food allergy asthma
Introduction
Introduction to food allergic asthma Food-induced asthma (FIA), also known as food allergic asthma (foodallergicasthma) or food allergy-induced asthma (foodallergy-inducedasthma), is a special manifestation of food allergy (FA). FA mainly manifests as skin, respiratory and gastrointestinal reactions such as rubella, laryngeal edema, asthma and diarrhea. It can also cause severe systemic allergic reactions. The prevalence of FA is between 1% and 2% in the total population. About 8% of children, the prevalence of asthma in patients with FA increased significantly, from 6.8% to 17%, and the prevalence of asthma in children who are allergic to milk is as high as 26%. In our population, FA The prevalence rate is 3% to 14%, and about 30% of asthma patients have a history of asthma induced by taking certain foods. basic knowledge The proportion of illness: 0.02% Susceptible people: no special people Mode of infection: non-infectious Complications: edema, anaphylactic shock
Cause
Food allergic asthma cause
Causes of the disease: There are many foods that can cause allergic symptoms. Already specific skin tests, food-specific IgE, food stimulation tests and other methods have confirmed that there are hundreds of foods that can induce respiratory symptoms such as asthma. The common foods include the following Kind:
Milk and dairy products (20%):
Milk and dairy products are the most common food allergens that induce asthma in infants and young children. A milk albumin in milk is the most allergic component of all milk components, due to the higher species of alpha lactoprotein. It is genus specific, so children who are allergic to milk can consider using goat milk instead.
Eggs (10%):
Eggs and egg products can cause allergies in patients of all ages. Among them, egg albumin in egg white is the main component that induces respiratory allergy. Egg yolk rarely induces allergies. Quail eggs, duck eggs and goose eggs can also induce respiratory allergy symptoms.
Seafood and fish products (20%):
Shrimp, crab, shellfish and oysters can induce asthma. For example, fish with reddish color such as squid and squid are susceptible to respiratory symptoms, and crustaceans such as shrimp and crab also contain high allergens. Ingredients, these allergens are usually heat-resistant, and cooked foods often induce allergic asthma.
Oil crops such as peanuts, sesame and cottonseed (10%):
Mainly related to the high protein content of these foods, once made into oil products, it rarely induces allergic symptoms, and it is not uncommon to eat asthma.
Beans (5%):
Such as soybeans and products, mung beans, green beans, kidney beans, lentils and beans.
Food (3%):
For example, wheat, corn, buckwheat and cereals, Baker's asthma is associated with exposure to wheat flour. In addition, mites in flour are also an important cause of respiratory allergies.
Fruits and nuts (3%):
Nuts such as peaches, apples, oranges, apricots, pineapples and strawberries, as well as walnuts, pistachios, hazelnuts and pine nuts.
Certain meats and their meat products (3%):
Allergies can be induced by including pork, beef, lamb, and chicken.
Some vegetables (5%):
Such as sage, gray cabbage, mushrooms, tomatoes, green onions, potatoes, cabbage, garlic and peppers.
Other food and food additives (5%):
Such as coffee, chocolate, beer, fruit wine, pollen health products and some edible insects (such as silkworm cocoons, grasshoppers, etc.) and MSG (sodium glutamate), sulfites and so on.
Pathogenesis: 1. The allergen component of food allergens is complex. At present, the extraction and detection of food allergens is limited to a few common foods, such as milk, eggs, fish, Peanuts, beans, nuts, meat and wheat, etc. The allergenicity of these foods has been confirmed by specific skin tests, specific IgE tests and challenge tests, and found that food allergens are water soluble. Small molecular glycoproteins, such as sarcoplasmic proteins and myofibrillar proteins in fish, -lactoglobulin (-LG) and milk albumin in milk, egg albumin in eggs, and proteases in pineapple are the main Allergen ingredients.
2. Routes and mechanisms of action Food allergens can induce asthma by:
(1) Ingestion through the gastrointestinal tract: pathogenic foods are digested and absorbed in the gastrointestinal tract, and allergen determinants cause the release of inflammatory mediators, which directly affect the bronchial tubes and induce asthma.
(2) The pathogenic food protein is absorbed in the gastrointestinal tract, and the food allergen determinant is directly transported to the lower respiratory tract through the blood circulation, and an allergen-antibody reaction occurs, causing bronchospasm.
(3) Inhalation through the respiratory tract: Certain food particles with pungent odor can induce asthma through inhalation through the respiratory tract, such as green onions and garlic.
