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Food Allergy and Allergen Management Lecture

Course & Session Context

  • Week theme: Food Safety; Thursday session devoted to Food Allergy & Allergen Management.

  • House-keeping

    • Quiz 1 results released during/after lecture; average high ⇒ quiz considered too easy.

    • Census date at midnight – ensure enrolment, team formation, and trajectory through course are clear.

    • Upcoming assessments: Quiz 2 (in-class, individual), short essay on Wegovy/Ozempic, group video assignment.

    • Slides uploaded to Moodle at 15:00.

Recap of Previous Sessions

  • Tuesday topics

    • Four contamination classes: physical, chemical, microbiological, allergen.

    • HACCP reviewed— must be “hammered into the brain.”

  • Today fills the deliberate gap left on allergen discussion.

Lecture Objectives

  • Differentiate food allergy vs food intolerance (IgE-mediated vs non-IgE hypersensitivity).

  • Identify major food allergen sources (Big 8 and local extensions).

  • Understand clinical mechanism (IgE, anaphylaxis) & terminology (immunoglobulin, anaphylactic shock).

  • Grasp policy/management & regulatory frameworks for allergen prevention, labelling & recalls.

Key Definitions & Concepts

  • Food Allergy: Immune-mediated hypersensitivity to otherwise harmless food components; can cause anaphylaxis.

  • Food Intolerance: Non-immune adverse reaction, often metabolic, pharmacologic, toxic, or idiopathic.

  • IgE: Immunoglobulin E antibody class central to rapid-onset allergic reactions.

  • Anaphylaxis / Anaphylactic shock: Severe, systemic, potentially fatal reaction; requires immediate epinephrine.

  • Immunoglobulin vs antibody – interchangeable in context.

  • Big 8 allergens: peanut, tree nuts, soy, milk, egg, wheat (gluten), crustacea, fish (+ sulfites).

Historical & Philosophical Frames

  • Lucretius: “What is food to one man may be fierce poison to others.”

  • Paracelsus (via Theophrastus): “The dose makes the poison.”

  • Hippocrates: “Let food be thy medicine and medicine be thy food.” Inspires the modern “Food is Medicine Institute” (Dariush Mozaffarian, Boston).

Food Intolerance (Non-Immune)

Classification Overview

  • Metabolic: Enzyme deficiencies (e.g. lactose).

  • Pharmacologic: Caffeine, vaso-active amines.

  • Toxic: Natural toxins in certain foods.

  • Idiopathic / Undefined: Sulfites, tartrazine, etc.

  • Anaphylactoid: Mimic allergy signs without IgE involvement; mechanism unclear.

Lactose Intolerance – Model Metabolic Disorder

  • Cause: Deficiency of \beta-galactosidase (lactase) prevents hydrolysis of lactose.

  • Reaction: \text{Lactose} \xrightarrow{\beta\text{-galactosidase}} \text{Glucose} + \text{Galactose}

  • Symptoms: Abdominal pain, flatulence, diarrhea.

  • Prevalence increases with age; varies ethnically (Nordic vs Southern populations).

Idiosyncratic Reactions (Reproducible, Unknown Mechanism)

  • Migraine triggered by chocolate.

  • Food colourants (tartrazine) causing hyperactivity.

  • Sulfiting agents provoking asthma.

Gluten-Related Disorders

  • Gluten = gliadin + glutinin proteins.

  • Population data (USA):

    • Gluten intolerance ≈ 6 % (≈20 million).

    • Coeliac disease ≈ 1 % (≈3 million).

  • Comparison table

    • Cause: Unknown vs autoimmune with genetic predisposition.

    • Severity: Discomfort vs life-threatening complications.

    • Diagnosis: Elimination diet vs biopsy/endoscopy & serology.

    • Treatment: Diet modification vs strict lifelong gluten-free; even trace elimination.

    • Practical tip: Toasting high-gluten bread reduces reactivity slightly.

Food Allergy (Immune-Mediated)

Types

  • IgE-mediated (rapid, classical).

  • Non-IgE-mediated.

  • Mixed IgE/non-IgE.

  • Cell-mediated.

Common Signs & Symptoms

  • Gastrointestinal: nausea, cramps, diarrhea.

  • Cutaneous: urticaria, eczema, angio-oedema.

  • Respiratory: rhinitis, bronchospasm, laryngeal oedema.

  • Cardiovascular (rare): hypotension.

  • Others: uterine contractions.

Mechanism of IgE-Mediated Allergy

  1. Sensitisation

    • Antigen (e.g. peanut protein) captured by dendritic cells.

    • Presentation to T-helper (Th2) cells.

    • Cytokine (interleukin) signalling transforms B cells → plasma cells.

    • Production of food-specific IgE antibodies.

    • IgE binds to mast cells & basophils (arming).

  2. Re-Exposure

    • Allergen cross-links IgE on mast cell surface.

    • Degranulation → histamine, leukotrienes, prostaglandins.

    • Clinical reaction (minutes to hours).

