Therapeutic measures in practical allergology include three stages: relief of allergy symptoms, acceleration of allergen elimination, and prevention of subsequent contact with it. In case of intolerance to essential foods, desensitizing immunotherapy is used.
It is also important to take into account the risk of cross-reactions, so after identifying an allergen, a specialist can limit the consumption of a number of dishes at once. Their exclusion from the diet reliably guarantees the absence of new episodes of food allergies.
The main stages of treatment consist of:
- Symptomatic therapy. Apply antihistamines in various forms of release – in the form of tablets, syrups (in pediatric practice) and nasal sprays. In most cases, a single dose of this group of drugs is enough to completely eliminate the manifestations of food allergies. In the case of a more severe course, their course application may be prescribed by a specialist.
- Elimination of the allergen from the body. It can be provided by the appointment of a special hypoallergenic diet, and pharmacological methods. In the case of a recent (several hours) ingress of a provocative product in the gastrointestinal tract, enterosorbents are effective – activated carbon, polysorb. They bind antigens in the intestinal lumen, preventing them from entering the systemic circulation. If several days have passed after the penetration of allergens, or they have been ingested for a long time, then their elimination is possible only naturally. It can be somewhat accelerated by infusion therapy or diuretic administration.
- Allergen-specific immunotherapy (ASIT). This stage of treatment is possible only after a thorough diagnosis of the pathology and an accurate determination of the provoking antigen. Appointed if the list of prohibited foods is too extensive, or it gets irreplaceable components of food. ASIT consists in the introduction of gradually increasing dosages of the allergen in order to develop immunological tolerance to it.
Food allergiesis the most common allergopathology, due to the significant variety of substances that make up human food. Approximately half of the patients are children under the age of 12 years; in older persons, the prevalence of the disease is reduced. More frequent occurrence of the disease in children is explained by contacts with antigens new to the body and increased reactivity in this period of life. In the future, most food compounds produce immunological tolerance, and allergies are much less common. There is a genetic predisposition to the development of this condition, which has a polygenic character. In some cases, the intolerance of certain products persists throughout life and may be complicated by cross-reactions and other allergic conditions (for example, bronchial asthma).
Causes of food allergies
Most cases of the disease are due to hypersensitivity of the first type, mediated by the release of IgE and activation of tissue basophils. The direct cause of the pathology is the entry into the gastrointestinal tract of protein compounds that are recognized by the immune system and trigger its abnormal response. Revealed a huge number of predisposing to food allergy conditions and characteristics of the body, some of which are characteristic only for children. This is another reason for the frequent development of an allergic reaction in the pediatric population.
Among the most common factors contributing to the emergence of food intolerance, there are:
- Features allergen. Hyperreactivity is more often caused by food antigens, which are highly immunogenic and capable of overcoming the barriers of the digestive system (in particular, the aggressive environment of the stomach) without degradation. Most of them are found in cow’s milk, fish, egg whites, grains, some fruits (strawberries, citrus fruits) and nuts. About 80% of all cases of the disease are due to hypersensitivity to these products.
- Genetic factors. The development of intolerance may be due to the hereditary and genetic properties of the organism. They can manifest an increased level of reactivity, anomalous activity of immunity and other conditions that facilitate the development of allergic reactions.
- Age features of the digestive tract. The occurrence of food allergies is facilitated by the high permeability of the gastrointestinal tract walls observed in children, low acidity of the gastric juice, and disturbances in the composition of the intestinal microflora. These conditions facilitate the contact of the allergen with immunocompetent cells that trigger the allergic process.
The probability of occurrence of the disease is also influenced by the amount of the allergen inside the body, the nature of the culinary treatment of products containing provocative substances. Product intolerance may be due to cross-allergy to pollen or household dust.
Sensitization of the body while causing airborne antigens, but the reaction can initiate and foods that have similar compounds in its composition.
Food Allergy Pathogenesis
In the process of developing food allergies, sensitization of the body initially occurs – it occurs during the first contact with an allergen. The latter is recognized by immunity cells, which, through a series of intermediate reactions, cause the formation of class E immunoglobulins specific to this proteinaceous compound. Antibodies of this type have the ability to adsorb on the surface of tissue basophils, remaining there for a long time.
When re-entering a provoking antigen, it binds to IgE, which activates mast cells, causing them to degranulate with the release of histamine. This biogenic amine causes the expansion of blood vessels, tissue swelling, irritation of the nerve endings – these changes are manifested by skin itch, urticaria, dyspepsia.
The peculiarity of food allergy in infancy is the exclusion of the sensitization stage from the pathogenetic chain of the disease. Antibodies against the allergen enter the child’s body transplacentally or with breast milk from the mother, who suffers from intolerance to certain products.
For this reason, it is especially important for women with allergies to control their diet during pregnancy and lactation, otherwise there is a risk of developing a pathology in the infant. But the duration of such a condition in children is insignificant – maternal antibodies are completely eliminated from the body several weeks after the cessation of natural feeding.
