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Author:  Australian Allergy CentreSeptember 24, 2015

Food Allergy versus Food Intolerance

Food allergy and food intolerance are commonly confused because the symptoms of food intolerance occasionally resemble the symptoms of food allergy. However there are important differences between the two.

A food allergy is an overreaction of the body’s immune system to an ordinarily harmless component within a food. The food is perceived as “foreign” and therefore threatening, so the immune system produces allergen-specific immunoglobulin E (IgE) antibodies to protect the body. In response to an “infestation” the IgE antibodies bind to food allergens; triggering the release of histamine from mast cells and an immediate hypersensitivity reaction.

A food intolerance is a chemical reaction rather than an IgE-mediated immune response. Chemicals within food cause reactions by irritating nerve endings throughout the body. Unlike a food allergy though, a food intolerance cannot illicit a severe allergic reaction, or anaphylaxis.

It can be difficult to tell the difference between the symptoms of food allergy and food intolerance. In general, symptoms caused by a food allergy develop very quickly after consuming the offending food. Symptoms of food intolerance can be immediate, but usually develop after 12-24 hours.  Furthermore, unlike with food allergy reactions, food intolerance reactions are usually related to the amount of food consumed. An individual with a food intolerance may be able to eat small amounts of the offending food without experiencing symptoms.

Common symptoms of food allergy include:
– Itching, burning or swelling around the mouth
– Runny nose, sneezing, nasal stuffiness
– Watery, itchy eyes
– Breathing difficulties, including wheezing, coughing and asthma
– Abdominal cramps, vomiting and diarrhoea
– Eczema, hives
– Anaphylactic shock
– Swelling of the tongue and throat
– Breathing difficulties
– Wheezing, persistent coughing and asthma
– Dizziness or loss of consciousness

Common symptoms of food intolerance include:
– Mouth ulcers
– Asthma-like symptoms
– Sinus problems
– Headache, migraine
– Nausea, abdominal pains/bloating and bowel irritability
– Burning sensations across the skin
– Tightness across the face and chest
– Chronic fatigue and general feeling of being run down
– Irritability and restlessness (more common in children)

In Australia, it is estimated 10% infants under 1 year of age, 4-8% of children under five years old and approximately 2% of adults experience food allergies. Peanuts, tree nuts, eggs, milk, wheat, sesame, fish, shellfish and soy are the cause of approximately 90 percent of food allergic reactions (ASCIA, 2015).

Food intolerance is more common than food allergies, surveys indicating up to 25% of Australians believe they have some form of food intolerance (NSW Food Authority, 2014). Foods that tend to cause intolerance reactions are dairy products including milk, cheese and yoghurt, chocolate, eggs (particularly egg white), flavour enhancers such as MSG, food additives, strawberries, citrus fruits, tomatoes and wine (particularly red wine). Intolerance reactions can also be triggered by natural food chemicals, such as salicylates, amines and glutamates.

The easiest way to treat a food allergy or intolerance is by eliminating the offending food or foods from the diet. As the chemicals involved in food intolerances can be found within many different foods, the approach is to identify the offending chemical and reduce intake of the group of foods containing it. In contrast, as the protein allergens within different foods are generally unique, management of a food allergy involves identifying and avoiding all traces of the particular offending food.

To diagnose a food allergy or intolerance is complicated, and individuals should always seek the assistance of a qualified medical professional. If a food allergy is suspected, upon taking a detailed medical history, a skin prick test or allergen-specific IgE blood test may be ordered. There are no reliable skin or blood tests for the diagnosis of food intolerance however. Food intolerances are diagnosed through a process of dietary elimination and challenge testing. This should always be done under the supervision of a doctor or dietitian (ASCIA 2014).

It is important to note that self-diagnosis of a food allergy or intolerance is dangerous and not recommended. Self-diagnosis can lead to unnecessary dietary restriction and subsequently, nutrient deficiencies. Without seeking professional advice, individuals also place themselves at risk for harm associated with the missed diagnosis of other potentially life-threatening medical conditions.

At the Australian Allergy Centre, we have a team of passionate and dedicated healthcare professionals who specialise in the diagnosis and management of food allergies. All medical consultations at the Australian Allergy Centre are bulk-billed and no referral is necessary. Skin prick testing for food allergens is available for $150. This panel covers milk, egg, a variety of grains, seafood, meats, fruits, vegetables and peanut. An extended nut panel is also available for $75. This panel includes peanut, walnut, hazelnut, pecan, pistachio, almond, macadamia, brazil, pine and cashew nuts.

For more information, or to book an appointment, contact the Australian Allergy Centre today on 1300 MY ALLERGY.

Reference List:

Australasian Society of Clinical Immunology and Allergy [ASCIA]. 2015. Food allergy. Information for patients, consumers and carers. Accessed July 31, 2015, http://www.allergy.org.au/images/pcc/ASCIA_PCC_Food_Allergy_2015.pdf

Australasian Society of Clinical Immunology and Allergy [ASCIA]. 2014. Food intolerance. Information for patients, consumers and carers. Accessed July 31, 2015, http://www.allergy.org.au/images/pcc/ASCIA_PCC_Food_intolerance_2014.pdf

New South Wales Food Authority. 2014. Allergy and intolerance. Accessed July 31, 2015, http://www.foodauthority.nsw.gov.au/_Documents/consumer_pdf/Foodallergies_brochure.pdf