Allergy is a strong immune reaction towards specific substances that come in contact with the human body. The substances in question, such as pollen, mites, food, drugs, are considered dangerous by the immune system, which activates the production of antibodies to counteract the harmful molecule. This biological mechanism is the basis of the allergic reaction, which usually occurs very quickly.
All allergies involve the immune system and therefore can be ascertained with blood tests, which measure the presence of antibodies against certain allergens.
In the case of food allergies following the ingestion of food, the allergic reaction can manifest itself in a more or less serious form. This can happen when the active ingredients of the food come into contact with the immune system of the gastrointestinal tract, or after the digestive process when the food components are transported by the blood until they come in contact with the immune cells of others organs.

Food intolerance is a reaction towards foods or substances contained in them that are less aggressive than allergy. Unlike allergies, it is not possible to demonstrate the involvement of the immune system through laboratory tests. This does not mean that any direct or indirect involvement of the immune system should be excluded.
Regardless of the various types of tests more or less accepted by official medicine, and used to research them, food intolerances are a phenomenon taken into consideration and studied only recently because of their worrying increase. We are most likely in the presence of different immune reactions than those related by allergies; for example, to some enzymatic reactions such as milk intolerance. This now so popular intolerance is due to the lack of the lactase enzyme in the body which allows you to digest lactose.

Many peoples do not consume milk and are deprived of the enzyme that allows digestion. Although the results of many research seem controversial, various diseases (colitis, arthritis, etc.) seem connected to the use of certain foods; in many cases, rapid and positive results are obtained by simply eliminating these from the diet.
Intolerances can cause health problems, even if there are no antibodies and immunoglobulins in the tests. Although they do not trigger serious reactions that can endanger life such as allergies, food intolerances act with a more or less delayed effect, and therefore it is not always easy to recognize them.
The causes of intolerances can be manifold: enzyme deficiencies, the presence of toxic substances in food (dyes, preservatives, pesticides used in agriculture, etc.), the release of histamine produced by our body.
In western countries, dairy products and cereals with gluten, at the basis of the daily nutrition of these populations, are among the main causes of allergies and intolerances. But we will talk more about these individual foods later on as they deserve great attention and certainly not for their benefits on the body.