The term food allergy refers to an immune response to a food, with unpleasant consequences for both the allergic person and their loved ones. As shown in studies, persistent food allergies are associated with a decrease in quality of life, even greater than that of children with insulin-dependent diabetes mellitus! Their prevalence has multiplied within the last decade and all the evidence suggests that they will be of emphatic concern in the future. The involvement of the immune system is the main differentiator between allergy and food intolerance (e.g. lactose intolerance, in which a deficiency of the lactase enzyme leads to symptoms such as "bloating" after consuming milk).
The best known food allergies, because of both their noisy expression and their dangerousness, are the so-called "immediate-type" food reactions. They gather some characteristics, such as:
1. Acute onset of symptoms, within the 1st (maximum 2nd)sthour after eating the food. With the exception of the consumption of some foods in combination with exercise, where immediate-type manifestations may occur after 3 hours, the temporal correlation with food intake is clear and often described by the parents themselves. Therefore, a child cannot, for example, 'pop out' (or 'pops') because of eating an egg the day before.
2. Reversal of the clinical picture within a few hours. It is not possible to have "petals" for 2 consecutive days and associate them with food consumed shortly before their appearance.
3. Symptoms may be present on the skin (the most common, with puffiness, i.e. rashes resembling a mosquito bite and swollen eyes/lips), gastrointestinal (vomiting, itchy mouth), respiratory (coughing, sudden hoarseness, shortness of breath) and circulatory (sudden dizziness, hypotonia). Respiratory manifestations in particular are the ones that usually determine the severity of the reaction, while children who already have a history in this direction (e.g. asthma) are more likely to have more severe reactions.
4. The most severe reaction that can occur is anaphylaxis, a systemic reaction (i.e. involving more than one organ), potentially life-threatening for the allergy sufferer. The only effective intervention we can make in this case is the use of adrenaline. Nothing less! The myth, which is unfortunately very widespread even among members of the medical community, that "fortunately cortisone was given and we were saved" is false, potentially dangerous and should be eliminated from medical practice as soon as possible.
5. Direct-type reactions are characterized by the presence and action of specific antibodies (IgE immunoglobulins) to food allergens-proteins. These are detected by special blood tests, such as RAST. But be careful! In only about half of the cases, a positive RAST value for a food implies clinical disease and it is the task of the allergist to evaluate the possible association. Food avoidance and exclusion diets based only on laboratory results are wrong and can have very negative consequences.. Direct food allergies in a large proportion occur in children with a history of atopic dermatitis and often follow this in a child's so-called 'atopic course', at the end of which come respiratory allergies (hay fever and asthma). As far as their natural course is concerned, it depends mainly on the type of food allergen that causes reactions. Thus, milk and egg allergies are usually overcome in preschool age, cereal allergies may persist somewhat longer, while fish and nut allergies usually persist into adolescence or even later in adult life.
A cornerstone for the diagnosis of food allergy of the direct type is the taking of a correct-observant- analytical history. The allergist can gather valuable information, separate the important from the unnecessary and prevent unnecessary manipulations. Skin prick tests (painless skin tests) and the necessary laboratory testing (detection of specific IgE with the classical RAST method and also with more modern molecular methods) are the next steps. In case the allergy is assessed as highly probable, specific advice is provided by the allergist, both on diet and on how to deal with a possible future reaction. In the opposite case, when it is judged that some symptoms are not consistent with a direct type of reaction to a food, it is administered in a controlled manner, in a specific setting and in the presence of the allergist. This procedure is called food challenge and is intended to "release" the food into the child's diet. The same procedure may be followed when it is considered that an allergy has passed and there is tolerance to the food.
Let us dwell a little on modern molecular diagnostics, which is also applied in our unit. It opens up new horizons since by detecting the specific protein subset of a food that causes the reaction, it allows us to make more precise approaches. For example, we can assess whether a future reaction to a food will be relatively mild or potentially severe as well as determine possible cross-reactivity with other foods. The treatmentof food allergy of the direct type has a "passive" version that means avoiding food in anticipation of a possible favourable natural course that will lead to tolerance and a more "active" version. In the second case, which is also applied in our Unit for some children who meet conditions for certain foods, the allergist actively attempts to increase the chances of tolerance. This is done by administering "hypoallergenic" forms of the foods (such as roasted milk or egg), administering related foods that the child tolerates (e.g. other nuts in peanut allergy) or by applying oral desensitization protocols (SOTI). This accelerates positive developments in terms of food tolerance or reduces the chances of a severe reaction to an "accidental" contact with a trace food. Finally, because in many cases even the most careful avoidance can fail, especially in cases of anaphylaxis, children and their
parents/ guardiansshould always have
dealing with a possible reaction. As mentioned above, a cornerstone of this approach is the use of adrenaline.