IgG Food Intolerance Tests: What does the science say?

I spend a lot of time as a pharmacist discussing side effects and allergies to drugs. For your own safety, I won’t recommend or dispense a drug until I know your allergy status. I don’t limit the history to drugs—I want to know anything you’re allergic to, be it environmental, food, insects, or anything else. Allergies can create true therapeutic challenges: We can’t dismiss any allergy claim, but as I’ve blogged before, there’s a big gap between what many perceive as an allergy and what is clinically considered a true allergy. My concern is not only avoiding the harm of an allergic reaction, but also avoiding the potential consequences from selecting a suboptimal therapy that may in fact be appropriate. You may need a specific drug someday, so  I encourage patients to discuss vague drug allergies with their physician, and request allergist testing as required.

Food allergies can be as real as drug allergies, and are arguably much harder to prevent. We can usually control when we get penicillin. But what about peanuts, eggs, or milk, all of which can also cause life-threatening anaphylaxis?  Food allergies seems to be growing: not only anaphylaxis, but more people believe they have some sort of allergy to food.  Allergy is sometimes confused with the term “intolerance”, which seems more common, possibly as the availability of “food intolerance testing” grows. Food intolerance testing and screening is particularly popular among alternative practitioners. Testing can take different forms, but generally the consumer is screened against hundreds of food products and food additives. They are then provided with a list of foods they are “intolerant” to. I’ve spoken with consumers who are struggling to overhaul their diet, having been advised that they are actually intolerant to many of their favourite foods. These reports are taken seriously by patients who believe that they’ll feel better if they eliminate these products. In the pharmacy, I’ve been asked to verify the absence of trace amounts of different fillers in medications because of a perceived intolerance.  Children may be tested, too, and parents may be given a long list of foods they are told their child is intolerant of. I’ve seen the effects in the community, too. Think going “peanut free” is tough? A public school in my area sent home a list of forbidden food products: dairy, eggs, bananas, tree nuts, peanuts, soy, sesame, flax seed, kiwi, chicken, and bacon. Were these all true allergies? It’s not disclosed. Anaphylactic or not, the parents had informed the school, and the school had banned the food product.

But can a simple blood test actually identify and eliminate food intolerance? That’s the question I wanted to answer.

When it comes to food intolerance testing, blood tests are just the start. Other methods used include vega testing, the K-Test, hair testing,and  applied kinesiology. But the blood tests are enjoying new popularity—and even pharmacies are now actively promoting these tests:

You might love food, but some food might not love you

The HEMOCODE Food Intolerance System can unlock your hidden food sensitivities

Speak with your Rexall Pharmacist today to learn about a painless blood test that can identify over 250 common foods that may be causing you unpleasant symptoms such as chronic fatigue, migraines, back pain, fibromyalgia, psoriasis, acne, diarrhea and constipation.

There’s a short video (above) that is very illustrative. Narrated by a pharmacist, it describes that a simple fingertip blood test is used to screen blood against 250 items. Test results are then reviewed by “naturopathic medical professionals” who will describe the foods and other products that you are intolerant to, and your degree of intolerance. You’re also advised:

Your personalized results also include recommended vitamins and supplements that are uniquely suited to the customer, based on the foods that are suggested to be eliminated from your diet, which are themselves, uniquely personal.

So the $450 blood test, includes dietary change recommendations as well as vitamin and supplement recommendation. The vendor explains it as follows:

By adding personalized vitamin and supplement recommendations, the Hemocode System will help consumers move towards optimal nutrition as they work to eliminate offending foods from their diets. No other food intolerance program offers this type of seamlessly delivered, highly customized solution. In addition to delivering a meaningful wellness benefit to their customers, the inclusion of dietary supplement recommendations as part of Hemocode creates an opportunity for retailers to recognize: accretive revenue from Hemocode System sales; incremental growth in their core vitamin program and an enhancement of their market differentiation.

This testing is also positioned as a weight loss plan:

Would I be able to lose weight with HEMOCODE?
Your chances of permanent success are excellent: HEMOCODE(TM) works differently than other conventional diets and rules out the yoyo-effect.

Is HEMOCODE a miracle diet?
It is not a miracle diet, but a scientifically based diet modification. Unlocking your HEMOCODE(TM) gets to the root of your problem. Food intolerances can be the cause of a weight problem and inhibit the success of losing weight with conventional diets. The HEMOCODE(TM) test looks at foods on a one-by-one basis for individual intolerances.

Hemocode is just one of several blood tests that’s marketed. There’s also the YorkTest in the United Kingdom and also Canada:

Food intolerance is all about how your bodys immune system the bodys natural defence against foreign substances, such as poisons and harmful bacteria reacts to specific foods. [sic]

Food intolerances are believed to arise when certain, incompletely digested food particles enter your bloodstream and are treated as foreign substances. This results in your immune system producing tailor-made antibodies (IgG), which attack the food in question. Some researchers believe this inflammatory response in the body can increase certain symptoms. Food intolerance has been associated with Irritable Bowel Syndrome (IBS), bloating, tiredness, constipation, diarrhea, cramping, eczema, headaches and migraines.

So just what is the evidence supporting the use of food intolerance tests?

Testing Principles

Diagnostic tests can be as pseudoscientific as treatments. To evaluate, we ask the following:

  • Analytic validity: How reliable is the testing? This includes within-laboratory and between-laboratory precision.
  • Clinical validity: How consistently and accurately does the test detect an objectively-measured clinical status? The test should be both sensitive (few  false negatives) and specific (few false positives). Patients in the same circumstances should consistently have the same test results.
  • Clinical utility: What is the natural history of the disorder? Will the use of the test make any difference in the outcome? Interventions taken should be evaluated and compared against no testing.
  • Ethical, legal, or social implications : What are the potential patient consequences of the use of the test, and its results? What if the results are erroneous?

It all boils down to a single question that must be satisfactorily answered before we proceed with testing: How has this test been validated?

What’s a Food Intolerance Blood Test Actually Testing?

Hemocode is an IgG blood test, according to the manufacturer (text now removed; cached version here):

The Hemocode System is a finger prick test that identifies specific immune system-based food intolerances.

Everything we eat can elicit a positive or negative reaction in the body. If you are intolerant to a certain food and you continue to eat it, your body will mount an inflammatory reaction which may manifest in a variety of lifestyle-affecting conditions such as headaches, chronic pain, digestive disorders and many other issues

The Hemocode food intolerance test is a statistically proven, doctor and pharmacist recommended IgG-related test that determines which foods are causing negative reactions.

The YorkTest is also an IgG test. There is no published information in the literature that describes either the Hemocode or the Yorktest, or their analytic validity for any of the products tested for.

Understanding IgE, allergies, and what IgG means

Food allergies are reaction to food proteins. They may be categorized as immunoglobulin E (IgE)–mediated (immediate) reactions, non–IgE-mediated (delayed) hypersensitivity reactions, and mixed reactions. IgE-mediated reactions are the ones we worry about when we hear about a “food allergy”: flushing, itchy skin, wheezing, vomiting, throat swelling, and even anaphylaxis. These reactions can occur immediately following exposure, and are the consequence of the interaction of allergens with IgE located on mast cells. The interaction causes the release of inflammatory chemicals like histamine and leucotriene, triggering the the allergic response which is typically skin related (itchiness, swelling and rash)  but may be anaphylactic as well.

