Having food allergies and intolerances myself, this topic is one that is particularly close to my heart and one that I am quite passionate about.
There is currently so much information available, particularly online, about how to test for food allergies and intolerance’s. Unfortunately, a lot of this information and the sites it is available on are unreputable sources and, more often than not, offer inaccurate advice and misinformation.
With those of us with food allergies and intolerance’s, or that have a family member or friend with these, it can become incredibly confusing and overwhelming trying to make our way through all the information, which, as mentioned above, unfortunately isn’t always accurate.
These sites take advantage of a particularly vulnerable group of people who are often desperate for an answer and resolution to their symptoms. They have usually been experiencing symptoms for a long period of time and, I know from my personal experience, are willing to try anything to get some kind of relief from their symptoms and a reason as to what is causing their symptoms.
Why Having the Right Test is Important
It is incredibly important to have a food allergy or intolerance properly diagnosed as some food allergies can be life-threatening. Determining the dietary triggers to your food allergies or intolerance’s will allow you to know which foods you can and cannot eat safely and which foods are likely to trigger your symptoms.
It is also important to know whether your symptoms are due to a food allergy or a food intolerance as these are not the same. A food allergy is due to our immune system reacting to a food protein that the body wrongly thinks is harmful, which causes a person to have a reaction and get symptoms. Whereas a food intolerance does not involve the immune system and reactions are rarely life-threatening. A food intolerance is when a person cannot properly digest or fully break down and absorb certain foods.
It will also allow you to avoid unnecessarily removing or restricting foods from your diet. Following a restrictive diet when it is not medically required can place us more at risk of nutrient deficiencies. These can have long-term negative effects on our health including digestive problems, skin conditions, fatigue, decreased cognitive function and can even lead to malnutrition.
Recommended, Proven & Validated Tests
In Australia, Medicare rebates are available for scientifically validated tests. What this means is that the test is proven to work in identifying whether you may have a food allergy and that you can be confident in the results that you receive from these tests.
However, it is really important that these tests are not used on their own and are used and interpreted alongside your detailed medical, diet and lifestyle history by your medical practitioner and dietitian.
Coeliac Screening Blood Tests
These tests should be conducted to eliminate whether the cause of a person’s symptoms is due to coeliac disease. Coeliac disease is an autoimmune condition which can significantly impact on a person’s health. These tests can include;
Anti-tissue transglutaminase antibodies (tTG-IgA)
Deamidated gliadin peptide (DGP) IgA and IgG.
Anti-endomysial antibodies (EMA).
If coeliac disease is left undiagnosed or untreated the surface area of our bowel can decrease which affects how we absorb nutrients, which can result in nutrient deficiencies. It can also affect other areas of the body including our bones and joints, organs and skin. So, it is very important to exclude this as a potential cause of symptoms.
Skin Prick Tests
Skin prick testing is currently the easiest way to test for allergies. A big benefit of these tests is that you can talk to your doctor about the results to your tests at the time they are done, rather than having to wait for results, as results are available within 20 minutes. Clinical studies have shown that skin prick tests improve how accurately allergies are diagnosed.
These tests are usually done on a person’s forearm. A drop of an extract of the allergen(s) your doctor is testing for is put on the location and a small prick is made into the skin. If you are allergic to the allergen a small itchy lump with a red circle , also known as a wheal and flare, will develop.
You may experience a small amount of discomfort, mainly from being itchy, but they are not usually painful and swelling usually subsides within a couple of hours. These are also usually tolerated well by children.
It is really important that these tests are only be performed by a trained health professional, such as a clinical immunologist, who will be able to accurately understand the results and safely conduct the test.
IgE Blood Tests
These tests were previously known as RAST (RadioAllergoSorbent Test) tests. IgE stands for Immunoglobulin E antibodies. These antibodies are a protein in the blood that is made, or produced, in response to a specific allergen, which the body sees as being harmful and combines with this. IgE blood tests measure the amount of these antibodies in the blood against a specific allergen.
These tests are usually recommended or performed when skin prick testing may not be able to be done. This can include those that take medications such as antihistamines or have severe skin conditions such as eczema.
Past testing is useful in testing for allergic contact dermatitis. This could be triggered by things such as preservatives in cosmetics, plants and metal. These tests are conducted by applying an allergen paste to a rash-free area of the skin using hypoallergenic tape. This is usually on a person’s back. The area has to be kept dry and the tape is left in place for 48 hours.
