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.

Aspect	Detail
What is gluten?	A protein found in wheat, barley, rye and sometimes oats (through cross-contamination)
Prevalence	Approximately 1 in 100 people in the UK (many undiagnosed)
Symptoms	Bloating, diarrhoea, constipation, abdominal pain, fatigue, weight loss, anaemia, mouth ulcers
Long-term effects	If untreated: malnutrition, osteoporosis, infertility, increased risk of intestinal cancer
Treatment	Lifelong gluten-free diet — there is no cure
Diagnosis	Blood test followed by intestinal biopsy

Foods to Avoid

Avoid	Because
Bread, pasta, cereals, cakes, biscuits	Usually made from wheat flour (contains gluten)
Beer and lager	Made from barley (contains gluten)
Soy sauce	Often contains wheat
Gravy and sauces	Often thickened with wheat flour
Some processed foods	May contain hidden gluten

Gluten-Free Alternatives

Instead of	Use
Wheat flour	Rice flour, corn flour, potato flour, buckwheat flour, almond flour
Regular pasta	Gluten-free pasta (rice or corn based)
Regular bread	Gluten-free bread
Wheat cereals	Rice-based or corn-based cereals
Regular oats	Certified gluten-free oats (uncontaminated)

Exam Tip: Coeliac disease is an autoimmune condition, not an allergy or simple intolerance. This is a key distinction. The immune system attacks the lining of the small intestine when gluten is consumed.

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Lactose Intolerance

Lactose intolerance is the inability to digest lactose, the natural sugar found in milk and dairy products, due to a deficiency of the enzyme lactase.

Aspect	Detail
What is lactose?	A sugar found naturally in milk and dairy products
What is lactase?	The enzyme that breaks down lactose in the small intestine
Cause	The body does not produce enough lactase enzyme
Prevalence	Very common — affects approximately 65% of the global population; more prevalent in Asian, African and South American populations
Symptoms	Bloating, flatulence, stomach cramps, diarrhoea, nausea (within a few hours of eating dairy)
Severity	Varies — some people can tolerate small amounts of dairy; others must avoid it completely
Treatment	Reducing or avoiding dairy; taking lactase supplements before eating dairy

Managing Lactose Intolerance

Strategy	Detail
Dairy-free alternatives	Soya milk, oat milk, almond milk, coconut milk, rice milk
Lactose-free dairy	Lactose-free milk, cheese and yoghurt (lactase enzyme added during production)
Hard cheeses	Cheddar, Parmesan and other aged cheeses contain very little lactose
Yoghurt	May be tolerated because the bacteria have partially digested the lactose
Lactase supplements	Tablets taken before eating dairy products help digest lactose
Calcium sources	If avoiding dairy, ensure adequate calcium from other sources: fortified plant milks, green leafy vegetables, tinned fish with bones, tofu

flowchart TD
    A["Lactose Intolerance"] --> B["Cannot digest LACTOSE<br/>(milk sugar)"]
    B --> C["Lacks the enzyme<br/>LACTASE"]
    C --> D["Symptoms: bloating,<br/>cramps, diarrhoea"]
    D --> E["Management"]
    E --> F["Dairy-free<br/>alternatives"]
    E --> G["Lactose-free<br/>dairy products"]
    E --> H["Lactase<br/>supplements"]
    E --> I["Small amounts<br/>may be tolerated"]

    style A fill:#e67e22,color:#fff
    style C fill:#3498db,color:#fff

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Managing Allergies: Practical Considerations

At Home

• Read all food labels carefully — allergens must be highlighted (usually in bold)
• Be aware of "may contain" warnings — these indicate cross-contamination risk
• Keep separate utensils and preparation areas for allergen-free cooking
• Teach children to recognise their allergen and ask about ingredients
• Keep adrenaline auto-injectors (EpiPens) accessible and in date