Food allergy refers to adverse food reactions induced by immunological mechanisms, including IgE-mediated and non-IgE-mediated food allergies. Typical food allergies are mediated by IgE.
1What are the common food allergens?
More than 90% of food allergies are caused by foods such as milk, eggs, seafood, nuts, etc.
1. Milk and eggs: Patients with allergies to milk and eggs are more common and have more severe conditions. Whey protein in milk and ovalbumin in eggs are the main allergenic components.
2. Seafood: fish, shrimp, crab and other seafood.
3. Meat: pigs, cattle, sheep and poultry. In mainland China, this type of food allergy is less common.
4. Oil crops and nut foods: oil crops such as peanuts, soybeans, sesame, etc., nut foods such as walnuts, almonds, hazelnuts, pistachios, cashew nuts, etc. These food allergies are rare, but the symptoms can be very severe.
5. Fruits: peaches, apples, pears, oranges (especially kumquats), bananas, pineapples, lychees and various melons and fruits.
6. Vegetables: People who are allergic to cabbage and greens are rare, but lentils, cucumbers, bean sprouts, carrots and celery can cause allergies, and almost all people who are allergic to soybeans are allergic to soybean sprouts.
7. Food additives: there are many allergies to food colorings, preservatives, preservatives and flavorings, among which allergies caused by tartrazine are the most common.
8. Certain fermented foods: For example, some patients are allergic to hops, some are allergic to edible yeast, and some are allergic to edible fungi.
2What are the factors that affect food allergies?
The severity of food allergy symptoms is related to the strength of the allergen in the food, but the more important influencing factor is the susceptibility of the host.
1. Food variety: The primary factor that determines food allergies is the food itself. Allergenic foods are the direct cause or irritant of food allergies, and the allergenicity of various foods is different.
2. Food intake: Food allergies are closely related to food intake, causing disease only when food antigens accumulate to a certain threshold, and the severity of symptoms is often proportional to food intake. People who are sensitive to certain foods, sometimes even if they consume very little food, can cause illness.
3. Genetic factors: play an important role in allergic diseases. If one parent has an allergic disease, the prevalence of food allergy in their children is 30%~40%. If both parents have allergic diseases, the prevalence of food allergies in their children is as high as 60%~80%. Different patients can have different allergic symptoms of the same food, and the severity of the symptoms can also vary greatly. The vast majority of food allergies are relatively mild, while severe food allergies can lead to shock and even death.
3What are the clinical manifestations?
1. Typical symptoms
(1) Skin manifestations: Acute urticaria and angioedema are the most common skin manifestations of food allergy. Patients may present with erythema and wheals (varying in size and severe itching) and edema of the face, lips, mouth, and throat. Oral allergic syndrome manifestations such as itching, irritation, and mild swelling of the lips, tongue, palate, and pharynx may also occur after ingesting allergic foods.
(2) Respiratory manifestations: Generally common in anaphylaxis caused by severe food allergy, including nasal itching, nasal congestion, runny nose, sneezing, nasal congestion, coughing, wheezing, etc., and severe cases may have dyspnea. Isolated food-induced allergic rhinoconjunctivitis or asthma is rare.
(3) Gastrointestinal manifestations: some patients with food allergies may have nausea, vomiting, abdominal pain, abdominal distention, diarrhea, more mucus or watery stools in the stool. More than half of children with food allergies can affect the digestive system, with bloody and mucus stools, difficulty eating, and in severe cases, growth failure, anemia, hypoproteinemia, etc.
(4) Other manifestations: systemic food allergic reaction can lead to hypotension and arrhythmia. It can also cause eye symptoms such as itching, tearing, and bulbar conjunctival hyperemia.
2. Non-IgE-mediated food allergic reactions and symptoms
(1) Food protein proctocolitis: the clinical manifestations are mainly diarrhea and blood in the stool, and the children are generally in good condition, and exclusively breastfed infants can also occur.
(2) Food protein enterocolitis syndrome: the condition is relatively critical, mainly manifested as vomiting, abdominal distension, diarrhea, and in severe cases, fever, electrolyte imbalance, hypoproteinemia, metabolic acidosis, etc.
(3) Food protein enteropathy: the main clinical manifestations are recurrent diarrhea, malnutrition, hypoproteinemia, etc. The disease is often prolonged and recurrent.
4What are the key points of diagnosis?
1. Medical history: A thorough medical history is of great value in diagnosing food allergies. The causal relationship between food and symptoms should be noted during the history. IgE-mediated food allergy symptoms occur quickly, and generally the onset occurs when the allergic food is eaten, the disease does not occur if the food is not eaten, and the onset occurs again after eating.
2. Clinical examination: including skin acupuncture test (or scratch test) and serum IgE test. Both are used to determine whether IgE is present. A skin acupuncture test is a test in which a liquid extracted from a certain food that may cause allergy is made on the skin to penetrate into the outer layers of the skin, and the results are then observed. Although serum IgE testing takes a long time, the results are accurate and reproducible. Some individuals have a positive needle stick and serum test results but develop a tolerance to the food and thus do not have an allergic reaction, which may be due to a lack of cofactors or low levels of IgE.
3. Food diary: is a supplement to the clinical history. The type of food eaten three times a day, the relationship between eating and the onset of symptoms, and the severity of symptoms should be recorded in detail so that patterns can be detected.
