Food allergy is various clinical manifestations of allergy associated with eating.
The etiological factor of food allergies is food containing proteins, polysaccharides, low mol. substances acting as haptens (food allergens). There are common food allergies to milk, eggs, fish, meat and products from these products (cheeses, butter, noodles, creams, etc.), vaccines against influenza, tick-borne encephalitis grown on chicken embryo allantois, as well as tomatoes , strawberries, raspberries, melons, garlic, beans, honey, nuts, chocolate, spices, citrus. Food allergy to meat, sometimes only to the one of certain animal species, is relatively common. In cases of food allergy to meat, a cross-reaction to the introduction of horse serum and contact with epidermal allergens are possible. The smell of a prepared product, especially fish can cause food allergies. If you are allergic to mushrooms, products, which contain yeast: beer, cheese, bread, can provokefood allergies. Additives and impurities contained in food: preservatives (benzoic and acetylsalicylic acid), food dyes, residual amounts of chemicals, penicillin added to feed, used to treat animals and therefore detectable in milk can have allergenic properties.
Food allergies associated with the intake of milk, occurs in 10% of newborns. Clinical manifestations of food allergies in children include early and late reactions. Early reactions develop within 1 hour from the moment of milk intake and provoke severe anaphylactic shock, including death, acute gastroenteritis, hemorrhagic diarrhea, vomiting, collapse, migraine, rhinorrhea, bronchospasm, swelling of the tongue and larynx . In childhood, “food” asthma accounts for 5% of cases. The development of nephrotic syndrome caused by the fixation of antibodies belonging to immunoglobulins E on the surface of the renal epithelium, and cases of allergic myocarditis are described. A number of food allergy manifestations are associated with the participation in its pathogenesis of antibodies related to immunoglobulins G and the formation of IR: thrombocytopenia, hemorrhagic diathesis, allergic vasculitis.
Heiner syndrome is described – eosinophilic reaction in children caused by intolerance to cow’s milk. It can provoke manifestations of gastroenteritis, profuse diarrhea, progressive weight loss combined with damage to the lungs (eosinophilic infiltrates, hemosiderosis), iron deficiency anemia, rhinitis, and delayed overall development. In the blood of patients, eosinophilia, precipitating and reagin antibodies against cow’s milk, an increase in the level of immunoglobulin E are determined.
Late manifestations of food allergies in children are mainly associated with skin lesions: atopic dermatitis, urticaria, angioedema. Symptoms of food allergies are observed in different parts of the gastrointestinal tract. They can provoke possible development of allergic stomatitis, gingivitis, damage to the esophagus with symptoms of edema, hyperemia, rash on the mucous membrane, feelings of difficulty swallowing, burning and soreness along the esophagus. They often affect the stomach. Such a lesion in the clinic is similar to acute gastritis: nausea, vomiting of food eaten, pain in the epigastric region, tension in the abdominal wall, eosinophilia of gastric contents. With gastroscopy, swelling of the gastric mucosa is noted, hemorrhagic rashes are possible. Allergic manifestations can proceed as a peptic ulcer and provoke its aggravation.
There are colicy or persistent pain, bloating, frequent liquid stools during enteropathy, in severe cases – tension of the abdominal wall, tachycardia, a drop in blood pressure. In the feces, undigested food, mucus, and sometimes mucous films (mucous colic) are defined. Clinic of intestinal lesions in food allergy has similarities with the picture of “acute abdomen” and suggests an acute appendicitis, intestinal obstruction, thrombosis of the mesenteric vessels. A picture of hepatic colic includes an increase in the size of the liver, a change in functional liver tests, food allergies can dramatically increase the clinical manifestations of hepatitis. In some cases, food allergies may be accompanied by painful itching in the anus.
In the chronic course of food allergy, the development of secondary disorders of the functions of digestion is possible: steatorrhea, absorption disorder syndrome, exudative enteropathy, iron deficiency anemia, gastric and intestinal bleeding. Among the common manifestations of food allergy in adults, there are migraines, asthma, bronchial asthma, persistent recurrent urticaria, dermatitis, in rare cases – anaphylactic shock.
Differential diagnosis of food allergy is carried out with enzymopathies, manifested by food intolerance, chronic inflammation of the gastrointestinal tract, occurring with a violation of absorption. It is necessary to take into account the possibility of a negative psychogenic reaction to food with vegetative symptoms, including intestinal, as well as the fact that food allergy, which forms on the background of the underlying disease most often of the gastrointestinal tract, may become its most severe clinical manifestation. Therefore, it is especially important to establish whether food allergies are primary or secondary in nature, to identify and treat the underlying disease: gastritis, most often with secretory insufficiency, cholecystitis, hepatitis, pancreatitis, enteritis, colitis, helminthiasis, cystic fibrosis.
Diagnosis of food allergies is aimed at detecting an allergen in order to eliminate it from food, in some cases, at conducting specific hyposensitization and identifying factors contributing to the development of allergy and the clinical manifestations of food allergy. Examination of the patient for food allergies should be aimed at determining the allergen, allergic susceptibility and factors contributing to the manifestation of food allergies. The following clinical and laboratory methods are used to identify the allergen:
- Allergy history; elimination diet – elimination of the suspected allergen and its products from food until the symptoms disappear, followed by a single connection of the product, either imperceptible to the patient, or blindly, using placebo. If it is difficult to guess the allergen, the diet is expanded, connecting in turn various products and observing the possible development of allergic symptoms.
- Coca’s test is an increase in pulse rate by 12-15 beats per 1 minute and a decrease in diastolic pressure by more than 10 mm Hg. st. after a single dose of the intended allergen (sample is simple to set, but not sufficiently informative).
