Food allergy and food intolerance are often confused, but their mechanisms, severity, and management are fundamentally different.
What Is Food Allergy?
Food allergy occurs when the immune system mounts an exaggerated response to specific food proteins. IgE-mediated reactions can develop within minutes and may cause hives, swelling of the lips and eyes, cough, and even anaphylaxis. The most common allergenic foods are peanuts, tree nuts, fish, seafood, milk, egg, wheat, and soy.
Food allergy diagnosis is made through skin prick tests, serum IgE testing, and the gold-standard double-blind placebo-controlled food challenge. Eliminating foods solely based on test findings without proper diagnosis may lead to nutritional deficiencies.
What Is Food Intolerance?
In intolerance, the immune system is not involved; the issue is usually enzyme deficiency or gut sensitivity. Lactose intolerance (lactase deficiency) is the most common example. Symptoms appear over hours, are dose-dependent, and include bloating, gas, cramping, and diarrhea. There is no anaphylaxis risk.
Gluten intolerance (outside celiac disease) is also increasingly recognized. It is called non-celiac gluten sensitivity; there is no clear biomarker, so diagnosis is based on elimination and reintroduction.
Allergy or Intolerance? Core Differences
- Allergy: immune-mediated, can be triggered even by very small amounts
- Intolerance: digestion-related, generally dose-dependent
- Allergy can be life-threatening; intolerance is non-life-threatening but distressing
- Both should be managed with dietitian guidance
Management: Elimination and Reintroduction
In both allergy and intolerance management, suspected foods are fully removed for 2-4 weeks, then reintroduced one by one to confirm triggers. Without dietitian supervision, this process can cause both underdiagnosis and unnecessary dietary restriction, especially in children where growth can be affected.