Food Intolerance vs Food Allergy

Food intolerance and food allergy are terms often used interchangeably. However, they are very different conditions with unique causes, symptoms, and management. Understanding the distinction between the two is vital for anyone experiencing adverse reactions to food, as the implications for health and treatment differ significantly.

What is a Food Allergy?

A food allergy occurs when a person’s immune system mistakenly identifies a specific protein in food as harmful. The immune system launches a response, releasing chemicals to fight off the “threat.”

The reaction can occur quickly, often within minutes to hours after eating the trigger food. In severe cases, the reaction can be life-threatening and requires immediate medical attention. This condition is known as anaphylaxis.

Common Food Allergens

Some foods are more likely to trigger allergies than others. Examples include:

• Nuts (e.g., peanuts, tree nuts like almonds and walnuts)
• Milk
• Eggs
• Shellfish (e.g., prawns, crab, lobster)
• Fish
• Soy
• Wheat

These are collectively referred to as the “big 8” allergens. While this list covers common triggers, allergies can develop to almost any type of food.

Symptoms of Food Allergies

Food allergies often present with symptoms affecting multiple body systems. These may include:

• Skin: Hives (itchy red welts), swelling (especially around the face, lips, and eyes), and itchy skin.
• Digestive system: Stomach pain, nausea, vomiting, and diarrhoea.
• Respiratory system: Difficulty breathing, wheezing, coughing, congestion, and a tight throat.
• Cardiovascular system: Light-headedness, fainting, or a rapid heartbeat.

Anaphylaxis includes more severe symptoms such as a drop in blood pressure, swelling of the tongue or throat, difficulty breathing, and a sense of doom. Without prompt treatment using an adrenaline (epinephrine) injection, it can be fatal.

Causes and Risk Factors

Food allergies are more common in children, but they can develop at any age. Some people outgrow allergies (e.g., to milk or eggs), while others, such as nut allergies, tend to persist for life.

Risk factors include:

• A family history of allergies
• Other allergic conditions like hay fever or asthma
• Early exposure to allergenic foods (though recent research suggests early introduction of allergens may prevent some allergies)

Diagnosing a Food Allergy

If a food allergy is suspected, you should consult a doctor or allergist. Diagnosis typically involves:

• Skin prick testing: A small amount of the suspected allergen is placed on the skin, which is then pricked to check for a reaction.
• Blood tests: Measures levels of immunoglobulin E (IgE), an antibody linked to allergic reactions.
• Oral food challenges: Conducted under medical supervision, small amounts of the suspected food are consumed to confirm an allergy.

Treatment and Management

Food allergies cannot be cured. Management focuses on avoiding the allergenic food and being prepared for accidental exposure.

Key steps include:

• Reading food labels carefully.
• Carrying an adrenaline auto-injector (e.g., EpiPen) if at risk of anaphylaxis.
• Informing schools, workplaces, and restaurants about the allergy.
• Working with a dietitian to ensure the diet remains balanced.

What is a Food Intolerance?

Food intolerance does not involve the immune system. Instead, it refers to difficulty digesting certain foods or a reaction to food additives. It is less serious than an allergy, but it can still negatively affect your quality of life.

Reactions often develop gradually, and symptoms may not appear until several hours after consuming the problem food. Unlike food allergies, life-threatening reactions such as anaphylaxis do not occur.

Common Food Intolerances

Intolerances often involve particular components of foods. Common examples include:

• Lactose intolerance: Difficulty digesting lactose, the natural sugar found in milk and dairy products.
• Gluten intolerance/Coeliac disease: A reaction to gluten (a protein in wheat, barley, and rye). Coeliac disease is an autoimmune condition, not just an intolerance.
• Histamine intolerance: An inability to break down histamine in certain aged or fermented foods like cheese, wine, and cured meats.
• Food additives: Some people react to preservatives or artificial colourings.

Symptoms of Food Intolerance

The symptoms of food intolerance usually affect the digestive system, but they can also cause discomfort in other areas. They often vary from one person to another but may include:

• Bloating
• Stomach pain
• Diarrhoea or constipation
• Gas
• Nausea
• Headaches or migraines
• Fatigue

Unlike food allergies, symptoms of food intolerance are less predictable and can depend on the amount of the food consumed.

Causes and Risk Factors

Food intolerances may result from various underlying issues, such as:

• Lack of enzymes: For example, people with lactose intolerance lack enough lactase enzyme to break down lactose.
• Sensitivity to chemicals: Natural or artificial substances in foods, such as caffeine, can sometimes cause reactions.
• Gut health: Imbalances in gut bacteria or digestive conditions, such as irritable bowel syndrome (IBS), may play a role.

Diagnosing a Food Intolerance

Diagnosing food intolerance is usually more challenging than diagnosing an allergy. There are no definitive tests for many intolerances. Health professionals may recommend:

• Elimination diets: Removing suspected foods from the diet temporarily, then reintroducing them one at a time to identify triggers.
• Breath tests: Used for lactose or fructose intolerance, these measure gases produced during digestion.
• Coeliac testing: Blood tests and a biopsy may identify whether gluten sensitivity is caused by coeliac disease.

A proper diagnosis is essential. Self-diagnosing and cutting out foods unnecessarily can lead to nutritional deficiencies.

Treatment and Management

Managing food intolerance typically involves reducing or avoiding trigger foods. Unlike allergies, small amounts of the food may be tolerated without causing symptoms.

Strategies include:

• Finding alternative foods (e.g., lactose-free dairy products).
• Using enzyme supplements for issues like lactose or histamine intolerance.
• Improving overall gut health through a varied and balanced diet.

Differences Between Food Allergy and Food Intolerance

Although food allergy and food intolerance can share some symptoms, they are very different in how they affect the body.

When to See a Doctor

You should seek medical advice if you suspect a food allergy or intolerance. Warning signs include severe symptoms like difficulty breathing, persistent stomach issues, or an inability to identify triggers. GPs can guide you on the next steps and, if needed, refer you to specialists.

Final Thoughts

• Always read food labels if you or someone you care for has an allergy or intolerance.
• Don’t self-diagnose. Instead, work with a healthcare professional.
• Be proactive. If a food allergy is confirmed, carry necessary medication such as an adrenaline auto-injector.
• Keep a food diary to help identify patterns that link symptoms to specific foods if you have a suspected intolerance.

Understanding food allergy versus food intolerance is critical for managing health. Each condition has its own challenges and solutions. Knowing the distinction helps you take appropriate action and maintain a good quality of life.