Geography and Nutrition
Eating habits and geographical distribution of allergies
There are allergies that are more frequent in certain geographical areas and others that are more common in different areas; all this seems to be related to the eating habits of the local population. This is because the greater the consumption of a food, the greater the probability that one can become aware of it.
Rice allergy , for example, is practically unknown in Italy and Europe, while it is very frequent in Asian countries, where the diet is almost exclusively based on the consumption of this cereal . The same goes for food allergy to peanuts , one of the most frequent in the United States where there is a high consumption of this food. In particular, its incidence is so high as to make it a real social problem (the possibility of including in public facilities, such as airports, areas where the consumption of peanuts is prohibited is being evaluated, since the simple inhalation of food particles can favor the appearance of the allergy). The same is becoming very common also in Europe and especially in the northern countries.
Another example is given by the allergy to kiwi , once unknown in Italy but which has become common since the 1980s, when the food became part of the normal dietary habits of Italians.
The correlation between the frequency of food consumption in geographical areas and the appearance of food allergies has recently been misrepresented and exploited to justify the cardinal principles of some “trendy” diets. According to these nutritional tricks, for too many centuries (to tell the truth millennia) the human being has eaten assiduously on wheat , towards which he would have developed a metabolic-immune resistance . For this reason, with the aim of losing weight and fighting many diseases of well – beingor of an inflammatory nature, it would be essential to eliminate many foods that are the basis of contemporary nutritional habits. For the moment, there are no scientific data to support this hypothesis.
|Foods most frequently implicated in allergic reactions in different countries of the world.|
|Scandinavian countries||Allergy to fish|
|United States||Allergy to peanuts|
|Mediterranean countries||Allergies to crustaceans and molluscs|
|Portugal||Allergy to snails (typical national dish)|
|German-speaking Switzerland||Allergy to celery|
|Italy||Allergy to celery, apple , kiwi, peach , walnut , peanut, tomato|
What does cross-reactivity mean and how to avoid it
Phylogenetically close animals and plants or belonging to the same family ( goat and sheep or tomato and eggplant ), can have very similar DNA regions . If these regions code for epitope protein fractions, on which antibody recognition occurs, cross reactivity is practically certain. This phenomenon explains why those who are allergic to tomatoes are often also allergic to aubergines or other solanaceae, such as pepper .
Those who are allergic to a certain food must therefore also pay close attention to the consumption of similar foods from a phylogenetic point of view.
Beware of hidden allergens in food!
In the food sector, soy lecithin is widely used which, due to its emulsifying properties , is a typical ingredient of many food products . Those who are allergic to soy must therefore also be particularly careful with those products to which it is added as an additive in the form of derivatives (lecithin, but also protein hydrolysates).
This danger has required greater attention in the labeling of food products. The so-called allergen directive requires, for example, to warn the consumer of the possible presence of allergens, specifying it on the label. Thanks to this directive, it is not uncommon to find on the packaging statements such as “produced in a factory where dried fruit is processed “. If the system has not been adequately sanitized before the conversion, it can happen that small residual particles contaminate the product, transforming it into a potential health risk for those who are allergic, for example, to peanuts .
Do transgenic foods contain more or less allergens?
DNA fragments from another botanical species are often included in the preparation of a transgenic plant. If this fragment of DNA codes for an epitope sequence, it can happen that the transgenic plant acquires an allergenic power, normally absent in its natural counterpart.
An example is that of soy of transgenic origin. In fact, there have been cases of people who are not allergic to soy who, feeding on it, have undergone an allergic manifestation. It was then found that this reaction was actually due to an allergy to the brazil nut , whose DNA had been used for the production of transgenic soy.
With the increasing spread of GMO foods, it becomes difficult for an allergic person to understand what he can and what he cannot eat. All this to the detriment of his health, since an allergy is dangerous not so much for the food itself, as for the possibility of coming into contact, without knowing it, with the allergenic food.
Obviously the same principle can be applied in reverse; genetic research is also aimed at producing new food varieties that DO NOT produce the sequences most often implicated in allergic reactions. Of course, this is a far from easy project to develop but, if successful, millions of consumers could finally enjoy those foods they had to avoid from a young age.