The term "food allergy" (AAL) is used for those adverse reactions to foods whose pathogenesis is immunologically mediated by IgE, using, on the contrary, the expression "food intolerance" for those other adverse reactions, where immunological mechanisms are not involved (Lactose intolerance). The incidence of ALA mediated by IgE ranges from 1-4% of the general population and up to 8% among those less than 3 years old. In most of the times, the age of onset is in the first year of life. Food allergy causes 100-200 deaths in the US each year.
Clinical Manifestations
The frequency of sensitization depends on the allergenic power of the food and in turn on the frequency of its consumption (it depends on the eating habits in each geographical area). So the allergy to peanuts and cereals is very common in the US but much less in Spain. In our environment, the most common causes of AAL are egg white, followed by cow's milk, and fish third. These three represent 85% of the food sensitivities in the child. Other common causes of AAL in Spain are fresh fruits (peach), nuts (walnuts), shellfish (crustaceans and molluscs), Anisakis (a larva that parasitizes sea fish) and legumes.
Children allergic to chicken egg white are also egg whites (leg, quail, partridge, pigeon) but not chicken or chicken. Those allergic to cow's milk are also allergic to other species (goat milk, sheep), but not to beef or veal or the epithelia of these animals. Those allergic to a fish, for example: to the sole can be to other more fish species, although not necessarily to shellfish (molluscs or crustaceans). Cross-Reactivity can also be observed between legumes (lentils, chickpeas, beans, beans, peas) or grasses (wheat flour, rye, barley, corn).
Regardless of this sensitization to multiple related foods, 46% of patients also have sensitization to two or more unrelated foods (eg: egg and milk). The symptoms experienced by these patients are the classic ones produced by any antigen that gives rise to an immediate type I hypersensitivity response. Its intensity depends on the degree of sensitization that the patient presents to that food and the degree of exposure to it (relationship stimulus-response).
In 80% of the cases they suffer cutaneous manifestations; Acute urticaria-angioedema of variable intensity, there may also be perioral rashes, pruritus, and enanthema in oral mucosa and occasionally glottal edema.
They follow in frequency the digestive pictures that appear alone or associated with 30% of the cases. They consist of vomiting or acute diarrhea, accompanied or not by colic pains.
Respiratory manifestations consist of rhinitis, cough and sometimes crises of asthma. In many cases, it is more by the inhalation of food (fish, vegetables) than by ingestion.
Although less frequent, they may suffer anaphylaxis, especially with nuts, eggs, fish, crustaceans, and milk.
Aeroallergens And Food Allergy
Food sensitization also appears as a consequence of an initial allergy to an aeroallergen (cross-reactivity), frequently encountering certain associations, such as polysensitization to southern European pollens and peach fruit, birch pollen (Northern Europe) and fruit of apple and hazelnut, Ambrosia pollen (USA) and watermelon, Artemisia and celery pollen (artemisia-celery-carrot-mustard and other spices), Hevea braziliensis latex (latex gloves) and avocado, kiwi, banana, chestnut, walnut and peach, pollen of Platanus hispanica and lettuce, house dust mites (coastal areas) and prawns or snails, bird feathers (parakeets, goldfinches, canaries etc) and chicken egg yolk (only in adults).
The severity of food allergy is usually lower when it comes from pollens (oropharyngeal pruritus) and greater when it comes from latex.
Food Allergy Enhancers
Patients sensitized to a food can be found who tolerate their intake without problems, but who, on the contrary, stop tolerating it if they concomitantly take an Ibuprofen-type NSAID, in other patients, it is alcohol and in others the exercise in the 4 hours following its ingestion. Heat can modify the structure of some proteins multiplying their allergenicity (lentils, peanuts, squid, shellfish).
Fish
Parvoalbúminas are by far the most important allergens of the fish, they are in all the species although not in the same amount, that explains why some species are less allergenic such as the family Xiphiidae [emperor] or Scombridae [tuna, mackerel]) that other Pleuronectiformes (rooster, turbot sole). They are not destroyed by heat and are not found in seafood. They are also not found in the Anisakis (fish parasite) that results in an independent allergy.
Seafood
They include crustaceans (shrimp, spider crab, barnacle, etc.), molluscs (bivalves clams, oysters, mussels, etc.) univalves molluscs (lapa, periwinkle, cañadilla, etc.) cephalopod mollusks ([squid, octopus, cuttlefish, etc. ]) The responsible allergens are proteins called tropomyosins, which are thermo-resistant and soluble, which explains their great abundance in the cooking water. Patients are usually allergic to crustaceans and molluscs, although any combination can occur; crustaceans and bivalves, cephalopods and bivalves, etc.
Tropomyosins are also found in mites and cockroaches, which leads to cross-reactivity with shellfish.
