Food allergies and intolerances are frequently mistaken for one another, primarily because the symptoms of food intolerance can sometimes mimic those of a food allergy. However, a crucial distinction lies in the body’s response: food intolerance does not involve the immune system. This fundamental difference means that unlike food allergies, intolerances do not trigger severe allergic reactions, also known as anaphylaxis. Furthermore, food intolerance cannot be detected through standard allergy testing. The Australasian Society of Clinical Immunology and Allergy (ASCIA) advises against non-evidence-based allergy tests, highlighting the importance of accurate diagnosis.
Food intolerance can be a complex issue to grasp. In essence, it describes situations where certain components within foods can provoke a range of adverse reactions in the body. These reactions can manifest as increased frequency and intensity of migraine headaches, skin rashes like hives, or digestive disturbances characteristic of irritable bowel syndrome (IBS).
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To gain a clearer understanding of the mechanisms behind allergies, you can watch the animated video “How Allergies Work” available on the ASCIA website.
Seeking a professional diagnosis from a clinical immunology/allergy specialist is vital for accurately identifying food allergies.
The Growing Prevalence of Food Allergy
Globally, allergies are on the rise, and food allergies have become increasingly common. The majority of food allergies emerge during the first year of life. Cow’s milk allergy stands out as one of the most prevalent allergies in early childhood, though most children outgrow this allergy before starting school.
Continued research is essential to deepen our understanding of the causes, diagnosis, and effective treatments for food allergies.
The Role of Heredity in Allergy
Genetics play a role in allergy susceptibility. Children with a family history of allergic diseases, such as asthma or eczema, have an elevated risk of developing allergies themselves.
While family history is a factor, it’s important to note that most children with food allergies do not have parents with the same condition. However, in families with one child already diagnosed with a food allergy, siblings have a slightly increased risk, although the overall risk remains relatively low.
Food Allergy: An Immune System Overreaction
Allergies are fundamentally an exaggerated response of the body’s immune system to a protein. These proteins, known as allergens, can originate from various sources, including:
- Foods
- Pollens
- House dust mites
- Animal dander (including fur, wool, and pollens carried indoors by pets)
- Moulds
In an allergic reaction, the immune system mistakenly identifies a typically harmless substance as a threat and reacts as if it were toxic.
Food Intolerance: A Chemical Reaction, Not Immune-Driven
In contrast to food allergy, food intolerance is characterized by a chemical reaction that occurs in some individuals after consuming certain foods or drinks. Crucially, this reaction is not an immune response. Food intolerance has been linked to conditions such as asthma, chronic fatigue syndrome (CFS), and irritable bowel syndrome (IBS).
Distinguishing Symptoms: Food Allergy vs. Food Intolerance
Differentiating between food allergy and food intolerance based on symptoms alone can be challenging. Typically, food allergy symptoms manifest rapidly, usually very soon after eating the offending food. While food intolerance symptoms can also appear quickly, they may sometimes be delayed, taking up to 12 to 24 hours to develop.
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Food intolerance reactions are often dose-dependent, meaning they are related to the quantity of food consumed. Symptoms may not arise until a certain threshold level of the food is reached, and this threshold varies from person to person.
It is important to remember that the symptoms of both food allergy and food intolerance can also be caused by other underlying medical conditions. Therefore, seeking a professional medical diagnosis from your doctor is essential for accurate identification and management.
Symptoms of Food Intolerance: Varied and Non-Allergic
The symptoms of food intolerance can be diverse and may include:
- Nervousness
- Tremors
- Sweating
- Palpitations
- Rapid breathing
- Headache, including migraine
- Diarrhoea
- Burning sensations on the skin
- Tightness across the face and chest
- Breathing problems resembling asthma symptoms
- Allergy-like reactions (though not immune-mediated)
Symptoms of Food Allergy: Immune System Response
Mild to moderate food allergy symptoms can include:
- Swelling of the lips, face, and eyes
- Hives or welts
- Tingling sensation in the mouth
- Abdominal pain, vomiting (these can also be signs of anaphylaxis in insect allergy)
Signs of anaphylaxis, a severe allergic reaction requiring immediate medical attention, include:
- Difficult or noisy breathing
- Swelling of the tongue
- Swelling or tightness in the throat
- Wheezing or persistent cough
- Difficulty talking or hoarse voice
- Persistent dizziness or collapse
- Pale and floppy appearance (in young children)
Action plans for managing anaphylaxis are readily available from ASCIA, offering guidance on first aid, management, travel, and treatment.
Body Parts Affected by Food Allergy: Systemic Reactions
Food allergies can affect various parts of the body due to the systemic nature of the immune response. Affected areas can include:
- Face, lips, and eyes (swelling)
- Tongue (swelling)
- Throat (swelling or tightness)
- Stomach (pain, vomiting – signs of anaphylaxis in insect allergy)
- Skin (rashes, such as hives or atopic dermatitis)
- Lungs (wheezing, cough, asthma – more common in children)
Severe Allergic Reactions to Food: A Life-Threatening Emergency
Anaphylaxis is a severe and potentially life-threatening allergic reaction that demands immediate medical intervention. Common triggers for anaphylaxis include foods like peanuts, tree nuts, seafood, wheat, milk, and eggs, as well as insect bites and stings, and certain medications.
