The distinction between food allergies and food intolerances is significant, as they involve different bodily mechanisms, symptoms, and management approaches.

1. Immune System InvolvementFood Allergy:
Involves the immune system, which mistakenly identifies certain food proteins as harmful. The immune response typically involves immunoglobulin E (IgE) antibodies, leading to the release of chemicals like histamine, which cause allergic symptoms.
Even a small amount of the allergen can trigger a reaction, and in severe cases, this can lead to anaphylaxis—a potentially life-threatening reaction.
Food Intolerance:
Does not involve the immune system. Instead, it is typically caused by the body’s inability to digest or metabolize a particular food component (e.g., lactose, gluten).Symptoms are generally less severe than those of allergies and are often dose-dependent. A person with an intolerance may be able to consume small amounts of the food without issues.

2. Onset of Symptoms

Food Allergy:
Symptoms usually appear within minutes to hours after consuming the allergenic food. In some cases, reactions are immediate and severe.
Food Intolerance:
Symptoms typically appear more gradually, hours after consuming the food, and may worsen if larger amounts are eaten.

3. Symptoms

Food Allergy:
Symptoms can be life-threatening and affect multiple systems, such as:
Skin: Hives, rash, swelling (angioedema)
Respiratory: Wheezing, shortness of breath, difficulty breathing, throat tightness
Gastrointestinal: Vomiting, diarrhoea, abdominal cramps
Cardiovascular: Drop in blood pressure, dizziness, fainting (as in anaphylaxis)
Food Intolerance:
Symptoms tend to be localized to the gastrointestinal system and include:
Bloating
Gas
Diarrheal
Stomach pain
Nausea

4. Common Causes

Food Allergy:
Common allergens include:
Peanuts, tree nuts, shellfish, fish, eggs, milk, wheat, soy.
Food Intolerance:
Common intolerances include:
Lactose intolerance: Inability to digest lactose (the sugar in milk).
Gluten intolerance (Non-celiac gluten sensitivity): Negative reaction to gluten found in wheat, barley, and rye (but not involving the immune system like celiac disease).
Histamine intolerance: Sensitivity to foods high in histamine, such as aged cheeses, wine, and fermented foods.

5. Diagnosis

Food Allergy:
Diagnosis typically involves:
Skin prick tests or blood tests (to measure specific IgE antibodies).
Oral food challenges (administering small amounts of the suspected allergen under medical supervision).
Food Intolerance:
Diagnosis is often based on symptom history and elimination diets, followed by food reintroduction to identify the offending substance.
Tests like lactose tolerance tests or hydrogen breath tests can diagnose lactose intolerance.

6. Severity and Risks

Food Allergy:
Severe and can lead to anaphylaxis, requiring emergency treatment (e.g., epinephrine injections).
Food Intolerance:
Generally uncomfortable but not dangerous, though some intolerances (like celiac disease, which is an autoimmune disorder) can have long-term health implications if unmanaged.

7. Management

Food Allergy:
Requires strict avoidance of allergenic food. Individuals with severe allergies may need to carry an epinephrine auto-injector (e.g., EpiPen) and should be prepared for accidental exposure.

Food Intolerance:
Management involves limiting or avoiding the problematic food, though small amounts may sometimes be tolerated. Some intolerances, like lactose intolerance, can be managed with enzymes (e.g., lactase supplements) that aid digestion.

Summary of Key Differences

Aspect Food Allergy Food Intolerance

Food allergy-Immune involvement Yes (IgE-mediated immune response),- food intolerance No (Digestive or metabolic issue)
Food allergy- Severity Can be life-threatening (anaphylaxis possible), food intolerance usually not life-threatening
Food allergy- Symptoms Skin, respiratory, gastrointestinal, cardiovascular- food intolerance Gastrointestinal primarily
Food intolerance- Diagnosis Skin tests, blood tests, oral challenge Symptom history,- food intolerance elimination diet, specific tests (e.g., lactose tolerance)
Food allergy- Management Strict avoidance, carry epinephrine Limit intake- food intolerance use digestive aids if available

Dr Geranmayeh