Professor Patrick Holford of Teesside University and Head of Science and Education at Biocare is a staunch advocate of direct to consumer IgG food intolerance tests and is impressed by the “sound science” that underlies these tests. Holford is convinced that:
The evidence for IgG antibody reactions as a basis for food intolerances continues to grow, including well designed randomised controlled trials, however, some health professionals just haven’t kept up to date. Perhaps it’s because a ‘home test’ takes the power away from the professional and puts it in your hands.
However, Holford is also swayed by the scientific research for a neck pendant that protects wearers from the evil eye of electromagnetic radiation so one might be tempted to generalise from that as to the scientific credibility of some of his endorsements. It is also indisputable that the expert consensus is that these IgG blood tests are of no value in the diagnosis of food intolerance.
Expert Opinion, the House of Lords and the ASA
There is no credible evidence that measuring IgG antibodies is useful for diagnosing food allergy or intolerance, nor that IgG antibodies cause symptoms. [ASCIA]
Clinical allergists and immunologists with impeccable research records and many years of clinical experience have explained that there is no scientific support for the role of IgG testing in the diagnosis of food intolerance. One particularly exasperated expert, the redoutable and remarkably compelling Dr Glenis Scadding, Consultant Allergist at the Royal Nose, Ear and Throat Hospital, characterised IgG tests for food intolerance as “a waste of money”:
What I do dispute is that it is worth making any attempt to identify IgG antibodies. We all make IgG antibodies to food….I see no way in which this can be used to guide diet.
I don’t think there’s any point in spending money on IgG antibody tests. You’re better off going to see a dietitian and using an exclusion diet followed by reintroduction. The IgG antibody tests are liable to leave patients on diets that are inadequate and patients often like to think they’re improving. They carry on in the teeth of very little improvement and may end up malnourished.
I think [self-testing kits] should be banned.
Back in 2006, the House of Lords appointed a committee to investigate allergy and allergic disease in the UK. The Committee investigated some important issues with implications for public health and public policy. They heard extensive evidence on the role of appropriate allergy testing and the lack of scientific support for currently available direct to consumer food intolerance or allergy tests.
Well, it rather seems as if the House of Lords Committee has greater confidence in the undisputed expertise of Scadding and other comparable experts rather than Holford who has no original clinical research or even indexed, peer-reviewed publications in this area. In a comprehensive report HL 166-I (pdf from which pg numbers are given), they make a number of good recommendations and provide some useful summaries. Pages 86-88 cover the issue of direct-to-consumer tests such as the YorkTest foodSCAN IgG test for food intolerance and the YorkTest–Allergy UK MAST IgE test for allergies to food and airborne allergens, amongst others. The committee noted:
Dr. Gill Hart, Technical Director of YorkTest Laboratories, a company which manufactures such tests, told us that the presence of either IgE or IgG antibodies does not necessarily prove whether a food allergy exists, but claimed that IgG could be used “as a marker that a reaction has occurred” (Q 742). However, there is limited evidence to support this claim.
Furthermore, the EAACI even discredited the use of well validated tests based on IgE antibodies if they are used on a self-testing basis. This was because the tests “cannot be interpreted without a detailed clinical history taken by an allergy-trained individual, thus over the counter and postal testing is open to misinterpretation unless expert opinion is available” (p 70)…
Dr Hart admitted that the mechanisms used in the tests were “unclear…”…
Given the lack of evidence for these services we were concerned to learn that Allergy UK recommended the Yorktest service for food intolerance. The charity acknowledged that a patient’s best option would be to consult a dietician, but noted that “being able to obtain a referral to a dietician who understands food intolerance is extremely difficult on the NHS” (p 303).
One might imagine that the BDA would argue that dietitians have a considerably better knowledge of food intolerance than people who rely upon the results of a test of no proven scientific or clinical efficacy or who find themselves recommending YorkTest on the rather desperate grounds of faute de mieux:
It’s a lack of other places to send these people to. Err, we would give the YorkTest purely because it’s the only one that has undergone trials-particularly for IBS and that’s what we would say, that we would [be] happy to endorse it for, would be for those kind of symptoms. Eh, but, you know, we wouldn’t recommend any other test.
Desperate people searching for solutions do not need to be fobbed off with expensive tests of no proven efficacy in the hope that it will provide a palliative of dubious duration. It is unfortunate that people who are already in distressed circumstances may restrict their social activities because of the perceived difficulty of living with allergies and intolerances that may be inappropriately diagnosed.
Holford Watch is not optimistic that Holford is heeding expert opinion but the House of Lords summed up their advice as follows (pg 87):
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 urge general practitioners, pharmacists and charities not to endorse the use of these products until conclusive proof of their efficacy has been established.
It almost seems gratuitous to add that the House of Lords aligns themselves with clinical experts in their notion of who is qualified to diagnose allergies and allergic disease (hint, it is not the typical holder of a Diploma ION nor an auto-didact nor self-proclaimed expert; pg 89):
An accurate diagnosis is key to treating an allergic condition adequately, and much depends on taking an accurate patient history with details of a patient’s symptoms, home and occupational environment, temporal and geographic features, relevant family history and any physical signs. Diagnostic tests are often based on skin tests, blood tests and challenge tests. But the results of tests are meaningless in isolation; they have to be interpreted in the context of the patient history, a difficult task which requires a solid training in allergy.