Over the 48 hours, observations of the site are conducted at different times. If a rash that looks similar to eczema appears, it can indicate a sensitivity to the allergen being tested.
Oral Allergen Challenge Tests
If the cause of a severe allergic reaction is unable to be established, an oral allergen challenge test may be needed to confirm a diagnosis. This is usually conducted by a clinical immunologist/allergy specialist who uses foods or medication to test for an allergic response. This is also completed in a safe clinical environment with resuscitation equipment available in case a severe allergic reaction occurs.
These are the gold standard for testing for food intolerance’s. They involve elimination of a particular food or foods for a short period of time, usually 2-6 weeks. This is then followed by a controlled reintroduction or food challenges to identify any dietary triggers to a person’s symptoms. These are completed under the supervision of an Accredited Practising Dietitian and a medical practitioner.
Hydrogen Breath Tests
This is a test I get asked about quiet often by my clients and is actually not a test that I would recommend.
Hydrogen breath tests are known to be used to investigate carbohydrate or sugar malabsorption, particularly in those with Irritable Bowel Syndrome (IBS). Carbohydrates which are commonly tested are called FODMAPs which include fructose, lactose and sorbitol.
Hydrogen breath tests are based on the idea that when the bacteria in our gut ferments, or breaks down, these carbohydrates which are unable to absorbed, gas is produced. This gas then diffuses or spreads into the blood stream and is then expelled in the breath.
However, these tests have limited usefulness in identifying carbohydrate malabsorption for a numerous reasons. These include;
Studies have shown that the occurrence of FODMAP malabsorption in those with IBS is actually similar to the general population when diagnosed via these tests, so no real difference is seen in those with IBS and those without IBS.
These tests are also rarely used for FODMAPs as these are poorly absorbed and broken down by everyone, not just those with IBS, an intolerance or malabsorption.
The amount of carbohydrates consumed, or the sugar load, in these tests is also very high. Consuming these amounts of carbohydrates speed up the transit time in all our guts which will increase malabsorption and the likelihood of everyone having these tests getting symptoms. Therefore, results found become clinically inappropriate as they are unable to determine a person’s true tolerance level.
The results of these tests are unable to be reproduced. For example, you may have a breath test one day and get a positive result and repeat the same test at another time and get a negative result.
These tests can give both false positives and false negative results. I know from my own person experience, I had a hydrogen breath test for lactose which came back negative, but I am most certainly lactose intolerant.
Total IgE Tests
Although total IgE antibodies may be higher in those with allergies, elevated total IgE antibody levels are also found in people who have eczema, parasite infections and some rare medical condition. Total IgE levels do not prove that the symptoms a person may be experiencing are due to an allergy. On the other end of the scale, normal IgE levels do not mean that an allergy can be excluded. Therefore, this test is not often recommended when testing for food allergies.
Eosinophils can cause inflammation in our tissues in allergies. These are a type of white blood cell that specialise in killing worms and parasites. High levels can sometimes be found in those with hay fever, eczema and asthma. However, as with total IgE tests, high eosinophil levels do not mean that sometimes symptoms are caused by an allergy and normal levels do not eliminate an allergy. Therefore, this test is not often recommended when testing for allergies.
Unproven and Unvalidated Tests
Unfortunately, these types of tests are often recommended by those practising complementary or alternative therapies. Not only are these not evidenced-based but can also be very pricey. I know of some of my clients that have paid close to $1000 to have some of these tests done.
Currently in Australia, unproven allergy tests and treatments are not regulated. This means they can still be listed by the Therapeutic Goods Administration (TGA) without even having to prove that they work. The only time that unproven tests claiming to treat, or cure allergies and other immune conditions are regulated, is if the person giving the advice or recommending the test is a registered medical practitioner.
These unorthodox tests can be misleading, and treatment based on the inaccurate results of these tests can lead to using treatment strategies that do not work and in some cases can even be harmful. But most importantly it can delay proper diagnosis of a food allergy or intolerance and the implementation of effective management and treatment interventions.
In Australia, there are no Medicare rebates available for these tests and their use is not recommended.
