Skip to Content

Food allergy

« Back to Glossary Index

**Group 1: Causes and Common Food Allergens**

– Allergic reactions develop after exposure to a food allergen.
– Food allergens cause about 90% of all allergic reactions.
– Common food allergens include milk, eggs, peanuts, tree nuts, fish, shellfish, soy, and wheat.
– In April 2021, sesame was recognized as the ninth mandatory food label allergen.
– Peanuts and tree nuts are common allergens causing severe reactions.
– Peanuts and tree nuts are common allergens affecting about 2% of the Western population.
– Egg allergies affect about one in 50 children but are often outgrown.
– Cows milk is a common allergen in infants and young children.
– Shellfish allergies are the most common food allergy in adults.
– Other common allergens include soy, wheat, and fish.

**Group 2: Symptoms, Diagnosis, and Impact**

– Symptoms of food allergies range from mild to severe and can include itchiness, swelling, vomiting, hives, and trouble breathing.
Anaphylaxis is a severe allergic reaction that can be life-threatening.
– Diagnosis involves medical history, elimination diet, skin prick test, blood tests, or oral food challenge.
– Management includes avoiding the allergen and having an emergency plan.
– In developed countries, about 4% to 8% of people have food allergies.
– Food allergies are more common in children than adults and appear to be increasing.
– Male children are more commonly affected than females.
– Some food allergies may resolve with age, while others persist.
Anaphylaxis is a severe allergic reaction that can be triggered by food allergens.

**Group 3: Prevention and Differential Diagnosis**

– Breastfeeding for over four months may prevent atopic dermatitis and cows milk allergy.
– Early exposure to allergens like eggs and peanuts can reduce allergy risk.
– Introducing peanuts early may prevent peanut allergies.
– Strict diet and complete avoidance can help prevent allergic reactions.
– Early introduction of allergenic foods within the first year may prevent food allergies.
– Lactose intolerance is not an immune reaction but due to enzyme deficiency.
– Celiac disease is a chronic autoimmune disorder affecting the small intestine.
– Irritable bowel syndrome.
– C1 Esterase inhibitor deficiency can be confused with allergy-triggered angioedema.
– Hereditary angioedema can present with abdominal pain and diarrhea.

**Group 4: Pathophysiology, Acute and Late-phase Responses**

– Allergic reactions can be IgE-mediated, non-IgE mediated, or a hybrid of both types.
– IgE antibodies are produced in response to allergenic proteins, initiating allergic reactions.
– Hypersensitivity reactions are categorized into four types based on immune system involvement.
– Food allergies can be caused by hypersensitivities to specific proteins in foods.
– The pathophysiology of allergic responses involves acute and late-phase reactions.
– Type I hypersensitivity reactions involve allergen exposure and immune cell responses.
– IgE antibodies bind to mast cells and basophils, sensitizing them to allergens.
– Degranulation of mast cells and basophils releases inflammatory mediators like histamine.
– After acute response mediators subside, late-phase responses can occur.
– Migration of other leukocytes to the initial site may lead to late-phase reactions.

**Group 5: Treatment and Epidemiology**

– Total avoidance of allergenic foods is the primary treatment for food allergies.
– Epinephrine should be used for systemic reactions like anaphylaxis.
– Immunotherapies aim to condition the immune system for specific responses.
– Omalizumab (Xolair) is an injectable asthma treatment effective for wheat, eggs, milk, and baked products containing allergens.
– Food allergies affect up to 10% of the global population.
– Children in western nations have higher allergy rates than adults.
– Regulations like the Food Allergen Labeling and Consumer Protection Act impact food handling.
– Food allergies cause numerous emergency room visits and deaths annually.
– Regulations impact the quality of life for children and caregivers.

Food allergy (Wikipedia)

A food allergy is an abnormal immune response to food. The symptoms of the allergic reaction may range from mild to severe. They may include itchiness, swelling of the tongue, vomiting, diarrhea, hives, trouble breathing, or low blood pressure. This typically occurs within minutes to several hours of exposure. When the symptoms are severe, it is known as anaphylaxis. A food intolerance and food poisoning are separate conditions, not due to an immune response.

Food allergy
Hives on the back are a common allergy symptom.
SpecialtyEmergency medicine, allergy and immunology
SymptomsItchiness, swelling of the tongue, vomiting, diarrhea, hives, trouble breathing, low blood pressure
Usual onsetMinutes to several hours of exposure
DurationLong term, some may resolve
CausesImmune response to food
Risk factorsFamily history, vitamin D deficiency, obesity, high levels of cleanliness
Diagnostic methodBased on a medical history, elimination diet, skin prick test, oral food challenge
Differential diagnosisFood intolerance, celiac disease, food poisoning
PreventionEarly exposure to potential allergens, omalizumab
TreatmentAvoiding the food in question, having a plan if exposure occurs, medical alert jewelry
MedicationAdrenaline (epinephrine)
Frequency~6% (developed world)

Common foods involved include cow's milk, peanuts, eggs, shellfish, fish, tree nuts, soy, wheat, and sesame. The common allergies vary depending on the country. Risk factors include a family history of allergies, vitamin D deficiency, obesity, and high levels of cleanliness. Allergies occur when immunoglobulin E (IgE), part of the body's immune system, binds to food molecules. A protein in the food is usually the problem. This triggers the release of inflammatory chemicals such as histamine. Diagnosis is usually based on a medical history, elimination diet, skin prick test, blood tests for food-specific IgE antibodies, or oral food challenge.

Management involves avoiding the food in question and having a plan if exposure occurs. This plan may include giving adrenaline (epinephrine) and wearing medical alert jewelry. Early childhood exposure to potential allergens may be protective against later development of a food allergy. The benefits of allergen immunotherapy for treating food allergies are not proven, thus not recommended as of 2015. Some types of food allergies among children resolve with age, including those to milk, eggs, and soy; while others such as to nuts and shellfish typically do not.

In the developed world, about 4% to 8% of people have at least one food allergy. They are more common in children than adults and appear to be increasing in frequency. Male children appear to be more commonly affected than females. Some allergies more commonly develop early in life, while others typically develop in later life. In developed countries, more people believe they have food allergies when they actually do not have them.

« Back to Glossary Index