It is important that an evidence-based approached should be used in the managment of allergies and allergic disease that have the potential to be life-threatening and can have a significant impact on quality of life. It is too common, particularly for parents who are desperate to help distressed children, that desperate people seek private testing that have no scientific or clinical support. Professor Gideon Lack specialises in the allergic mechanisms of asthma in children. He was sufficiently concerned about the importance of appropriate advice and testing that he conducted a survey of the allergy advice parents have received before they attended his paediatric allergy clinic: his findings were both eye-opening and alarming.
We found almost 50% had received alternative health care advice about allergies before coming to see us. I would say that of the children who come to our clinic at least 10% and possibly up to 20% have received unsound advice; these children will face nutritional problems.
The redoutable Dr Scadding may not have achieved her tongue-in-cheek wish that such direct to consumer tests as the ones lauded by Holford should be banned but it is a good sign that the House of Lords report makes such strong recommendations urging charities and responsible professionals not to endorse such tests until there is evidence of clinical efficacy.
The ASA recently reproved YorkTest for inappropriate claims that IgG blood tests are diagnostic of food intolerance.
We concluded that the evidence submitted was not sufficiently robust to prove the efficacy of the tests for diagnosing food allergy or intolerance.
Hidden Food Allergies
Patrick Holford and Dr James Braly have written a book: Hidden Food Allergies: Is What You Eat Making You Ill? The book announces:
One in two people, including up to 70% of the chronically ill, suffers from a hidden food allergy. Are you one of them?
The book is a tour-de-force that links common symptoms to IgG food intolerance and ‘allergies’. The statistics are drawn from opinion surveys and audits of people who have used the blood test: there is no support for these numbers in the general clinical literature.
In our experience, the vast majority of people have no idea their health problems may be related to eating specific foods. Most people’s food allergies are truly hidden from them…
Chances are, however, that food intolerances or allergies are adding to your burden, and in many cases, are prroving to be the main cause of any health problems…We’ll let you know about the amazing scientific advances that mean you can now identify food allergies from a pinprick of blood using a simple home test kit…
What’s more, we’ll explain why you become intolerant to certain foods by revealing the underlying causes of most food allergies, and how to eliminate these causes and thereby reduce your allergic potentil. We’ll explain how to ‘desensitise’ yourself to foods you’re allergic to so you can eat them once more, a process that usually takes just three months.
Some types of allergies, of course, are for life. If you have this kind, you can’t desensitise yourself completely – but you can reduce the severity of your allergic symptoms using natural, drug-free methods, and we will show you a range. [pg. viii-ix]
The book is notable for linking IgG food intolerance (or ‘allergies’) and ‘leaky gut syndrome’: there is no support for such a link in the clinical literature.
It wasn’t until the 1980s that published research began to demonstrate that a fundamental mechanism behind IgG food allergy was the penetration of large molecules of incompletely digested food through a leaky intestinal lining into the blood stream… [pg. 86]
Allergies and leaky gut syndrome is one of those chicken-or-egg situations. There’s good reason to suppose that having a more permeable digestive tract is what precipitates food allergies in the first place, while having a food allergy encourages a leaky gut by inflaming the digestive tract wall. While you can test for increased intestinal permeability, it’s highly likely that you have a degree of increased permeability, especially if you have multiple food allergies or digestive symptoms. [pp. 139-40]
The authors inform the reader that it may take the following tests to identify allergies:
tests exist to identify deficiencies in digestive enzymes, leaky gut syndrome, and the balance of bacteria and yeast in the gut. They can be arranged through nutritionists… [pg. 112]
[To identify your allergies you may need] an IgG food allergy test, a coeliac screening test and possibly an IgE food allergy test. [pg. 126]
The authors advise the extensive use of supplements to heal the gut: they caution that the supplements are necessary to reduce allergic potential and that the benefits of an elimination diet may not be possible if the gut is not ‘healed’ first. There is no clinical support for the gut-healing programme that the authors recommend for these ‘allergies’.
The authors attribute too much significance to the slight findings of the scant research that has been conducted for IgG-led elimination diets and IBS: this research has been discussed elsewhere and does not support the authors’ claims for it (cf, Dr Scadding’s comments above). I
More recently, Holford is impressed by the evidence value of an audit of a customer survey for YorkTest. This is particularly poignant in the light of the testimony of one of the authors, Hart, who admitted that IgG levels do not prove that an intolerance/allergy exists (see above). Hardman and Hart acknowledge the equivocal status of IgG as a marker for food intolerance in the introduction to the paper that gives an account of the customer survey:
the exact role of IgG antibodies as markers of food intolerance in general is not clear. IgG antibodies to food antigens are often present in healthy individuals and are generally considered to be part of the normal immune response to food allergens [refs].
The Hardman and Hart audit does not provide support for the value of IgG tests as a diagnosis of food intolerance: Quote Mining and Misrepresentation: Poor Ways to Claim Clinical Validation or Sound Science; More Allergy and Intolerance Testing Nonsense: Part 1; Food Allergy and Intolerance Tests: YorkTest Gives Evidence to the House of Lords . It is rather unfortunate that even though Hardman and Hart understand this about their paper, Patrick Holford does not.
The expert consensus is that there is no clinical or scientific support for the use of IgG blood tests in the diagnosis of food intolerance.
It is inappropriate that people are led to believe that there are clinically validated blood tests available to diagnose such conditions as food intolerance.
The public understanding of the issues of allergy and allergic disease is confused when issues of intolerance, sensitivity and allergy are discussed as if they are equivalent.