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Allergy and Intolerance Testing

Updated: Sep 25, 2020

Food. Oh how we love it! If only all foods loved us back though. Sadly far too many of us are suffering symptoms needlessly, without understanding that there are ways we can actually start to understand this to connect the dots. While there isn't a magic solution that makes it all super simple given immunity is complex, there are a range of options available to at least get started. The journey to determining triggers certainly starts with having a better understanding of what we're dealing with, so we can help understand how meaningful test results may be.

Here is my overly simple overview centered around my understanding.

(A reminder that I'm not a doctor or naturopath and these are my opinions for information purposes only)


Our immune systems are programmed to fight infection to maintain a healthy internal environment. Its role is to protect us daily from foreign agents or pathogens and so it acts when it discovers an intruder - and that response can be vigorous. When a pathogen can't be cleared, our innate (non-specific) immune systems switches to an adaptive (specific) process at the cellular level, with multiple biochemical processes to identify and eliminate 'bad guys' from the body. Lymphocytes are created in the bone marrow, which secrete proteins (antibodies) that specifically bind to foreign molecules (antigens) and marks them for clearance/destruction.

An antigen is any substance that causes your immune system to produce antibodies, typically proteins, and an allergen is any antigen that causes an allergic reaction. The interaction between an antibody with an antigen is the basis for the allergic response, and as little as one single molecule could trigger it. There are five different types of antibodies produced by our immune system: Immunoglobulin A (IgA), IgG, IgD, IgM, IgE.

Given that the term allergy is often bandied about, it's important to note a "true" allergy (also known as an IgE mediated allergy) is when after coming into contact with an antigen, the immune system has previously identified it as a foreign invader and creates IgE antibodies against it, which bind to the antigen and then histamine release is triggered by mast cells. This is a highly inflammatory process and symptoms range from person to person, from quite mild through to potentially life threatening. Histamine acts as a messenger, traveling to the site of irritation to activate a particular response (such as inflammation or increased mucous production) to try and expel it from the body. The allergic reaction generally depends on the amount of histamine released and reactions can be immediate or delayed. Symptoms of a IgE mediated allergy often involve those places where mast cells are most abundant; the surface of the skin, the nose, the eyes, the lungs and the GI tract so symptoms such as hives, welts, scratching, sneezing, wheezing, eczema, coughing and digestive distress are common, with the most serious being anaphylaxis (a rare severe reaction that has catastrophic consequences if adrenaline is not injected into the bloodstream fast enough). What we see as allergic reactions can also be seen as attempts by the immune system to clear the antigen from the body as fast as possible using the nose, sinus, lungs/airways, eyes, ears, skin and/or the gastrointestinal tract. Why does our immune system misfire at food proteins, and allow allergies to occur? Well, that's a topic for a whole other article or ten, but we do know allergies require at least one exposure for antibody development to occur. This process is known as sensitisation and can happen at any time and at any age. Generally when I see the types of symptoms outlined, I will suggest allergy testing as at least a place to start because it's vital to remove known allergens for a period of time to allow the gut healing process to occur in a more efficient manner.


An intolerance can sometimes look quite similar to an allergy but with two key differences - IgE antibodies are not created and anaphylaxis does not occur. It's also sometimes cumulative, meaning you can have some before there is a response.

IgG-mediated Intolerance

IgG antibodies are more aligned to white blood cells, and reactions are typically delayed (up to four days) or digestive in nature but there is still a highly inflammatory process taking place deep within the body. While intolerances are considered far less serious than their IgE mediated cousins, they are possibly more common.

Digestive Intolerance (Lactose, Fructose, Gluten etc)

Where there is an absence of a compound needed to fully digest (break down) a food. causing problems in the gut.

For example, a lactose intolerance is where we have stopped producing the lactase enzyme, meaning we cannot digest lactose, milk sugar. These enzymes occur naturally in breastmilk or raw cow's milk but are destroyed by heat in pasteurised milk, meaning those who are lactose intolerant can often digest raw milk assuming no sensitivity to the protein exists.

