What is nut allergy?
Allergic reactions to foodstuffs occur where the body reacts to individual proteins in the food. Nut allergy is viewed as one of the most common food allergies, and is a type of allergy which often lasts a lifetime. One of the reasons for it being so common is that a large percentage of the population have pollen allergy, which causes cross-allergy and/or cross-reactions, including to nuts. (See Useful facts on cross-reactions).
A peanut, from a biological perspective, is not a nut but a pulse. Therefore, some individuals with peanut allergy also have sensitivity and may develop allergic symptoms when they eat other pulses such as green peas, soya, beans, lupine flour and lentils.
Allergy to peanuts was, up to a few years ago, relatively rare in Norway. Now, more and more cases of this type of allergy are being seen. One explanation may be that peanuts have become more common in foodstuffs and in snacks, but also that patients and doctors have become more attuned to this type of allergy.
What reactions do nuts/almonds/peanuts cause in allergic individuals?
Allergies to nuts/peanuts can cause very strong reactions, but not in all individuals.
The most common reactions to ingestion of nuts are itching and swelling in the mouth and throat. Flare-up of eczema, urticaria, stomach pains and vomiting are also symptoms that may arise. In individual cases, life-threatening reactions may occur (allergic shock). Reactions to almonds are not as common as reactions to nuts.
In Sweden, possible fatal cross-reactions have been reported in instances where individuals with peanut allergy have reacted strongly to ingested soya and similar cross-reactions to lupine flour have been reported in France. It has not been possible to verify this from studies in other countries.
What do individuals react to?
The reaction results from proteins in nuts/almonds/peanuts. In some individuals nut dust can cause a severe allergic reaction.
How is allergy to nuts/almonds/peanuts treated?
Food allergy is treated by excluding the non-tolerated foodstuff from the diet.
Nuts, almonds and peanuts have no common allergy-provoking substances (allergens). This means that individuals who are allergic to one are not necessarily allergic to the others.
What foods contain nuts/almonds/peanuts?
Foodstuffs which often contain nuts include cakes, biscuits, breakfast cereals, salads, bread and baguettes; spreads containing nuts, desserts, crushed nougat, chocolate, ice cream, some types of pesto, some foreign dishes, e.g. oriental dishes. Vegetable oil may be based on peanuts. If the product is refined it will not usually contain residual nut proteins. Conversely, cold-pressed oils can contain protein residue. Almonds are found in marzipan, and cakes with an almond base, e.g. almond sticks.
Lupine flour, which is used in baked goods, contains proteins which cross-react with peanuts.
Lupine flour has been found in hotdog buns after the reporting of serious reactions affecting an individual with peanut allergy having eaten a hotdog bun.
Remember that nut allergies do not become weaker with cooking or baking of the product.
Who gets allergies to nuts/almonds/peanuts?
Children appear to react more strongly than adults. Approximately half of children with peanut allergy react to odour, taste or touch, compared to only 10% reacting in adults.
Peanut allergy occurs more commonly in children with atopic eczema.
Peanut allergy is a strong allergy which appears, in most instances, to last a lifetime. Small children may however grow out of it.
Labelling of foodstuffs:
A number of foodstuffs are labelled with “May contain traces of nuts”. This does not mean that nuts have been added to the foodstuff, but that the product may have come into contact with nuts during manufacture. Most individuals with nut allergy can tolerate a trace quantity of nuts and can eat products labelled “May contain traces”. The individual must, in consultation with their doctor, establish whether the allergies are so serious that they should avoid nut traces.
Nuts are always labelled with their own name (hazelnuts, walnuts, etc.). Be aware that nougat and chocolate may contain nuts and that marzipan and macaroons are made of almonds.