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is food intolerance testing valid?


Intolerances to certain foods can be disruptive, uncomfortable and painful. When suffering digestive complaints, you may often feel you are reacting to everything, which can be infuriating and upsetting often leading to anxiety towards eating in general. With so much information out there it can be hard to ascertain where to start when it comes to diagnosis, let alone wondering about whether food intolerance testing is valid for getting the answers you seek.

When it comes to food intolerances, it’s good to start with understanding the nature of the beast as such. Firstly, it can be hard to identify the offending food, especially when most reactions can onset between 12 – 36 hours after their consumption. Often there is focus on what food was consumed last, when in reality it is more often the food causing the problem was consumed days ago. Furthermore, there may be more than one food that is causing digestive problems which in turn heightens the person’s ability to identify detrimental foods.

IgG & IgA food antigen testing can help identify problematic foods. This type of testing is useful for picking up specific foods currently consumed in your diet, which may be causing an IgG or IgA mediated response. This can be described simply as the immune system making an increased amount of immunoglobulins (IgG and IgA in this case) to foods as a reaction to the compounds within the food the body does not like at this current stage.

There are in-fact several immunoglobulins within the body. The ones commonly associated with food reactivates are the aforementioned IgG and IgA along with IgE more commonly associated with food allergies. IgE food allergy panels are frequently used by GPs for suspected food reactivates, but it is important to note that this type of IgE testing is only testing for allergies, not for food antigens reacting to IgA or IgG.

Through serum (or blood spot) testing these Immunoglobulin responses can be used to identify reactive foods. The JCN Clinic most commonly utilises IgG & IgA food intolerance testing (along with IgE where deemed necessary) to help clients identify food intolerances. Through nutritional consultation and investigation we help clients to remove problematic foods from their diets, though please note this may be short term depending on the underlying cause of the heightened reactivity in the first place. It is integral that food intolerance investigation is done in unison with investigating digestive issues and metabolic problems that are often the drivers exacerbating the immune response to foods.

The JCN Clinic utilises the ELISA method as our food intolerance testing method of choice through our functional labs partners. We have found this test invaluable with helping clients identify current trigger foods and therefore facilitate a more appropriate dietary plan for their individual needs as we work on improving our clients overall digestive health. Studies continue to show the reliability of ELISA testing for elucidating multiple levels of allergen proteins.

 It is not new to say that IgG & IgA food intolerance testing is controversial within the circles of practitioners, immunologists (who work more specifically with allergies) and allergists. Allergists see no real basis for its testing methods and say the science just isn’t there to back it up as a diagnostic tool for allergies. This is true from an allergy diagnostic perspective, however food intolerances are expressed differently in the body and are not an immune reaction. They are a ‘humoral’ mediated reaction, which initiate a chemical response different to a true allergy.

 Studies have shown causative relationships between IgG testing methods (ELISA based) and reduction of symptoms when dietary protocols are followed in relation to the test results. For instance, a study published back in in Gut 2004 showed a correlation between eliminating foods from diets based on IgG testing and a reduction of IBS symptoms. (W.Atkinsons et al, Gut 2004)

 A 2010 double blind cross over study published in Sage Journals found that dietary restriction based on IgG testing showed a reduction in the frequency of migraine attacks. (Alpay. K et al, Sage Journals, 2010).  An additional article published in the Journal of Nutritional and Metabolism looked at the detection of antibodies against food antigens using IgG, IgE, IgA and IgM antibodies and found that determination of antigens would be beneficial by testing foods against all antibodies, inclusive of IgG. (Vojdani. A, Nutrition & Metabolism, 2009).  

 A review article published in 2010 in Nutrition in Clinical Practice concluded “IgE-based testing continues to be the gold standard for suspected food allergies. Among modalities used by many conventional and alternative practitioners, immunoglobulin G (IgG)–based testing showed promise, with clinically meaningful results. It has been proven useful as a guide for elimination diets, with clinical impact for a variety of diseases.” 

 Also in this review article stated “Disclosing the basis for food reactions continues to present a diagnostic challenge, and testing for food allergies in the context of an appropriate clinical history is paramount to making the correct diagnosis.” (MD Mullin, GE et al, NCP, 2010)

As nutritional practitioners this highlights for us the importance of complete and thorough case taking and considering all aspects of a persons health concerns when working with food intolerances.

As stated above, please note that food intolerance testing is not enough on it’s own to give sound health. At the root of food intolerances, particularly multiple intolerances, is commonly an inflamed and sub-optimal functioning digestive system. It is always imperative to treat the digestive system along with removing trigger foods in unison. When this process is done correctly, with time, most clients can reintroduce low reactive foods again without too many concerns. 

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Jessica Cox is a qualified practicing Nutritionist with a Bachelor Health Science (Nutrition) and over 15 years of clinical experience. She is the founder and director JCN Clinic, published author and established recipe developer. Jessica is well respected within health and wellness space for her no fad approach and use of evidence-based nutrition.

Jessica Cox

Jessica Cox is a qualified practicing Nutritionist with a Bachelor Health Science (Nutrition) and over 15 years of clinical experience. She is the founder and director JCN Clinic, published author and established recipe developer. Jessica is well respected within health and wellness space for her no fad approach and use of evidence-based nutrition.

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