Irritable Bowel Syndrome (IBS)

The causes are considered a mystery by mainstream medicine, but a significant feature of this chronic condition is the range of digestive distress symptoms - likely driven by inflammatory foods that are hard to digest (dairy, gluten, grains are common).

Coeliac Disease

While this involves the immune system and antibodies are created, it also does not come with the risk of anaphylaxis. Triggered by eating gluten, a protein in wheat and other grains, serious health issues may occur if left unmanaged. Strict avoidance of gluten at all times is incredibly important on a positive result. You'll need to ingest gluten daily for 6 weeks if you wish to pursue reliable testing.

Histamine Intolerance

Not a true intolerance but rather an indication of too much histamine circulating in the bloodstream, overwhelming the body's capacity to degrade/clear efficiently.


This pretty much covers everything else - where there is an adverse reaction of some kind, but not defined by any of the above. You could be sensitive to specific food additives or compounds such as MSG, sulphites, salicylates, amines etc. Some children will display huge behavioural or physical changes on ingestion but testing shows nothing.

The harsh reality is that there are usually consequences of choosing inflammatory foods in some way, or if we have impaired digestive systems that struggle in general.

In a nutshell...

  • An allergy causes the immune system to create IgE antibodies that initiates a protective response to remove the allergen using our organs.

  • An intolerance can look similar to an allergy but isn't. The reaction is delayed, cumulative or perhaps it's just that your body can't process/eliminate the food efficiently.

  • A sensitivity isn't well defined but when you come across it, not so great things may happen to you.

  • Crappy foods that are hard to digest will likely make you feel crappy and tired.

So now we better understand the differences between allergies, intolerances and sensitivities, we can move onto what tests are available...

It's important to state that I believe all tests have their limitations and risk of false positives or negatives - the body is the gold standard - but they can help us get a better understanding especially when patterns are hard to identify. We don't want to remove nutrient dense foods unnecessarily, so if we are dealing with symptoms it makes sense to understand what substances may be triggering an inflammatory or protective response in the blood so we can be more selective. It's also important to match symptoms to testing - not all allergic symptoms will be identified by blood testing so a range is sometimes helpful. The results aren't necessarily fixed, they just show us a snapshot at that particular time, but they can give us big clues especially alongside a food and symptom diary (see my template here).

Testing for Allergies

If you think you might be dealing with an allergy, to get a formal diagnosis you'll need to see your doctor or an immunologist. They will take a history, do a physical check and then can order the tests. Unfortunately some doctors are still very resistant to the idea allergy testing is relevant so my suggestion is to find one who will work with you. My daughter's first GP completely dismissed the idea she could have allergies and said I needed to keep drinking milk. We got a second opinion from a more open minded doctor who agreed to the testing which showed a dairy allergy so high, we needed to carry an EpiPen Jr at all times. Because I was stubborn and followed my gut, we were able to get her allergies diagnosed before she started solids. Allergies are diagnosed via two methods (outside of a supervised food challenge). For an allergy to develop, there must have been at least one single previous exposure HOWEVER we are exposed to a lot of things daily without our direct awareness and can become sensitised without realising - via breastmilk or formula, food ingredients, ingredients in pharmaceuticals etc.

There are three types of allergies: food, chemical and environmental.

RAST (radioallergosorbent) blood test

Blood is drawn in the usual way, and a lab analyses the sample to measure the level of IgE antibodies created in the blood in response to the allergens requested on the form. Generally, the higher the level, the more likely an allergic reaction but it cannot forecast the potential severity of this reaction. It's my preferred test for symptoms such as eczema and asthma, and helps to establish a baseline for comparison with future tests.

Skin Prick Test (SPT)

Measures the size of the welt our skin produces when exposed to a tiny amount of the allergen, giving a rough indication to how severe an actual reaction may be. Often considered more reliable for environmental or contact allergens and helpful for understanding if histamine intolerance is involved, it also does not help with determining if the body is sensitive in any other way. Considered unreliable for infants under 12mo of age, you also have to ensure no antihistamines or steroids are used within 24 hours of the test. Also known as a scratch test. Can give different results to the blood test, and is often the preferred test of many doctors if they agree to testing.