Not all reactions follow this cascade. Non-IgE-mediated allergic reactions can cause localized (e.g., contact dermatitis) or generalized reactions, which are usually gastrointestinal or dermatological in nature. Celiac disease is a non-IgE related allergic reaction. Finally, some allergic disorders are both IgE and non-IgE mediated, such as atopic dermatitis (eczema).

Beyond the IgE mediated reactions, there are a number of possible reactions to food, which may be termed “food intolerances”. Not immune-system based, they’re more common than allergies. They include conditions like lactose intolerance, gastroesophageal reflux (GERD), enzyme deficiencies, metabolic conditions, infections and other processes. It’s a catch-all term by definition.

So where does immunoglobulin G (IgG) come in? IgG molecules mediate interactions of cells with different cellular and humoral mechanisms. IgG antibodies signify exposure to products—not allergy. IgG may actually be a marker for food tolerance, not intolerance, some research suggests:

That research is continuing. But given the lack of correlation between the presence of IgG and physical manifestations of illness, IgG testing is considered unproven as a diagnostic agent as the results lack clinical utility as a tool for dietary modification or food elimination.

The Evidence Check

I sought to understand the literature supporting IgG blood tests. There are no citations on the Hemocode website, and the term Hemocode does not appear in Pubmed. The Yorktest website cites a placebo-controlled study which it claims demonstrates its IgG test reduced symptoms in patients already diagnosed with irritable bowel syndrome (IBS). This finding has been criticized for multiple shortcomings, suggesting the effectiveness of the test in this population remains to be established.

In light of the lack of published clinical trials that validate Hemocode or Yorktest, I looked for consensus opinions and statements on IgG testing from allergy and immunology experts. Here’s what I found, emphasis added:

From the American Academy of Allergy, Asthma and Immunology & American College of Allergy, Asthma and Immunology: Allergy diagnostic testing: an updated practice parameter:

IgG and IgG subclass antibody tests for food allergy do not have clinical relevance, are not validated, lack sufficient quality control, and should not be performed.

And from the the American Academy of Allergy, Asthma and Immunology (AAAAI) Practice Paper, Current approach to the diagnosis and management of adverse reactions to foods [PDF]:

Some tests are considered unproven in regard to the diagnosis of specific food allergies. Those for which there is no evidence of validity include provocation-neutralization, cytotoxic tests, muscle response testing (applied kinesiology), electrodermal testing, the “reaginic” pulse test, and chemical analysis of body tissues. Measurement of specific IgG antibodies to foods is also unproven as a diagnostic tool.

From the European Academy of Allergy and Clinical Immunology [PDF]:

Testing for blood IgG4 against different foods is performed with large-scale screening for hundreds of food items by enzyme—linked immunosorbent assay-type and radioallergosorbent-type assays in young children, adolescents and adults. However, many serum samples show positive IgG4 results without corresponding clinical symptoms. These findings, combined with the lack of convincing evidence for histamine-releasing properties of IgG4 in humans, and lack of any controlled studies on the diagnostic value of IgG4 testing in food allergy, do not provide any basis for the hypothesis that food-specific IgG4 should be attributed with an effector role in food hypersensitivity.

In contrast to the disputed beliefs, IgG4 against foods indicates that the organism has been repeatedly exposed to food components, recognized as foreign proteins by the immune system. Its presence should not be considered as a factor which induces hypersensitivity, but rather as an indicator for immunological tolerance, linked to the activity of regulatory T cells. In conclusion, food-specific IgG4 does not indicate (imminent) food allergy or intolerance, but rather a physiological response of the immune system after exposition to food components. Therefore, testing of IgG4 to foods is considered as irrelevant for the laboratory work-up of food allergy or intolerance and should not be performed in case of food-related complaints.

From the National Institute of Allergy and Infectious Diseases Guidelines for the Diagnosis and Management of Food Allergy in the United States [PDF]: Nonstandardized and Unproven Procedures; Guideline 12:

The (Expert Panel) recommends not using any of the following nonstandardized tests for the routine evaluation of IgE-mediated (food allergy):

  • Basophil histamine release/activation
  • Lymphocyte stimulation
  • Facial thermography
  • Gastric juice analysis
  • Endoscopic allergen provocation
  • Hair analysis
  • Applied kinesiology
  • Provocation neutralization
  • Allergen-specific IgG4
  • Cytotoxicity assays
  • Electrodermal test (Vega)
  • Mediator release assay (LEAP diet)

From the Australasian Society of Clinical Immunology and Allergy (ASCIA):

Inappropriate use of Conventional Testing: Food specific IgG, IgG4; Use: Diagnosis of food sensitivity / allergy.

Method: Antibodies to food are measured using standard laboratory techniques.

Evidence: Level II

Comment: IgG antibodies to food are commonly detectable in healthy adult patients and children, independent of the presence of absence of food-related symptoms. There is no credible evidence that measuring IgG antibodies is useful for diagnosing food allergy or intolerance, nor that IgG antibodies cause symptoms. In fact, IgG antibodies reflect exposure to allergen but not the presence of disease. The exception is that gliadin IgG antibodies are sometimes useful in monitoring adherence to a gluten-free diet patients with histologically confirmed coeliac disease. Otherwise, inappropriate use of food allergy testing  (or misinterpretation of results) in patients with inhalant allergy, for example, may lead to inappropriate and unnecessary dietary restrictions, with particular nutritional implications in children. Despite studies showing the uselessness of this technique, it continues to be promoted in the community, even for diagnosing disorders for which no evidence of immune system involvement exists.

From the Allergy Society of South Africa, Position Statement: ALCAT and IgG Allergy & Intolerance Tests [PDF]:

We are constantly consulted by colleagues, health funders and practitioners about the reliability and appropriateness of the ALCAT and IgG food allergy tests for patients with suspected allergies and other disorders. We would like to provide the following information to the readership of the journal and to the public.
The manufacturers and suppliers of ALCAT and the IgG test claim that the tests have diagnostic value in identifying substances responsible for allergic and intolerance reactions. These tests are being marketed directly to the public and health professionals, claiming to be more effective than traditional skin prick tests or serum specific IgE tests, particularly for delayed allergic reactions.  The manufacturers of the ALCAT test argue that orthodox allergy practice does not recognize delayed allergic reactions, when in fact these reactions are universally acknowledged to play a role in up to 30% of the spectrum of allergic reactions!
To date neither ALCAT nor IgG has been shown to have any predictive value in the diagnosis of allergy or intolerances.


The second test marketed with insufficient documentation is the IgG test for food allergies. Specific IgE determination and its diagnostic value have been documented for over three decades in being specific for allergic disorders. Although IgG does play a role in the allergic response, there is no evidence to suggest that it has a diagnostic value in predicting food allergens or other substances that may be affecting individuals. The IgG test is also marketed as effective in predicting foods implicated in Attention Deficit Disorder and obesity. There is no published evidence for these claims.

I also found review papers from immunologists and allergy experts:

From the Department of Pediatric Pneumology and Immunology, University Children’s Hospital Charité, Berlin: Unproven diagnostic procedures in IgE-mediated allergic diseases [PDF]:

The determination of specific IgG-antibodies in serum does not correspond with oral food challenges (5). In cow’s milk intolerance proved by oral challenge, no increased IgG-antibodies could be found (6). IgG milkspecific antibody levels are similar in children with early and late-type clinical reactions (7). Furthermore, there is no evidence that IgG subclasses (8) or the IgE/IgG4 antibody ratio (9) are reliable diagnostic tools. A study of 27 children with hen’s egg allergy found that children with a positive challenge tended to have a higher IgE/IgG 4 ratio and a higher IgG1/IgG4 ratio than those with anegative challenge test, but concluded that oral provocations are still necessary to confirm diagnosis of food allergy (10). A large study in 601 newborns, infants, children and adults showed that the determination of IgA and IgM antibodies did not contribute to the diagnosis of food allergy (11). Since IgG-antibodies to common dietary antigens can be detected in health and disease (12), the determination of food-specific IgG is of no clinical relevance (13) and should not be part of the diagnostic work-up of food allergy.

