Allergic reactions to food have increased significantly in the last few years. Recent statistics suggest that food allergy now affects 6-8% of young children in the UK and around 1-2% of adults.
There are various forms of food allergies and these can have a important impact on daily life for many families. Therefore, it is paramount that food allergies are correctly identified and families are able to recognise and manage allergic reactions if these should occur.
Food allergy is an exaggerated reaction towards food proteins like nuts, egg or milk. Exposure to the allergen causes the release of mediators like histamine that can cause hives, swellings, abdominal discomfort with vomiting and diarrhoea, runny nose and eyes, difficulty in breathing or even more severe forms of anaphylaxis with dizziness and collapse which can be life-threatening. Some rare forms of food allergies can happen with a delayed-onset and can be less dangerous and usually are outgrown in early childhood.
In smaller children, delayed onset food allergy needs to be considered if a patient presents with severe eczema, treatment resistant gastro-oesophageal reflux or severe vomiting after feeds, colic with diarrhoea or constipation or poor weight gain,
Adult-onset food allergy are more common than previously believed, but also food allergy developed during childhood can persistent over the years, especially to nuts, fish, shellfish and sesame. Children tend to outgrow food allergy to milk, egg and wheat. Adults with eczema can have undiagnosed food allergies although to a less extent in comparison with children but precise identification can help improve eczema.
Diagnosis of food allergies
Allergy skin prick testing or specific IgE blood testing and oral food challenges together with a careful clinical history can help you diagnose food allergy accurately. Regular revaluation of food allergies can point towards outgrown food allergies.
The most common form of food allergy is oral allergy syndrome also known as pollen-food syndrome. This is due to similarity between proteins in fresh fruits, vegetables and raw nuts and proteins from pollen. This is considered a milder form of food allergy in comparison with true food allergy to nuts for example where a patient experiences anaphylaxis after food intake. This can happen de novo and most common new reactions happen to nuts, seeds, seafood and various fruits and vegetables. In rare situations, food allergy can happen in the presence of a co-factor for example exercise and we see that usually when a food is eaten just before physical exercise in food-dependant-exercise induced anaphylaxis. Therefore these patients need careful assessment by an experienced allergist to identify the possible trigger.
Can food allergy be cured?
Interestingly, recent research has shown that food desensitisation also known as oral immunotherapy can be performed by administering increasing amounts of the culprit food allergen. The goal is to increase the immune tolerance to a certain allergen so that larger amounts or accidental exposure will not cause allergic reactions. The downside is that it has to be continue in one’s diet otherwise the desensitisation is lost. Nevertheless, the primary therapeutic strategy in food allergy is avoidance and this requires extensive patient education on how to read labels on packaged foods, prepare safe meals at home and avoid allergen exposure in restaurant meals.