Development of Food Allergies: Role of Age and Environment

What is considered pathological in adulthood (poor function of the enzymatic systems and reduced immune response) is extremely common in the neonatal period. In fact, when it is born, the baby’s immune system is still incomplete.

A too early weaning can therefore determine the onset of food allergies, first of all because the enzymatic function is not complete (some proteins are not perfectly digested) and secondly because the intestinal mucosa is not yet fully efficient (it can let itself be crossed by food antigens ); the same goes for the immune system. It is therefore no coincidence that most allergies occur in the first period of life (in pediatric age the most common food allergy develops towards cow’s milk). Fortunately, within 3 years, there is a regression in 44-87% of cases, with consequent desensitization of the organism. Conversely, the later the allergy appears, the lower the probability of its spontaneous regression.

Environmental factors

What are the environmental factors that affect food allergies?

The incidence of food allergies is constantly growing, especially in industrialized countries. The blame is often placed on various environmental factors even if not all have been shown to be actually involved

Environmental factors NOT involved

Contrary to what was initially hypothesized, environmental factors are NOT involved in the mechanism of food allergies:

  • Smog
  • Stress
  • Reduced exercise
  • Smoking.

Scientific studies have confirmed that these factors have no role in the development of allergic diseases and, even if they can increase the synthesis of endogenous histamine and make the symptoms more evident, they cannot be considered the cause of the increased incidence of allergic diseases.

Environmental factors actually involved

  • Too much hygiene and small families: The main factors involved in this worrying phenomenon should instead be sought in excessive hygiene and in the small number of families. It has in fact been observed that children from small families are more likely to develop allergies than those who live in extended families.
  • GDP: Another interesting aspect is that the percentage of allergies in industrialized countries is proportional to GDP: the richer the country, the higher the percentage of allergic inhabitants. The same relationship also applies within the single core family, where the incidence of allergies is directly proportional to the socio-economic level.
  • Vaccines: if the use of vaccines, disinfectants and antibiotics protects us from numerous diseases, on the other hand, when used in a manic way, they subtract stimuli from the immune system which, not coming into contact with its natural enemies, not to get too bored divert its attention to food-borne allergens. Pharmacological studies have shown that under normal conditions T lymphocytes producegamma interferon , which in turn stimulates the production of antibacterial and antiviral antibodiesor cellsnatural killer. In environments where excess hygiene predominates, there is instead a greater production of immunoglobulins E, that is, those antibodies directly responsible for food allergies.

The explanation should therefore be sought above all in the excessive level of hygiene compared to the past, understood as reduced exposure to antigens .

What factors can interfere with the symptoms of food allergies?

There are also other factors, food or otherwise, that can interfere with the severity of symptoms associated with allergic manifestations.

Cold and histamine

Some food allergies become more serious in the winter because the cold stimulates the production of histamine which, when added to that released during allergic reactions , determines more evident symptoms.

Number of allergens

In the presence of an allergy to several antigens, the allergic manifestation becomes more intense when several allergens are present at the same time.


In a recent study it was observed that the incidence of atopic diseases and autoimmune diseases in rich countries is proportional to the GDP (Gross Domestic Product) and within these countries it is proportional to the socio-economic level of the family.
The increase in allergies would be due to a reduced chronic exposure to infectious agents in the first years of life, this:

  • thanks to the use of antibiotics
  • thanks to vaccines
  • for the best hygienic conditions
  • because the foodsare less contaminated with microorganisms
  • because the waterwe drink is practically sterile

When the immune system does not encounter “natural enemies” it redirects its attention to other exogenous molecules. Under normal conditions, T lymphocytes produce interferon-gamma which stimulates the production of antibacterial and antiviral antibodies and killer cells. In environments where excess hygiene predominates, the immune system produces interleukin (IL4) which in turn induces the production of IgE antibodies .


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