Food Allergic Asthma

　　How is food-induced asthma caused? Briefly described as follows:

　　1, Etiology

　　A wide variety of foods can cause allergic symptoms, and methods such as specific skin tests, food-specific IgE, and food challenge tests have confirmed that there are already hundreds of foods that can induce asthma and other respiratory symptoms. Common foods include the following several types:

　　1, Milk and milk products. Milk and milk products are the most common food allergens that induce infantile asthma. Alpha-lactalbumin in milk is the most allergenic component among all milk components. Due to the high species specificity of alpha-lactalbumin, children allergic to milk can consider using goat's milk as an alternative.

　　2, Eggs and egg products. Eggs and egg products can cause allergies in patients of all ages, among which the ovalbumin in the egg white is the main component that induces respiratory allergies. The egg yolk rarely induces allergies. Quail eggs, duck eggs, and goose eggs can also induce allergic symptoms of the respiratory tract.

　　3, Seafood and aquatic products. Fish, shrimp, crabs, shellfish, and clams, etc., can all induce asthma. For example, fish with red flesh, such as trout and salmon, are prone to induce respiratory symptoms, and shellfish such as shrimp and crabs also contain a high level of allergen components. These allergens are usually heat-resistant, and cooked food often induces allergic asthma.

　　4, Peanuts, sesame seeds, and cotton seeds, etc., oil crops. Mainly related to the high protein content in these foods, once made into oil products, allergic symptoms are rarely induced. Asthma attacks triggered by raw peanuts are not uncommon.

　　5, Beans. Such as soybeans and their products, mung beans, green beans, kidney beans, lentils, and broad beans, etc.

　　6, Cereals. Such as wheat, corn, buckwheat, and grains, etc., Baker's asthma (Baker's asthma) is related to the contact with wheat flour. In addition, mites in flour are also an important cause of respiratory allergies.

　　7, Fruits and nuts. Peaches, apples, oranges, apricots, pineapples, and strawberries, as well as walnuts, pistachios, hazelnuts, and pine nuts, etc. The kernels of nuts.

　　8, Certain meats and their meat products. Including pork, beef, lamb, and chicken can all induce allergies.

　　9, Certain vegetables. Such as chrysanthemum, grey grass, mushrooms, tomatoes, scallions, potatoes, cabbage, garlic, and chili, etc.

　　10, Other foods and food additives. Such as coffee, chocolate, beer, fruit wine, health products made from pollen, and certain edible insects (such as silkworm pupae, locusts, etc.), as well as monosodium glutamate, sulfites, and the like.

　　二、发病机制

　　1、食物的变应原性。食物中的变应原成分是复杂的，目前对食物变应原的提取和检出仅限于少数几种常见的食品，如牛奶、鸡蛋、鱼类、花生、豆类、坚果类、肉类和小麦等。这些食物的变应原性已通过特异性皮试，特异性IgE检测和激发试验等所证实，并发现食物变应原是一种水溶性小分子糖蛋白，如鱼肉中的肌浆蛋白和肌原纤维蛋白，牛奶中的β-乳球蛋白（β-LG）和甲乳白蛋白，禽蛋中的卵白蛋白，菠萝中的蛋白酶是主要的变应原成分。

　　2、作用途径和机制。食物变应原可以通过以下途径诱发哮喘：

　　（1）经胃肠道摄入：致病性食物在胃肠道消化吸收，其变应原决定簇导致炎性介质释出，吸收而直接作用于支气管，诱发哮喘。

　　（2）致病性食物蛋白在胃肠道被吸收，食物变应原决定经血液循环直接运送到下呼吸道，发生变应原-抗体反应，引起支气管痉挛。

　　（3）经呼吸道吸入：某些具有刺激性气味的食物微粒可以经呼吸道吸入诱发哮喘，如大葱和大蒜等。

     食物过敏性哮喘可出现喉头水肿 ，严重时有呼吸困难发生 ，甚至出现过敏性休克等，严重危害患者健康，甚至威胁患者生命，因此应该及时治疗。

　　食物过敏性哮喘的临床表现是多样的，急性哮喘发作可以单独出现，但大多伴有全身的过敏症状，也可表现为慢性哮喘。

　　1、呼吸道症状。呼吸道症状包括喘息，往往在进食后数分钟到数小时内发作，同时两肺可闻及哮鸣音，在婴幼儿，牛奶诱发的哮喘症状较常见，喘息有时是唯一的，应予以重视。而慢性哮喘的表现很不同，轻症病人可能仅仅表现为持续的咳嗽或运动诱发哮喘。

　　2、全身过敏症状。本病病人，特别是成年人，发作时往往伴有其他的全身过敏表现，包括皮肤瘙痒、风疹、喉痒甚至水肿、恶心、呕吐、腹痛、腹泻和结合膜充血；也可以产生严重的全身过敏反应，甚至过敏性休克。

　　食物过敏性哮喘如何预防？简述如下：

　　1、避免过敏食物的摄入是预防的首要措施。

　　2、吸入色甘酸钠、尼多酸钠也有较好的防治效果。

　　3、患有食物过敏性哮喘的儿童，进食过敏食物时常常可以诱发更为严重的全身过敏反应，甚至过敏性休克。因此应让家属学会注射肾上腺素等急救措施。

　　What checks should be done for food allergic asthma? Briefly described as follows:

　　Firstly, the items to be checked for food allergic asthma

　　1. Lung ventilation function.

　　2. Challenge test.

　　3. Skin test.

　　4. Serum immunoglobulin E (IgE).

　　5. Skin test.

　　Secondly, pay attention to the following issues when implementing the food challenge test:

　　1. Strictly control the amount of stimulating food, usually starting from 100mg, gradually increasing the amount. If the patient can tolerate 8-10g of suspected food or reach the daily intake of the food, it can be judged as negative.

