The Facts

"Food Allergy", these words are frequently related to a variety of specific, or non-specific symptoms or whenever the mechanisms of a reaction are not clearly established. The following definitions should help to characterize each situation.

1. Food hypersensitivity
   
   Reactions mediated by the immune system; the "true" food allergies.
   
   
   • IgE-mediated food hypersensitivity
     
     Most often involving the skin (urticaria, atopic dermatitis, angioedema...), the respiratory tract (laryngeal edema, asthma...); these reactions can be life-threatening (anaphylaxis)
     
     
   • Non-IgE-mediated food hypersensitivity
     
     Does not involve food-specific IgE antibodies (IgE's are the "allergy" antibodies; gastrointestinal symptoms (diarrhea, vomiting) in infants or toddlers are the most common clinical picture. Approximately half of the milk allergies are non-IgE-mediated.
     
     
     
2. Food intolerance
   
   These reactions are not mediated by the immune system, they are "fake" food allergies.
   
   
   • Enzyme deficiencies
     
     The most known clinical expression in this category is lactase deficiency. The majority of non-Caucasians lack this enzyme and may present colics, diarrhea and flatulence after ingesting moderate or large quantities of milk.
     
     
   • Toxic reactions
     
     May be provoked by toxins released by germs such as Shigella or E. coli contained in contaminated foods.
     
     
   • Idiosyncrasic reactions
     
     Some people may be more sensitive to histamine or tyramine found in foods such as some cheeses, or red wine, and have skin flares after eating these foods.
     
     
   • There are many more ill-defined reactions to foods...
     

food@diogenes.hcuge.ch