Fact Sheet Tree Nut Allergy Page 1
Fact Sheet Tree nut allergy Page 1
What are tree nuts? What are the symptoms of The term tree nut is commonly used to tree nut allergy? mean nuts (Almond, Brazil, Cashew, Reactions can range from mild to severe. Chestnut, Hazelnut, Hickory, Macadamia, Mild reactions consist of hives around Mixed nuts, Pecan, Pine, Pistachio and the mouth where the nuts have touched Walnut). This is to distinguish them from the skin or more generalised hives on peanuts (sometimes also known as other parts of the body. Another common groundnuts) because tree nuts come symptom is abdominal pain and vomiting from a different plant family. People who which occurs soon after eating the tree are allergic to peanuts are not nut. More severe reactions have necessarily allergic to tree nuts, but coughing, wheezing, difficulty breathing people who are allergic to one tree nut or hoarseness of the voice due to an have a tendency to be allergic to other allergic reaction occurring in the airway. tree nuts. It is rare (but possible) for these symptoms to occur alone without hives What is tree nut allergy? and/or vomiting. It appears that Tree nut allergy is a reaction which reactions to cashew nut are more likely occurs after ingestion of tree nuts. The to be severe than reactions to peanut. symptoms usually occur within minutes When symptoms of an allergic reaction in but occasionally up to 2 hours following the airway occur the reaction is called the ingestion. These symptoms are due anaphylaxis. Approximately one quarter to IgE (allergy) antibodies against nut to one half of tree nut allergic children proteins. In a recent study of Australian who develop symptoms on tree nut nut allergic children, allergy to peanut exposure have respiratory signs which was the most common (83%), followed indicate a more severe allergic reaction. by cashew (13%) and other nuts (4%) In the most severe cases collapse and (almond and pecan, hazelnut and loss of consciousness and can occur. walnut). Nut allergy commonly presents Very rarely very sensitive individuals have around 2-4 years of age. Allergic died from the severe allergic reaction reactions to tree nuts often occur the (anaphylaxis). first time the child is known to be exposed to the nut. How is tree nut allergy diagnosed? How common is tree nut In most cases the clue to tree nut allergy allergy? is the start of symptoms soon after Peanut allergy is the commonest nut exposure to the nut. The presence of allergy and affects about 1% of children. allergy IgE antibodies to nut can be It is the commonest cause of serious confirmed by an allergy skin prick test or food allergic reactions. In a Western a blood test (called a RAST test). It is community about 1 in 500 children important to realise that not every child (0.2%) react to tree nuts. It seems that with a positive allergy test will develop allergy to some tree nuts, eg cashew nut, symptoms on exposure to that nut. The is becoming more common. Tree nut interpretation of the test should be allergy is likely to occur in individuals discussed with your doctor. If your child with other allergic diseases (asthma, has a positive allergy test but has never atopic dermatitis, and other food eaten tree nuts your doctor will allergies). determine the chance of developing a reaction if there is exposure to tree nuts.
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Fact Sheet Tree nut allergy Page 2 The allergy tests are not very helpful in types and not just the ones to which they predicting whether a reaction to nut will have reacted. be mild or severe. How do I avoid exposing my Can tree nuts cross-react child to tree nuts? with peanuts? The most important step in managing There is a low rate of cross reaction tree nut allergy is avoidance of exposure between peanuts and tree nuts. The to the nuts which cause allergic allergens of tree nuts are more likely to reactions. One study showed that a cross react with other tree nuts than with quarter of nut-allergic children were peanuts. As an example most children unable to correctly identify the type of with allergic reactions to cashew nuts do nut to which they were allergic. not react to peanuts as well. Children Avoidance of nuts can be difficult as they with cashew nut allergy may be more can be hidden in many foods. For likely to react to pistachio nut which example cashew nuts may be hidden in a comes from a closely related plant wide variety of commonly ingested foods, family. such as Asian meals, sweets, ice cream, cakes, chocolates and commercially Will my child react to all prepared pesto sauce. It is important to use common sense and read food labels types of nuts? carefully. Note that beans, legumes Your child is most unlikely to react to all (pulses), nutmeg and coconuts are not types of nuts; however, allergic reactions closely related to nuts and are usually to more than one nut are common. Most allowed in the diet unless the child has (>80%) school age children with a nut reacted to one of these before. allergy will react to at least one other type of nut on allergy testing and 40-50% Where possible check labels particularly will be have a reaction to more than one with the following foods that could type of nut if exposed. Other children may react to only one type of nut; contain tree nut. however it is frequently simpler to avoid all types of nuts. Sensitisation to tree Check the ingredient list of these foods nuts may increase with increasing age. for peanuts and other nuts: For this reason your doctor may repeat the allergy tests to a range of nuts from time to time. In general children who have a nut allergy should avoid all nut