　　2. Avoid the suspected food for two weeks before the challenge.

　　3. Stop using antiallergic and anti-inflammatory drugs one week before the challenge; if the patient cannot discontinue treatment, it is occasionally possible to perform the test under the use of β2-agonists, aminophylline, or inhaled corticosteroids, but the drugs used in the test should be consistent with those used with the placebo for comparison.

　　4. Use standard symptom scores or lung ventilation function tests for judgment.

　　5. If a double-blind experiment is conducted, it should ensure that the amount of stimulating food is equivalent to that of the placebo.

　　6. The tested food is often taken in capsules or mixed in meat soup to disguise its taste.

　　7. Since food challenge tests can trigger more severe asthma attacks, they should be performed under conditions with rescue equipment; those with severe asthma symptoms are generally not suitable for this test.

　　Food allergic asthma patients should pay attention to their food choices, as it may sometimes be related to life and death. It is important to remember clearly the foods to avoid.

　　1. Preferable to eat

　　Diet should be warm, light, and soft, and can be eaten in small meals. It should be avoided to be allergic to other foods to avoid losing the necessary nutritional balance. During asthma attacks, it is also advisable to eat less bloating or difficult-to-digest foods such as beans and sweet potatoes to avoid abdominal distension and compression of the chest, which can worsen respiratory difficulty.

　　2. Avoid eating

　　Avoid foods that can cause allergies or asthma. Many foods such as fish and shrimp (seafood), sesame, shellfish, nuts (cashews, peanuts, etc.), dairy products, even wheat products, can act as allergens and trigger asthma attacks. In addition, some foods may be suitable or unsuitable for different patients due to their taste and properties, such as asthma patients often have phlegm and turbidity in the body, so pork, fish, or fatty and greasy foods should not be eaten at this time, as they can help dampness and produce phlegm. At this time, it is better to eat radish, luffa, Job's tears, tangerine, ginkgo, and other expectorant and diuretic foods; for patients with internal heat or phlegm heat, it is not advisable to eat spicy and刺激性 foods such as chili, Sichuan pepper, mustard, fennel, as they can warm the body and transform heat. Green beans, rapeseed, bitter melon, pomelo, and other cooling substances can be eaten.

　　Generally, asthma patients should avoid (or eat less) foods such as egg yolks, roosters, fatty pork, lamb, dog meat, seafood, clam, crab, shrimp; papaya, chive, chrysanthemum, bamboo shoots (or dried bamboo shoots), peanuts, preserved vegetables, chili, pepper; saccharin, flavoring, colorants, chocolate; ice cream and other cold drinks, carbonated drinks, alcohol, coffee, strong tea, and so on.

　　The following is a brief description of the treatment methods for food-induced asthma:

　　I. Treatment

　　Removing allergens and avoiding the intake of allergenic foods is the primary measure for treatment. In most cases, a diet plan suitable for the patient and free of food allergens can often make food-induced asthma patients recover without medication. The requirements for a diet plan suitable for food-allergic asthma patients are that it should remove allergens from food while ensuring that the patient receives enough nutritional components. To ensure adequate nutritional components, a suitable nutritional substitute should be chosen to replace the food removed from the diet. For infants allergic to milk, an

　　2. Drug treatment:Antiallergic drugs are the main drugs for the prevention and treatment of food-induced asthma, and they have good preventive and therapeutic effects on respiratory symptoms caused by food, such as ketotifen and terfenadine, which have good efficacy. The inhalation of cromolyn sodium and nedocromil (nedocromil sodium) also has good preventive and therapeutic effects. For patients with severe symptoms of food-induced asthma, inhaled corticosteroids can be used, and β2-agonists can also be inhaled if necessary to relieve symptoms.

　　3. Desensitization therapy:Food immunotherapy (desensitization) is one of the treatment methods for food-induced asthma, and it should start with an extremely small amount of allergenic food and gradually increase the amount of food in grams to make the patient tolerant to allergenic food. During the tolerance treatment process, food-specific skin tests or food challenge tests can be performed every 2 to 5 years to determine whether the patient has become tolerant to allergenic food. However, there is currently insufficient evidence to support the effectiveness of oral or extraintestinal immunotherapy for food-induced asthma, and this method has certain risks, so caution is required.

　　4. Promote breast-feeding:Especially for infants with a family genetic predisposition (atopy), breast-feeding should be encouraged because human milk does not contain the main allergen components found in cow's milk.

　　II. Prognosis

　　If proper measures are taken after onset, the prognosis is generally good.