching and hives as well as food intolerance symptoms in people who are sensitive to salicylates.

Peanuts contain high amounts of lectins. Lectins are another possible cause of food intolerance. Usually cooking foods with lectins makes them more digestible and can reduce the symptoms of food intolerance, peanut lectins however are heat stable, so their effect is not reduced by cooking.

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

Peanut allergy is often linked to LTP Syndrome, where similarly shaped proteins in other plants resemble those in almonds and elicit an allergic reaction.

You may have Pollen-Food Allergy Syndrome if you suffer from peanut allergy with oral allergy symptoms to 3 or more of the foods mentioned in the cross reactivity section.

Allergy to peanut is sometimes linked to Celery-Mugwort-Spice Syndrome as the sensitising allergen is a profilin protein called Art v 4, these proteins are also sometimes also called Bet v 2 proteins.

There is a link between peanuts and Latex Food Syndrome. The plant involved in latex allergy Hevea brasiliensis, the rubber tree plant, has an allergen called Hev b 8 which is a profilin protein. Those very sensitised to latex may have a contact allergic reaction from other foods or plants containing profilin proteins, there is less evidence of this than sensitisation to other latex linked proteins like hevein and chitinases.

Common foods involved in LTP allergy include kiwi, strawberries, sunflower seeds, walnut, apple, mulberry, banana, pea, apricot, cherry, plum, almond, peach pomegranate, raspberry, tomato, grape, celery, peanut, asparagus, cabbage, broccoli, chestnut, lemon, tangerine, orange, hazelnut, lettuce, lentils, lupin, green bean, pear, mustard, wheat and maize.

Other fruits containing profilins include celery, lychee, soyabeans, walnut, lupin, almonds, mustard, hazelnut, kiwi, pineapple, chilli, melon, orange, strawberry, apple, banana, aubergine (eggplant), peach, pear, tomato, dates, cherry, carrot, barley and wheat. Allergic reactions to some of these foods may be considered a marker of profilin hypersensitivity.

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

Other foods containing 7S seed storage proteins not mentioned in the list above are coconut, lupin, lentils, macadamia nuts and peas.

Almonds are the only other tree nut which contain 11S seed storage proteins, but not 7S or 2S proteins.

Other oleosin proteins are found in hazelnuts, buckwheat, palm oil and sesame seeds.

Defensin proteins are found as food allergens in celery, peanuts, mango, sunflower seeds and horse chestnuts and as pollen allergens in soya, woodworm and mugwort.

You can download a Peanut 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 peanuts.

Note that these food lists are not exhaustive, the most up to date information is on the Cross Reactivity Tool.

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