Baked goods Croissants Ice creams Biscuits, baklava Dried fruit mixes Pastries Pesto Pasta sauces Breads and buns Flavourings (natural) Salads/ salad dressings Breakfast cereals eg Fried food (peanut oil) Sauces muesli Cakes Gravy Snack foods Chocolates Health bars, eg muesli Soups bars, energy bars, nut bars Chocolate spreads Home made food Takeaway/restaurant foods Confectionery ie lollies, Hydrolysed/textured Turkish delight fudge vegetable protein (HVP & TVP) xcvxcvxcv Crackers Vegetarian foods
Fact Sheet Tree nut allergy Page 3
What about foods with a school and teenage years. Those children who have had more severe label that says "may allergic reactions with breathing contain traces of nuts"? problems are probably less likely to outgrow their allergy than children with Many foods carry a warning on the label milder reactions. Your doctor can "may contain traces of nuts". This usually sometimes determine whether the nut indicates that the food is made in a allergy is still present by performing facility that also makes a food containing allergy tests and by giving your child a tree nuts or peanuts. However unless supervised challenge in hospital to that there is a mistake the food does not nut. Occasionally the nut allergy may usually contain any nut. Some foods are come back in people who have outgrown more likely to be contaminated with nuts their allergy. than others, especially if they are made on the same machinery as foods containing nuts eg chocolate, icecream Is my child likely to have a and muesli bars. Discuss what to do severe reaction from casual about foods labelled "may contain traces of nuts" with your doctor. contact with tree nuts on benches, other children's What is an Epipen? hands or by smelling tree Epipen is an emergency device which nuts? injects a dose of adrenaline into the muscle. It is used to treat severe No. There is no research to confirm that reactions to nuts (anaphylaxis). The drug severe reactions from can occur by adrenaline reverses the severe allergic touching or smelling tree nuts without reaction and can be lifesaving. nut ingestion. Some people can develop localised symptoms e.g. hives where the nut touches the skin and this has the Should my child carry an same meaning as a positive skin test. A Epipen? small proportion of nut allergic people are sensitive to such small amounts of All allergists agree that children who nuts that they may develop symptoms have had a serious reaction to nuts with from eating trace amounts of nuts, and involvement of the breathing passages perhaps this is why some people have should have an Epipen. The need for been thought to react to ‘touching’ nuts. other children to have an Epipen Some very sensitive people may develop depends on a number of factors which wheezing if they inhale nut vapours should be discussed with your doctor. If formed during cooking, however this is you have an Epipen it is very important extremely rare. that you understand how and when to use it and that you have a written anaphylaxis action plan provided by your Can I prevent nut allergy in doctor. my future children? There are no methods which can Can my child grow out of guarantee a child will not develop nut tree nut allergy? allergy. There is no evidence that avoiding nuts in pregnancy or in the diet Only about 10% of subjects will outgrow of lactating mothers prevents nut allergy their tree nut allergy. Most preschool in their babies. children who have tree nut allergy will
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Fact Sheet Tree nut allergy Page 4
Where can I find more information on the Internet?
The CHW diet sheets available on www.chw.edu.au/parents/factshe ets/ The Australian Society of Clinical Immunology and Allergy (ASCIA) website contains useful information on food allergy written by Australian specialists (www.allergy.org.au). The patient support group Anaphylaxis Australia offers valuable updates and tips for dealing with food allergies (www.allergyfacts.org.au).
Written by the Department of Allergy and Immunology The Children's Hospital at Westmead.
xcvxcvxcv This fact sheet is for education purposes only. Please consult with your doctor or other health professional to make sure this information is right for your child. This document was reviewed on 7th July 2010
www.chw.edu.au www.sch.edu.au www.kaleidoscope.org.au © The Children’s Hospital at Westmead, Sydney Children’s Hospital, Randwick & Kaleidoscope * Hunter Children’s Health Network – 2005-2010