Bloating, headaches or a rash after meals can leave you wondering which food is to blame, and a food sensitivity test can look like a quick answer. Here is what these tests can and cannot show, how allergy, intolerance and "sensitivity" differ, and what to ask before you cut anything out.
Allergy, intolerance or sensitivity: what is the difference?
A food allergy is your immune system reacting to a protein in a food. Reactions usually start within minutes or hours and range from a mild rash to life-threatening anaphylaxis. Healthdirect — Food intolerance
A food intolerance does not involve the immune system. Your gut has trouble digesting or absorbing a food, causing symptoms such as bloating, wind, diarrhoea or stomach pain, and the more you eat, the worse you tend to feel. Healthdirect — Food intolerance
"Sensitivity" has no single meaning. ASCIA uses it for reactions to natural food chemicals such as amines and salicylates, which is one type of intolerance. ASCIA — Food intolerance
Coeliac disease is different again: an autoimmune disease triggered by gluten that can damage the small bowel. Healthdirect — Coeliac disease
What does a food sensitivity test actually measure?
A common type of food sensitivity test checks your blood for IgG, a type of antibody, to a long list of foods. ASCIA, the peak body for allergy specialists in Australia and New Zealand, notes these tests are still promoted, particularly online. ASCIA — Evidence-based allergy tests
The catch is that IgG to foods is common in healthy children and adults, with or without symptoms. It reflects exposure to a food, so a long list of "high" results may simply mirror what you eat often. ASCIA — Evidence-based allergy tests
ASCIA says there is no credible evidence that IgG testing helps diagnose food allergy or intolerance. ASCIA — Evidence-based allergy tests It groups IgG testing with kinesiology, vega testing and hair analysis as inaccurate and unreliable. ASCIA — Food intolerance
There is no specific test for food intolerance, which is part of why it can be hard to pin down. Healthdirect — Food intolerance An RACGP article for GPs makes the same point. RACGP — Food allergy and intolerance
Which tests do have a place?
For a suspected food allergy, your doctor may arrange skin prick or blood tests that measure IgE, the antibody involved in allergic reactions, and sometimes a food challenge. Healthdirect — Food allergies These tests help diagnose allergy but are negative in intolerance. ASCIA — Food intolerance
Coeliac disease can be screened for with blood tests and confirmed with a small bowel biopsy. Do not stop eating gluten before you are diagnosed, because it can make the tests less accurate. Healthdirect — Coeliac disease Our post on coeliac disease and testing has more.
Why should an elimination diet be supervised?
For intolerance, the reliable way to tell whether food plays a part is a short, temporary elimination diet, then bringing foods back in a controlled way, supervised by a dietitian and a doctor. ASCIA — Food intolerance If symptoms do not settle, something else is likely to be the cause. Healthdirect — Food intolerance
Cutting foods out has costs:
- long-term restriction can affect nutrition, especially in children ASCIA — Food intolerance
- avoiding dairy can lower your calcium intake, and some restrictive diets have been linked with eating disorders Healthdirect — Food intolerance
- restrictions based on misleading test results can trigger anxiety about food and, in young children with eczema, have been linked with developing a true allergy to foods they used to tolerate ASCIA — Evidence-based allergy tests
For children, healthdirect recommends that exclusion diets are managed by a paediatric gastroenterologist. Healthdirect — Food intolerance For food and a child's skin, see children's eczema and food.
What should I ask a naturopath or GP before testing?
Keep a simple diary of what you ate, when symptoms started and how long they lasted. Then ask:
- What does this test measure, and is it recognised for diagnosing allergy or intolerance?
- How would the result change what we do?
- Could something else explain my symptoms?
- Should coeliac disease or a food allergy be ruled out first?
- If we remove a food, for how long, how do we bring it back, and who checks my diet stays balanced?
- Would a dietitian or an allergy specialist help?
- What will the test cost, and is any of it rebated?
When to see your GP
Call triple zero (000) straight away for signs of a severe allergic reaction, such as a swollen tongue, swelling or tightness in the throat, wheeze or trouble breathing, a hoarse voice, dizziness or collapse. Healthdirect — Food allergies
See your GP if:
- you think you have a food allergy or intolerance Healthdirect — Food intolerance
- you notice blood in your poo, unexplained weight loss, a fever or severe diarrhoea, or your symptoms are severe or ongoing Healthdirect — Irritable bowel syndrome
- you are thinking of cutting out a whole food group, which healthdirect advises against without medical advice Healthdirect — Food allergies
What can we talk about at Melbourne Wellness?
At an initial naturopathy consultation we can go through your health history, what you eat and the symptoms you have noticed, and help you organise your questions. If anything points to an allergy, coeliac disease or another medical cause, we will encourage you to see your GP.
