What are the common food allergens? In infancy, 90% of food allergies are associated with eight foods, including milk, eggs, soy, wheat, peanuts, fish, shrimp, and nuts. Peanut and nut allergies can last for several years, even into adulthood. Which children are prone to food allergies? 1. Genetic factors: Genetic factors are predisposing factors for food allergies. Children with a positive family history of atopic diseases (including asthma, allergic rhinitis, atopic dermatitis, food allergy) (at least one first-degree relative with an allergic disease) and children who have had sensitization to food or environmental allergens are considered to be at high risk. 2. Environmental factors: cesarean delivery, early or late addition of solid foods in infancy, excessive intake of vitamin preparations, and exposure to tobacco smoke may increase the risk of developing food allergy. What are the manifestations of food allergy? The most commonly affected organs in infants and children with food allergy are the skin, gastrointestinal tract, whistle tract and mucous membranes. In mild cases, only skin and gastrointestinal symptoms are manifested; in severe cases, changes in the whistle circulatory system and even shock and death may occur. Other signs that may be found are cyanosis of the lower eyelids (“allergic eye shadow”), pale edema of the nasal mucosa, and wheezing sounds in the lungs. Dry skin, rash and post-rash scratching. Common signs and symptoms of allergy: 1. Gastrointestinal manifestations: vomiting, diarrhea, gastroesophageal reflux, constipation (with or without perianal rash), bloody stools, iron deficiency anemia; in severe cases: growth lag, iron deficiency anemia, hypoproteinemia, enteropathy or severe colitis. Skin manifestations: atopic dermatitis, facial, lip and eyelid edema (angioedema), post-feeding urticaria, pruritus; in severe cases: hypoproteinemia, growth retardation or iron deficiency anemia. 3. Inhalation manifestations (non-infectious): itchy nose, runny nose, otitis media, chronic cough, wheezing; in severe cases, acute laryngeal edema or airway obstruction may occur. 4. Eye manifestations: eye itching, lacrimation, transient eyes, bulbar conjunctival congestion. 5. Systemic manifestations: persistent restlessness and abdominal pain ≥3 days/week (crying/irritability ≥3 hours/day) for more than 3 weeks, growth retardation; in severe cases, anaphylaxis may occur. How to determine food allergy? Based on history, physical examination, clinical presentation, allergen skin prick test, serum food-specific IgE test screening, and food avoidance test and food provocation test. Intervention and treatment: Although food allergies often become tolerated with age, early treatment is important to improve the prognosis. Usually treatment consists of two parts, one is to prevent the occurrence of allergic symptoms by avoiding allergenic foods, and the other is to relieve allergic symptoms that have already appeared through medication. (1) Strictly avoid allergenic foods: It is the only effective way to treat food allergy. All allergy-causing foods should be completely excluded from the diet, and other foods that can ensure normal growth and development of infants and children should be used as substitutes. To avoid malnutrition or premature exposure to allergenic foods due to long-term avoidance, it is recommended to re-evaluate every 3-6 months to adjust the duration of avoidance diet treatment. For children with a family history of anaphylaxis, nut or seafood allergy, or a history of severe allergic symptoms, the duration of dietary avoidance should be extended appropriately. (2) Food substitution: Milk is a nutritional necessity for infants and it is important to use appropriate food substitution for infants and children with milk allergy. Human milk-fed infants with milk allergy are advised to continue human milk feeding, but the mother should avoid foods containing milk proteins. Because milk avoidance may affect the mother’s nutrient intake, lactating mothers should also have regular nutritional assessments. Non-human milk-fed infants with cow’s milk allergy can be fed with amino acid formulas or deeply hydrolyzed protein formulas. Amino acid formulas do not contain peptides and are made entirely of free amino acids in a certain ratio, making them ideal food substitutes for infants with cow’s milk allergies. Deeply hydrolyzed protein formulas are made by heating, ultrafiltration, and hydrolysis of cow’s milk proteins to form dipeptides, tripeptides, and small amounts of free amino acid end products, greatly reducing antigenicity. Because deep hydrolyzed protein formulas have better taste than amino acid formulas and are tolerated by more than 90% of children, deep hydrolyzed protein formulas are preferred for moderate food allergies. If the child cannot tolerate the deep hydrolyzed protein formula or has severe milk allergy or multiple food allergy, the amino acid formula should be used for treatment. Amino acid formulas (elemental diet) are recommended for those with severe allergy symptoms, non-IgE-mediated food protein enteropathy, and other concomitant growth disorders. The course of treatment should be at least 3 to 6 months. Results are usually seen after at least 1 to 2 weeks. Persons who have experienced life-threatening clinical manifestations such as severe systemic allergic reactions (e.g., anaphylaxis), angioedema, etc. should continuously avoid any foods containing milk proteins. Due to cross-allergic reactions and nutrient deficiencies between soy and cow’s milk, soy protein formulas are generally not recommended for treatment; infants and children ≥6 months of age with genuine economic difficulties and no soy protein