IgG Blood Tests
This is another test that I get frequently asked about by my clients. Unfortunately, this is one that some of my clients have had done prior to seeing me that has led them to unnecessarily eliminate and restrict many foods from their diet.
IgG stands for Immunoglobulin G antibodies. This test claims that higher IgG levels to a food(s) indicate that a person has a food intolerance. There is currently no credible scientific evidence to support the use of this test in diagnosing food allergies or intolerance’s or that these antibodies can cause a person symptoms.
IgG antibodies simply shows that we have been exposed to a food, not that we have a disease or condition as a result of being exposed to a food. I like to describe these almost like the “bouncers” of our immune system that keep track of any of the foods that we have eaten or been exposed to before. Almost like ticking off guests on a guest list at an event…Oh yes, seen you before, tick!
Even with scientific studies showing the ineffectiveness of this test, it continues to be promoted in the public and I very often see misleading advertisements promoting these. They are not recommended to be used as a tool for diagnosing food allergies or intolerance’s.
Cytotoxic Food Testing
These include Bryan’s test and the Alcat test. These are blood tests which mix white blood cells with a food and claims that if they increase in size this shows that a person has an allergy to that food.
In Bryan’s test the white blood cells are assessed under a microscope. Whereas, the Alcat test analyses the blood samples on a laboratory machine. The results found during these tests are not the same as those obtained using clinically proven methods for allergy testing.
There is no scientific basis or rationale for these tests. The results to these tests have been scientifically shown to be unable to be reproduced. When the same blood sample is tested multiple times, different results are found.
This test works on the idea that foods can cause an imbalance of energy in the body and claims to be able to diagnose a food intolerance by testing how our muscles react to particular foods. During this test a person holds a glass vial which has the particular food in it and the person conducting the test then tests how the muscle responds.
This test is not recommended as scientific research shows that the results obtained from these tests are no better that those by chance. This unfortunately can lead to the unnecessarily elimination of food from the diet which, as mentioned above, can have many negative health consequences.
This test claims to be able to identify a disease by measuring electrical currents in the body. A person holds a positive electrode in one hand and a negative electrode in the other and a sealed container with an “allergen” in it is put into the electrical circuit. A change in electrical current is said to identify that a person is allergic to that food.
Scientific research studies show that the results from these tests are no better than those obtained by chance. When this technique has been formally examined, results show that practitioners are unable to tell the difference between healthy people and people with allergies and also between an allergen or placebo control solution. As with cytotoxic tests, the results found during these tests are not the same as those obtained using clinically proven methods for allergy testing.
These unproven allergy tests often unnecessarily recommend a long list of food that need to be removed and excluded from the diet. As I mentioned above, eliminating foods from the diet when it is not required and in the absence of sound nutrition advice can lead to nutrient deficiencies and malnutrition.
This test claims to be able to diagnosis various conditions by examining patterns in the iris of the eye. This test is based on completely theoretical ideas which have not been proven to work. The concern with this test is that our irises are as individual to each person as a fingerprint and do not change and as such can be used as “biometric identification markers” to differentiate us from each other.
Scientific studies show that the practitioners using this technique are unable to identify a healthy person from a sick person. When given pictures of irises of the same person that were taken only moments apart, practitioners gave the same person different diagnoses.
This test is used in testing for drug use, such a, marijuana, and for lead and mercury poisoning. However, it’s use in testing for allergies has no scientific basis and is unproven. This test is conducted by sending off a small strand of hair to a laboratory where energy fields in the hair and measured. This is then compared to a set of pre-determined data and claims to be able to identify a food intolerance or sensitivity.
This test claims to measure the frequency of different body organs using an analysis of a person’s voice by a computer. It is said to work on the idea that our internal organs talk to each other by sound waves and that each of our organs vibrate at specific frequencies, which can detect if an organ is not functioning normally. This technique is not based on any scientific principles and there is no evidence that these results are useful in diagnosing allergies or any other type of condition.
In these tests a pulse is measured before and then again 15 minutes after eating a particular food. An increase of 10 beats per minute is said to indicate a food intolerance. This test is not recommended as scientific research shows that there is no relationship between an elevated pulse rate and a food intolerance.
Other Unproven Tests
Other tests with no scientific basis include reflexology, stool and oral neutralisation tests. These are not proven to work and therefore have no clinical role in diagnosing or managing any kind of medical condition.
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