Food Intolerance

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Food intolerance is a broad term that is used to describe a wide range of adverse reactions to foods, that cause symptoms after eating some foods. These include stomach pain, bloating, gas/flatulence, diarrhoea, irritable bowel syndrome (IBS), rashes, hives (urticaria), recurrent mouth ulcers or headaches. If food intolerances are not properly managed, these symptoms can adversely affect general health and wellbeing.

Food intolerances are sometimes confused with, or mislabeled as food allergies.  Food intolerances involve the digestive system, whilst food allergies involve the immune system. Unlike Immunoglobulin E (IgE) antibody mediated food allergy, food intolerances (except for sulphite and benzoate reactions) do not cause anaphylaxis (severe allergic reactions), that can be life threatening.

Non-IgE mediated food allergies are sometimes called food intolerances, however these conditions involve the immune system, so they are different to food intolerances, that do not involve the immune system.  

Types of adverse reactions to foods 

Adverse food reactions can be grouped as follows:

Adverse food reaction

 

Whilst some symptoms may be similar, food allergies are different to food intolerances (shaded in the above table), which include:

Natural substances in foods can cause food intolerances

Foods are composed of proteins, carbohydrates, fats, various nutrients and several natural chemicals. These following naturally occurring substances often add flavour and smell to food but they can trigger symptoms in some people.

Diagnosis of food intolerances

Food intolerances can often be difficult to diagnose. Some substances within foods, and the quantity (dose) of foods eaten, can increase the frequency and severity of symptoms. These include stomach pain, bloating, gas/flatulence, diarrhoea, IBS, rashes, hives or headaches,

Diagnosis of adverse reactions to foods should be based on clinical history, response to treatment and testing. Skin prick tests or blood tests for allergen specific IgE are negative for food intolerances.  However, they are useful if the history suggests that food allergy (as opposed to intolerance), is the problem.

The best approach is to first see your doctor to:

Management of food intolerances may involve elimination diets

Once a diagnosis is made, a clinical history may help identify the role of diet or other factors that make symptoms worse. 

The only reliable way to determine if diet is playing a role is by people being placed on a temporary elimination diet, under the supervision of a dietitian and medical practitioner.

If removing the food from the diet helps, this is followed by challenges under controlled conditions to identify food triggers which may need to be avoided in the future.

It is important that elimination diets are temporary, so they should only be undertaken for a short term trial period, under strict medical supervision, as a diagnostic tool. Prolonged restricted diets can lead to problems with adequate nutrition, particularly in children.

It is important to note that low salicylate and low amine diets should not be used for investigation of food intolerance until other potential causes for reactions are explored.  

Unorthodox tests can be misleading

Some people use unorthodox methods for diagnosing health problems. Several misleading tests have been promoted for diagnosing food allergies and intolerances, without any credible evidence, amd at significant expense as these tests are not rebated.

These tests include cytotoxic food testing, Vega testing, kinesiology, allergy elimination techniques, iridology, pulse testing, Alcat testing, Rinkel's intradermal skin testing, reflexology, hair analysis and IgG food antibody testing. Not only do these tests lack any scientific rationale, but have been shown to be inaccurate and unreliable in published studies.

Treatment based on inaccurate results is not only misleading, but can result in ineffective and sometimes harmful treatments, and delay the proper management of food allergies and intolerances. 

Other adverse reactions to food

There are many other adverse reactions to foods, apart from allergy and intolerance, including:

© ASCIA 2019

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Updated May 2019