What is a Food Allergy?

By Dr Ananya Mandal, MD

Food allergy refers to the adverse reaction the body's immune system has to certain foods in some individuals. While most allergic reactions are mild and easily managed, these responses can also be serious and life threatening, causing anaphylaxis and even death.

Symptoms

Some of the symptoms of food allergies include:

  • Itchiness within and around the mouth, throat and ears
  • Raised, blotchy bumps forming a rash called nettle rash or urticaria
  • Swelling of subcutaneous tissue (angioedema) around the lips, tongue and palate
  • A very severe form of allergic reaction is known of as anaphylaxis. The symptoms of anaphylaxis include difficulty in breathing, swelling inside the airways and larynx that can cause choking, dizziness and even loss of consciousness. Angioedema of the lips, hands, feet and face may also occur. In addition, blood pressure can fall rapidly leaving the skin cold and clammy and sending the patient into shock

Causes

In the case of allergic reactions to food, the immune system identifies the proteins contained within food as foreign bodies and mounts an attack in the same way as it does when microbes and bacteria are detected. The immune system releases several chemical mediators such as histamine that lead to symptoms of the allergy. Most commonly, food allergies are triggered by the immunoglobulin E (IgE) antibody.

Some of the common food allergies found in children include egg and milk allergies, while adults are more likely to be allergic to fruit and vegetables. Nut allergies, on the other hand, are seen commonly across all age groups.

According to the Food and Drugs Administration (FDA) the eight most common food types to cause allergies are:

  • Eggs
  • Milk
  • Fish
  • Shellfish
  • Nuts
  • Wheat
  • Soybeans

Treatment and prevention

The best way to prevent food allergies is to avoid the food allergen completely. Food and food products as well as cosmetic labels should be read carefully to see if the ingredients contain any food that a person is allergic to.

Antihistaminic agents can be used to control mild allergic reactions. In patients with anaphylaxis, however, emergency treatment should be administered and this is usually given in the form of an adrenalin injection.

Reviewed by Sally Robertson, BSc

Sources

  1. http://www.nhs.uk/conditions/food-allergy/Pages/Intro1.aspx
  2. http://www.niaid.nih.gov/topics/foodallergy/documents/foodallergy.pdf
  3. http://www.doe.mass.edu/cnp/allergy.pdf
  4. http://www.food.gov.uk/multimedia/pdfs/publication/loosefoodsleaflet.pdf
  5. http://www.aaaai.org/Aaaai/media/MediaLibrary/PDF%20Documents/Practice%20and%20Parameters/Food-allergy-guidelines-Dec-2010.pdf
  6. http://www.fda.gov/downloads/Food/IngredientsPackagingLabeling/UCM220117.pdf

Further Reading

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