5 What are the principles of treatment?
1. Avoid allergenic foods: The most effective way is to avoid foods that trigger allergies. When the allergen is identified, the allergenic food should be avoided or warmed up enough to reduce the allergen's sensitization capacity. When the allergen is not identified, the patient's diet can be restricted in the short term, and the patient can take turns to replace the food suspected of allergy within 2~4 weeks.
2. Desensitization therapy: For foods with high nutritional value and frequent consumption, desensitization therapy can gradually enhance the body's tolerance to food. For example, for people with cow's milk allergy, milk can be diluted in desensitization therapy without causing an allergic reaction at the initial use, and then increased daily or weekly quantitatively until it reaches the necessary daily requirement and the increase does not produce allergic symptoms. Food can sometimes be processed to remove or reduce allergens, often by heating, enzymatic breakdown, or fermentation.
3. Drug treatment: For patients with food allergy attacks, according to the type, nature and severity of their symptoms, drugs are used for symptomatic treatment. The drugs used include corticosteroids, epinephrine and antihistamines, such as loratadine, cetirizine, azestidine, etc., all of which have good efficacy and no serious adverse reactions. Clinical studies in recent years have shown that oral omalizumab (combined with anti-IgE) has a good effect on the treatment of peanut allergy and cow's milk allergy. At present, the research on transcutaneous immunotherapy mainly focuses on peanut and milk allergies.
6How is specialty care done?
1. First aid nursing: be familiar with common allergenic foods and their corresponding clinical characteristics and rescue measures. The patient is placed in a semi-sitting and recumbent position with the head tilted to one side to keep the airway open. Inhaled oxygen (2L/min) to relieve dyspnea. Follow the doctor's instructions for ECG monitoring and closely monitor the patient's vital signs. If necessary, open an intravenous line immediately and take medication as prescribed. In special cases, a prescribed dose of epinephrine should be injected every 5~10 minutes. If the patient is unconscious, a soft object should be inserted into the patient's mouth.
2. Skin care: Food allergies may cause skin damage, and the area around the damaged skin should be kept clean and dry, and medication should be taken appropriately. For patients with skin rashes, choose cotton and soft towels and use 32~34 °C warm water for skin scrub bathing, with gentle movements, and avoid using alkaline soap and other lotions. After the bath, saline is given to scrub the rash. Use a sterile medical cotton swab dipped in calamine lotion to rub the rash, shake it fully when using, and after rubbing, it is advisable to have a thin layer of white liquid on the surface of the rash, 2~3 times/day, 3~4 times/day when the itching is severe, avoid contact with eyes, mouth and nose. Patients with itchy skin should be given cetirizine hydrochloride tablets 5mg or cyproheptadine hydrochloride tablets 25mg orally according to the doctor's instructions. For patients with unbearable itching, diphenhydramine is injected intramuscularly as prescribed.
3. Diarrhea nursing: For patients with food allergic diarrhea, montmorillonite powder is given according to the doctor's instructions, and patients are instructed to take it on an empty stomach. Probiotics can be given to improve the balance of intestinal microecology. People who are dehydrated should be given proper fluids as prescribed. Patients with no obvious vomiting should be given oral rehydration salts, and those with obvious dehydration should be given intravenous fluids according to the doctor's instructions, and the principle of intravenous rehydration should be strictly implemented, the infusion speed should be paid attention to, and the 24-hour intake and output should be accurately recorded. At the same time, strengthen perianal care, wash the perianal skin with warm water and wipe dry after defecation to keep the skin of the buttocks clean and dry. If the skin is red or ulcerated, comfrey oil or a baking lamp physiotherapy can be used to promote dryness and healing of the wound.
4. Complication nursing: Food allergy can cause complications such as rhinitis, conjunctivitis, bronchial asthma, Henoch-Schonlein purpura, headache, recurrent oral ulcers, arrhythmia, nephritis, uremia and other complications.
5. Observation of the patient's condition: closely monitor the changes in the patient's condition, and observe the changes in the patient's complexion, consciousness, body temperature, pulse, respiration, and blood pressure. The frequency and amount of stool, whether there is vomiting and the amount of vomiting, skin elasticity, peripheral circulation of limbs, urine output, etc. Observe for signs of hypokalemia, hyposodium, and metabolic acidosis. Observe the location, extent, severity, time, number, speed of rash and other allergic symptoms.
The above is quoted from:
Introduction
Immune-related diseases refer to a series of clinical diseases caused by immunodeficiency, abnormal immune function, or immunomodulatory disorders as the main or important pathogenesis. As the immunopathogenesis of diseases continues to be elucidated, the types and scope of immune-related diseases are expanding and expanding. This book systematically expounds the common or typical immune-related diseases in clinical practice and their nursing measures, closely follows the clinical practice, and highlights the latest progress at home and abroad. The book consists of 15 chapters, including the overview part that introduces the basis of immune-related diseases and the immune response and its regulatory mechanism, and the monograph part that introduces common or typical immune-related diseases in blood, cardiovascular, digestive, respiratory, genitourinary, endocrine, nervous, eye, ear, nose and throat, skin and other systems or parts.
END
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![Minbao Classroom: Why do babies have allergies?[fig]](data:image/gif;base64,R0lGODlhAQABAIAAAP///wAAACwAAAAAAQABAAACAkQBADs=)