Food intolerance or food sensitivity tests have been around for a little while now, with many companies charging hundreds of dollars to tell you what foods are giving you grief.

But how accurate are these tests? And are they really worth the money?

Unfortunately, they are about as accurate and helpful as an online “Which character from Friends are you?” quiz.

So whilst they may be a bit of fun, the result doesn’t really mean anything. And they definitely should not inform any dietary or lifestyle changes.

If anything, having these results tell you that you are intolerant to lots of different foods may even have a negative impact on your health.

You may unnecessarily cut out food groups from your diet resulting in nutrient deficiencies or it may cause anxiety around eating certain foods resulting in a placebo reaction to said food.  

Apart from lactose, there is no other food intolerance that can be diagnosed with a laboratory test of your blood, stool or urine. This also includes breath testing.

The Difference Between a Food Allergy And Food Intolerance 

The terms food allergy and food intolerance are often used interchangeably, however, they are very different. 

And it is important to establish the difference between them. Particularly in the context of testing. 

Food allergies result in an immune response after ingestion of the food to which someone is allergic too. The symptoms of an allergy are typically noticeable within minutes to hours after ingestion and look like typical allergic reactions. 

The reaction may present with itching, swelling, hives, a rash, vomiting, and/or wheezing.

A severe reaction could even result in life-threatening anaphylaxis.  

On the other hand, an intolerance is more likely to be predominately gut related symptoms such as:

• Bloating
• Excessive gas
• Abdominal pain
• Constipation
• Diarrhea 
• Flatulence

This is secondary to the food not being able to be digested properly by the body. 

Other people may also feel like they get headaches, fatigue, “brain fog” or belly pain with various foods or additives and preservatives which they are sensitive to.

Symptoms may occur within hours or even after a couple of days as the culprit of the symptoms builds up in the system from a series of smaller quantities being ingested. 

There is also typically a threshold in which a person can consume the food they are sensitive to, without symptoms. It is only once they pass that threshold that symptoms will occur. 

Food intolerance is not life threatening but it can be uncomfortable which is still worth addressing in many cases. 

The best example of a food allergy versus a food intolerance, is in regards to dairy.

People can have a dairy allergy in which case all dairy products will evoke an allergic reaction, which can be very serious in some cases. 

On the other hand, someone else may be lactose intolerant. In which case they should avoid consuming higher lactose dairy products. But if they happened to have a bowl of ice-cream, it wouldn’t be the end of the world.

They may need to run to the bathroom and pass the dairy products in a less than comfortable way, but they don’t need to be rushed to the emergency room. 

What is Food Sensitivity?

Food sensitivity is a term used frequently by companies selling these food intolerance or sensitivity tests.

But the term actually has no validated medical definition. 

It is a vague and broad term in which we tend to group all non-serious reactions to different foods. 

Since it isn’t a well defined term, it would be impossible to provide someone with a test for food sensitivities. 

How do you test something that doesn’t have an actual definition? What would you even be testing for?

What Tests Are Available?

When your body has an allergic response to a food, it forms an antibody called immunoglobulin E or better known as IgE.

IgE testing is available, and is validated by medical research in allergies. 

Other common tests include a prick/scratch test and food exposure tests. However, these are only for allergies and are not validated for any type of intolerance or sensitivity. 

It is also important to note that these allergy tests are not done as a general screening for allergies. 

Physicians will only complete these tests when there is a history of allergic reaction.

False positives are very common in allergy testing, so an allergen history is very important in conjunction with this testing. 

Food exposure is the most accurate way to test for an allergy. This is where a patient is given a food suspected of being an allergen to them, in increasing dosages until a response occurs.

If an allergy is present, a reaction will absolutely occur. If there is no allergic reaction, that person is clearly not allergic to that food. 

IgG Testing – The “food sensitivity test”

IgG testing is typically what is provided during a ‘food sensitivity test’. IgG is also an antibody, like IgE, but instead of measuring an allergic response, it is known as a memory antibody.

IgG testing is simply a measurement of exposure. So it can show up when you have had a food that you have eaten before.

This means that the results of this testing is simply a reflection of your current diet, not a measure of food sensitivities, allergies, or intolerances. It may actually even be a sign of tolerance when IgG levels increase in reaction to a certain food. 

We don’t even know what a normal range is for IgG and the specific foods that are tested for.

