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Food Allergens

Why food allergies are increasing

  • 3 things to know
  • A2 1

Overview

How IgE-mediated allergy and anaphylaxis develop, rising admissions, the hygiene, old friends and dual-allergen exposure hypotheses, the LEAP study, the microbiome and vitamin D.

What you need to know

Answer each one before you reveal it.

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Numbers

What did the LEAP study find, and how has UK advice on introducing allergenic foods changed?

Key term

What is a food allergy, and how does an IgE-mediated allergy develop?

Key term

What is a food allergy?

Questions from this subtopic

Each one with the model answer underneath.

  1. 1

    What is a food allergy?

    Model answer

    A food allergy is an immune system reaction to a specific food protein. Even a tiny amount can trigger symptoms, which can be life-threatening.

  2. 2

    Describe how an IgE-mediated food allergy develops.

    Model answer

    On first exposure the immune system is sensitised and makes IgE antibodies against the food protein. Later exposure makes mast cells release histamine and other chemicals, causing symptoms.

  3. 3

    What is anaphylaxis?

    Model answer

    Anaphylaxis is a severe, rapid allergic reaction affecting breathing, circulation or both. Anaphylaxis needs immediate treatment with an adrenaline auto-injector and emergency care.

  4. 4

    What trend in UK hospital admissions for food anaphylaxis has been reported?

    Model answer

    Hospital admissions for food-induced anaphylaxis in the UK roughly tripled between 1998 and 2018. The analysis of national data was led by Conrado and published in 2021.

  5. 5

    What is the hygiene hypothesis?

    Model answer

    The hygiene hypothesis proposes that less exposure to microbes in early childhood leaves the immune system poorly trained. The immune system then overreacts to harmless substances such as food proteins.

  6. 6

    How has the hygiene hypothesis been refined into the old friends idea?

    Model answer

    The old friends idea stresses the loss of helpful microbes that humans evolved alongside. Reduced contact with nature, animals and diverse gut bacteria matters more than cleanliness alone.

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