[Food Safety & You] Food Allergy vs. Food Intolerance

February 23, 2022


  • Food allergy refers to the medical condition in which the body’s immune system mistakenly treats proteins in certain food as a threat, and hence, proceed to defend with immune reactions
  • Food intolerance refers to the difficulty our digestive system has with digesting certain foods which results in an unpleasant physical reaction

Cause / Trigger

Food allergy

  • Food allergy is induced by proteins presented in specific food items.
  • Majority of food allergies are caused by 8 common food categories:
    1. Milk
    2. Egg
    3. Soy
    4. Wheat
    5. Peanuts
    6. Tree nuts e.g. almond, cashew, etc.
    7. Fish
    8. Shellfish e.g. prawns, crabs, etc.
  • The consumption or even just physical contact with small traces of these allergens may already trigger a reaction

Food intolerance

  • Food intolerance can be caused by a much wider spectrum of foods and mechanisms including but not limited to:
    1. Absence of a particular enzyme needed to digest one food, e.g. lactose intolerance is caused by the lack of lactase;
    2. Irritable bowel syndrome, a chronic condition triggered by foods high in FODMAPs, a group of short-chain carbohydrates not digested and absorbed properly in the gut; 
    3. Sensitivity to certain food additives, e.g. sulfite which is commonly used in wine and preserved foods;
    4. Recurring stress or psychological factors;
    5. Celiac disease, a chronic condition triggered by the consumption of gluten;
  • The intensity of food intolerance may vary depending on the amount of food consumed. For example, a person with lactose intolerance may suffer from bloating after consuming a glass of milk, however, be able to enjoy a scoop of ice cream without any issue due to the difference in lactose content.

Symptoms & Reaction Time

  • The symptoms of a food allergy almost always develop a few seconds or minutes after eating the food, which include:
    1. Tingling or itching in the mouth;
    2. Itchy red skin rash; 
    3. Swelling of the face, mouth, throat or other areas of the body;
    4. Difficulty swallowing;
    5. Wheezing or shortness of breath;
    6. Nausea to vomiting;
    7. Abdominal pain to diarrhoea;
    8. Anaphylaxis, a set of severe symptoms including swollen tongue, breathing difficulties, tight chest, trouble swallowing or speaking, dizziness and even a collapse;
    9. Death in extreme cases;
  • Food intolerance symptoms are never life threatening and generally less severe. While food allergies may onset immediately, food intolerance usually kicks in within a few hours of consumption:
    1. Stomachache, bloating, and/or diarrhoea
    2. Skin rashes and itching

Diagnosis & Management Physiological conditions may vary among individuals. If you suspect food allergy or food intolerance in yourself or your child, please consult your physician and dietitian for a proper assessment and diagnosis in order to implement dietary adjustments to ensure safety and optimal nutrition as needed.

References: Centre for Food Safety, National Health Service (UK), Mayo Clinic. Food allergy vs. food intolerance, Monash University