With IgE testing, we know what the typical and normal range is for the foods that are tested through years of controlled, quality research. 

IgG testing on the other hand, has not been rigorously verified in this way and should not be used to determine any issues with bodily response to foods. 

“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 food allergy or intolerance, nor that IgG antibodies cause symptoms.”

Australasian Society of Clinical Immunology and Allergy

Don’t perform unproven diagnostic tests, such as immunoglobulin G(lgG) testing or an indiscriminate battery of immunoglobulin E(lgE) tests, in the evaluation of allergy.

American Academy of Allergy, Asthma & Immunology

How Do You Identify a Food Intolerance?

It is very common for people to feel as though they have a food intolerance and are unsure exactly what they are reacting to. 

So the prospect of having one or two simple tests to tell you exactly what foods to avoid, sounds pretty enticing.

If only it was that easy.

The only reliable way to identify a food intolerance is through an elimination diet.

This is often a long and tedious process. So although research tells us it is the most accurate way, it can be a really hard sell.

If you are working with a dietitian, which is highly recommended, it can also be quite costly. 

Elimination Diets

There are two main elimination diets verified by research. They are the low FODMAP diet and the food chemical elimination diet.

Low FODMAP Diet

The Low FODMAP diet, created by Sue Shepherd and her team in Melbourne, Australia, is a temporary elimination diet that aims to reduce symptoms of Irritable Bowel Syndrome (IBS).

So if you are suffering from frequent gastrointestinal symptoms such as bloating and issues with bowel movements, the low FODMAP diet may be for you.

However, only proceed with the low FODMAP diet once coeliac disease and inflammatory bowel disease have been ruled out by your physician.

During the low fodmap diet, you will be required to eliminate all high-FODMAP foods from your diet.

Because this is a very restrictive diet, this should not be done for a long period of time.

After the elimination process, if symptoms have cleared, the reintroduction phase will begin.

This is where foods are systematically trialled in the diet to see if a reaction occurs. These foods are also tested in varying quantities to be able to know more about a person’s level of tolerance. 

Food Chemical Elimination Diet

The food chemical elimination diet may be considered when:

1. The low FODMAP diet did not assist with gut-related symptoms AND other conditions such as IBD and coeliac have been ruled out 
2. The person sufferers from non-gut related symptoms such as headaches, hives, swelling, fatigue, flu-like symptoms, and/or aches & pains that may be food related but are not allergic reactions 

Like the low FODMAP diet, this diet follows the process of elimination and a systematic reintroduction to test for intolerances and thresholds for reactions. 

The food chemical elimination diet focuses on cutting out and testing natural food chemicals such as salicylates, amines, and glutamate as well as food additives and preservatives.

One good example of a food chemical elimination diet is the RPAH diet.

Closing Thoughts 

There is no validated test that can tell you what foods you are sensitive to or have an intolerance to. 

The reason these tests sell so well is that they have great marketing teams behind them and honestly make themselves look like legitimate medical tests. 

Having this testing done is more likely to do harm than good, as many people will receive results that tell them they should no longer eat a whole range of foods.

These foods are typically the foods that the individual consumes a lot of and hence why they show up on the test in the first place. 

This can lead to nutritional deficiencies by unnecessarily reducing food variety.

There is also the possibility that someone may experience anxiety around consuming certain foods after seeing these test results.

Anxiety has a huge impact on the gut and that alone could result in IBS-like symptoms. 

Even if you have had a food sensitivity test, eliminated a whole host of food from your diet and are feeling much better, you may have unnecessarily cut food some foods from your diet.

It is common for these IgG tests to result in a huge list of ‘sensitivities’. If you cut all of these foods out, it may have included a small handful that are relevant to you but likely also included many foods that you digest just fine.

Furthermore, if someone is experiencing symptoms whether it be gut-related, ‘brain fog’, migraines, or fatigue and these tests come back positive to some food sensitivities. That person will likely attribute their symptoms to those sensitivities and not seek further medical advice.

If an underlying condition such as anemia, coeliac disease, or even something as serious as cancer, is present and the cause of these symptoms, they could be completely missed as the investigation stops with these unvalidated tests. 

If you are experiencing symptoms whether gut-related or more generalised, you should always see a doctor. The doctor will eliminate any other possibilities before focusing on food-related causes. They may then engage an allergy specialist and/or dietitian in your treatment for the diagnosis of food allergies or intolerances.