When you’re allergic to a substance, your immune system mistakenly believes it is dangerous and produces immunoglobulin E (IgE) antibodies in an attempt to neutralize it. According to The George Mateljan Foundation:9
“Antibodies are long, branched molecules that have places for recognition and binding (attachment) of the antigen on one side, and a site on the other end that can call into action other immune responses. An antibody will only bind one specific antigen and nothing else.
When the antibody binds, or sticks, to the dangerous molecule it is acts like a red flag identifying the molecule as something potentially damaging that should be removed.
Your macrophage cells are often called the ‘scavenger’ cells of the immune system and are specifically designed to remove damaging molecules from the body.
After the antibody binds to a dangerous molecule the macrophages consume the molecule, taking it out of circulation and destroying it.”
Chemicals such as histamine released into your bloodstream during this process can lead to a battery of symptoms any time you eat the food (although symptoms may not appear until hours later). With a food intolerance, on the other hand, your immune system is not involved.
Instead, symptoms of food intolerance may be caused by your body having difficulty breaking down or digesting certain foods or food ingredients. An intolerance may also be caused by your body’s reaction to a certain food additive.
While the most common allergenic foods are peanuts, tree nuts, fish, shellfish, soy, wheat, milk and eggs, food intolerances are most commonly due to lactose, gluten, preservatives and additives and tyramine (common in cured meats, aged cheeses and smoked fish).