  • Memory: Sensitisation often long-lasting but can wane; not strictly permanent.

Diagnosis & Thresholds

  • Skin Prick Test (SPT)

    • Small extracts of suspected foods scratched into forearm/back.

    • Wheal ≥ control indicates sensitivity.

  • Oral Food Challenge / Dose-Response

    • Incremental ingestion starting sub-mg levels under medical supervision.

    • Example: 0.4\,\text{mg} peanut (≈0.1\,\text{mg} protein) elicited symptoms in the most sensitive patient recorded.

  • In vitro IgE assays (RAST, ImmunoCAP) supplement clinical tests.

Case Study – Delayed Peanut Reaction (Video)

  • 7-year-old Max, known peanut allergy & asthma, ingested tiny granola bar bite at school.

  • Immediate oral itch/swelling → ER; delayed severe respiratory failure.

  • Required CPR + ECMO lung bypass; first such use for peanut reaction at facility.

  • Highlights: delayed onset, life-threatening potential, importance of school protocols.

Big 8 & International Variations

  • Codex Big 8: peanut, tree nuts, soy, milk, egg, wheat (gluten), crustacea, fish (+ sulfites often grouped).

  • Australia/NZ adds: sesame, lupin (Big 10 locally).

  • Other jurisdictions add: celery, mustard, buckwheat, molluscan shellfish, mango, peach, pork, tomato.

Stakeholder Responsibility Framework

  1. Consumers

    • Declare allergies, read ingredient lists & allergen statements.

    • Make informed choices.

  2. Manufacturers / Packaged-Food Producers

    • Robust allergen management (risk assessment, cleaning, segregation).

    • Clear, consistent labelling of intended & potential unintended allergens.

  3. Food Service Establishments

    • Staff training; communicate allergen content & cross-contact risks.

    • Implement validated cleaning & prevention protocols.

Regulatory & Labelling Landscape

Codex Alimentarius

  • UN/FAO global reference for food standards; 1995 FAO expert consultation began allergen labelling focus.

FSANZ (Food Standards Australia New Zealand)

  • Provides standards, recall notices; dynamic website recommended for students.

  • Recalls dominated by undeclared allergens in dairy, nut & cereal products.

PEAL – Plain English Allergen Labelling (Australia, 2021-)

  • Mandatory plain language for allergen names ("egg", "milk", etc.).

  • Ingredients & ‘Contains’ summary required; formatting rules (bold, underline, etc.).

PAL – Precautionary Allergen Labelling

  • Voluntary advisory for cross-contact risk.

  • Typical phrases

    • “Manufactured in a facility that also processes peanuts.”

    • “May contain traces of tree nuts.”

  • Jurisdictional differences

    • Phrase “may contain” disallowed in USA & Japan (seen as vague); permissible in Canada, EU, AUS/NZ.

Cross-Contact Sources

  • Shared lines, inadequate cleaning, employee errors.

  • Agricultural: shared harvesters/storage.

  • Complex global supply chains; co-packers; local facility limitations.

  • Cleaning demands similar to Halal/Kosher production requirements (multiple validated wash cycles).

Recall Data Snapshot (FSANZ)

  • Majority of allergen-related recalls due to undeclared allergens.

  • Emphasis on continuous monitoring & transparent public notice (posters at Coles/Woolworths shelves).

Industrial & Business Considerations

  • Contrast with Pharma sector:

    • Pharmaceuticals: small volume, high margin.

    • Food: large volume, low margin ⇒ higher logistical complexity, larger recall impact.

  • Co-packers must adopt principal brand’s allergen standards; contractual & reputation risk.

Additional Resources & Reading

  • Lancet article on food allergy mechanisms.

  • FSANZ recall portal.

  • Food is Medicine Institute (Tufts University, Boston).

  • Allergy & Anaphylaxis Australia; work by Prof. Alice Lee (UNSW) on allergen management.

Ethical / Practical Implications Discussed

  • Societal reliance on regulatory infrastructure due to loss of innate foraging knowledge.

  • Need for global harmonisation vs local cultural/legislative nuance.

  • Balance between consumer autonomy and manufacturer accountability.

In-Class Interactive Elements

  • Kahoot quiz reinforced:

    • Lactose intolerance = metabolic disorder.

    • PAL meaning, examples.

    • Big 8 additions (sesame & lupin for Australia).

    • Celiac = autoimmune.

    • Cross-contact is accidental.

    • High fever not typical of food allergy.

  • Leaderboard crowned “Cindy” winner.

Key Take-Home Messages

  • Allergy ≠ Intolerance; immune system determines distinction.

  • Only a small set of foods (Big 8/10) cause >90 % reactions → enables focused risk management.

  • Even microgram quantities (e.g. 0.4\,\text{mg} peanut) can trigger severe responses.

  • Effective allergen control is a shared duty: consumer vigilance, strict industrial practice, transparent regulation.

  • Labelling evolution (PEAL, PAL) aims to deliver clarity without alarmism; remains an area of ongoing policy refinement.