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Anyone who has eaten something that didn’t agree with them knows it can be an unpleasant and uncomfortable experience, whether it be due to an allergic reaction, a food intolerance or a dose of food poisoning. While food poisoning is generally well understood, the difference between a food allergy and a food intolerance is often confused, especially these days where eliminating foods because of their perceived reaction in the body is so common.

So, let’s clear up what’s what when it comes to the difference between a food allergy and a food intolerance.


What is the difference between a food allergy and a food intolerance?

What is a food allergy?

Food allergies occur when a person’s immune system mistakes certain food proteins eaten as being harmful. The immune system reacts by flooding the body with chemicals (such as histamines) that cause unpleasant, uncomfortable and what can be scary physical symptoms. Allergic reactions normally come on suddenly and, if left untreated, can be fatal.

Anaphylaxis is the most severe form of allergic reaction and causes symptoms that affect the respiratory, skin, cardiovascular and gastrointestinal systems.

90% of all food-triggered anaphylactic reactions are caused by just nine foods. They are; egg, milk, peanuts, tree nuts (e.g. cashews, almond), fish, shellfish (e.g. prawn and lobster), sesame, soy and wheat. However, there are more than 170 foods known to have triggered anaphylactic reactions.

Symptoms of an allergic reaction:

  • Hives, welts or body redness
  • Swelling of the face, lips, eyes
  • Abdominal pain
  • Vomiting
  • Tingling/scratchy sensation in the mouth
  • Drop in blood pressure

Symptoms of anaphylaxis:

  • Symptoms listed above plus;
  • Swelling of the tongue
  • Swelling in the throat
  • Difficult and noisy breathing
  • Difficulty talking and/or hoarse voice
  • A wheeze or persistent cough
  • Dizziness and possible collapse
  • Young children can appear pale and floppy

There is no cure for a food allergy. The only way to prevent a reaction is to avoid any foods that cause an allergic reaction.

What is a food intolerance?

Most intolerances are not caused by the immune system reacting but rather a reaction that occurs in the digestive tract. While they can cause extreme discomfort, most food intolerances are less severe than allergies.

In fact, a lot of people who do have food intolerances can eat small amounts of trigger foods without symptoms. Food intolerance symptoms come on gradually (although people with Irritable Bowel Syndrome might not agree with that!) and include bloating, nausea, cramps, wind, headaches or fatigue.

Food intolerances can be caused by:

  • The body not making enough enzymes needed to properly digest a food. A common example is lactose intolerance, where people do not produce enough of the enzyme lactase to break the lactose down into galactose and glucose which
  • Irritable bowel syndrome
  • A sensitivity to food additives
  • Sensitivity to naturally occurring chemicals in food such as amines (found in bananas, red wine, chocolate, pineapple) glutamate (found in mushrooms, soy sauce, tomatoes) and salicylates (found in fruit, vegetables, herbs and spices)
  • Coeliac disease. Coeliac disease is slightly different as it doesinvolve the immune system. However, people with Coeliac disease are not at risk of anaphylaxis

When the symptoms don’t fit a food allergy or an intolerance

There are some conditions that can be exacerbated by eating certain foods which are neither related to an allergic reaction or a food intolerance. A couple of examples include rosacea, which is a facial skin condition and gout, which is a type of arthritis. People with rosacea often find that alcohol, spicy food, some fruits and vegetables cause the skin to ‘flare up’. Attacks of gout have been found to be brought on by consumption of alcohol, meat, offal, shellfish, fructose and foods containing yeast (e.g. Vegemite).

Food Labelling

Because of the potential to cause food allergies and anaphylaxis, The Food Standards Code requires foods and food products to declare if they contain any of the Top Nine allergens (peanuts, tree nuts, milk, eggs, sesame, fish, shellfish, soy and wheat. In May 2017, lupin was added to the Top Nine allergens that must be declared. Gluten containing cereals (wheat, rye, barley, oats, spelt) also must be declared on food labels given their potential to cause damage to the gastrointestinal tract of people with Coeliac disease.

 What is the difference between a food allergy and a food intolerance?


Post originally published May 2012



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