Food allergy
An abnormal immune reaction to a food, characterised by the production of IgE antibodies against a protein in that food, triggering varied symptoms (from hives to anaphylaxis).
A food allergy always involves an immune reaction via immunoglobulin E (IgE). When the allergen comes into contact with the immune system, mast cells and basophils release large amounts of histamine, triggering a reaction within seconds to 30 minutes.
Typical symptoms: hives, swelling of the lips or eyelids, itching in the mouth (oral allergy syndrome), rhinitis, asthma, diarrhoea, vomiting and anaphylaxis.
A blood test (RAST) or skin prick test can confirm the presence of specific IgE.
A fresh angle: in Canada, 6% of young children and 3-4% of adults have a food allergy, which means that 96-97% of adults do not but believe they do. The confusion with intolerance is massive.
A dangerous trap: confusing allergy with intolerance can delay a true diagnosis or create unnecessary restrictions. A true allergy requires complete avoidance; an intolerance is graduated and can sometimes lessen by restoring gut flora.