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Food allergy

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A food allergy is an abnormal immune response to certain foods. Usually, the immune system protects the body from harmful pathogens like viruses. In a person with an allergy, the immune system mistakenly identifies harmless food proteins as threats. This reaction can cause symptoms ranging from mild itchiness to life-threatening emergencies. In the developed world, approximately 4% to 8% of people have at least one food allergy. These conditions are more common in children than in adults, and their frequency appears to be increasing.

Signs and symptoms of anaphylaxis
Signs and symptoms of anaphylaxis

The biological mechanism of a food allergy involves specific proteins and antibodies. When a person is exposed to an allergen, their immune system may produce immunoglobulin E, or IgE. These IgE antibodies act as markers by binding to specific molecules in the food. This process is known as allergic sensitization. Once the IgE antibodies bind to the food proteins, they trigger the release of inflammatory chemicals. One of the most notable chemicals released is histamine.

Histamin - Histamine
Histamin - Histamine
Allergy degranulation processes 01
Allergy degranulation processes 01

Histamine is responsible for many common symptoms, such as itching. Reactions are categorized into three groups based on these mechanisms: IgE-mediated, non-IgE mediated, or a hybrid of both types.

Symptoms can manifest in many different ways depending on the individual. Common signs include hives, skin rashes, and itching of the mouth, lips, or throat. Some people experience swelling, known as angioedema, in their face, eyelids, or tongue. Other symptoms involve the digestive system, such as vomiting, diarrhea, or abdominal pain. Respiratory issues like wheezing, shortness of breath, or a hoarse voice are also possible. If the reaction affects the respiratory tract and blood circulation, it is called anaphylaxis. If a person's blood pressure drops significantly during this time, they may enter anaphylactic shock.

Certain foods are much more likely to trigger these reactions than others. In the United States, nine specific allergens must be clearly listed on food labels. These include milk, eggs, peanuts, tree nuts, fish, shellfish, soy, wheat, and sesame. The inclusion of sesame was made mandatory following the FASTER Act signed by President Biden in April 2021. Peanuts are a member of the legume family and affect about 2% of the Western population. Peanut allergies often cause more severe reactions and anaphylaxis than other food allergies.

US Allergen Information Example
US Allergen Information Example

Tree nuts, such as almonds, cashews, and walnuts, are also common triggers.

Different types of food allergies behave differently as a person grows. Some allergies, such as those to milk, eggs, and soy, often resolve as children get older. For example, egg allergies affect about one in 50 children but are frequently outgrown by age five. However, allergies to nuts and shellfish typically do not go away. Shellfish is the most common food allergy found in adults and includes both crustaceans, like shrimp and lobster, and mollusks, like mussels and squid. Fish allergies are often more common in countries where fish consumption is high.

Exposure to allergens can happen through several different routes. While eating the food is the most common path, inhalation and skin contact can also cause sensitization. In certain jobs, such as seafood processing or industrial baking, workers may inhale airborne particles. This can lead to respiratory symptoms like "baker's asthma." Skin contact is also a factor, particularly for those with impaired skin barriers. For instance, peanut allergies are more common in adults who had oozing or crusted skin rashes as infants.

Epikutanni-test
Epikutanni-test

Managing food allergies requires careful planning and strict avoidance. It is vital to prevent cross-contact, which occurs when allergens are unintentionally transferred to safe foods. This often happens through shared cooking equipment or surfaces that were not properly cleaned. In the United States, the FDA distinguishes cross-contact from cross-contamination, which refers to biological or chemical contaminants. To prepare for emergencies, many people carry an epinephrine autoinjector. This device provides a dose of adrenaline to help manage severe reactions.

epipen
epipen

Wearing medical alert jewelry is another common safety measure.

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File:Signs and symptoms of anaphylaxis.png
Signs and symptoms of anaphylaxis.png
File:Histamin - Histamine.svg
Histamin - Histamine.svg
File:Allergy degranulation processes 01.svg
Allergy degranulation processes 01.svg
File:Allergy skin testing.JPG
Allergy skin testing.JPG
File:Epikutanni-test.jpg
Epikutanni-test.jpg
File:epipen.jpg
epipen.jpg
File:US Allergen Information Example.jpg
US Allergen Information Example.jpg
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