From the Department of Paediatrics, National University Hospital , Singapore, Diagnostic tests for food allergy [PDF]:

INAPPROPRIATE TESTS :Food-specific IgG tests
Tests for food-specific IgG are marketed as IgG radioallergosorbent tests and vary in offering measurements of total IgG toward a food, or IgG4 with or without food immune complex assay. The measurement of such specific IgG antibodies and their subclasses, primarily IgG4, is based on the fact that the titre falls after a period of withdrawal of the specific food antigen.
Thus, some physicians opt to use such a modality to diagnose food allergies. Unfortunately, the determination of specific IgG antibodies in serum does not correspond with oral food challenges.(43) Burks et al conducted a study of antibody responses to milk proteins in patients with milk-protein intolerance proved by oral challenge, and found that no increase in IgG antibodies was noted.(44) In another study, Shek et al concluded that foodspecific IgG or IgG4 does not add any information to the diagnostic workup of food allergy.(45) Furthermore, most people develop IgG antibodies to foods that they eat, and this is a normal immune response indicating exposure but not allergic sensitisation.(20) Recent studies have shown that the IgG response may even be protective, and thus prevents or protects against the development of IgE food allergy. Hence, there is no convincing evidence to suggest that this test has any diagnostic value for allergy.

Other reviews and commentary identified included the following:

From the UK House of Lords Science and Technology—Sixth Report on Allergy:

We are concerned both that the results of allergy self testing kits available to the public are being interpreted without the advice of appropriately trained healthcare personnel, and that the IgG food antibody test is being used to diagnose food intolerance in the absence of stringent scientific evidence. We recommend further research into the relevance of IgG antibodies in food intolerance, and with the establishment of more allergy centres, the necessary controlled clinical trials should be conducted. We urge general practitioners, pharmacists and charities not to endorse the use of these products until conclusive proof of their efficacy has been established.

From the Food Allergy Initiative:

IgG Testing: This test checks your blood for the presence of food-specific immunoglobulin G (IgG) antibodies. Unlike IgE antibodies, which occur in abnormally large quantities in people with allergies, IgG antibodies are found in both allergic and non-allergic people. Experts believe that the production of IgG antibodies is a normal response to eating food and that this test is not helpful in diagnosing a food allergy.

Interestingly, IgG tests are also rejected as unproven by at least one insurer, Aetna:

IgG RAST/ELISA Testing: There is no evidence that IgG antibodies are responsible for delayed allergic symptoms or intolerance to foods.

A consumer advocacy group investigated different allergy tests, including IgG, and noted the following:

Researchers from the consumer group trialled alternative tests that claim to diagnose food intolerances through analysis of blood samples or strands of hair, changes in electric current, or resistance to pressure applied to their legs or arms. They found that:

  • The tests diagnosed 183 intolerances – although the researchers actually had just one medically confirmed allergy and one food intolerance between them
  • Identical blood and hair samples sent under different names to the same company produced different test results
  •  There was little or no overlap between test results from different companies
  • The testers felt the practitioners applied more pressure when measuring resistance for certain foods – which they were then told to avoid
  • The tests recommended excluding up to 39 foods – which could make it difficult to eat a balanced diet and lead to nutritional problems.

The tests cost between £45 and £275 each, but an expert panel of medical specialists and a dietitian that assessed the results felt that none had diagnostic value for genuine allergies or intolerances.

The UK’s Advertising Standards Authority has evaluated the marketing of the YorkTest and the claim the test is clinically validated, and noted the following:

YorkTest provided three papers to support their claims for the FoodSCAN intolerance tests and believed those showed that the presence of IgG antibodies in the blood was indicative of food intolerances. however, we were concerned that the studies were conducted on people suffering from chronic medical conditions such as IBS and migraine and considered that those findings did not support a general claim for diagnosis of food intolerance. We noted one of the studies was published in an academic peer-reviewed journal, but also noted that although the study concluded that IgG tests may have a role in the treatment of irritable bowel syndrome symptoms, it did not refer to food intolerance among the general population and also stated that futher clinical research was required. We acknowledged that the independent charity Allergy UK endorsed YorkTest’s FoodSCAN range with one of their Consumer Awards but also noted this was based on anecdotal evidence (self-reporting) that individuals felt they were benefiting from using the tests. We concluded that the evidence submitted was not sufficiently robust to prove the efficacy of the tests for diagnosing food allergy or intolerance.

On this point, the ads breached CAP Code clauses 3.1 (Substantiation) 7.1 (Truthfulness) 50.1 (Health Beauty and Therapies)


At present, there are no reliable and validated clinical tests for the diagnosis of food intolerance. While intolerances are non-immune by definition, IgG testing is actively promoted for diagnosis, and to guide management. These tests lack both a sound scientific rationale and evidence of effectiveness. The lack of correlation between results and actual symptoms, and the risks resulting from unnecessary food avoidance, escalate the potential for harm from this test. Further, there is no published clinical evidence to support the use of IgG tests to determine the need for vitamins or supplements. In light of the lack of clinical relevance, and the potential for harm resulting from their use, allergy and immunology organizations worldwide advise against the use of IgG testing for food intolerance.


Posted in: Basic Science, Diagnostic tests & procedures, Health Fraud, Herbs & Supplements, Naturopathy, Science and Medicine

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51 thoughts on “IgG Food Intolerance Tests: What does the science say?

  1. Jan Willem Nienhuys says:

    The testers felt the practitioners applied more pressure when measuring resistance for certain foods – which they were then told to avoid

    The probably refers to the Electrodermal test (Vega) mentioned with a link to

    The Vegatest is a variant of electroacupuncture as devised by the German physician Reinhold Voll (EAV). Voll combined the crazy machines of Albert Abrams, maybe E-meter technology of Scientology and acupunctuyre and homeopathy. The idea was that one measures skin resistance at acupuncture points. So the patient holds an E-meter kind of cilinder in one hand (or places bare feet on a plate), and the current supposedly runs through the circuit formed by probing electrode (which is pressed hard onto the acupuncture points), the body and the other electrode back to the machine. Supposedly if one probes an acupuncture point related to the hart or a part thereof the skin resistance in the acupuncture point indicates what’s wrong. The current can be too high (i.e. low resistance of the skin at the acupuncture point) or too low (high resistance) or first high and then drop off.

    Like the Abrams oscilloclast the machine can also be used for finding the correct cures. For this part of the circuit is replaced by a metallic rack (a ‘honeycomb’) in which closed glass phials are placed with homeopathic cures. If one of the cures is suitable, it is believed that this will normalise a deviant current. In this manner one can quickly determine which one of the phials contains the ‘active’ medicine.

    Now you can see how this can be modified for allergy testing. Just put closed glass phials with various allergens in the rack. If some of them worsen the current deviations then one should henceforth avoid that allergen. Probably some of these machines have been ‘preprogrammed’ with the ‘frequencies’ of the most common allergen, and then a quick examination (which merely costs a few hundred dollars) will provide a neat printout with all allegens to avoid, with a Miranda quack warning on the bottom.

