What is a food allergy

Food Allergy

True food allergy is a reaction involving the immune system where the body sees the food as harmful and   makes specific antibodies (called IgE antibodies) to ‘fight off’ the allergens found in these foods.  This results in the release of histamine and other naturally occurring chemicals in the body.  It is this release of histamine and chemicals, which produce the symptoms we recognise as an allergic reaction.

Symptoms caused by an allergic reaction to food can range from skin reactions: which include itching and rashes (urticaria); swelling (angioedema), gut symptoms, vomiting, stomach ache, diarrhoea.  Respiratory symptoms such as coughing, sneezing, asthma, blocked or runny nose.

In the most severe cases symptoms may develop rapidly and can be life threatening so require urgent medical attention.  Symptoms may include swelling of the lips, tongue, or face, shortness of breath, throat constriction and breathing difficulties.  Loss of consciousness can occur in extreme cases.  This collection of symptoms is known as anaphylaxis.  Normally symptoms arise within a few minutes of eating or coming in to contact with an offending food, although they may be delayed by up to a couple of hours.  Those at risk of anaphylaxis should have an adrenaline device available.  The GP can prescribe this if it is necessary.

Thankfully true food allergy is actually quite rare, affecting approximately 2% of the adult UK population and up to 8% of children.  Should you suspect that you or your child may be suffering from a food allergy, you should speak to your GP who will be able to help you or may refer you for specialist advice to a hospital allergy clinic.

The foods that most commonly cause allergic reactions are peanuts, tree nuts (such as almonds and Brazils), eggs, milk, fish, shellfish, and sesame.  You should be aware that any food can cause an allergic reaction and some foods are more likely to cause reactions in certain ethnic groups.

Key points on food allergy

  • Food allergy involves the body’s immune system and is a reaction to a specific food or foods
  • Symptoms can be mild or severe and can involve the skin, gut, breathing or the whole body circulation
  • Some GPs have the skills to diagnose and manage foods allergies.  For the more difficult cases or where multiple or severe food allergy exist, referral to an NHS allergy specialist service in a hospital is recommended by NICE 2011 (the National Institute of Clinical Excellence)
  • Patients with food allergy should be referred to a dietitian to help with the practical management of their food allergy.
  • IgE food allergies are easy to diagnose and if the culprit foods are totally excluded it is possible to remain completely free from any symptoms.
  • Reactions are often to trace amounts so complete exclusion is essential
  • Some people can tolerate a well-cooked version of the food but will react to the food in its part-cooked or raw state.  e.g. egg in a cake is often tolerated but the same person will react to boiled and scrambled eggs and mayonnaise.