allergy can be treated with soy protein formulas as an alternative. Goat milk or other animal milk is not recommended for replacement therapy. Mild milk allergy (mainly refers to mild eczema) infants: long-term use of amino acid formula and deeply hydrolyzed protein formula is generally not recommended. You can try to add moderately hydrolyzed protein formula after 1 to 3 months of using amino acid formula and deeply hydrolyzed protein formula, and continue to use it if you can adapt to it; if you cannot adapt to it, you should try to add moderately hydrolyzed protein formula after 1 to 2 years. You can also try moderately hydrolyzed protein formula directly. People with egg and other food allergies: in principle, they should also avoid it. Whether to add them again after clinical symptoms have improved should also be decided based on the situation of people with similar milk allergies. Allergy in breastfed infants: Breastfeeding is generally not discontinued and the mother may engage in dietary avoidance. The mother may avoid allergenic foods for at least 2 weeks, and in some children with atopic dermatitis and enterocolitis, the mother may avoid allergenic foods for up to 4 weeks. If the infant’s allergy symptoms improve significantly and disappear after the mother avoids the allergenic food, the mother may add the avoided food to the diet and resume it if the symptoms do not reappear. If symptoms reappear after the addition of a food, the mother should avoid that food completely during breastfeeding. If the mother’s diet does not improve the child’s symptoms, the mother should return to her normal diet. Addition of transitional foods for infants: ensure that they do not contain allergy-inducing food components. For single egg, soy, peanut, nut and seafood allergies, avoidance will not affect the infant’s nutritional status because they are not the primary source of nutrients for the infant and can be provided by other foods. For children with multiple food allergies, a hypoallergenic diet formula can be used, such as cereals, lamb, cucumber, cauliflower, pear, banana, canola oil, etc., with only salt and sugar as seasonings; at the same time, the reaction after eating should be closely observed to reduce the occurrence of rare food allergies. A group of dietary regimens that contain no or very few allergens should be developed during dietary avoidance therapy. It is recommended that a rescue card be created for children, including information on allergic foods, treatment, and contacts for use in the event of an emergency. Parents should read the dietary ingredient list of the item before purchasing food to avoid purchasing foods with allergenic food ingredients. 2. Medication Severe allergy symptoms can be relieved by short-term medication, such as antihistamines, mast cell stabilizers, glucocorticoids, etc. Prognosis 80% to 85% of milk and egg allergic children can obtain immune tolerance by the age of 3 years; peanut, fish, soybean and nut allergies last longer; multiple food allergies are not easy to obtain immune tolerance or the time needed to obtain tolerance is prolonged. Prevention (1) Pregnant mother’s life and diet: The effect of prenatal control of the mother’s diet on the prevention of infant allergy is unclear and caution should be exercised. Maternal smoking increases the risk of infant allergy, and active and passive smoking should be avoided as much as possible. (2) Lactating mother’s diet: Food allergens can be passed to the infant through breast milk, but at low levels. Lactating mothers of infants at high allergy risk (parents or siblings with genetic allergies, etc.) should reduce the intake of commonly allergenic foods, including: milk, eggs, peanuts, shelled seafood, etc. (3) Infant diet: The most important route of exposure to exogenous allergens during infancy is the digestive tract, and food is the main allergen. Early infant diet should be based on dairy products. (1) Main methods: Exclusive breastfeeding can effectively reduce the occurrence of allergies during infancy. Breastfeeding is recommended for the first 6 months after birth. If an allergic disease has occurred in an exclusively breastfed infant, it is recommended that the mother should attempt to avoid suspected allergenic foods such as milk and make adjustments to the local diet. Infants generally delay the addition of solid foods until after 6 months of age, and for allergy-prone foods (e.g., milk, eggs, etc.) it is recommended that they be added after 12 months of age. ②Secondary approach: moderately hydrolyzed protein formula can be used for mixed or manual feeding of infants at high allergy risk. It is recommended to use it as early as possible after initiation, as early exposure to whole milk formula may lead to sensitization of the organism. Feeding should continue through infancy and solid foods should be added gradually after the immune and digestive systems are moderately well developed (after 6 months of age). ③Soy milk formula: not recommended for the prevention of allergic diseases in children. (4) Probiotics (yuan): Appropriate use of probiotic strains (prebiotics) with clear functions has a role in the prevention of allergies in infancy. (4) Environmental control: For infants who have developed food allergy, it is recommended to reduce the amount of dust mites in the environment, including reduction of indoor dust accumulation, control of indoor ambient temperature and humidity, and for children with proven dust mite allergy, use anti-mite bedding if available. when recurrent whistling infections or chronic cough symptoms occur around 12 months of age, inhalation allergen allergy evaluation should be performed to avoid blind antibiotic treatment.