    There are many variants of these machines. For the description of one see :

    Now acupuncture points are meaningless, the idea that the skin resistance in acupuncure points cabn tell you anything about patients is nonsense squared, but the idea that homeopathic stuff or whavever other stuff in closed glass phials can influence electrical current nearby is nonsense cubed. The idea is probably that the ‘frequencies’ of the stuff in the phials are carried by the current and hence affect the body in a specific way. Such ideas can only occur to people without the foggiest idea of physics.

    Needless to say that it has nothing to do with IgE, IgG, allergy or intolerance. Diagnoses can even be that a person is suffering from a mercury overload because of an ancestor who worked in a factory where mercury was used.

    It is a scam, but it is quite possible the scammers believe all this themselves, but if the patients willingly pay lots and lots of money for this, why should the doctor then also not believe it? In the Netherlands (2001) there was a famous case of a person who got the diagnosis ‘no cancer’ from such a machine used by a trusted doctor when she was worried about a small lump in her breast. Two years later she had died a horrible death from untreated breast cancer. Although a well known medium probably coaxed hert in avoid regular treatment, the conviction ‘no cancer’ stemmed from a vega test.

    Later on, another physician used an even simpler machine, the biotensor. That is basically a dowsing rod, which is held alternatingly over the body and whatever is the supposed cure or cause of disease. If it moves above the ‘whatever’, this is seen as an indication of something. Again, it is unbelievable that people fall for that, but they do.

  2. LovleAnjel says:


    They could also be using applied kinesiology. The practitioner has the patient come into contact with an ingredient, then presses down on their outstretched arm. Supposedly, if the person is intolerant/allergic that arm becomes “weaker” and easier for the practitioner to push around. It was used by a quack on MTV’s True Life episode “I’m Allergic to Everything”, to diagnose some poor college kid with extensive allergies, and then to prove that his quack herbal remedies work. Sadly he used applied kinesiology to show her that his regimen of crap had cured her verified, pre-existing seafood allergy, and she had soem shrimp and had to be hospitalized. He rationalized this failure as the patient not re-introducing the food into her diet correctly.

  3. Calli Arcale says:

    What a scam. If the mention of a “naturopathic physician” to interpret the results weren’t enough to mark it a scam, the claim that it will provide effective weight control proves it. “It’s a food intolerance test! It’s a weight control diet!” But does it also make julienne fries?

    Celiac disease — you describe this as a non-IgE-mediated allergy. I had always heard it wasn’t an allergy at all, in the sense that it can’t be acquired and it’s not a response to an allergen. Rather, a chemical formed during the digestion of gluten and absorbed by the gut is mistaken for an immune system signal due to a particular mutation that makes their bodies unable to distinguish between gluten and this immune signal. But I am the first to admit I really don’t have a good grounding in immunology, and one thing I *have* definitely learned is that the word “allergy” seems to be rather fuzzy.

    1. Scott Gavura says:

      @Calli Arcale:

      Celiac disease is an an allergy to gliadin, a protein found in wheat, barley and rye. It is non-IgE mediated. To diagnose, blood is tested for IgA antibody human recombinant tissue transglutaminase (IgA-tTGA) or endomysium (IgA-EMA). IgA tTGA is both highly sensitive (90%–96%) and specific (>95%) for celiac disease. Responsive results are followed by biopsy.

      The full diagnostic workup is described in more detail here: AGA Institute Medical Position Statement on the Diagnosis and Management of Celiac Disease.

  4. Bogeymama says:

    Thank you Scott! As a fellow pharmacist, I too am disappointed to see some of our colleagues go this route. As a mother of a child with “real” allergies, I am grateful for this thorough review. The last several years have seen alot of growth in IgG testing, and it is muddying the waters for those of us who have to deal with potential anaphylaxis. Food allergies are a “specialty” for all woo practitioners, and several misguided friends have suggested I try and heal my son through acupuncture or herbs. It is very hard to keep a straight face, but ever harder to understand why on earth anyone thinks they would know more about allergies than an allergist?

  5. icewings27 says:

    My gastroenterologist sent me for a rather expensive blood test for Celiac. Was this bogus, or is there a legitimate test for it?

    Also, in the absence of actual tests for food intolerance, are “challenge” diets a valid alternative? My niece supposedly suffers from several of these intolerances and has eliminated gluten, sugar, and food dyes from her (now very boring) diet. She occasionally “challenges” one of the forbidden items and if she perceives a negative reaction in some very subjective way, she puts that food back on the do-not-eat list. And of course, all of this requires frequent visits to her pseudo-doctor for guidance and supplements. I smell a scam!

  6. CarolM says:

    Is it possible to lose the enzyme for digesting certain foods? I stopped eating eggs for several years, and when I brought them back into my diet they seemed to make me feel sick to my stomach a couple hours later. I kept at it though and it seems to be okay now.

    It makes me wonder what would happen to people who eschew all wheat products etc in the interests of some “paleo” approach.

  7. Dawn says:

    I have experienced 1 true allergic reaction to a medication (weirdly enough, Prilosec – after using it then taking a 3 year break) – starting with mild itching on the soles of my feet and progressed to severe itching, then to my hands, then hives on my trunk, face, wheezing. I wouldn’t be willing to undergo that again. It scared me to death as I was alone in my office. Took an oral Benadryl (all I had) and vomited it (and everything else in my stomach) up 5 minutes later. Always wondered if the vomiting helped recovery by getting rid of some of the capsule/medication.

    However, as a child I was “allergic” to scallops. No other seafood. But no matter whether I knew they were in a food (mixed into a casserole) or served openly, they made me vomit. I avoided them for years. Then, as an adult, tried a tiny bite of a freshly cooked scallop. No vomiting. Over the years I’ve tried them more often and the only way they seem to still bother me is fried (and no, no other fried seafood bothers me). Do I understand it and does it make sense? No. And I don’t consider vomiting a “true” reaction so don’t give it when asked about allergies. The Prilosec? Heck yeah, that I give as an allergy.

    My ex-husband is allergic to mold-based cheeses (Parmesan, Blue, Asiago, etc) which he attributes to his documented Penecillin/cephalosporin allergy. (Even skin contact – and he’s a pharmacist, to boot to the PCN drugs gives him a lovely rash and hives – like the time he inadvertantly splashed a little on his skin when re-constituting a vial to add to an IV piggyback) . Is that a common drug/food crossover, similar to iodine and seafoods?

  8. Live Blood Analysis has also been pushed in the UK to detect food intolerances. Although there is no evidence that it can do anything of the sort, and the ASA have adjudicated against such claims, Groupon have carried on promoting it:

  9. LovleAnjel says:


    I’m pretty sure your body stops making the enzymes, but can be coaxed into producing them again. I know vegetarians who moved back to a meat-based diet, and they had to be very careful about re-introducing meats so they wouldn’t get sick.

  10. humesghost says:

    Thanks for this thorough review, Scott. I was reading about this just yesterday in the Toronto Star (, and it seemed pretty bogus – the pure reliance on anecdotal evidence, and recommendation to consult a naturopath are quite reliable bullshit flags. But I didn’t have time to check out if there was any real science behind these tests. It sounds like there isn’t, which doesn’t surprise me.

  11. Jann Bellamy says:

    The California Senate is trying to combat “food intolerance” quackery. The California Senate recently passed Senate Bill 352 and sent it on to the California Assembly for consideration. The bill provides that the practice of chiropractic does not include the treatment of hypersensitivity to foods, medications, environmental allergens, or venoms, “including, but not limited to, the use of laser therapy for those purposes.” It prohibits a chiropractor from advertising that he or she provides or is able to provide those services and specifies that a violation constitutes cause for discipline by the Board of Chiropractic Examiners.

