Is it a food allergy or intolerance?

Food allergies and intolerances are becoming increasingly common and the rise of the self-diagnostic, pseudo, unorthodox tests tends to follow. With all the misinformation out there, people tend to self-diagnose or claim to have a specific “allergy” or “intolerance”, with a huge lack of understanding of what either really is. So, is it food intolerance or a food allergy that you may be suffering from?  

Many of us suffer unpleasant reactions and symptoms after consuming certain foods, causing us to think that we are “allergic” to that food.  In most cases, you might be intolerant, however, it all depends on whether your immune system is involved or not. Understanding the difference between food intolerance and a food allergy is essential as diagnosis and dietary management differs for both.

What is a food allergy? In simple terms, a food allergy is your immune system’s reaction against a specific food protein, where it responds to that food as a harmful substance.This response involves the release of allergy antibodies called IgE antibodies against that particular protein. Allergic reactions would then follow and can manifest in many ways; from minor symptoms such as a rash, itching or hives to more serious reactions such as swelling of the tongue, tightness of the throat and breathing difficulty.  For this reason, a food allergy can be fatal.

The most common foods people are allergic to include:

  • Egg
  • Cow’s milk
  • Peanuts
  • Tree nuts (cashews, walnuts, hazelnuts and almonds)
  • Fish and shellfish
  • Soy
  • Wheat

Food allergies are common in children where they tend to grow out of it , however some allergies can be lifelong e.g. seafood and nut allergies. Adults can also develop allergies against certain fruits and vegetables and this is known as an oral allergy syndrome. Common food allergens in adults include treen nuts and stone fruit such as plums and apricots to name a few. 

Allergy food concept. Food on wooden table

Diagnosing a food allergy involves skin prick tests or blood tests for allergen specific IgE (RAST), which will help your doctor confirm which allergens you are sensitive to. It is important to note that allergy test results cannot be used on their own and must be considered together with your medical history.

Now, moving onto food intolerances…Symptoms of food intolerances are wide and varied and can affect many different systems in the body. Some of the possible symptoms include migraines, irritability, diarrhoea, nausea, bloating and abdominal pain. With an intolerance, the immune system is not involved and no antibodies are produced against the food consumed. Common food intolerances include lactose and wheat intolerance but can also include a whole list of food chemicals such as salicylates, amines and glutamates.

It is important to note that medical advice is recommended to eliminate other causes of such symptoms. Food intolerance can be a possibility worth investigating if there is no established medical cause for such symptoms. 

A large number of so called intolerance tests have inundated the healthcare scene with their false claims of diagnosing food intolerance. First of all, contrary to the practice of some medical, alternative and natural therapy clinics, there are no blood tests that reliably identify food intolerances. These tests are usually very expensive and often indicate a very long list of trigger foods to be avoided.  Unfortunately, the only way to identify a food intolerance is to undergo an elimination diet  under the supervision of an accredited dietitian. This diet is a very bland, low chemical diet that is followed for a minimum of three weeks. Subsequently, each suspected food or chemical is introduced and challenged one at a time. If symptoms reoccur after a food is challenged, then it is likely that the substance introduced was responsible for triggering the symptoms. Another diet that a dietitian might suggest is a low FODMAP diet. I won’t go into too much detail with regards to this specific diet but more information can be found here. 

From experience, the most common unorthodox tests of allergy & intolerance testing are those that are based on IgG food antibody testing. IgG antibodies are proteins produced by the immune system in response to exposure to external triggers, like pollens, foods or insect venom. IgG antibodies to food are commonly detectable in healthy adult patients and children, whether food-related symptoms are present or not. There is no credible evidence that measuring IgG antibodies is useful for diagnosing a food allergy or intolerance, nor that IgG antibodies cause symptoms. Despite studies showing the uselessness of this technique, it continues to be promoted.

If you do choose to get tested for an allergy or intolerance – don’t be afraid to ask the practitioner these questions:

  • Is there scientific evidence that it works? Has such evidence been published?
  • How much does it cost?               
  • Why doesn’t my own doctor suggest this type of treatment?
  • What are the qualifications of the practitioner recommending the treatment?

So, whether it is a food allergy or intolerance, make sure you seek the right kind of help and build your certified management team, which should include a qualified dietitian, a GP or a board certified allergist. If you suspect an allergy or intolerance, get in touch to find the right approach for you! 

The Australasian Society of Clinical Immunology and Allergy (ASCIA) is the peak professional body of Clinical Immunologists and Allergists in Australia and New Zealand. The ASCIA website is an excellent resource for knowing more about allergies & diagnosis.


  1. It’s good to know that the blood test are pointless. I was never sure of the science behind why people thought it was a good measurement of intolerance. Thanks for clearing things up!

  2. I had no idea that adults could end up developing allergies to fruits and vegetables. Do you happen to know what the symptoms of oral allergy syndrome would be? Lately, I feel a lot more congested after eating certain fruits, but I’m not sure what’s happening. It sounds like I should be checked out for this oral allergy syndrome!

    • Hi Maggie,

      Typical symptom of an oral allergy syndrome is a “tingling”/itchy sensation on the lips or in the mouth or throat, which can also involve swelling of the tongue. You can definitely talk to your doctor about this and perhaps keep a food and symptom diary as a benchmark to check whether you can identify any triggers.

  3. My son keeps having digestion issues, and I’m pretty sure it’s because of something he eats. He is still young, so I’m glad to hear that if he has an allergy, there is a chance that he could grow out of it. After reading this, I think that it would be best to have him tested, so that we can figure out exactly what he is allergic to.

    • Hi Jackie,

      Definitely a good idea to get it checked by your son’s paediatrician. He can then refer you to a dietitian or an allergist if they do suspect a food allergy.

      Please be careful though not to undergo any of these so called food intolerance or IgG testing as they are unreliable and are not clinically used as a diagnostic tool.

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