Prevalence and risk factors of allergic reactions to food

Clinical and Translational Allergy today publishes research on the way an allergic reaction is triggered in the body and how this affects the way it can be identified. Co-author Kate Grimshaw explains more here.

Food Hypersensitivity is the umbrella term used to describe any condition where there is a reproducible reaction to a food upon eating it. It can include the two different types of Food Allergy (Immunoglobulin (Ig) E mediated, which is sometimes called a ‘true allergy’, and Non-IgE-mediated) and other types of reactions often referred to as ‘intolerances’.

There is an on-going debate as to how common such reactions are (particularly in children) and what may be causing them. To investigate this, an EU funded project (EuroPrevall) recruited pregnant women across nine different European Countries.

1140 women from the UK were recruited from Winchester and its surrounding area as part of this study (called the PIFA study in the UK) and the children were followed up until two years of age. The findings from this study are published in Clinical and Translational Allergy (Grimshaw et al).

What did we find?

The study is the first to look at the prevalence of two different types of food hypersensitivity and the risk factors associated with them. Most food allergy research studies on prevalence and risk factors have only looked at IgE mediated food allergies.

Risk factors differed between IgE mediated and non IgE mediated reactions.

These results show that in the UK, over half of the children who reacted to milk did not have an IgE mediated allergy whereas for the vast majority of children who reacted to egg and peanut, their reaction was IgE mediated.

Risk factors differed between IgE mediated and non IgE mediated reactions. For IgE mediated food allergy, eczema and rhinitis increased the risk of development but for Non IgE mediated food allergy increased risk was associated with having a dog in the house! A healthy eating pattern was found to be protective for both types of reaction.

What does this mean?

The findings from this study are important for two reasons:

  • These results highlight that many children are reacting to foods without there being any IgE involved. Food reactions not involving IgE cannot be diagnosed using blood or skin tests. Therefore it is important that health care professionals recognize that a child may be reacting to a food despite tests results being negative. The only way to diagnose non IgE mediated food hypersensitivity is to remove the food to see if symptoms improve and then reintroduce it to see if the symptoms reappear. This was how the children in this study were diagnosed.
  • In this study, there was only one modifiable factor found to reduce the risk of developing food hypersensitivity. This was for the infant to have a ‘healthy diet’. Such a diet was characterized as being predominantly home-cooked food and containing fruits, vegetables, fish and chicken.

The children involved in this study are now being re-assessed at school age in a study called iFAAM.

The children involved in this study are now being re-assessed at school age in a study called iFAAM. 400 children have already taken part. They have completed a short 15 minute online questionnaire and many have also had a clinical assessment.

Finding the missing families

Lead researcher Professor Roberts and his team are looking for the missing 740 – finding them will help us understand why some older children develop asthma and allergies and some do not.

If you are one of the missing families please feel free to get in touch with the study team by calling 023 8120 6160, emailing iFAAM@southampton.ac.uk or visiting the iFAAM website.

For further information/detail about these research results please see this website.

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