    We could use a lot more legislation like this.

  12. icewing27- I wouldn’t distrust your doctor just yet. I’m not a medical person, but I believe there are antibody blood tests that help diagnose celiac disease…just as there are other valid antibody blood test for other auto-immune disorders. I believe there are also some specific tests for other food intolerance, such as a lactose hydrogen breath test. I suspect that Scott was saying that there is no broad spectrum test that identifies all food intolerance, not that there are no tests for individual intolerance.

    I’ll let Scott clarify, though.

  13. CarolM says:

    LovlAngel, thanks. I never thought of of that kind of problem for vegetarians and looked it up.

    This makes me think that people ought to be really careful when giving up a basic food staple completely…

  14. TsuDhoNimh says:

    **Identical blood and hair samples sent under different names to the same company produced different test results

    **There was little or no overlap between test results from different companies

    If that is the case, it’s not a “test”, it’s a SWAG (stupid wild-assed guess).

    If you can’t reproduce your OWN results on duplicate samples, you are either incredibly sloppy, filling in results at random, or the procedure is so subjective that it’s impossible to get the same results.

    If two labs running the same test can’t come up with the same diagnosis, one or both is either incredibly sloppy, filling in results at random, or the procedure is so subjective that it’s impossible to get the same results.

  15. Zetetic says:

    Jann Bellamy:

    That California senate bill 352 piqued my interest so I found a text on line. It’s interesting to note that committee action thus far has made a sort of hallow victory of this initiative. The original text is this:
    “This bill would specify that the practice of chiropractic does not include the treatment or diagnosis of hypersensitivity to foods, medications, environmental allergens, or venoms, and would prohibit a chiropractor from advertising that he or she provides or is able to provide those services, as specified.” In the bill, in its current state and as I understand not yet passed, the words “or diagnosis” are lined through for proposed removal. It appears that chiropractors will still be able to diagnose food hypersensitivities! They can keep doing their dubious AK and order these worthless IgG tests but just can’t treat specifically based on the results. Of course, they’ll find a way around this and sell their supplements anyway, I’m sure.

  16. Just an added comment this list “dairy, eggs, bananas, tree nuts, peanuts, soy, sesame, flax seed, kiwi, chicken, and bacon.” may sound very long, but I think it’s important to consider the size of the school and cross allergies. Several of those allergies are fairly common. My daughter, at a relatively small elementary has had children with verified (the child breaks out in hives) allergies to tree nuts, eggs and peanuts in her class. Also one severe allergy can represent several items, people with latex allergies can often be cross reactive to banana, avocado, chestnut and kiwi.

    I have no idea about the chicken or bacon…very sad to be allergic to bacon.

  17. JPZ says:


    Nice try (clap, clap)

    But you, in typical form, forgot to mention the science behind lactose intolerance (which by your post’s title could be very deceptive):

    *whisper to the audience* He has a bit of trouble with nutrition insights.

    Glad thanks that I am using a government reference lest I be banned from here. Oh wait, that didn’t work for another thread. Dang, I had so much more to share.

  18. Bogeymama says:

    JPZ, is there somewhere in that document you linked to that discusses the validity of IgG testing to diagnose lactose intolerance? Otherwise, I’m not sure what your point is. He mentioned lactose intolerance among the non-immune-mediated food intolerances, but to discuss the science behind it would be an entirely different subject, as is the subject of Celiac Disease. This was just about the bogus IgG testing that consumers are being offered to purchase on their own, which are becoming more mainstream as they are now being offered in pharmacies. Many consumers are falling into this trap, and thus making things difficult for themselves nutritionally. It is also falsely elevating the numbers of people who claim to have food allergies, and like I said before, muddying the waters for those whose allergies are legitimate.

    I’m getting rather tired of others claiming milk allergy because it makes little Johnny hyper! Or a wheat allergy because it makes them fatigued. Just more excuses to sell useless supplements, all while confusing teachers and schools when every allergic child has different symptoms to look out for.

  19. Harriet Hall says:

    Scott wrote:
    “Not immune-system based, they’re more common than allergies. They include conditions like lactose intolerance, It’s a catch-all term by definition.”

    He was mentioning some things that IgG testing does NOT apply to. Why on earth would you think he should have mentioned the science behind lactose tolerance in an article about IgG testing? Logically, if he did that he would have to also cover the science behind gastrointestinal reflux (GERD), enzyme deficiencies, metabolic conditions, infections and other processes. That was not only unnecessary but would have made his article interminably long.

    Your comments are becoming tiresome and trollish.
    If you have anything of substance to share, please do that instead of this kind of inappropriate nitpicking.

  20. Oh well, I’m afraid JPZ is beginning to look a bit silly in his attempt to gadfly.

    But maybe I’m going to look silly to. This line in the article has been bothering me. ”  Children may be tested, too, and parents may be given a long list of foods they are told their child is intolerant of. I’ve seen the effects in the community, too. Think going “peanut free” is tough? A public school in my area sent home a list of forbidden food products: dairy, eggs, bananas, tree nuts, peanuts, soy, sesame, flax seed, kiwi, chicken, and bacon. Were these all true allergies? It’s not disclosed. Anaphylactic or not, the parents had informed the school, and the school had banned the food product”

    The comment that the reason’s for the “banning” of the food isn’t disclosed and the implication that we should assume that these bans are suspect if there are not related to an anaphylactic reaction bothers me. in my experience some school food bans merely cover foods taken into the class for parties, some cover food offered to children without direct permission from the parent, some are broad bans that include the whole school. This doesn’t say which.

    As a parent who has had to make very particular diet request for my child, post surgery, I rely on school personal and parents volunteering in class to take my child’s requirements seriously, not question them because they are not related to a documented allergy, or they sound strange, or seem restrictive to someone who has no idea of the medical context And I don’t think I should have to make my son’s medical history public in order to be taken seriously.

    It’s great to cast doubt on CAM, but please focus on the CAM, not casting doubt on the parents or schools who are trying to provide a safe and comfortable environment for a student population that, due to our educational system’s admirable commitment to mainstreaming, has an increasing number of diverse health and dietary needs.

    1. Scott Gavura says:


      My statement wasn’t meant to dismiss allergies. I treat allergies very seriously. True allergies can have a profound effect on all aspects on one’s life. That’s why it’s critical to know the difference between allergies and intolerances, so there’s a better understanding of the respective risks, and their management. Evaluations, diagnoses, and management advice based on tests that lack clinical validity increases the challenge for facilities like schools to create safe environments for those with life-threatening allergies.

  21. Bogeymama says:

    micheleinmichigan I get your frustration. But I also get Scott’s frustration. I follow the food allergy media very closely, and there have been many cases where parents fight back at those kids that are the cause of food bans. (Case in Florida last year got WAY out of hand – the parents felt their children’s RIGHTS to have peanut butter at school trumped the safely of a Grade 1 student’s right to a safe environment) It really creates a toxic environment, and is made worse when every parent demands a different set of rules. Most major food allergy advocacy groups do not support any type of food ban. Rather, they recommend broad anaphylaxis readiness training for all school staff, promote availability of Epipens (not locked away in the office) and rules about no sharing food, wiping desks, etc. Too much to go into here. The point is that all kids can be kept safe if a few simple rules are followed, and food bans don’t have to happen at all. Nut bans are still implemented because they are easy to ban, and most food companies label appropriately wrt nuts. Sadly, anaphylaxis can also happen with milk (2nd most common cause of death from food allergy after nuts) and egg is increasingly common as well (and, technically, any food item that contains a protein – soy, wheat, seafood being the other common ones). Can you imagine trying to enforce a ban on milk? No products made with butter, cheese, yogurt, etc. No pizza! No grilled cheese! Some parents demand it, but I never have. Our allergist told us that even with a ban in place, do you honestly expect 200-300 sets of parents to be able to read and decipher labels for your child’s allergens like you can? You have to always assume that the allergen could be present.

