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It’s most likely you do, as around 1 in 20 children have a food allergy. It’s 1 in 10 for babies and less for older children as many babies grow out of their food allergy by the time they go to school.

What is an allergy?

An allergy occurs when the immune system reacts to a substance (allergen), which is usually harmless (e.g. food, pollen, animal dander and dust mite) or bites, stings and medications. This results in the immune system producing allergy antibodies, which identify and react with foreign substances. Reactions include hives, swelling of the lips, eyes or face, vomiting or wheeze. The reaction can be mild to severe. Anaphylaxis is the most severe allergic reaction.

What are the most common food allergens?

In babies and young children, the most common foods that cause an allergic reaction are eggs, cows milk and peanuts. Nine foods cause 90% of food allergic reactions, including cow’s milk, egg, peanut, tree nuts, sesame, soy, fish, shellfish and wheat. Peanut, tree nuts, shellfish, fish, sesame and egg are the most common food allergens in older children and adults. It is compulsory for packaged foods to identify any ingredients that contain one of more of these nine allergens.

Less common symptoms of food allergy include infantile colic, reflux of stomach contents, eczema, chronic diarrhoea and failure to thrive in infants.

Food intolerances

Food allergy and food intolerance are commonly confused as symptoms of food intolerance occasionally resemble those of food allergy. However, the following difference should be noted: food intolerance does not involve the immune system and does not cause severe allergic reactions (known as anaphylaxis). Food intolerance does not show on allergy testing. In addition, symptoms of food allergy occur very soon after an allergen food is eaten. Symptoms of food intolerance can take a day or two to appear as the reaction may take a certain amount of the food to be eaten before a reaction occurs.

Reliable diagnosis is important

When a child has had an allergic reaction to a food, your doctor will normally ask a series of questions that may help to narrow down the list of likely causes such as foods or medicines consumed that day. This approach will also help to exclude conditions that can sometimes be confused with food allergy and anaphylaxis.
Skin prick allergy tests or allergy blood tests help to confirm or exclude potential triggers. Sometimes a temporary elimination diet under close medical and dietetic supervision will be needed, followed by food challenges to identify the cause. Long term unsupervised restricted diets should not be undertaken, as this can lead to malnutrition and other complications such as food aversion.

While the results of allergy testing are a useful guide in determining whether the person is allergic, they do not provide a reliable guide to whether the reaction will be mild or severe.

Can food allergy be prevented?

Guidelines for the prevention of food allergies have been developed by the Australasian Society of Clinical Immunology and Allergy (ASCIA).

These guidelines are relevant for all families, including those in which siblings or parents already have food allergies or other allergic conditions

The main points are:

·       It is not recommended to exclude any foods from the mother’s diet during pregnancy or breastfeeding.

·       Introduce solids around 6 months – no earlier than 4 months. There is no reason to avoid certain foods when introducing solids. Introducing the common allergen foods such as eggs, cow’s milk, peanuts, shellfish, soy and wheat.

·       There is good evidence that introducing peanut into the diet of infants who already have severe eczema and/or egg allergy before 12 months of age can reduce the risk of these infants developing peanut allergy. If this applies to your infant, you should discuss how to introduce peanut with your doctor who has experience with food allergy.

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