Food Allergy or Food Intolerance?

The terms “food allergy” and “food intolerance” are sometimes used interchangeably, but are in fact quite different.  While a person might declare that they are allergic to a particular food, in some cases they are actually referring to a food intolerance rather than an allergy – a condition which, while unpleasant, may not be quite as serious.

A true allergy in the traditional sense is an acute immune response (IgE antibody) to a food or other substance, which causes the body to react almost as if the substance is toxic.  This is known as a Type 1 Allergy. The reaction is usually immediate and can result in symptoms such as difficulty breathing, swelling of the tongue or lips, skin rashes or hives, swollen throat, water and itchy eyes, or in severe cases anaphylaxis.  Common food allergies are eggs, nuts, milk and shellfish.

Delayed onset allergies, or food intolerances, involve an immune response (IgG antibody) and are a lot more common than traditional allergies. The offending food causes a defense reaction by the immune system and if the food continues to be eaten the symptoms can be very unpleasant and, if left untreated, can lead to serious issues down the track. The symptoms of IgG food intolerance typically include digestive problems (IBS, bloating, stomach pains, diarrhea, constipation, weight gain), tiredness, fatigue, headaches, skin conditions, sore joints and depression.

Common food intolerances include:

  • Gluten intolerance – sensitivity to the protein components of some grain foods such as wheat, oats, barley, rye…
  • Dairy intolerance – difficulty digesting dairy food due to a reaction to milk proteins. This is not to be confused with Lactose intolerance which is an enzyme deficiency and inability to properly digest milk sugars (lactase).

Quick comparison table: IgE Food Allergy vs IgG Food Intolerance?