    I hear you about the privacy – if FAAN and Anaphylaxis Canada’s recommendations were followed by schools and parents, food bans would not be necessary, and your child’s medical information could easily be kept between you and the relevant school staff.

    This is why I have such a problem with so-called allergies diagnosed by IgG. After I spend an hour with the staff teaching them about how to recognize symptoms of anaphylaxis, how to give Epi etc, these kids come in with allergies but have a completely different set of symptoms to watch for, and require no special treatment. It’s very confusing for the teachers, and makes them question the seriousness of all kids’ allergies.

    A little girl died a few weeks ago after she was given a peanut on the playground at school. No Epipen was given. These deaths do not have to happen. Everyone just needs to get on the same page!


  22. @Bogeymama, I totally get Scott’s frustration with the IgG food testing. I only wish the statement I quoted didn’t (unintentionally) seem to support the attitude that I’ve felt I had to deal with. That attitude is that any odd sounding food request by a parent is met with suspicion, eye rolling and an assumption that the parent is overprotective or loony. I would rather people assume, unless there is evidence to the contrary, that the parent has a good reason for their concerns, rather than feel entitled to see medical documentation before agreeing that the parent is only making a reasonable effort in her child best interest.

    Of course when I say people, I mean parents in the community, I do understand that schools may need to see letters from doctors, etc to efficiently implement any food or safety plan.

  23. @Scott Gavura, I did not take it that you dismissed allergies. I took it more that you were viewing a list of restricted foods with a critical eye as it somewhat narrowly applied to allergies. This critical eye may lead some to be dimissive of food restrictions that are needed by individual children but may not be related to severe allergies.

    Of course it’s hard to imagine that a full school ban would be needed for non-allergy related food items, but in my experience many of these lists are not full school bans. They are a list of things not to bring for classroom parties, snacks or sharing with other children.

  24. Also Scott Guarva -” Evaluations, diagnoses, and management advice based on tests that lack clinical validity increases the challenge for facilities like schools to create safe environments for those with life-threatening allergies.”

    I completely agree with this statement, though. Schools should be able to manage these restrictions based on science and/or evidence, not funky market gimmick tests.

  25. CanLabs says:

    We are CanLabs and represent the YorkTest FoodScan in Canada.

    While we agree that many food intolerance tests do lack scientific validation, we do believe that this is not a fair characterization of the YorkTest FoodScan. We believe that it is unfair to suggest that no patients will benefit from IgG testing due to the above mentioned criticisms. Other respected physicians and scientists share a different view then those found in the posting above. For example, consider the following review article –

    Thank you for allowing us to participate in your discussion.

    CanLabs Inc.

  26. Michael Kruse says:


    If, according to that article, testing for IgG is at best controversial (see conclusion), is it not therefore unethical to be offering it as a service outside of a clinical trial? The IgE testing in that article was shown to be the gold standard, so by offering something that is not the gold-standard for allergy/sensitivity testing, you are offering a substandard service, no?

  27. florasubspecies says:

    I’m going to cry foul on your paper. No one is saying that individuals with IBS symptoms shouldn’t be screened for legitimate intolerances like celiac disease. Gluten intolerance is well-defined in the literature and can present with IBS-like symptoms. However, this is specific, directed use of these tests in individuals with high clinical suspicion, and because IgGs are woefully non-specific, the typical antigen for assessing gluten intolerance is IgA. The paper itself claims that individuals can experience no symptoms at all, or continue to have symptoms months after consuming the antigen. In the first case, why are we treating someone with no clinical disease (since IBS is defined as having no clinical findings) and no symptoms? In the second case, if there is such a massive temporal dissociation between symptoms and the antigen, how is this biologically sustained and furthermore, how can you prove that the antigen caused the symptoms in the first place?

    Basic knowledge of epidemiology demonstrates that unless your test is nearly perfect and the prevalence of the disease is high, there is VERY little value to doing screening of asymptomatic patients and/or low risk populations. You’re offering the test to individuals that you have no reason to suspect food intolerances in aside from vague symptoms like “headaches.” An unproven test finding unproven correlates to unproven food intolerance is ridiculous at best and irresponsible at worst.

  28. CanLabs says:

    @Michael Kruse

    There is more to the summary:

    “IgG antibody testing for delayed food sensitivity remains controversial. However, data suggest that eliminating foods identified using IgG antibody food testing in IBS can result in significant symptom improvement.”

    As such, we feel that it would be unethical to prevent patient access to such a service that has been shown to “result in siginificant symptom improvement” for patients with IBS.

    For clairity, IgE is the gold standard for food allergy testing, not for delayed food intolerances.

  29. Bogeymama says:

    My favourite line in the linked-to paper:

    “When test results indicate IgG sensitivities to a large number of foods, many alternative practitioners have anecdotally observed an associated increased intestinal permeability rather than frank food intolerances.”

    How exactly does an alternative practitioner observe increased intestinal permeability? Some kind of scanner?

  30. @CanLabs

    I believe your “appeal to ethics” is insincere:

    1. You linked to a highly criticized study for which Scott Gavura already provided an adequate rebuttal:

    2. CanLabs apparently has the one study you promote as your “validation” of your tests, when in reality the study did not “validate” the tests.

    3. You ignore multiple reviews and newer studies that find absolutely no diagnostic quality for IgG food allergies:

    4. You ignore essentially the collective knowledge of the world’s allergy authorities finding that IgG food allergy tests are devoid of diagnostic ability. Instead, CanLabs/YorkTest would rather molest one sentence of a study into somehow being evidence for all of the claims on your website.

    5. You ignore the fact that, to an allergy doctor, the way food allergies are diagnosed is irrelevant. They would not care if its done by skin or by blood. In fact, skin allergy testing is tedious and time consuming. I’m sure they would welcome with open arms a simple blood test if it had any diagnostic quality.

    6. No where on the front page of your website do you indicate that the food tests you provide are “experimental”, “controversial”, or “unproven.” Instead you offer package deals which include the blood tests along with pamphlets on treating food intolerances, as if these kits are an effective way to diagnose and treat food allergies/intolerances.

    7. Your website is alarmist in nature. It insinuates that up to 45% of the population suffers from food allergies by making the claim:

    According to the leading medical charity Allergy UK, as many as 45%* of the population suffer from food intolerance which, whilst not life threatening can make all aspects of life very uncomfortable for sufferers.

    Your website then goes on to imply that we should all have food allergy tests performed in order to avoid suffering from generic symptoms. This 45% figure is an *estimate from a survey* from an allergy charity website (Allergy UK.) Therefore, essentially useless data is being used to worry people into taking these tests which have no proven diagnostic ability.

    8. You base other claims on your website from surveys (not research) performed by Allergy UK.

    9. There are financial ties between YorkTest and Allergy UK. YorkTest Laboratories is listed as a “corporate partner” on the Allergy UK website.

