Anton Emmanuel on why IgG testing for intolerances is not a useful diagnostic tool

Dr Anton Emmanuel is a Senior Lecturer in Gastroenterology at UCL. He has also studied the use of IgG testing kits – specifically, Yorktest testing kits. His research has been referred to (very likely inappropriately) by Yorktest in defence of their products. He is also one of the experts listed as backing Food Intolerance Awareness – which refers people to Yorktest for IgG tests.

When Radio 4’s Case Notes investigated food intolerance, Emmanuel was interviewed re IgG testing. We were surprised to hear him offering a rather (in our opinion, appropriately) negative assessment of the diagnostic value of such tests for identifying food intolerances.

Emmanuel is introduced by the presenter as not being very impressed with testing kits, and describes this process of testing as “not nearly as specific as one would like it to be”. For Emmanuel, the fact that wheat, yeast etc. come up often on these tests probably reflects “as much as anything else, our exposure to these things in our diet” rather than a specific intolerance/allergy.

Emmanuel is not impressed with these tests due to, among other issues:

  • No external standard as to levels which show intolerance: the tests rely on internal standards which aren’t as robust as one might like.
  • The effects in the patients Emmanuel has seen using these tests have largely been unimpressive, period. Even where patients did appear to benefit, results have not been great in the longer term.
  • A slightly leaky gut may lead to an IgG response to various proteins. It is erroneous to tie this response to specific proteins.

We share a number of these concerns. We would hope that Emmanuel will robustly raise these concerns with Food Intolerance Action (the special interest group set up by Allergy UK), in order to challenge their support of the Yorktest IgG tests which Emmanuel criticises so effectively. Emmanuel’s words add even greater weight to the House of Lords Science and Technology Committee’s point that

Given the lack of evidence for these services we were concerned to learn that Allergy UK recommended the Yorktest service for food intolerance

For further reading, see also our summary page of IgG intolerance and allergy testing.

BPSDB

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8 Comments

Filed under food intolerance, patrick holford, yorktest

8 responses to “Anton Emmanuel on why IgG testing for intolerances is not a useful diagnostic tool

  1. Wulfstan

    Patrick Holford really can’t help himself. A few days ago, you miniblogged a paper to do with vitamin A and C levels and asthma. In Holford’s hands that story has undergone some not so subtle alterations so that it is now all about a familiar food allergy test:

    Today’s study showing a strong association between lack of vitamin C and A and asthma is consistent with an emerging view that asthma, and other inflammatory diseases, are a result of a number of diet-related factors including lack of antioxidants, omega 3 fats in oily fish and an increase in high allergen foods such as wheat, milk and yeast….

    When your body switches into a state of inflammation, which is much like going on red alert, the gut-related immune system is much more likely to attack foods as if they were foes. This results in more anti-food antibodies. These IgG antibodies become specifically targetted against foods. The most common target foods are milk and wheat, high in a protein called gliadin. Yeast and egg reactions are also quite common. A pinprick home test can determine such food allergens and, if these foods are avoided, and a high anti-inflammatory diet, plus appropriate supplements, is followed most asthma sufferers experience considerable relief.

    Is there any indication that asthma is primarily related to diet or that YorkTest led dietary modifications would alleviate it?

    • Not your fault, Wulfstan but the Dietary antioxidants and asthma in adults study to which Patrick Holford links is not the subject of the news item. The study in question is not yet in PubMed or even Thorax online so grief knows why some people who have probably not seen the full paper are commenting on it.

      Nonetheless, your point stands that it has been transformed into a shilling opportunity for York Test and Holford’s own particular take on such matters.

      NB: Bizarrely, Holford’s blog is set up so that the first paragraph is not always available in the blog post. The paper link to which Wulfstan is referring is only available from the home page.

      • Wulfstan

        I’m cringingly (is that a word?) embarrassed.

        It’s not as if you don’t mention his difficulties with references. On top of the problems with the migraine references and others you’ve mentioned, does this mean that it is officially impossible to underestimate Patrick Holford?

        Thanks for the response to the other questions.

    • Is there any indication that asthma is primarily related to diet or that YorkTest led dietary modifications would alleviate it?

      And should also have said, crudely, no and definitely not in response to your questions. Sorry – distracted by the fact that the man Holford can’t get his references or links right.

      • Claire

        My Behind the Headlines rss feed is carrying the full text of a BTH treatment of this story dated 17 April but I can’t for some reason link from the feed to the ‘official’ version, despite having registered etc.

        This is being discussed on one of Asthma UK’s forums (General forum, thread name ‘asthma preventable?”) and somebody called Marian Slee has weighed in about the Vitamin A deficiency theory. A quick google reveals that she has a website promoting ‘asthma relief the easy vitamin way’

  2. Randall

    Why is Anton Emmanuel a member of the Expert Panel if he is reporting that the test is useless but the organization recommends it?

  3. Claire

    This US-based paediatrician, specialising in asthma, allergy and clinical immunology is not convinced of the utility of IgG to food tests:

    “…I can see value of EBM in the practice of allergy by board-certified allergists especially in an environment where the label of ‘allergy’ is given too loosely. In my practice I am seeing conditions labeled as allergy (apraxia, autism, sensory integration defects, ADHD to name a few) because tests for allergy return as positive. Many times the clinical condition and the test has nothing to do with allergy. IgG to food would be a prime example. I have seen significant amounts of money spent and hopes of families dashed by the use of tests and therapies that are not evidence-based. …”

    I’m guessing he wouldn’t be impressed by Holford’s ‘hidden allergies’ hypothesis.

    • It’s not a message that is getting much traction. I don’t know how the lack of support for this test can be explained in better terms to the people who are interested in the information. The problem may be that people have already decided to take the test and look for information to confirm that decision (confirmation bias) rather than evidence against it. E.g., it never occurs to this person to question the accuracy of the YorkTest when she receives some odd results.

      Well, I got the results of the food intolerance test on Wednesday and ho hum. As I knew already, it tells me I am intolerant to cow’s milk and soya bean, but I am also intolerant to…all oily fish, turkey, chicken, duck, pork and lamb. I don’t know where the duck and pork come from because I don’t eat those (I will ask the nutritionist next week) but chick and turkey, oh dear. We have those a lot for dinner. Turkey came worse than chicken. The oily fish came from the omega 3 capsules I had been having and have now stopped taking those as I believe they could have been the cause of the recent IBS I’ve been suffering from in the mornings…So it will be chicken and lamb first to eliminate, cow’s milk and soya I already don’t eat because I knew I couldn’t eat them. [Emphasis added.]

      So, a positive result of food substances already excluded from the diet that should (according to the IgG hypothesis of food intolerance) not provoke such a response after prolonged abstinence. Even if you accept the IgG hypothesis, it is unlikely that the fish oil rather than actual fish should be provoking an adverse response and slightly surprising that it is sufficient to provoke much of an IgG response (FSA on issue of fish allergy (IgE) and fish oil supplements).

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