that’s why they are on the rise – time.news

2023-09-12 11:01:33

by Anna Fregonara

Anything that inflames the skin can trigger an immune reaction: children with atopic dermatitis are five times more likely to develop a food allergy. How to do prevention and available therapies

Each of us knows at least one person who says they are allergic to a food. Eggs, milk, soya, wheat, shellfish, fish, fruit, vegetables, dried fruit and seeds are just some of the foods we hear most often complained about, so much so that products without a certain ingredient are multiplying in shops. Among children, allergies doubled from 2000 to 2018, according to an analysis published in Washington Post, from the Centers for Disease Control and Prevention, and likely grew further in subsequent years. Even in Italy, food allergies are on the increase, begins Mona Rita Yacoub, Allergology Area coordinator at the Unit of Immunology, Rheumatology, Allergology and Rare Diseases IRCCS San Raffaele Hospital in Milan. But why do we all suddenly seem allergic to something?

The role of the skin

According to Christopher Warren, professor of Preventive Medicine and director of population health at the Center for Food Allergy and Asthma Research at Northwestern University, a possible response in the skin. If a substance enters our body from the oral route, it is probably a useful nutrient and the body tends to tolerate it. If, however, a dangerous parasite enters through the skin and the body reacts to defend itself. So anything that inflames the skin or facilitates the entry of foreign substances is more likely to trigger an immune reaction. It is no coincidence that a child with atopic dermatitis, an inflammatory skin disease, is five times more likely to develop a food allergy than someone who does not suffer from it. a plausible concept, continues Yacoub. We are born with a genetic predisposition to develop an allergy (called atopy), a predisposition that is associated with a skin barrier defect that leads to sensitization to the most common allergens. In fact, those who suffer from atopic dermatitis are more often a candidate for becoming allergic to inhalants and foods. Let’s keep in mind that environmental factors are added to this, such as air pollution or infections, particularly viral ones, which can lead to the genetic predisposition being expressed or not at any age.

The hygiene hypothesis

Even the so-called hygiene hypothesis – according to which exposing yourself to fewer germs and developing fewer infections due to better hygiene standards, antibiotic therapies and vaccinations corresponds to having more allergies – can help explain why this condition is on the rise.

Prevention

Unlike in the past, today the guidelines indicate, to facilitate the induction of tolerance and reduce the risk of becoming allergic,

expose children to all foods after weaning. In this way, tolerance is promoted, allowing the immune system to train when it is best to learn, underlines Yacoub. Obviously, familiarity must be evaluated because if there are cases of serious allergies in the family it may be worth applying some precautionary rules. This is why it is essential to rely on an allergist pediatrician to receive targeted advice and avoid the risk of the child developing nutritional deficiencies with do-it-yourself diets.

Allergy and intolerance

Allergy and intolerance are not the same thing and it can become dangerous to interchange the terms. Allergy is a reaction to an allergen, a protein, which activates the immune system through the production of certain antibodies, IgE (immunoglobulin E). These antibodies trigger the release of histamine, a biochemical substance responsible for expelling the “invader”. The release of histamine can occur at the level of a single area such as the skin, giving rise to itching and/or urticaria, or systemically, at the level of multiple organs and systems giving rise to anaphylaxis. The reaction of our body, therefore, can range from simple itching in the oral cavity (the so-called oral allergic syndrome) to anaphylactic shock which can be life-threatening, underlines the expert. Intolerance – currently the main ones are those to lactose, milk sugar, and to gluten which causes celiac disease – is instead a generic term: it indicates various adverse reactions to foods that are not caused by an allergic mechanism.

Most common allergies in children

In children the most common allergies are those to eggs and milk, but after the age of six many become tolerant because their immune system has developed and has improved its ability not to react to harmless proteins such as those contained in foods, says the specialist. In more severe cases, oral tolerance induction therapy is considered. an approach that is practiced only in specialized centers and consists of trying to induce tolerance of minimal doses of the food and is done mainly in children to reduce the risk of serious allergic reactions from contamination.

Allergies in adults

In adulthood, the most frequent are the so-called cross allergies between pollen and foods which occur when there are proteins in common. For example, a person allergic to grass pollen may develop oral allergy syndrome when eating raw tomatoes or aubergines and a person allergic to birch pollen may develop it after consuming apple, hazelnut, celery, carrot and other raw vegetables. Cross allergy also occurs in the case of mites: those who are allergic may have reactions with shrimp due to the presence of a protein, tropomyosin, in common between mites and crustaceans, explains Yacoub. Then there are food allergies in the strict sense, when the sensitization occurs orally, as in the case of sensitization to fish or to molecules typical of dried fruit or certain vegetables. An allergenic molecule characteristic of the Mediterranean area is the Lipid Transfer Protein (LTP). It is found, for example, in peach and in fruit of the Rosaceae family, therefore apricot, cherry, plum and in dried fruit, mainly in the peel. The important thing is that today we can differentiate the molecule to which the patient is sensitized. Each molecule has well-defined properties, such as resistance or otherwise to heat and gastric digestion, and is associated with a different level of severity of the reactions. Thanks to molecular diagnostics, it is therefore possible to tell the patient whether he should avoid that food completely or whether he can only eat it cooked.

Present and future therapies

We are ever closer to an innovative therapy, concludes the allergist. Specific immunotherapy approaches are starting to appear, therefore the creation of targeted vaccines for food allergens. Right now he limits himself to a few allergens like peanut. We need to wait some more time for these therapies to become available for the other most common allergens in Europe. It is important to remember that in patients with food allergies and concomitant asthma it is essential to implement adequate therapy for the respiratory disease as uncontrolled asthma represents a risk factor for more serious food allergies.

September 12, 2023 (modified September 12, 2023 | 11:03)

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