Food allergy occurs when our immune system responds abnormally to foods. The underlying immune response may be IgE-mediated, IgE-independent, or a mixture of both. The incidence of food allergies has increased significantly, especially in recent years. The most common foods that cause allergies in children are cow's milk (2.5%), eggs (1.3%), peanuts (0.8%), wheat (0.4%), soy (0.4%) and hazelnuts (0.4%). 0.2%) and shellfish (0.1%). In adults, pollen allergies often cause cross-reactivity with food allergies. Early childhood allergies to milk, eggs, soy, and wheat resolve by approximately 80% by school age. Hazelnut, peanut and seafood allergies usually persist. Although reactions to vegetables and fruits appear to be common (about 5%), these reactions are generally not serious.
The immune system develops tolerance to the majority of food antigens and remains unresponsive. This is called oral tolerance. Antigen presenting cells (intestinal epithelial cells and dendritic cells) and regulatory T cells play a leading role in the development of oral tolerance. Intestinal epithelial cells process the luminal antigen and present it to T cells via the MHC class II complex. This presentation causes anergy. Intestinal flora is also thought to play a role in oral tolerance induction. Some studies say that probiotics have the potential to protect against allergies by creating a tolerogenic bacterial environment. It seems that the normal intestinal flora and oral tolerance formation in humans after birth are of great importance in the immune regulation of food allergies.
If the underlying immune response in food allergies is IgE-mediated, our immune system perceives the proteins in foods as a threat and produces IgE-type antibodies against them. starts. When sensitive individuals encounter the same food, it binds to previously formed IgE antibodies and causes the release of many substances, mainly histamine, from mast cells. Clinical findings develop depending on the effects of these substances.
Symptoms that develop due to non-IgE mechanisms involved in the development of food allergies appear later. Bloody, mucusy defecation is observed Three types of allergic proctocolitis; Food protein-induced enterocolitis syndrome, which is characterized by persistent vomiting several hours after food intake, is an example of these. This condition can be caused by foods such as cow's milk, soy, and eggs.
Allergic reactions can be seen in a wide range, from mild local symptoms to serious life-threatening anaphylaxis, as in oral allergy syndrome.
IgE-mediated food allergies
Cellular-mediated late-type food allergies
I- IgE Mediated Food Allergies
Urticaria angioedema may occur in a sensitive person due to ingestion of food. Then symptoms begin within minutes to 2 hours. Itchy urticarial plaques form. Sometimes the tongue and lips swell. It is due to increased permeability of capillaries and small vessels. Food is the causative agent in approximately 20% of acute urticaria. In children; Eggs, milk, peanuts and other nuts play a role. In adults, fish, shellfish and peanuts are the most common causative agents. The role of food in chronic urticaria is much lower and has been found to be around 2-4% in some studies.
Oral allergy syndrome: It is also called pollen-food syndrome. First, pollen allergy develops through inhalant exposure. Then, the symptom occurs when food that cross-reacts with it is consumed. Itching, burning, and sometimes angioedema occur in the tongue, lips, palate, and throat within minutes after ingesting the food. Ear itching, feeling of congestion in the throat may also develop may. It usually occurs by eating raw fruits and vegetables. Oral allergy syndrome is not typically seen in the cooked form of these foods. The foods in question here are; apples, pears, kiwis, hazelnuts, carrots and celery, and the symptoms are more evident during the pollen season. In the diagnosis of this type of allergy, a prick test should be performed with fresh food. The antigen structure that causes oral allergy syndrome in commercial antigens is distorted and may give false negative results.
Gastrointestinal anaphylaxis: After ingestion of the causative food, symptoms begin within minutes to 2 hours. Nausea, vomiting, abdominal pain, abdominal cramps and diarrhea may occur. The symptoms are not always very severe. Symptoms that may be overlooked in the baby or child, such as periodic abdominal pain and vomiting; Secondary to this, it may manifest itself with loss of appetite in the child.
Acute rhinoconjunctivitis: Isolated rhinoconjunctivitis due to food allergy is very rare. It is often accompanied by other allergic symptoms. Symptoms begin within minutes to 2 hours after food intake. Redness around the eyes, itching and watering in the eyes, nasal congestion, runny and itching, and sneezing are added.
Bronchospasm: Asthma or isolated “wheezing” is a very rare symptom of food allergy. The responsible food may increase bronchial hyperreactivity; However, it is very rare that it can trigger an asthma attack. Inhalation of antigens released into the air while cooking sensitive food or for other reasons becomes more important in bronchospasm.
Food-related anaphylaxis: IgE-dependent systemic reactions can vary in severity, from mild urticaria to shock. Symptoms begin immediately (minutes to 2 hours) after ingesting food. It may also be biphasic and may flare up again 1-2 hours after the first reaction.
