Food Allergies and Intolerances

This lesson covers food allergies and food intolerances, as required by the AQA GCSE Food Preparation and Nutrition specification (8585), section 3.5. You need to understand the difference between an allergy and an intolerance, know the most common allergens, and understand how to manage dietary needs for people with these conditions.

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Allergy vs Intolerance

It is essential to understand the difference between a food allergy and a food intolerance:

Feature	Food Allergy	Food Intolerance
What it is	An immune system reaction to a specific food protein	A digestive system reaction; the body cannot properly digest a food
Severity	Can be life-threatening (anaphylaxis)	Unpleasant but not life-threatening
Amount needed	Even tiny traces can trigger a reaction	Usually requires a larger amount to cause symptoms
Speed of reaction	Usually rapid (within minutes to 2 hours)	Can be delayed (hours to days after eating)
Immune system	Involved — produces antibodies (IgE)	Not involved
Examples	Nut allergy, milk allergy, egg allergy	Lactose intolerance, coeliac disease
Symptoms	Swelling, hives, breathing difficulties, anaphylaxis	Bloating, stomach pain, diarrhoea, headaches

flowchart TD
    A["Adverse Reaction<br/>to Food"] --> B["Food ALLERGY<br/>Immune system reaction"]
    A --> C["Food INTOLERANCE<br/>Digestive system reaction"]

    B --> D["Rapid onset<br/>Minutes to 2 hours"]
    B --> E["Can be life-threatening<br/>ANAPHYLAXIS"]
    B --> F["Triggered by<br/>tiny traces"]

    C --> G["Delayed onset<br/>Hours to days"]
    C --> H["Unpleasant but<br/>NOT life-threatening"]
    C --> I["Usually needs<br/>larger amounts"]

    style B fill:#e74c3c,color:#fff
    style C fill:#e67e22,color:#fff
    style E fill:#c0392b,color:#fff

Exam Tip: The key distinction is that allergies involve the immune system and can be life-threatening, while intolerances involve the digestive system and are unpleasant but not fatal. This is the most commonly tested difference.

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The 14 Major Food Allergens

UK food law requires that 14 major allergens are declared on food labels and menus. These are:

Number	Allergen	Common Foods Containing It
1	Celery	Soups, stocks, salads, celery salt
2	Cereals containing gluten	Wheat, barley, rye, oats; bread, pasta, cakes, biscuits, beer
3	Crustaceans	Prawns, crab, lobster, crayfish
4	Eggs	Cakes, quiche, mayonnaise, pasta, ice cream
5	Fish	Fish sauce, Caesar dressing, Worcestershire sauce
6	Lupin	Lupin flour in bread, pastries
7	Milk	Cheese, butter, cream, yoghurt, chocolate, many processed foods
8	Molluscs	Mussels, oysters, squid, snails
9	Mustard	Sauces, dressings, marinades, processed meats
10	Nuts (tree nuts)	Almonds, walnuts, cashews, pecans, pistachios, Brazil nuts
11	Peanuts	Peanut butter, satay sauce, groundnut oil, many Asian dishes
12	Sesame	Bread, hummus, tahini, some Asian dishes
13	Soya	Soy sauce, tofu, soya milk, many processed foods
14	Sulphur dioxide/sulphites	Dried fruit, wine, soft drinks, sausages

Exam Tip: You do not need to memorise all 14, but you should know the most common ones: milk, eggs, peanuts, tree nuts, wheat (gluten), fish, shellfish and soya. These account for the vast majority of allergic reactions.

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Common Food Allergies in Detail

Nut Allergy (Peanuts and Tree Nuts)

Nut allergy is one of the most common and most dangerous food allergies:

Aspect	Detail
Types	Peanuts (actually a legume, not a nut) and tree nuts (almonds, walnuts, cashews, etc.)
Prevalence	Affects approximately 1–2% of the UK population
Severity	Can cause anaphylaxis — a life-threatening reaction
Symptoms	Swelling of lips/throat, difficulty breathing, hives, drop in blood pressure, anaphylaxis
Treatment	Adrenaline auto-injector (EpiPen) for severe reactions; antihistamines for mild reactions
Hidden sources	Peanut oil, marzipan (almonds), praline, nougat, some curries and Asian sauces
Alternatives	Seed butters (sunflower, pumpkin), coconut (usually safe), seed-based snacks

Milk Allergy

Aspect	Detail
What it is	Allergy to proteins in cow's milk (casein, whey)
Most common in	Children under 3; many outgrow it
Symptoms	Hives, swelling, vomiting, diarrhoea, eczema, breathing difficulties; rarely anaphylaxis
Not the same as	Lactose intolerance (which is a digestive problem, not an immune reaction)
Alternatives	Soya milk, oat milk, almond milk, coconut milk, rice milk
Hidden sources	Chocolate, biscuits, bread, sausages, processed foods

Egg Allergy

Aspect	Detail
What it is	Allergy to proteins in egg white (and sometimes egg yolk)
Most common in	Young children; many outgrow it by age 5
Symptoms	Skin rash, swelling, vomiting, breathing difficulties
Hidden sources	Mayonnaise, cakes, pasta (some types), batter, meringue, ice cream
Alternatives	Egg replacers (commercial products), flax eggs, chia eggs, mashed banana (in baking)

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Coeliac Disease (Gluten)

Coeliac disease is an autoimmune condition (not a simple allergy or intolerance) in which the body's immune system attacks its own tissues when gluten is eaten. This damages the lining of the small intestine, reducing its ability to absorb nutrients.