Symptoms of food allergies
The clinical picture of the pathology is quite varied, statistically more often recorded skin symptoms that occur within 2 hours after a meal. Itching develops, rash of various localization, usually of erythematous character.
Some patients complain of urticaria and other edematous phenomena on the skin surface. Depending on the severity of the allergy and the nature of the provoking substance, these symptoms may persist for several hours or days. After that, provided there is no contact with the allergen, the skin manifestations usually disappear completely and completely. With continued use of a dangerous product, an allergic reaction is recorded again, with each new episode characterized by more pronounced and severe symptoms.
Food allergies can be manifested by disorders of the gastrointestinal tract in the first hours after consuming allergenic products. Patients complain of abdominal pain, nausea, and sometimes vomiting and diarrhea. With a particularly high allergic readiness of the body, these symptoms can develop at the time of the meal. Dyspepsia is accompanied by swelling of the mucous membranes of the oral cavity, lips, surface of the tongue. Sometimes this allergic process leads to nasal congestion, lacrimation, conjunctivitis, which creates a false picture of pollinosis or intolerance to household dust.
Certain foods (peanuts, some fish, strawberries) contain allergens that cause severe systemic reactions – angioedema and anaphylactic shock, accompanied by spasm of the larynx and a drop in blood pressure. In patients with bronchial asthma, hypersensitivity to food components may trigger the development of an attack by the mechanism of cross-allergy. A number of patients noted the appearance of headaches, fatigue and weakness after eating foods with provocative products.
Food Allergy Complications
The most severe complication of food allergy is anaphylactic shock caused by massive basophil degranulation and the release of a large amount of histamine. It occurs with a predisposition to intolerance to certain products or with prolonged disregard for the manifestations of the disease.
The continued entry of the allergen into the body leads to a gradual increase in symptoms and ultimately provokes the development of shock.
If the allergy is accompanied by vomiting or diarrhea, then prolonged contact with the antigen can lead to electrolyte disturbances. Other complications include the occurrence of cross intolerance to pollen or household dust antigens, skin infection as a result of scratching and damage.
Diagnosis of food allergies
The definition of food allergies is made by an allergist, an immunologist, and the close and trusting contact of the doctor with the patient or his parents (in the development of pathology in children) is important. For the diagnosis of the disease using the data of anamnesis, the results of laboratory and immunological studies, as well as provocative tests. The latter should be used only in the case of relatively low body reactivity and ease of allergies. If there is a risk of systemic reactions (angioedema or anaphylactic shock), research involving patient contact with the allergen is prohibited.
Confirmation of the diagnosis and determination of the provoking product is carried out according to the following algorithm:
- Inspection and collection history. Examines the patient’s skin to determine the nature and severity of rash, in controversial cases, you may need to consult a dermatologist. The food history is analyzed: it turns out which products have been consumed in recent days and in what quantity. Based on this, the range of possible allergens is limited, which facilitates further research.
- Lab tests. In general, the analysis of blood insignificant eosinophilia is determined only with strong or repeated episodes of allergy. According to the indications, nasopharyngeal swabs, smears-prints from the conjunctiva are subjected to microscopic examination – they also show eosinophils. Biochemical blood test reveals a high level of immunoglobulin classes E and G.
- Allergic skin tests. For accurate determination of the allergen using application tests or prik-test. At the same time on the skin cause the standards of antigens that have come under suspicion during the interrogation of the patient. The development of redness and edema is a positive reaction and indicates the presence of allergy intolerance.
- Immunological analyzes. These include enzyme-linked immunosorbent assay (ELISA) and radio-allergosorbent test (RAST). They are carried out to determine the type of provoking antigen with a high reactivity of the body, when skin tests are excluded. These tests accurately determine the presence of allergen-specific IgE in the patient’s blood.
Differential diagnosis of food allergies should be carried out with other diseases of an allergic nature (pollinosis, atopic dermatitis) and skin pathologies (eczema, infectious lesions). With the development of dyspeptic disorders, it is necessary to eliminate the risk of foodborne illness or other diseases of the digestive system.
Sometimes symptoms similar to allergies can occur due to the use of unusual or exotic dishes. Usually, these states disappear spontaneously within a few hours and rarely recur.
Prediction and prevention of food allergies
The prognosis of food allergy is favorable, especially with the development of the state in childhood – as the child grows, food intolerance gradually disappears and practically does not manifest itself in the future. In the case of severe reactions to peanuts, seafood and some fruits, quite often patients have to give up their use for life.
In addition, they are advised to carry first aid equipment for anaphylactic shock (for example, a special pen with adrenaline). Prevention is reduced to the restriction of the use of high allergic risk products in baby food and during pregnancy, and, in the presence of reactions, to their complete withdrawal from the diet.