    10. The Allergy UK website, which CanLabs apparently depends upon for its epidemiological data, states ( ):

    There is controversy about the role of IgG; it may be present in the blood as a ‘marker’ for the foods we eat most often, rather than actually being involved in the food intolerance reaction. Nevertheless, some people find the test helps them decide which foods to avoid.

    Note that IgG tests are not tests for true food allergy.

    11. You list very generic symptoms (headache, or eczema, or acne, or joint pain, or fatigue, etc) and when any one of these individual symptoms is selected, your website explains the cause of the symptom as possibly due to food allergy. Example:

    Do you suffer from tiredness and fatigue?

    If you find that you constantly feel tired, did you know that the food you are eating could be the root of the problem? According to leading charity Allergy UK up to 45% of the population suffers from food intolerances. YorkTest has a food intolerance programme that can help you to identify which foods you are reacting to.

    For every single symptom listed, YorkTest identifies it as a possible food allergy and suggests allergy testing.

    12. YorkTest Laboratories apparently has a history of selectively quoting studies and implying that surveys or articles are published in places, such as BMJ, when they are really not:

    For these reasons, as I already stated, I believe your “appeal to ethics” is insincere. I believe you violate patient trust by presenting YorkTest IgG food allergy tests as if they are high diagnostic quality tests. I believe your company is acting unethically by offering these tests as part of a “package” to diagnose and treat unproven food intolerances. I believe your company selectively presents data or dubious quality to give the appearance these food tests have diagnostic quality when in fact they do not.

    Speculation: I am highly suspicious about the similarity between the YorkLabs and Allergy UK websites. The strange “help lines” in the top-right corner and the same glossy buttons raise concern. Also, that YorkTest gives away a free membership to Allergy UK if a client buys a package deal from YorkLabs is concerning.

  31. Quill says:

    SkepticalHealth wrote: “Instead, CanLabs/YorkTest would rather molest one sentence of a study into somehow being evidence for all of the claims on your website.”

    I want to thank you for your thoughtful, well-cited post in general and in particular for the best use of the word “molest” I’ve seen in many years. :-)

  32. Quill, thank you kindly!

  33. Thanks for this. I have a friend who took her six-yr-old to a naturopath who did a finger-prick blood test for food allergies. Of course the not-doctor found that this child is allergic to practically everything. The extensive list includes both wheat and corn, along with peanuts and a slew of other major food groups and obscure additives. The entire family, including a younger sibling, has had to completely alter their lifestyle, and the kiddo is in the process of internalizing her new identity as Allergic-To-Practically-Everything. The kiddo’s vague gastrointestinal symptoms have abated, thus confirming the naturopath’s allergic-to-practically-everything diagnosis. Their child feels better, and that’s all that matters.

    What is the impact of a seriously restricted diet on children? This is not the only family I know whose children are allergic to the bulk of food groups that my own kids eat.

  34. JPZ says:

    Geesh, because he describes “food intolerance” and tried to describe what the “science says.” Just because others misuse the term “intolerance” does not mean that the public consuming that information will parse false definitions of “intolerance” and the more prevalent condition of “lactose intolerance.” I suppose we could survey the audience whether the sidebar about lactose intolerance reaches them, but can we accept the difference between a motivated broadcast opinion and a passive survey?

  35. joeedh says:

    In my case, IgG tests were used for precisely the reason this blog states: to test for the presence of allergens, which might’ve been exacerbating a gastrointestinal sore of some kind. It wasn’t that I was allergic to the foods directly, it was that some foods would irritate the digestive tract, and once the underlying problem was fixed I’d no longer be bothered by those foods.

  36. luarky says:


    Also, in the absence of actual tests for food intolerance, are “challenge” diets a valid alternative? My niece supposedly suffers from several of these intolerances and has eliminated gluten, sugar, and food dyes from her (now very boring) diet. She occasionally “challenges” one of the forbidden items and if she perceives a negative reaction in some very subjective way, she puts that food back on the do-not-eat list.

    A hypoallergenic elimination diet, followed by food challenges, is actually the “gold standard” for diagnosing food allergies that don’t appear in the standard skin or blood IgE testing. The process has a lot of pitfalls, though – a lot of reasons why they can fail to diagnose an allergy that’s there, or give people the wrong impression.
    The virtue of elimination diets is that they don’t make assumptions about the mechanism. They DO seem to be looking specifically for reactions mediated by the immune system, since the “hypoallergenic” part means eliminating common food allergens.
    The point of the elimination diet is not just to see if symptoms might go away, but also that the body does something to suppress the symptoms from the food allergies, and if you stop eating everything that you have an immune reaction to, then after the elimination diet, a reaction will become obvious. I experienced this over and over, very blatantly, so I’m sure it’s a real phenomenon.
    But, whatever the body is doing to suppress the symptoms, it’s not specific to a particular allergen. So if you don’t eliminate everything you’re allergic to, you might not have an obvious reaction to a food challenge.
    The idea behind IgG antibody testing is apparently that the symptoms of a lot of delayed food allergies are caused by IgG immune complexes, which circulate in the blood and cause symptoms in various parts of the body.
    I have a LOT of delayed food allergies, which I figured out using (several) elimination diets and food challenges. I start feeling bad about half an hour after eating a food I’m allergic to, then within a few hours I’m sick and I stay sick for 2-6 days. I described my food reactions in more detail in
    The best guess about what’s going on with those kinds of food reactions, seems to be that it’s immune complexes, a kind of serum sickness from food. I looked up symptoms of serum sickness, and there are a lot of similarities to my food reactions. I’ve seen reactions similar to mine described by many different people.
    I didn’t trust IgG antibody testing to give accurate results, so I never got it, except for gluten – I did have high IgG antibodies to that.
    A hospital lab can test for IgG antibodies to food, at least the local hospital here does. Perhaps they are more accurate than places online like York Labs.
    However, I’ve wondered if I should have gotten IgG testing. I’ve spent many months total, maybe a year, sick from food challenges. Whatever is happening to my body during these sicknesses might be rather ugly and maybe cause permanent damage. Perhaps I could have avoided a lot of sickness by getting IgG antibody testing from a good lab.
    Just having negative results for IgE food antibodies with skin/blood tests does not BEGIN to imply that it’s not an immune reaction.
    First, there might be reactions that aren’t IgE-mediated. There are IgA, IgG and IgM antibodies in the gut, the IgE is under the gut lining.
    For example, free light chains – a piece of an immunoglobulin wandering around by itself – can apparently cause degranulation of mast cells in mice, see
    Lots of papers on free light chains in allergy, that I haven’t looked at.
    People with rheumatoid arthritis have higher than normal levels of IgG and IgM in their intestinal fluid, though not necessarily in their blood,
    Some people with schizophrenia are gluten-sensitive – as determined from high IgG and IgA antibodies to gluten in their blood – but the immune reaction to gluten is different from the celiac immune reaction. See
    And so on, there’s probably a great deal more.
    ALSO, there seems to be a lot of evidence that people can have IgE-mediated allergies that are local, in various mucous membranes, like the nose, bronchial tubes, lungs, in the conjunctiva around the eyes, and in the gut. So people can have allergic reactions without having IgE antibodies to the allergen in their blood, it all happens locally. Mucous membranes have associated lymphoid tissue, and it seems that this can take the place of lymph nodes in the process of allergic sensitization.
    There’s good evidence that people can have inhalant allergies even though skin and blood tests for allergies are negative, see
    This concept of local allergy has been dubbed “entopy”, and there’s a good review article on that at
    This article doesn’t say much about local allergies in the gut except that local hypersensitivity does occur there. Another article mentions some evidence for local allergies in the gut, see Also
    Food reactions that don’t appear in skin or blood tests for IgE allergy, have passed double-blind challenges.
    The current tests that you can get for IgE food allergy are totally inadequate for diagnosing the actual range of immune reactions to food.
    I have reactions to very tiny amounts of food allergens. I’ve gotten my 4-day sicknesses from things like a single vit. E capsule with soybean oil in it; from nibbling a trace of peanut butter that was under a fingernail, after I fed peanut butter to the squirrels; and so on. And these allergies have lasted for > 8 years of not eating the food, although my reactions are much less severe than they used to be.
    I find some of this person’s niece’s allergies dubious. Being allergic to sugar itself doesn’t make sense. Beet sugar or cane sugar? Traces of beet protein or cane protein would be in the sugar, and you can react to that. But beet and cane are unrelated plants, so an allergy to beet sugar would be separate from an allergy to cane sugar. A reaction to sucrose itself is unlikely in small quantities. I don’t know whether someone might be sensitive to a food dye.
    People commonly come to wrong conclusions about what is really bothering them in their food. People who’ve been diagnosed or decided they have one allergy, seem to be reluctant to consider any other allergies. Like people who are gluten intolerant, and have problems after eating beef, decide that because the cow was grain-fed, they’re getting gluten in the beef! This always sounded very unlikely to me.