Food-related exercise-induced anaphylaxis: It is a condition that occurs with heavy exercise within 2-4 hours after ingesting the food. If exercise is not performed recently before or after the food, there will be no reaction. It is attributed to mast cell activation with exercise. It is mostly seen in young adults. It is seen with celery, wheat, fruit, peanuts, fish and seafood.
II- IgE Associated / Cellular Mediated
Atopic dermatitis: IgE mediated or non-IgE mediated -May be mediated by IgE r. 90% of it begins before the age of 1. It has a typical distribution. It is extremely itchy, recurrent and chronic. . It occurs most frequently with milk, eggs, soy, wheat and peanuts. Food allergy should be considered in atopic dermatitis that occurs in the first 6 months and does not respond to topical steroids. If it is IgE-mediated, the responsible food can be determined by skin prick test or specific IgE determination. For non-IgE-mediated mechanisms, as in other allergic diseases, elimination and subsequent provocation can be performed for about 2 weeks, and the responsible food can be detected through improvement-exacerbation reactions in the lesions.
Allergic eosinophilic esophagitis: It is seen in every period from infancy to adolescence. It is more common in adults. Refusal to feed, restlessness, vomiting, and growth retardation are observed in infants, while in children, complaints such as abdominal pain, vomiting, gastro-esophageal reflux disease-like complaints, difficulty in swallowing, food disgust, and in adolescents, complaints such as dysphagia, feeling of food getting stuck in the esophagus, nausea, reflux-like complaints, and growth retardation are observed. It shows itself. Reflux does not respond to treatment. Diagnosis is made by examining the typical history and multiple biopsy samples taken from the gastrointestinal tract. Eosinophil infiltration is seen in the biopsy. The allergy improves with the elimination of the detected food for about 3 months. Fully hydrolyzed amino acid formula is recommended as food for babies.
Allergic eosinophilic gastroenterocolitis: There is eosinophil infiltration that can progress from the gastric and intestinal mucosa to the serosa. Peripheral eosinophilia may also be seen. There is no vasculitis. Muscle layer thickening with eosinophil infiltration leads to obstruction-like findings. Chronic or intermittent abdominal pain, nausea, irritability, loss of appetite, growth retardation, weight loss, diarrhea, anemia, and protein-losing gastroenteropathy symptoms may occur. It can be seen at any age. Serum IgE level is high. 50% of patients have an atopic disease. Prick skin tests are positive for some food and inhalant allergens.
Asthma: Triggering an attack with food is rare in chronic asthma. Inhalation of food may cause bronchospasm. Steam from cooked food may also be effective.
III-Cellular Mediated
Contact dermatitis: It usually develops due to contact with food. raw foods has a greater role. It is more common in professions such as fisherman and butcher. "Patch" test can be applied in diagnosis.
Dermatitis herpetiformis: It progresses with very itchy papulovesicular rashes on the extensor surface of the arms and legs and on the buttocks. It has a chronic course. It is associated with gluten-sensitive enteropathy. It can occur at any age. It may be confused with celiac disease or atopic dermatitis. Gastrointestinal complaints are minimal or absent. Although gastrointestinal lesions are similar to Celiac disease, they can be differentiated by pathological evaluation in biopsy. Lesions resolve within a few months with a gluten-free diet.
Allergic proctocolitis: There is abundant or occult blood in the stool. It is usually seen in babies younger than 6 months. It depends on cow's milk or soy protein taken directly or through breast milk. The babies appear completely healthy. The lesion is in the distal large intestine. There is only blood in the stool. The amount of blood is variable. While it can be seen directly, occult blood can be found through examination. Once you eliminate the culprit food, dramatic improvement is seen within 72 hours. It disappears between 6 months and 2 years of age with allergen elimination.
Food protein enterocolitis: Also called protein intolerance. It is seen in the first three months of life. There is typical persistent vomiting and recurrent diarrhea. It may cause dehydration. Vomiting occurs 1-4 hours after feeding. If the food that causes allergy is continued to be given, it may cause bloody diarrhea, anemia, abdominal distension and growth retardation. Symptoms develop due to cow's milk protein or soy-based formula. Rarely, cow's milk protein transferred through breast milk may also be a factor. Similar enterocolitis syndromes may be seen in older infants and children with sensitivity to eggs, wheat, rice, oats, peanuts, other oilseed snacks, chicken and fish. There is occult blood, neutrophil and eosinophil infiltration in the stool. Since food absorption is impaired, reducing substance positive may be detected in the stool due to sugar malabsorption. Developing secondary disaccharidase deficiency also causes diarrhea to last up to 2 weeks. Despite the diet, the recovery time for symptoms is prolonged and the skin prick test is negative. By eliminating the responsible allergen, symptoms usually improve within 72 hours; It happens again with provocation. Complete recovery varies between 6 months and 2 years.
Food protein enteropathy syndrome
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