is food intolerance testing credible?

An online follower bought my attention to an article posted recently regarding the reputability of food intolerance testing. The article in question had me decide it was time for a blog post on a hotly debated subject between complimentary practitioners, nutritionists, dieticians, doctors and immunologists. Is food intolerance testing a waste of time, or is it worth its merit?

The article in point came from foodconnection.org, Doctors Positions on Food Intolerance Blood Tests. This article noted from a quoted 2008 report, “Food intolerance blood tests claim to diagnose a delayed allergic condition that has never been shown to exist. Moreover, these tests will not provide any information on pharmacological food intolerances, which is a sensitivity to food chemicals – amines, salicylate, benzoate, artificial colors, preservatives, etc. – that does not involve the immune system.”

First off, food intolerance tests do not claim to diagnose a delayed allergic condition at all. They have nothing to do with an allergic response, as allergic reactions are an IgE mediated response. Food intolerance testing utlises IgG mediated food testing, which is an entirely different kettle of fish. An IgG mediated reactivity is a ‘humoral’ mediated reaction, which initiate a chemical and physiological response to ingested foods, different to a true allergy.  These types of reactions are often of delayed onset to a food antigen, occurring anywhere from up to 72 hours to presentation of symptoms. Unlike an allergic reaction potentially as dangerous as anaphylaxis, IgG food sensitivities are not deemed life threatening.

Furthermore, IgG specific food intolerance testing is aimed at primarily that, foods. From a clinical perspective, when it comes to food chemicals such as amines and salicylates I find elimination diets more appropriate, as these types of sensitivities are very convoluted and difficult to pinpoint. Additionally, food chemical sensitivities are nowhere near as common as food intolerances; hence the availability of IgG testing providing a medium of test that offers the most common reactive foods certainly makes practical sense.

The report also stated “many serum samples show positive IgG4 results without corresponding clinical symptoms.” I must ask, what are these corresponding clinical symptoms? I can say quite confidently from many years working with food intolerances that clinical symptoms are not always present in the realm of classic digestive upsets. They can include malaise, headaches and skin conditions for instance. They are inherently diverse in their presentation within the body and differ greatly from person to person.

Elimination diets will always be a fantastic tool for identifying food intolerances, and realistically the gold standard, however in this modern day and age many people will not commit to the time and the annoyance that it creates, which makes food intolerance testing so much more accessible and useful. Majority of my clients are willing to trial 1-2 foods with an elimination diet, yet once you start asking for more they are quick to point out that this type of method is not feasible for them given their lifestyle.

When if comes to the utlisation of food specific IgG testing, it is vital that all types of IgG testing are not put into the one arena. There is a plethora of questionable intolerance testing methods now available in a variety of chemists and health food stores, which are additionally being utilised by some practitioners. It is paramount to understand that there are different methods of IgG testing, with one in particular being the most reputable and most well researched, the ELISA method.

The ELISA method (enzyme-linked immunosorbent assay) is used to identify and detect the presence of an antigen in a sample, in this case a blood sample. The ELISA form of testing has been shown in a variety of studies to be a positive and useful adjunct to the overall treatment of food intolerances and associated health concerns.

For instance, a 2012 study published in The Journal of International Medical Research documents a controlled study on 77 patients with IBS and 26 healthy controls. When tested for IgG sensitivities not only were food reactants found to be higher in the IBS (irritable bowel syndrom) group, but additionally, after 12 weeks of exclusion of foods based on IgG specific antibody food testing participants saw a significant improvement in IBS symptoms. The testing method utilised was the ELISA method.

A 2014 study looked at food specific IgG antibody guided elimination diets and found a positive reduction of asthma symptoms. The article presents “two clinical cases of individuals who experienced a reduction in asthma symptoms, decreased dependence on pharmacological therapies, and increased quality of life by eliminating foods that demonstrated reactivity to immunoglobulin G levels identified through serum testing.” The testing method utilised by this case study was the ELISA method.

Similary, this 2010 study published in Sage Journals found in a randomized cross over study that food elimination diets followed after IgG ELISA testing showed a reduction in frequency of migraine attacks. From a clinical perspective I have without question seen a reduction of headaches and migraines after removal of reactive foods from clients diets.

Surely looking at a broad spectrum approach when it comes to investigations of food intolerances and allergies is warranted. This 2009 study looked at testing reactivity of all immunoglobulin’s to raw and processed foods and concluded that that the determination of allergy and sensitivity to foods could certainly be improved by measuring IgE, IgG, IgA and IgM antibodies against both raw and processed food antigens.

Within the sphere of my own clinical practice, I have been using the ELISA method for close to 10 years with fantastic outcomes as a diagnostic tool alongside thorough case taking.  Variables will always be present between each individual, therefore the entirety of a persons history should be considered in regards to symptoms, medications, demographics and diet history before using IgG testing as the only diagnostic tool for food elimination dietary changes as concluded by this 2013 study.  The most important aspect of utilising these test results is combining them with a specific and individualised food plan that is nutritionally balanced to meet a clients needs (to ensure no deficiencies result), alongside digestive restoration to improve the overall health and function of the digestive tract. With monitoring and the correct treatment, often clients can reintroduce a selection of the foods that have first appeared reactive.

Unfortunately there are questionable practices that utilise alternative methods of testing that not only give questionable results, but also leave clients with no dietary guidance other than elimination of the foods listed on their results. These types of tests can quickly give all IgG testing a bad name leaving a sour taste. This I believe, like the original article of discussion highlights an area of concern in regards to poor health management and therefore potential health associated effects.

There are more than one articles around aimed at slamming IgG testing, and it seems the baton gets passed back and forth between debating studies and their efficacy from one side to the other. Of course the strength of a study is invaluable. Surely those who deem the ELISA testing method as ‘unscientifically valid’ and turn their back on it’s potential benefits cannot ignore the data showing its promise and potential in the correctly applied clinical setting.

To surmise, I believe the above highlights the importance of finding a qualified practitioner or doctor to perform not only tests that are reputable, yet also a practitioner that is able to facilitate building your digestive health and ensuring your nutritional balance. I firmly believe from my own experience with a multitude of clients that IgG food intolerance testing (ELISA method) in conjunction with IgE testing and sound case taking can benefit clients to no end.

2012, HONG G, et al The Value of Eliminating Foods According to Food-specific Immunoglobulin G Antibodies in Irritable Bowel Syndrome with Diarrhoea, The Journal of International Medical Research

2015, K. Virdee, ND et al, Food-specific IgG antibody–guided Elimination diets Followed by resolution of asthma symptoms and reduction in pharmacological Interventions in two patients: a Case report, Global Advances in Health and Medicine

2010, K, Alpay et al, Diet restriction in migraine, based on IgG against foods: A clinical double-blind, randomised, cross-over trial, Sage Journals

A Vojdani, 2009, Detection of IgE, IgG, IgA and IgM antibodies against raw and processed food antigens, Nutrition & Metabolism

2013, Qiang Zeng et al, Variable Food-Specific IgG Antibody Levels in Healthy and Symptomatic Chinese Adults, PLOS One

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.