Nuts
Walnut and almond nut are the most frequent allergy producers in Spain. They also include hazelnuts, cashews, pistachios, sunflower seeds, pumpkin seeds, chestnuts, brazil nuts, peanuts, pecan nuts, flax seeds, sesame seeds, and pine nuts. The reactivity between them is variable depending on the dry fruit involved.
Vegetables
Lentils, chickpeas, and peas. Less common white beans and pints. On the contrary, allergy to soybeans is rare, despite being very common in Anglo-Saxon countries. The most frequent are tomato, lettuce, carrot, celery, cabbage, eggplant, and peppers. They are followed by onions, garlic, spinach, squash, and asparagus.
Fruits
The most common is the peach (rosacea) is always the initial rosacea and from there crosses with other rosacea (nectarine, apricot, apple, pear, cherry, plum, strawberry, blackberry, almond).
Other important fruits are a kiwi, mango, pineapple, melon, watermelon, avocado, and grape.
Spices
Pepper, anise, ginger, sesame, cumin, and paprika among the most common.
Profilins
They are heat-sensitive proteins that are not resistant to gastric digestion, which explains why they only give mild allergic reactions at the level of the oropharynx (Oral Allergy Syndrome [OAS]). They are part of the cytoskeleton of many plants which leads to cross-reactivity among a multitude of fruits-vegetables-pollens.
Plant Defense Proteins:
They are found mostly on the skin and are distinguished:
The allergens belonging to Group 10, known as homologs of Bet v 1 (major allergen of birch pollen). They are thermo and sensitive acid so that like the profilins their ingestion only produce ODS. The primary sensitizer is birch pollen (inhalation, producing pollinosis) and hence cross-reactivity with some fruits (apple, etc.).
Lipid Transfer Proteins (LTP):
Very resistant to digestive enzymes and temperature. This explains its ability to sensitize through the digestive tract and why its ingestion can lead to serious allergic reactions. One of the first fruits in which they were described was in the peach (Pru p 3). LTPs are found in many fruits, vegetables, and pollens.
Chitinases:
They are allergens associated with the latex-fruit syndrome. Those allergic to latex have secondary cross-reactivity with banana, avocado, chestnut and kiwifruit among other fruits.
Storage proteins:
They intervene in the maturation germination and development of the seeds. They are associated with severe allergic reactions by peanuts, as well as other legumes and nuts.
Alpha-gal:
It is an oligosaccharide found in red meat (pork, ox, etc.) also in the viscera (kidneys, liver, corns) and also in the cetuximab (cancer drug). Unlike other food allergens, in this case, the reaction begins between 2-6 hours after ingestion, probably because it is absorbed in the intestine with fats. It is necessary that the patient has been bitten in the previous weeks or months by the deer tick.
Diagnosis
The adverse reaction to suspect food and the underlying immunological mechanism must be demonstrated. In clinical practice, the steps to follow are:
Clinical history: It must be detailed, collecting the nature and severity of the symptoms, age of onset, the temporal relationship between the ingestion of suspect food and clinical syndrome. The possible role of food additives and foods with cross-reactivity, as well as intercurrent diseases (infections), should be assessed. In the infant, it is necessary to detail the introduction of different foods and their tolerance. If you have had breastfeeding, if you have interspersed with isolated milk bottles, etc. Determine the presence of personal and/or family history of atopy.
Demonstration of hypersensitivity: It is done through skin prick tests. If the skin tests to food (s) are positive, it is useful to differentiate within a given food, to which protein (s) the patient is sensitized, since not all allergenic proteins have the same clinical relevance, in our Center, we determine it through the ISAC.
Checking the intake-symptom ratio: Among patients with sensitization to food (prick, RAST or positive CAP), approximately 30%, tolerate their intake without problems (subclinical sensitization). Therefore, it is obvious that if history is not clearly suggestive, it is necessary to corroborate that this sensitization has clinical relevance. This can be done through food challenge tests.
Differential Diagnosis
It must be done with other processes not due to food but that occurs with vomiting/diarrhea (cystic fibrosis, etc.) and with adverse reactions to food but of non-immunological cause (intolerance to lactose, etc.) or immune-mediated IgE (enteropathy) by diet proteins, celiac and others).
Treatment
Once the diagnosis is made correctly, the treatment consists of eliminating the food responsible for the picture. In extremely sensitized patients (fortunately the least frequent) fatal reactions have occurred after the ingestion of small amounts of the forbidden food that was masked in others (for example: peanut in chocolates) or even by contact with the oral mucosa without ingestion (after receive a kiss from her boyfriend who had previously eaten a chocolate with peanut or after biting a tortilla sandwich that he did not eat). It is important to read the labeling of food, the European Union requires manufacturers to warn about the presence of "traces" of gluten, crustaceans, eggs, fish, peanuts, soybeans, milk, nuts, celery, mustard, sesame seeds, dioxide of sulfur and sulfates.