Both immune and non-immune mechanisms may be involved in the pathogenesis of FIA, mainly immune mechanisms, the most important of which are IgE-mediated immediate allergic reactions, while other immune responses may also include immune complex-mediated allergies and T Lymphocytes (mainly Th2 subpopulations), etc. All other non-immune-induced asthma, such as sulfite or aspirin-induced asthma, should be classified as "food intolerance", alcohol-induced asthma (alcohol) -induced asthma is a manifestation of Asians. It is caused by alcohol metabolism, especially the difference in acetaldehyde metabolism characterized by acetaldehyde dehydrogenase deficiency. Endorphins may be the cause of alcohol-induced asthma.
Prevention
Food allergic asthma prevention
1. Avoiding the intake of allergic foods is the primary measure of prevention.
2. Inhalation of sodium cromolyn, sodium nidicin also has a good control effect.
3. Children with food allergic asthma can often induce more severe systemic allergic reactions or even anaphylactic shock when eating allergic foods. Therefore, family members should learn to take first-aid measures such as adrenaline.
Complication
Food allergic asthma complications Complications edema anaphylactic shock
Laryngeal edema can occur, severe breathing difficulties, and even anaphylactic shock.
Symptom
Food allergic asthma symptoms common symptoms wheezing alcohol allergies abdominal pain diarrhea shock nausea
The clinical manifestations of FIA are diverse. Acute asthma attacks can occur alone, but most are accompanied by systemic allergy symptoms and can also be manifested as chronic asthma.
1. Respiratory symptoms include wheezing, often occurring within minutes to hours after eating, while both lungs can smell wheezing. In infants and young children, milk-induced asthma symptoms are more common, and wheezing is sometimes unique and should be taken seriously. However, the performance of chronic asthma is very different, and mild patients may only show persistent cough or exercise-induced asthma.
2. Systemic allergy symptoms FIA patients, especially adults, often accompanied by other systemic allergic manifestations, including: itchy skin, rubella, itchy throat and even edema, nausea, vomiting, abdominal pain, diarrhea and conjunctival congestion; Produces a severe systemic allergic reaction or even anaphylactic shock.
Examine
Food allergic asthma check
The food allergen skin test was positive and serum immunoglobulin E (IgE) was detected.
The PD20FEV1 lung ventilation function is generally based on PD20FEV1.
Pay attention to the following points when implementing food stimulation tests:
(1) Strictly control the amount of food to be stimulated, generally starting from l00mg, gradually increasing the amount, if the patient can tolerate 8 to 10g of suspicious food or reach the daily intake of the food, the patient can be judged as negative.
(2) Fasting suspicious food 2 weeks before the challenge.
(3) Stop anti-allergic and anti-inflammatory drugs 1 week before the stimulation; if the patient can not interrupt the treatment, occasionally can also be carried out with -agonist, aminophylline or inhaled corticosteroids, but used in the test The drug should be consistent with the placebo for comparison.
(4) Judging by standard symptom score or lung ventilation function test.
(5) If a double-blind trial is performed, it should be ensured that the amount of food stimulated is comparable to that of placebo.
(6) The food to be tested is often used in capsules or mixed in broth and swallowed in juice to mask its taste.
(7) Because the food stimulation test can induce more serious asthma attacks, it should be carried out under the condition of rescue equipment; those with severe asthma symptoms are generally not suitable for this examination.
Diagnosis
Diagnosis of food allergic asthma
diagnosis
1. A careful history of medical history includes the following aspects: the time relationship between the intake of certain foods and asthma attacks; the reversibility of asthma induced by the same food; the history of atopic diseases, the history of other allergic diseases and the history of family allergies. Wait.
2. Food allergen skin test, specific lgE detection food allergen skin test is the main method for preliminary screening of allergic food, can provide skin test results of various foods in 15 ~ 20min, more use scratch method or prick Although the intradermal injection method is more sensitive, it has low specificity, more false positives, and has been used less. The dilution of the food allergen extract used for the routine skin test is: vegetables, fruits 1:10, meat. High-protein foods such as eggs and dairy products are 1:100. Determination of allergen-specific IgE antibodies in serum by RAST and ELISA is also a common method for determining allergen components in foods and "standardization" of food allergen extracts. method.
3. Exclude the diet (elimination diet) to remove suspicious food in the diet for 7 to 14 days to observe whether the symptoms persist. If the symptoms disappear, the FIA can be diagnosed initially; if the symptoms are suspicious, a food challenge test is needed to further confirm the diagnosis; Symptoms persist, food allergies may not be a major factor.
4. The food challenge test is the most reliable method for diagnosing food-induced asthma. It is suitable for patients who have been diagnosed by medical history and excluded from the diet and the above laboratory tests. The method is divided into: open method (non-blind method) ); single-blind method; double-blind placebo-controlled method.
Respiratory diseases associated with other foods include gastroesophageal reflux, cystic fibrosis, diaphragmatic hernia, and tracheoesophageal fistula.
