As parents, ensuring our children’s health and well-being is always a top priority. Among the various concerns that arise, allergies, especially those related to nuts, often take centre stage. Hazelnut allergy is one of the most common tree nut allergies in the UK, US and Europe. In this article, we explain where hazelnuts are found, cross-reactivity, the link to pollen allergies, symptoms of an allergic reaction, testing, diagnosis and management.
Hazelnuts can be found in praline, chopped nuts, nut spreads such as Nutella, and breakfast cereals. They can be ground and incorporated into cookies, cakes, and various desserts. Additionally, hazelnut oil serves as a cooking ingredient. Tree nut (and peanut) allergies are responsible for the most severe food related allergic reactions, including life-threatening (anaphylactic) or even fatal reactions.
Cross-reactivity versus Co-reactivity
Cross-reactivity and co-reactivity is an essential concept to understand when dealing with nut allergies. Individuals with peanut and tree nut allergies frequently experience reactions stemming from various nut types; sometimes these are due to related allergens (such as cashew and pistachio – known as cross-reactivity), but they can also react to nuts that do not originating from closely related plant species (known as co-reactivity).
Primary Versus Secondary Allergy to Hazelnuts
In primary hazelnut allergy, the allergic reaction is triggered by IgE antibodies directed against proteins present in hazelnut that withstand processes like heat and digestion. This type of hazelnut allergy is responsible for the more severe reactions, including life-threatening (anaphylactic) reactions. In children with this type of primary hazelnut allergy, they often require adrenaline autoinjectors as part of their food allergy treatment plan as well as antihistamines.
In secondary hazelnut allergy, the allergic reaction is triggered by IgE antibodies directed against proteins present in hazelnut that are broken down by processes like heat and digestion. This can be observed in individuals with hay fever due to tree pollen allergies. This arises due to a cross-reactivity between tree pollen allergens, particularly from birch pollen, alder, and hazel trees, and related proteins found in hazelnuts.
This is due to the compounds present in tree nuts that bear a striking resemblance to pollen allergens. This type of hazelnut allergy is responsible for milder reactions, primarily affecting the mouth and giving rise to a phenomenon called pollen food syndrome also known as “oral allergy syndrome” (OAS). In children with this type of primary hazelnut allergy, they often require only antihistamines for their food allergy treatment plan.
Symptoms of Primary Hazelnut Allergy
Possible reactions, from least severe to most severe, can include:
- Itching sensation in the mouth, throat, eyes, ears, skin, or other regions
- Hives – local or generalised
- Swelling in the lips, tongue, or face, also known as angioedema
- Difficulty swallowing or hoarse voice
- Sneezing, nasal congestion or a runny nose
- Sensations of nausea, abdominal discomfort, vomiting, or diarrhoea
- Wheezing or coughing
- Breathlessness
- Going pale, floppy or lethargic
Symptoms of Secondary Hazelnut Allergy
Reactions are usually milder and localised to the mouth or face:
- Itching sensation in the mouth, tongue or ears
- Itchy throat and tickly cough
- Localised hives around the mouth
- Mild swelling in the lips
- Sensations of nausea, abdominal discomfort, vomiting
Diagnosis and Testing
If you suspect your child might have a hazelnut allergy, it’s crucial to consult a doctor for proper allergy diagnosis and food allergy management. Skin prick testing is a common method used to determine whether a child is allergic to hazelnuts. During this test, tiny amounts of standard extracts of the hazelnut allergen are placed on the skin and any local wheal (bump) is measured.
This helps the doctor identify the likelihood of whether your child is allergic to hazelnut, but not the severity of reaction. To differentiate between primary and secondary food allergy, an allergy blood test can measure the proteins inside hazelnut that your child is allergic to to confirm whether your child has primary or secondary hazelnut allergy (or a mixture of both).
The gold standard of testing is the oral food challenge, which can be performed if there is uncertainty with the diagnosis or if the skin or blood tests indicate that your child has grown out of their hazelnut allergy. At Children’s Allergy Doctors, we can arrange an oral food challenge or supervised feed (in clinic) to confirm whether your child is allergic or tolerant to hazelnut.
Managing Hazelnut Allergy
Once your child is diagnosed with a hazelnut allergy, there are several measures you can take to ensure their safety. Avoiding eating hazelnuts and products containing forms of hazelnut is the primary step.
Always read food labels carefully, as hazelnuts might be present in unexpected places. Following the introduction of Natasha’s Law, food businesses are now required to include full ingredients on pre-packed for direct sake foods. Reactions to nuts might also emerge due to concealed nut components or minute traces of nuts and specific seeds unintentionally incorporated during food processing or production.
Always be cautious when dining out and inform restaurant staff about your child’s allergy to prevent cross-contact (previously known as cross-contamination) where traces of the allergen are present in the food due to the use of similar utensils or food preparation sites.
Avoidance of all tree nuts is commonly recommended in patients allergic to any tree nut; however, children with one nut allergy may go on to develop more nut allergies if this approach is taken. At Children’s Allergy Doctors, we recommend finding out which nut your child is allergic to and then introducing other nuts to prevent the development of further nut allergies.
Oral Immunotherapy for Hazelnut
At Children’s Allergy Doctors, we are proud to offer Food Oral Immunotherapy (OIT) also known as Food Allergy Desensitisation, Oral Desensitisation (OD) or Food Desensitisation to hazelnut.
This is a process where you gradually introduce increasing amounts of the hazelnut into the child’s diet under supervision, to reduce the risk of allergic symptoms to accidental exposure to hazelnut and reduce severity of reactions, thereby reducing social restrictions and improving quality of life.
At Children’s Allergy Doctors, we offer this only in preschool children. The process takes 4-14 months depending on the hazelnut protocol your child is allocated to (which is personalised to their risk of reaction).
How can Children’s Allergy Doctors help?
Here at Children’s Allergy Doctors we provide a full range of services for all allergy conditions. We aim to be with you every step of the way, from allergy diagnosis to helping you with food allergy management and treatment.
Hazelnut allergies, like other food allergies, can be concerning for parents. Understanding the potential allergic reactions, cross-reactivity, and testing methods is essential for managing your child’s health effectively. With proper precautions and awareness, your child can lead a healthy and happy life, even with allergies.
If you would like to find out more about hazelnut allergy or any other aspect of children’s allergies, please contact our practice team on 0203 146 7721 or email admin@childrensallergydoctors.com.