This is simplified information about nut allergies – there are more resources available at the bottom of the page for further reading for those who are interested in knowing more.
Nuts are edible fruits which are protected by a hard outer shell. They are an important food as they are rich in nutrients and protein.
As with other groups of foods we cannot lump all nuts together in terms of allergy – different nuts contain different combinations of allergenic proteins, so they are not easily defined or categorised.
You may be allergic to one specific type of nut, a combination of tree nuts or all tree nuts. For those who are anaphylactic it may be best to avoid all products containing nuts due to the cross contamination during production.
Which 'nuts' aren't nuts?
are not considered to be true nuts. They are in the Fagaceae
family of plants. They do contain Bet v 1 proteins, chitinase and lipid transfer proteins, so can still cause allergic reactions to those with allergies to these proteins.
are in the Aracaceae
family of plants and are more closely related to bananas and pineapple than they are to other tree nuts. Coconuts do contain 7S seed storage proteins, so are sometimes linked to nut allergies.
is in the Myristicaceae
family of plants which include spice, so it is not considered to be a tree nut.
are often lumped under the term 'nuts', but are in fact legumes
. They are in the Fabaceae
family of plants which includes other foods like soya, beans and pulses. They do contain 2S, 7S and 11S seed storage proteins as well as lipid transfer proteins, oleosins, defensins and Bet v 1 proteins, so are likely very cross reactive with other tree nuts.
(also called pignolia) are the small, edible seeds from certain species of the Pinaceae family which are pine trees. They contain 2S seed storage proteins. These are panallergens commonly associated with tree nuts, peanuts, legumes and seeds.
butter is made from the oil of a fruit found in Africa. Shea nuts are NOT classified as tree nuts globally with the exception of the USA, where it is included in their list of tree nuts which should be avoided by those with a nut allergy. Shea is actually very unlikely to cause contact allergic skin reactions.
should not be confused with horse chestnuts or sweet chestnuts, which are not related. These are more closely related to sedges and rushes.
Which nuts are related?
Working out which nuts are related can be confusing as many of them have the same species and genus name but are known by multiple names.
In the table below you can see some nuts are closely related as they have the same family name, but the genus and species name is slightly different. For example, hickory, pecan and walnuts all look very different but are in same family – Juglandaceae
Table showing which nuts contain which allergenic proteins
Table is sorted alphabetically by species to show which nuts are the same but have multiple names.
Information in this table is from multiple resources – please visit the Food Allergy Index
for information on each food.
You can download a Nuts & Seeds Factsheet from the Allergy Resources Ko-fi Shop
for just $0.50 (£0.40 or €0.45).
Seed Storage Proteins
Seed Storage Proteins are split into three main types, 2S seed storage albumins
, 7S seed storage globulins
(also called vicilin) and 11S seed storage globulins
(also called legumin). Albumins are water soluble proteins found more often in nuts and seeds, globulins are found more often in nuts.
Seed storage proteins are the most common allergen associated with nut, seed and legume allergies and have a greater potential to cause a severe allergic reaction which may include anaphylaxis if accidentally ingested.
Seed storage proteins are heat stable, meaning that heating (and in many cases, freezing or processing) does not damage the shape of the protein, so it does not lose its ability to cause allergic reactions.
You can download a Seed Storage Protein 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 to avoid if you think you have an allergy to seed storage proteins.
Other foods containing seed storage proteins are tree nuts, peanuts, sesame, kiwi and coconut.
Lipid Transfer Proteins
Lipid Transfer Proteins
(also called LTPs) are panallergens found in many groups of foods and can cause serious allergic reactions. It is often the allergen found to be linking what initially looks like lots of random food allergies together. Lipid transfer proteins are stable when cooked or processed.
Foods containing LTPs are almonds, apple, banana, cherry, celery, kiwi and peach.
Bet v 1 Proteins
Bet v 1
allergens are linked to Pollen Food Allergy Syndrome
, which was previously called Oral Allergy Syndrome. These terms are still used interchangeably.
