Food allergy: causes, symptoms, diagnosis, treatment and prevention
Food allergy is considered as a type of food intolerance.It develops as a result of complex immunological reactions of the body to a particular allergen present in food.This type of hypersensitivity reaction of an immediate type plays a huge role in the formation and further development and progress of most pathologies with an allergic component in childhood.Table of contents: Classification Clinical manifestations of food allergies Diagnosis Causes of food allergies The most significant allergens The mechanism of food allergy development and related pathologies Treatment of food allergies
Food allergy develops as a result of consumption of quality products that are common to most people,In some cases may resemble food poisoning.This disease, like many other hypersensitivity reactions, often leads to the development of acute conditions, including Quincke's edema, anaphylactic shock and vascular lesions( vasculitis).
In addition, the pathological process is able throughout the patient's life to maintain chronic diseases of the respiratory, digestive and excretory systems.
- is a true allergy( it is based on immunological mechanisms);
- pseudoallergic reactions( develop with the use of histamine-liberators);
- intolerance due to enzyme deficiency;
- psychogenic intolerance of certain products.
Note: histamine-liberators are compounds that do not themselves cause sensitization of the body, but promote the stimulation of cells responsible for the release of the mediator of the allergy-histamine.The most famous histamine-liberators, in particular, are citrus, chocolate, coffee and mustard.
Clinical manifestations of food allergies
Symptoms of food allergy differ in variety. As a result of the use of specific products may occur:
- pain in the abdominal region( often spastic);
- skin itching;
- appearance of skin elements( rashes) on the entire surface of the body;
- marked swelling of the lips;
- swelling of the face and neck area( possible).
Important: in childhood, food allergy is often manifested in the form of diathesis. Some patients may have separate manifestations of cheilitis( inflammation of the lips) and stomatitis( inflammation of the oral mucosa).Quincke's edema, respiratory symptoms( runny nose, shortness of breath) and exacerbation of atopic dermatitis are not excluded.
DiagnosisRecommended to read:
Diagnosis is based on the clinical picture, patient complaints and data obtained by objective examination.In addition, a number of laboratory studies are carried out.It is also necessary to clarify the family allergic anamnesis, ie, to find out whether there are among the relatives of the patient suffering from allergies to food or non-food substances.First of all, it is important to establish a clear causal relationship between the consumption of a certain food product and the emergence( exacerbation) of clinical symptoms of allergy.It is also necessary to identify the nature of the rash on the skin and the degree of damage to the organs of the digestive tract.Anthropometric data of the patient( height and weight) are compared with age norms.
Children with food allergies often lag behind in development.It is important to pay attention to the nature of the patient's breathing.Difficulty breathing through the nose may indicate an allergic rhinitis( runny nose), and coughing and characteristic whistling during breathing often speak of exacerbation of bronchial asthma.As additional methods of examination, chest X-ray and laryngoscopy are performed.When complaints about problems from the gastrointestinal tract are shown, esophagoscopy( esophagus examination) and gastroduodenoscopy( examination of the stomach and duodenum).The methods allow an objective assessment of the degree of mucosal lesions.
Important: of the most advanced laboratory methods for identifying food allergies deserves special attention to the definition of sensitivity to various kinds of allergens in eight tests. During the laboratory blood test in patients with food allergy, the increased content of eosinophils and also the high level of immunoglobulin E are almost always determined. To detect specific IgE antibodies, an enzyme immunoassay and a radioallergosorbent test are used( the latter is the most informative).
Causes of food allergy
Specialists identify a number of the most significant factors predisposing to the emergence of food allergies. The most common reasons are:
- family( genetically determined) predisposition;
- Obtaining a child antibodies during fetal development and during breastfeeding;
- a short duration of breastfeeding;
- the age of the baby during sensitization( the very first contact with a certain allergen);
- the nature of the allergen, its volume and frequency of entry into the body;
- low level of local immunity in the digestive system;
- high permeability of the gastrointestinal mucosa;
Important: according to medical statistics, male faces suffer from food allergies 2 times more often than women.
The high incidence in childhood is explained by the fact that the immune system is not completely formed, and immunoglobulin A in the body is synthesized relatively little.In addition, in the digestive tract of the baby much less enzymes and hydrochloric acid are produced.
The most significant allergens
One of the most powerful and widespread allergen products is cow's milk.Up to 90% of cases of food allergy development in children are associated with it.The reaction to this product develops in toddlers during their transfer from breastfeeding to artificial.A powerful allergen is the fish proteins and proteins contained in seafood( caviar, mollusks, etc.).