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Within minutes of exposure to the allergen, an individual experiencing anaphylaxis can develop severe symptoms, such as:
- Difficult or noisy breathing
- Swelling of the tongue
- Swelling or tightness in the throat
- Wheezing or persistent cough
- Difficulty talking or hoarse voice
- Persistent dizziness or collapse
- Pale and floppy appearance (in young children)
Several factors can influence the severity of anaphylaxis, including exercise, heat, alcohol consumption, the amount of food ingested, and food preparation methods.
Emergency Treatment for Anaphylaxis: Prompt Action is Key
To prevent serious harm or fatality, anaphylaxis requires immediate treatment with an adrenaline (epinephrine) injection into the outer mid-thigh. The person experiencing anaphylaxis should not stand or walk. If there is no improvement after 5 minutes, further doses of adrenaline may be necessary. Administer adrenaline first, followed by an asthma reliever puffer if needed.
Individuals considered at risk of anaphylaxis by their doctor are typically prescribed an adrenaline injector, such as an EpiPen® or Anapen®, which delivers a single, fixed dose of adrenaline. These patients should also have a personalized ASCIA Anaphylaxis Action Plan.
Adrenaline injectors are designed for use by non-medical personnel and are readily available from pharmacies.
Common Causes of Food Allergy: The Usual Suspects
Peanuts, tree nuts, eggs, cow’s milk, wheat, sesame, fish, shellfish, and soy are responsible for the majority of food allergic reactions. Peanut allergy is particularly prevalent in older children, with only about one in four children outgrowing it.
Common Causes of Food Intolerance: Identifying Triggers
Foods commonly associated with intolerance reactions in sensitive individuals include:
- Dairy products, such as milk, cheese, and yoghurt
- Chocolate
- Eggs, especially egg white
- Flavour enhancers like MSG (monosodium glutamate 621)
- Food additives
- Strawberries, citrus fruits, and tomatoes
- Wine, particularly red wine
- Histamine and other amines found in certain foods
Pinpointing the Culprit: Diagnostic Approaches
Identifying the trigger food can be straightforward when symptoms appear within minutes of consumption. However, when the cause is unclear, diagnostic tests may be necessary. These can include:
- Keeping a detailed food and symptom diary to identify patterns.
- Under the guidance of a clinical immunology/allergy specialist or dietitian, implementing an elimination diet to remove suspected foods for two weeks, followed by gradual reintroduction to monitor for reactions (except in cases of anaphylaxis).
- Skin prick tests using food extracts or IgG blood tests.
ASCIA strongly recommends using only evidence-based allergy tests to ensure accurate diagnosis.
Managing Food Allergy and Intolerance: Dietary Strategies
The primary approach to managing both food allergy and food intolerance is to eliminate the offending food(s) from the diet. In some cases of food intolerance, tolerance may develop over time with avoidance, allowing for gradual reintroduction in small amounts.
Before making significant dietary changes, it is crucial to seek advice from a clinical immunology/allergy specialist or dietitian for personalized guidance.
Preventing Food Allergy in Children: Current Recommendations
Preventing food allergies in children is an active area of ongoing research. Current findings suggest:
- Prenatal: Avoiding allergens during pregnancy has not been conclusively proven to prevent allergies in children.
- Postnatal: Exclusive breastfeeding for the first 4 to 6 months appears to offer protection against the development of allergies in early childhood.
- Introducing solid foods, including those considered allergenic, around 6 months of age (but not before 4 months) is recommended, ideally while continuing breastfeeding.
- Breastfeeding mothers are not advised to avoid allergenic foods in their own diets.
- Soymilk formula has not been shown to prevent allergy development in children.
- Partially hydrolysed cow’s milk-based formula (HA formula) is not recommended for allergy prevention.
Managing Severe Food Allergy in Schools and Childcare
Allergic reactions, including anaphylaxis, are common in children, although fatalities are rare. All schools and childcare services in Australia are required to have an anaphylaxis management policy in place. Teachers receive training in recognizing and responding to allergic reactions through ASCIA Anaphylaxis e-training and practice using adrenaline injector training devices.
Banning specific foods in schools and childcare settings is generally not recommended as it can create a false sense of security and is difficult to enforce effectively. A more effective strategy involves educating staff, students, and the wider community about anaphylaxis risks and implementing comprehensive strategies to minimize exposure to known allergens. The Allergy Aware website provides numerous helpful resources.
Food Allergen Avoidance: Reading Labels Carefully
If you have a diagnosed food allergy, it is essential to avoid the specific allergen. Familiarize yourself with terms used on food labels to describe common allergens. Examples include:
- Milk protein: milk, non-fat milk solids, cheese, yoghurt, caseinates, whey, lactose
- Lactose: milk, lactose
- Egg: eggs, egg albumen, egg yolk, egg lecithin
- Gluten: wheat, barley, rye, triticale, wheat bran, malt, oats, cornflour, oat bran
- Soy: soybeans, hydrolysed vegetable protein, soy protein isolate, soy lecithin
- Salicylates: strawberries, tomatoes
The National Allergy Strategy has developed a resource hub to support best practices in food allergen management.
Food Laws and Labels: Mandatory Allergen Declarations
Since December 2002, the Australia New Zealand Food Standards Code mandates the declaration of certain foods and substances on food labels, including:
- Cereals containing gluten and gluten products
- Shellfish and their products
- Eggs and egg products
- Fish and fish products
- Milk and milk products
- Tree nuts, sesame seeds, and their products
- Peanuts
- Soybeans and their products
- Added sulphites in concentrations of 10 mg/kg or more
- Royal jelly, bee pollen, and propolis (when presented as food or present in food)
These foods must be declared if they are used as ingredients, components of compound ingredients, food additives, or processing aids.