The foods with which it is cross-reactive must also be eliminated, although not all, but on the contrary, only those in which we have proven that they are capable of producing symptoms in the patient. For example, if you are allergic to peach (rosacea) it is often clinically only 1 or 2 of the group, tolerating others.
With the vegetables, we only avoid those that produce clinical sensitization, which may be a lentil and/or chickpea and/or pea. On the contrary, beans are usually tolerated.
With nuts, starting at age 6, only those that we consider being clinically relevant in the patient are excluded, based on the ISAC and oral provocation tests.
In those cases of sensitization to multiple unrelated foods that prevent to be able to perform a correct elimination diet, a treatment with CGDS can be tried orally, cheaply but unfortunately often not very effective. Much more useful is the subcutaneous administration of Omalizumab every 2-4 weeks, which is a monoclonal antibody that blocks IgE, the problem is that its price greatly limits its use.
Parenteral (injections) and sublingual vaccines have in some cases achieved some efficacy. For example, some (though not all) of the patients receiving immunotherapy against birch pollen, develop tolerance to the apple. In isolated studies, it was observed how sublingual immunotherapy with hazelnut extract or peach extract managed to increase the deactivation threshold, although not complete tolerance.
Much more effective are oral immunotherapy treatments, with a success rate for milk and eggs that exceeds 90% of cases. In the center, we are currently doing it in children from 6 years of age who have not developed their tolerance to these foods in a natural way and in whom the food reaction was not serious (anaphylaxis or laryngeal edema). It consists of orally giving increasing doses of the food in question, for example in our center, with milk, we start with only 12 μL and it is increased until we reach 200 mL. With the egg, one starts with 1 mg of white and reaches 33 mL (the white of an egg). The increments are always done in the clinic (every week) and the patient maintains these doses daily at home. This type of treatment requires that the patient go to the clinic weekly for about 4 months. It is globally quite safe, being for the majority of the patients the reactions only occasional and mild (discomfort of the stomach or urticaria.) Eosinophilic Esophagitis is a complication that only very occasionally appears.
Patients who have suffered moderate or severe reactions should wear an adrenalin auto-injector, in the event of anaphylaxis due to the inadvertent ingestion of the prohibited food (hidden food).
Evolution
Young children with food hypersensitivity to milk or eggs, in 85% of cases, lose their clinical sensitivity at 3 years of age. In the case of the egg, it takes something more, spontaneously remitting in 65% of the cases at 6 years of age.
With legumes they also tend to overcome it, on the contrary, those allergic to fish or nuts, it is common to never lose clinical awareness. For example, in the USA, only 1 in 5 children allergic to peanuts develop tolerance with age.
Patients with a history of anaphylaxis, especially older children and adults should not undergo a provocation. The persistence of skin tests or CAP positive to the food does not necessarily indicate that it will not tolerate it. On the contrary, the negativization of these usually correlates well with tolerance to food. The molecular study can help predict which patients are more likely to tolerate food (see ISAC)
Food Allergy, General Advice:
Allergens in food are usually proteins. The treatment of the allergy to a food protein consists of strictly avoiding foods that contain it. For this, we must take into account the following recommendations:
► Avoid eating the food that produced the allergic reaction, but also those of the same family with which you can share common proteins and produce the same reaction.
► Read food labels to familiarize yourself with their technical and scientific names. For example, milk may not appear as an ingredient, but the label may indicate the presence of casein (a protein in milk). Egg white often appears as albumin. With processed foods, it is practical to familiarize yourself with certain brands and not change frequently.
► To avoid eating a "hidden" allergen at meals outside the home, they should consult about the ingredients when eating at restaurants or other homes.
► Report to the school. The school staff should be fully informed of the foods to which the child has allergies and should be responsible for eliminating them from their diet. Children with severe food allergies should bring all prepared food from home.
► Educate your child so that he does not accept food from other children and avoid the foods to which he has allergies, as long as his age allows him to understand it.
► Your child may also have a reaction by contact or inhalation of the food. In addition to ingestion, children very sensitive to food, such as fish and shellfish, may present a reaction, even serious, when inhaling the vapors of their cooking and there may also be a reaction to direct or indirect contact with objects contaminated by food (cutlery, napkins). , etc.), the hands of the person who has been manipulating the food or even kissing them immediately after eating it. In the case of very sensitive patients, it is essential to use personal kitchen utensils and tableware.
► You can not take cooking broths, nor should the oil in which the allergenic food has been cooked be used for the allergic.
► If your child is small, put a label on your clothes indicating your allergy, you can ask at our center for labels that adhere with the iron.
► In the case of presenting a reaction due to accidental ingestion of the food, you should follow the instructions and treatment recommended by your doctor.
0 Comments