- Leukopenic index (Vidal’s test – Vaughan) – a decrease in the number of leukocytes 1 hour after the allergen was taken per 1000 cells with an initial level of at least 3.5 thousand in 1 mm3 (the sample is informative in 70% of cases).
- Thrombocytopenic index – a decrease in the number of platelets after 30, 60, 90 minutes after a single dose of the proposed allergen is not less than 25% relative to the initial level.
- X-ray method – a violation of the motility of the gastrointestinal tract with the joint introduction of an allergen with a barium suspension: increased peristalsis of the stomach and intestines, rapid evacuation of food from the stomach, spasm of the pylorus;
- Study of respiratory function after taking the allergen in case of suspected “food” bronchial asthma;
- Aspiration gastrobiopsy after the introduction of the allergen increase in the number of goblet cells and eosinophilia of gastric secretion, accumulation of lymphocytes, plasma cells in the stroma (the recommended dose for the test is 100 g of the substance or 100 ml of liquid);
- Determination of antibodies against allergen — skin tests: application, scarification, intradermal, PACT, Shelley reaction, mast cell degranulation test, leukocytolysis reaction.
The treatment of food allergies in the acute period is aimed at relieving the main clinical manifestations: anaphylactic shock, angioedema, asthma, bronchial asthma. With the threat of asphyxia caused by swelling of the larynx, it is necesssary to conduct a tracheostomy. Treatment of food allergies includes washing the stomach and intestines in order to remove the allergen and then transfer it to parenteral nutrition until the allergic manifestations are eliminated. In severe cases, glucocorticosteroid preparations are prescribed (intravenous hydrocortisone-125 mg, dexazone – 4-8, prednisolone – 15-30 mg with a gradual decrease in dose as the clinical manifestations subside) and antihistamines (first injection, later in combination with diazolin, tavegil fencarol).
In the period of remission or in the latent course, the treatment of food allergies should combine diet therapy with desensitizing drugs and therapy of the underlying disease that contributed to the development of food allergies. An elimination diet is aimed at eliminating the known allergen and dishes containing it. If the allergen cannot be identified, all products that can cause allergy symptoms are excluded. The recommended diet includes a weak tea with a small amount of sugar, dried white bread, cereal (buckwheat and oatmeal “oat-flakes”, first in the water, and then with the addition of a small amount of sunflower oil). A few days after the complete elimination of allergic manifestations, the diet begins to be expanded due to the alternate addition of food to the diet. During this period, it is recommended to keep a food diary in which it is necessary to record each eaten product, its quantity, method of preparation. At the same time, specific diagnostics and provocation tests can be carried out. The appearance of food allergy signs when adding a new product indicates its allergenicity.
Several variants of an elimination diet have been proposed, each of which excludes certain types of products with common allergenic properties.
Diet 1: rice, rice sponge cake, rice bread.
Diet 2: rye, corn, corn tortillas, corn and rye buns, rye bread.
Diet 3: beets, asparagus, carrots, spinach, potatoes, tomatoes, beans, lemon jelly, beet or cane sugar, olive and sesame oil, bread mixed with soy, lamb, chicken meat, bacon, baking soda, salt, vinegar, pineapple , apricot, pear, grapefruit, lemon, peach, plum.
Diet 4: milk, cane sugar.
The first two diets include food types that are rarely allergens, the first three exclude milk, eggs, and wheat, the fourth — meat, eggs, and wheat. Diets are valuable not only from a medical but also from a diagnostic point of view.
For treatment of patients with food alleles, unloading-diet therapy has been spread, it is advisable to carry out with persistent recurrent skin manifestations associated with food intake and attacks of “food” asthma. This type of treatment should be carried out only in a hospital with possible subsequent repeated courses and a diet between them. In all cases, food allergy sufferers need a strict restriction or complete ban on spices. spicy, salty foods, meat, fish products, carbohydrates (sugar, jam, honey), alcoholic beverages, including beer. Food should be rich in vitamins. It is important to avoid overeating.
Culinary processing reduces the allergenicity of products. Boiling milk for 15-20 min causes denaturation of the albumin fraction, which in most cases significantly reduces allergenicity. Condensed milk, passed in the process of manufacturing high-temperature processing, and dairy products are less allergenic than fresh milk, and can be carefully consumed in small quantities. The allergenic properties of eggs during cooking are greatly reduced, while the allergenicity of the fish decreases slightly.
Desensitizing non-specific therapy for food allergies is a course of treatment with calcium gluconate, sodium thiosulfate, histaglobulin. Intal is becoming increasingly common: in the form of powder and microclysters. Treatment of the underlying disease of the gastrointestinal tract should be directed at correcting gastric secretion, normalization of biliary excretion (blind sensing, choleretic herbs) and include antibacterial sanitation of the inflammatory process, normalization of the intestinal flora with dysbacteriosis, the use of enzyme preparations (festal, mexase, mexoforma, pancrereosis, mexase, mecoformal .) and protease inhibitors for pancreatitis.
It is possible to perform specific hyposensitization in food allergies to common foods that make up an important part of the diet: milk, wheat. A week before the treatment, the allergen and products containing it are completely eliminated from the diet. Water-soluble products are diluted with boiled water at a ratio of 1: 5, 1:10, 1: 100 and 1: 1000. The patient receives the product from the maximum dilution orally in a teaspoon two or three times a day and, in the absence of food allergy, gradually decreases dilution. Fresh solutions are prepared every one to two days. Parenteral desensitization does not apply. The course of treatment is designed for several months, with the positive effect of the patient are warned of the need to continue to refrain from frequent or excessive intake of the product that caused food allergies.
Prevention of food allergies includes the careful use of foods with increased allergenicity in children with an allergic predisposition and in adults with various manifestations of allergies or diseases of the gastrointestinal tract. It is advisable to limit highly allergenic products during pregnancy due to the risk of fetal allergy.