Difference between allergies and intolerances Food allergy is a complex phenomenon, which begins with the “sensitization” phase, which occurs when the body comes into contact with one or more food-borne proteins, which it does not recognize as its own. It then begins to produce specific antibodies, belonging to the IgE class, to try to neutralize the substances, which it reads as foreign.
These antibodies interact with particular receptors, present on the surface of mast cells. In the sensitization phase, the patient has no symptoms, but whenever the organism subsequently comes into contact with the antigen, towards which it is sensitized, it will trigger the allergic reaction. This is triggered by the degranulation of mast cells, with a cascade of events, including the release of chemical mediators, such as histamine. The allergic reaction can start within seconds of exposure to the antigen, or appear only after a certain amount of time. For example, cat dander allergy can occur 24 hours later. Food allergies appear quite quickly. A feature of food allergies is that, after sensitization, a minimal dose of antigen is sufficient to trigger the reaction.
Food intolerance – symptoms
The allergic patient must limit as much as possible contact with the food to which he has become sensitized.Food intolerance or allergy? Food intolerance causes some typical symptoms of food allergies, such as nausea, vomiting, diarrhea and abdominal cramps. This is the reason why the two terms tend to be confused. In reality, food intolerances, unlike allergies, are always linked to a threshold dose of the offending nutrient, which every individual should know, to avoid exceeding it. Another key difference is that the immune system is never involved in food intolerance.
In most cases, food intolerance is linked to enzymatic dysfunctions, such as the lack or total lack of enzymes necessary to digest certain nutrients. The deficiency of lactase, an enzyme necessary for the digestion of the sugar present in milk, is known. However, the difference between food allergies and intolerances is subtle and is often not fully understood, especially by laymen. Both are non-toxic reactions and affect only some patients who, due to genetic or subsequently acquired causes, have a sensitivity towards some nutrients.
Food allergies, I repeat, are sudden reactions and are mediated by the immune system. Almost always the proteins contained in certain foods induce the production of antibodies, type E immunoglobulins (IgE), which activate mast cells, cells that release substances, such as histamine, which cause symptoms such as itching, coughing and rhinitis. These food allergies are called IgE mediated and are mostly hereditary.
Other forms of allergies, on the other hand, derive from defense mechanisms, not mediated by Ig-E and involve other immune cells, the T lymphocytes. Care must be taken, because this mechanism is common to some forms of intolerance. Intolerances are mediated by an activation of B lymphocytes, with production of IgG and IgA antibodies, caused by protein fractions of food, but T lymphocytes and interleukins may also be involved. See deepening: Gluten sensitivity (or non-celiac intolerance to gluten), food pseudo-allergies and wheat allergy IgE-mediated food allergies cause disorders that appear immediately after ingestion of the food in question.
Food intolerances are more frequent than allergies and cause slow reactions, which can arise after hours or days of repeated ingestion of the food. They are caused by macronutrients, micronutrients, additives, trace elements present in ingested food and have a pathogenetic mechanism that is not always known. They can be due to enzymatic deficiency of the organism, to irritative effects on the intestinal mucosa, to effects deriving from the fermentation of food residues or to other still unknown causes. In case of enzyme deficiency, there are assimilative problems, which can be investigated and tested. If it is a reaction of the organism to substances present in food or subsequently produced by the intestine by fermentation and the reaction recurs with each intake and is dose-dependent.