  37. luarky says:

    Also, there has been a lot of research on non-celiac gluten sensitivity, which affects about 10% of people. See
    It’s also an immune reaction to food, but according to this study (very detailed!) it mostly involves the innate immune system, with some involvement from the adaptive immune system. And no autoimmunity. Celiac disease is an autoimmune disease, but non-celiac gluten-sensitivity is not.
    In this study, about half the gluten-sensitive people had positive IgA and IgG antibodies to gluten. It doesn’t say how many had just IgG antibodies to gluten, leaving open the question of whether IgG antibodies might be diagnostic for gluten sensitivity.
    Also, I think allergists would generally agree that skin and blood tests for IgE food allergies are not very good, they often have false positives as well as false negatives. So even with the well-known kind of IgE food allergy, if someone tells a pharmacist they have to avoid something, they might be wrong, if they just go by allergy tests.
    People who are told they have a food allergy based on IgG antibodies, are likely to check it by eliminating then trying the food – so they are not necessarily just going by a lab test when they say they have a food allergy.
    Celiac disease was radically underdiagnosed in the United States in 2003, when a big epidemiological study found it at a rate of 1/133 – see I read that at the time, it was being diagnosed in the US at a rate of 1/5000! If you had the “typical” symptoms of losing weight, diarrhea, fat in the stools, you MIGHT get diagnosed. But what they found was that most celiacs don’t fit that picture. The “typical” celiac was actually atypical. I probably have celiac disease.
    From asking on a celiac mailing list, my kind of food reactions are quite typical for celiacs. It’s similar to the usual celiac reaction to gluten. Celiacs often have delayed food allergies to foods without gluten. So some of the people who say they have food allergies that don’t show up on skin or blood tests, actually have celiac disease.

  38. Spurll says:

    Great article, Scott! I believe that there’s a (minor, but perhaps important) typo, however: you refer to “gastrointestinal reflux (GERD)”, when I believe you should be referring to “gastroesophageal reflux”.

  39. Mel says:

    I’ve felt suspicious of food intolerance testing, which is why I haven’t resorted to it. But I’m pretty sure I do have some food intolerances, and food sensitivities are real enough. Which is why I felt compelled to get on here and address some of the comments.

    First off; why so down on alternative medicine? Yes, there are ineffective treatments in that realm, but conventional medicine has offered up its share of ineffective or even detrimental treatments over the years as well…and still does. To be blunt, what does conventional medicine ever actually cure, other than infections? That’s hardly an original question, but it’s completely relevant. I remember following my instincts and the advice of my mother-in-law back when I was pregnant, instead of what doctors and nurses were pressing on me. I refused an episiotomy, which were done routinely at that time, and didn’t suffer the same problems so many women have had with improper healing, for example. I also refused to gain more weight (I gained 15 lbs. total, and they insisted I needed at least 25 lbs.), which they kept urging me to do. They’ve since abandoned that idea. My child was born perfectly healthy, and I had zero stretch marks and regained my pre-pregnancy build quickly. Why are there so many dogmatic, uncompromising attitudes out there when medical knowledge is perpetually evolving?

    To the person who said no one could know more about allergies than an allergist, Oh, indeed? What does an allergist know? Can they tell you precisely what caused your particular body to be allergic to something that is harmless to someone else, and why? Can they CURE your allergy?

    To the person acting dismissive towards food intolerances because they aren’t allergies; what right have you to illegitimatize someone else’s personal experience? If someone feels radically better after eliminating a food from their diet, who the hell are you to tell them they don’t, or that their quality of life doesn’t matter? This kind of attitude isn’t just obnoxious and ignorant…it’s just plain stupid. Humans still know VERY little about the world and all it contains. Know-it-alls make fools of themselves.

  40. Scott says:

    First off; why so down on alternative medicine? Yes, there are ineffective treatments in that realm, but conventional medicine has offered up its share of ineffective or even detrimental treatments over the years as well…and still does. To be blunt, what does conventional medicine ever actually cure, other than infections?

    What does CAM ever cure? Or actually benefit? Well, NOTHING. Or at least, nothing known. Once it’s established to work, it becomes just medicine. CAM is [i]by definition[/i] comprised of stuff which is either not known to work, or known NOT to work.

    That’s hardly an original question, but it’s completely relevant.

    Actually, there is exactly zero relevance – any claimed failings of real medicine do not therefore make CAM effective. They are completely independent points.

    Why are there so many dogmatic, uncompromising attitudes out there when medical knowledge is perpetually evolving?

    Ask the CAM providers. They’re the ones who refuse to look at evidence and adapt their practice accordingly.

    To the person who said no one could know more about allergies than an allergist, Oh, indeed? What does an allergist know? Can they tell you precisely what caused your particular body to be allergic to something that is harmless to someone else, and why? Can they CURE your allergy?

    Can anyone else? No, they cannot. Allergists not knowing everything is not, by any stretch of the imagination, evidence that anybody else knows more.

    To the person acting dismissive towards food intolerances because they aren’t allergies; what right have you to illegitimatize someone else’s personal experience?

    Pointing out that intolerance and allergy are completely different things is not “acting dismissive” or “illegitimizing” anything.

    Know-it-alls make fools of themselves.

    Mourn for the legions of irony meters which just melted down.

  41. Tamper says:


    Thank you for this post.

    Have you looked into allergen vaccines yet? They are offered by places such as the Breakspear Medical Group who appear to provide no evidence for their ‘science’. I believe that they are currently setting up outposts in Australia and possibly Germany to whom they will supply antigen vaccines for further dilution. As far as I am aware, the antigen vaccines are created by exposing the allergen to distilled water or somesuch for 14 days in order for the water to absorb its ‘frequency’. Once the vaccine is ready it is diluted into graded amounts and injected into the arm to monitor the reaction and find the ‘end point’, which will then be added to a ‘cocktail’ and injected at least once daily with up to 25 other allergen vaccines all mixed together. It’s amazing stuff, they even have a vaccine for UV light.

    There doesn’t appear to be too much in the way of scientific discussion about such practices on the internet.


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