In this syndrome a person first becomes sensitised (allergic) to a tree or plant pollen. The most common in Pollen Food Allergy Syndrome is birch tree pollen. The allergenic protein in birch tree pollen is called Bet v 1. A person can then find themselves allergic to other proteins in foods which are similar to Bet v 1 proteins, often called Bet v 1-like or Bet v 1 homologues. Bet v 1 proteins are found in a wide range of foods including fruits, vegetables, nuts, seeds and grains.
The symptoms of this syndrome are called oral allergy symptoms as they can cause sneezing, itchy mouth and lips as well as a scratchy throat and tongue. All in all, these fruits can cause a general irritation of the mouth, nose and throat. It is very rarely serious enough for the throat to close as it does in anaphylaxis.
The Bet v 1 allergens are often referred to as ‘heat labile’, meaning that the proteins are damaged by heat and lose their ability to cause an allergic reaction. There are more proteins in the skin of the fruit than in the flesh and seeds. If you can eat the fruit once heated or peeled with no or reduced allergic reactions then you should be able to determine if this is Pollen Food Allergy Syndrome or a true IgE allergy (an IgE allergy will have immediate symptoms which may include anaphylaxis, swelling and/or hives).
Other foods containing Bet v 1 allergens are peanut, celery walnut, cherry, apple, peach and pear.
are panallergens which have the potential to cause allergic reactions over lots of groups of foods and cause people to suffer from multiple food allergies.
Allergic reactions to profilins are linked to oral allergy symptoms, more specifically they are linked to Celery-Mugwort-Spice Syndrome
, which is a subtype of Pollen Food Allergy Syndrome.
Profilins are less likely to be cause anaphylactic allergic reactions and the proteins themselves are easily denatured with heat and processing.
Other foods containing profilins include celery, peanut, walnut, lupin, almonds, mustard and other various fruits, grains and vegetables.
Tamarind contains a chitinase
protein, this is one of the allergenic proteins responsible for Latex Allergy
, it has cross reactivity with similarly shaped proteins in the skin of the fruit which can cause an allergic reaction; this is called Latex Food Syndrome
Chitinase allergy is usually linked to the skin of fruits such as banana, mango, jackfruit and kiwi.
proteins are a lesser-known allergenic protein found in plants. The proteins are involved in preventing the build up of oil molecules and may have a role in lipid store degredation during plant germination.
Oleosin proteins have been shown to maintain their shape after thermal processing, for example, studies have shown that roasted peanuts (in their shell) had more allergenic oleosin proteins than peanuts which were not heated.
Other food containing oleosin proteins include peanut, hazelnut, sesame, buckwheat and quinoa.
If you are interested in which foods contain which allergenic proteins you can visit the Food Allergy Tool Page
Why do some foods have no named allergens?
Some of the nuts in the table above have no allergens listed. The World Health Organization (WHO) has a database where they record all well studied allergens in certain foods. If there are none recorded then there have not been enough studies into this food. If you are interested in what is needed by the WHO before they add an allergen to their nomenclature database you can look at that HERE
Most of the entries in the table above are supported by the WHO allergen database and some are from individual studies. The ones that are assumed due to similar genus’ have been discounted.
If you are interested in cross reactivity of foods the most up to date information is on the Cross Reactivity Tool.
What are salicylates?
are chemicals made by plants as a defence against insects and disease. Some people have an enzyme deficiency which means they don’t digest salicylates very well, causing gastrointestinal and asthma symptoms.
Nuts which contain salicylates include almonds, Brazil nuts, macadamias and walnuts.
What are lectins?
are carbohydrate binding proteins found in lots of plants. They are very common in legumes, but also found in some nuts. They can cause gastrointestinal symptoms which can be reduced by cooking or soaking nuts.
Nuts which contain lectins include almonds and hazelnuts.
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