Sensitivity to fish protein in most cases does not disappear as it grows up( in contrast to hypersensitivity to milk).98% of toddlers suffering from food allergy show an intolerance to any fish protein, and 10% react only to certain varieties.About 60-80 toddlers out of 100 with food allergy react actively to the protein of chicken eggs.Often in parallel, there is a hypersensitivity to chicken meat and chicken broth.Among the products of plant origin, cereal crops such as wheat and rye, as well as a number of fruits( particularly citrus fruits) and berries( strawberries, etc.) are most often used as allergens.
At least one in five children with food allergies cause the disease to react to products, during the manufacture of which used some fungi( kefir, kvass, buns, cheese).To avoid the development of negative reactions from the diet of such children, it is advisable to exclude yoghurts, cabbage, dairy products containing malt and dried fruits.
Important: allergy to "food" fungi is often accompanied by a hypersensitivity reaction to tetracycline and penicillin antibiotics.With care, it is necessary to give such patients the preparation of vitamins of group B.
In the probability of development of food allergies, the common products can be divided into 3 groups: group I - products with a high probability of risk:
- cow milk;
- eggs( protein);
- fish and seafood;
- natural honey;
- mushrooms( mainly - forest);
- cocoa beans( chocolate);
II group - moderate probability of allergy development:
- green( Bulgarian) pepper;
- buckwheat groats;
- rabbit meat.
III group - products, the use of which gives a low probability of food allergy:
Please note: in many cases, the hypersensitivity reaction does not arise on the product itself, but on a variety of dyes, flavors and preservatives that some modern manufacturers add even to food adapted for young children. When determining the cause of food allergy, it is important to consider the high probability of having a so-called "cross-allergy" between food components and non-food compounds.This will make a safe diet for a person suffering from allergies, such as wool or pollen from plants.
Mechanism for the development of food allergies and related pathologies
In the process of food processing, all exogenous( food-ingested) antigen proteins are transformed into non-allergenic or tolerogenic forms.In the digestive tract, due to the presence of its own immune system, immunity to exogenous compounds is determined.The barrier functions of the gastrointestinal tract are largely associated with very high concentrations of immunoglobulin A, contained in the mucus that covers the intestinal wall.
If a person has a genetically predisposed predisposition, then a hypersensitivity reaction develops upon contact with a particular foreign protein.Initially, sensitization takes place, and when this protein recurs in the gastrointestinal tract, an accelerated synthesis of a special protein, immunoglobulin E, begins. It is fixed on the mast cells and provokes the release of a large amount of the mediator, histamine.This substance and other biologically active compounds ultimately determine the clinical symptoms of food allergy.With hypersensitivity, mast cells are activated in the so-called "shock organs".When hypersensitivity to components of food products, such, as a rule, are the skin and organs of the digestive tract.Respiratory organs may also be affected, resulting in the development of respiratory allergy symptoms. In some cases, patients develop pseudoallergic reactions due to diseases of the digestive tract.In connection with the pathological changes in the gastrointestinal mucosa, the producing and histamine-containing mast cells become more accessible to histamine-ligating compounds.The clinical manifestations of this pathology very much resemble the "classical" reactions of immediate type hypersensitivity, but the level of immunoglobulin E in pseudoallergic reactions, as a rule, is within the normal range.Under such conditions, the mast cells of many shock organs are affected.There are frequent urticaria( itching and rash on the skin) and it is not ruled out that such a serious complication as Quincke's edema.
Food intolerance due to enzyme deficiency is due to an inborn lack of lactase and sugarase enzymes.The first is responsible for the fermentation of milk sugar, and the second is for sucrose.Lactase and a sugar deficiency are manifested by diarrhea and( more rarely) by meteorism.There is also a lack of an enzyme responsible for the absorption of the plant protein gluten.
Note: food allergy should be differentiated from food intolerance caused by mental disorders.This pathology is observed relatively often and has nothing to do with hypersensitivity reactions.Various deviations in eating behavior require consultation of a neurologist and psychiatrist.
Treatment of food allergy
In severe hypersensitivity reactions, the product that provoked them should be excluded from the diet.
Important: in some cases, after several years, the allergy( for example, to milk) may disappear, but you must use caution once again to consume certain foods!Allergy to fish and crustaceans persists throughout life.
With hives and edema Quincke, antihistamines are indicated( H1-blockers).Severe manifestations of food allergies require a course of treatment with glucocorticoids.In some cases, it is advisable to take Cromolin regularly before meals.About the methods of treatment and prevention of food allergies in children in this video review tells Dr. Komarovsky:
Plisov Vladimir, physician-phyto-therapeutist