Testing for Intolerances and Sensitivities

Now we're entering the murky world of non-diagnostic testing. These methods aren't validated or approved by the medical establishment and they will likely caution you against them. I can see the reasoning but at the same time I can also see that allergy testing is very limited in its application as well and we have to be careful in suggesting that if an allergy test is negative, a food is automatically beneficial to include. When an individual is not able to address their symptoms, seeking further information is often helpful however none of these are perfect. I remind you to do whatever research you feel necessary before deciding whether to proceed, but I will outline some of them here because I know they have helped many including myself.

IgG Food Intolerance Testing

Because only IgE antibodies are considered relevant for allergy diagnosis, this means testing for IgG must be privately funded (and is expensive - prohibitively for many). I often see parents reintroduce allergens too early under the misguided belief that if the IgE test is clear, the immune system is now a-ok with the food this isn't always the case. IgG testing is useful in helping determine elimination diets for chronic conditions related to autoimmunity or inflammation because even though no immediate reaction occurs, there is immunity activity occurring at a deeper level. Some labs have also added Candida to the IgG test given yeast can cause significant issues with the gut.

If you'd like to order the IgG food panel which includes testing for 96 foods, I sell these at-home blood spot kits so email me to discuss suitability. I rarely recommend them at the beginning of a gut healing journey.

Applied Kinesiology

I am fascinated by this modality however I've also seen that it can be misused and completely incorrect so prefer to utilise it when all other testing methods have failed. Kinesiology is the study of movement but Applied Kinesiology was created later by a chiropractor as a form of muscle testing to ask the body if it is sensitive. The individual (or a proxy/surrogate) is asked to hold a vial containing the energetic imprint of an item or the item itself - and pressure is put on a limb to test the body's response. If the limb holds firm when gently pressed, that item is considered "fine" but if it cannot easily stay firm against the slight pressure, then the body is seen to be weakened by exposure to that item and it's deemed a trigger.

Hair Strand Analysis

This is when strands of hair is examined under a machine that measures energy patterns to identify potential triggers and it also claims to be able to make other health insights. It's non invasive. Often referred to as allergy testing by some which is completely incorrect, I personally DO NOT recommend these tests as I find them hugely unreliable, excessively expensive and a huge trigger of overwhelm and stress as the results often have no context - just long lists.

Elimination/Provocation Challenge - The Gold Standard

The most practical, but not quickest, way of identifying triggers of unpleasant reactions whether they be physical, emotional or behavioral etc. It is not a diagnostic tool and I do not recommend anyone does this for known or suspected severe allergies unless with the express knowledge and supervision of your doctor or immunologist.

Basically you eliminate suspected triggers or a period of time - until symptoms reduce/disappear and then reintroduce back in the foods, one by one, at least four days apart. If you react in any way, immediately, delayed or cumulatively, it's likely you're still sensitive and may need to eliminate again while you continue your efforts. Often I'm asked "could that reaction on reintroduction have been a coincidence?". My answer is generally, no but it is possible. Trust your observations for what they are, and if you're not sure, go through the process again (assuming the reaction was not severe).

I won't outline a specific elimination diet here as I prefer to tailor them, but generally I consider that reactions trump negative test results with the philosophy that the body never lies.


The best way to start the gut healing process is to avoid key inflammatory triggers. The reason testing is often key is that a body dealing with a chronic inflammatory response cannot be in an optimal state at the same time, especially if dealing with symptoms such as eczema. While it's on the skin, it's usually more an indication of what's happening in the blood. I really encourage we all learn to LISTEN to our bodies - some responses are more subtle than others. This is a helpful and practical way of finding out what foods are helping you thrive, and what foods are not and it's something you can start doing today. All the best for your allergy and intolerance testing journey. I hope this will help and if so, please do feel free to share on.



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