Health Freedom and Food Intolerance Testing

I’ve talked about IgG testing previously, but in case you need a refresher, an IgG test is a blood test that proposes to improve your health by identifing food “intolerances” (not necessarily allergies). I’ll leave the rest of the primer to Scott Gavura, a Canadian pharmacist who writes for both Skeptic North and Science Based Medicine:

IgG blood tests like Hemocode and YorkTest are clinically useless for diagnosing food intolerances, yet pharmacies imply otherwise. These tests claim to identify sensitivity to hundreds of products – yet not one has been validated. That’s because there no proven correlation between positive results on an IgG blood test and a true food intolerance. Not only are these tests use to shape dietary modification, they’re also used to sell supplements – another unproven use of IgG testing. Yet despite recent cautions against this testing, it continues to be offered.

A host of professional organisations including the American Academy of Allergy, Asthma and Immunology, the Australasian Society of Clinical Immunology and Allergy, the British Dietetic Association, and many more have all recommended that consumers avoid using these tests to diagnose allergies or intolerances, because the evidence just isn’t there.

IgG

In response to my previous post about Dr. Elaine Chin’s scientifically bankrupt endorsement of IgG testing, a reader going by the pseudonym “Still Searching” had this to say:

Many people suffer from chronic conditions that traditional medical practitioners have been unable to alleviate. [Although] the relationship between chronic health conditions and IgG response and use of IgG test results may not be proven, there is a significant amount of anecdotal evidence of dramatic improvements in health through use of elimination diets and similar. Should we wait decades for medical proof before investing $200 in a simple test that might lead to a change in diet that might significantly reduce chronic depression? Pharmaceutical companies will gladly invest the millions of dollars to fund scientific studies because they stand to make 100′s of millions of dollars in profits from successfully patented drugs. Who is going to fund expensive scientific studies that result in reduced drug use and changes in diet? Such studies will come slowly. Meantime, I think this is a small investment, with much better odds than, say, continuing to seek advice from doctors who have been unable to help for years. It’s important to know this testing is unproven, but we all need to inform ourselves before choosing any course of treatment, and make our own informed choices.

While I’m sympathetic to some of the sentiments that this person has expressed (and I certainly appreciate the courteous and thoughtful manner in which it was done—it’s a rarity hereabouts), I do not share the commenter’s apparent optimism that the results of IgG tests are at all useful in determining intolerance to foods, for reasons that I think are quite clear by now.

Should we wait decades for medical proof before investing $200 in a simple test that might lead to a change in diet that might significantly reduce chronic depression?

The $200 is a reference to the fact that another commenter mentioned that he or she wasted that much money on an IgG test that proved worthless. For many people, $200 is rather a lot to pay, but potentially worse is the fact that any given IgG test is sure to prompt the customer to eliminate certain foods from their diet, probably unnecessarily, which is a major inconvenience at the very least.

And a change in diet might significantly reduce chronic depression? Well, whether it’s worth the $200 depends on how likely it is that you’d see an improvement. And for that, we want to see clinical data. If you disagree, I have a rock for sale that may interest you: it might prevent tiger attacks.

Pharmaceutical companies will gladly invest the millions of dollars to fund scientific studies because they stand to make 100’s of millions of dollars in profits from successfully patented drugs. Who is going to fund expensive scientific studies that result in reduced drug use and changes in diet? Such studies will come slowly.

They’re certainly not going to bother funding such studies when they realise that they can just sell the service to people whether it works or not. That’s why so many companies that sell nutritional supplements are owned by major pharmaceutical corporations: because of the way the these products are regulated (hint: very, very poorly), they don’t have to invest the research dollars before they turn a profit. (Alacer Corporation, the manufacturer of “Emergen-C”, is owned by Pfizer for example.) Which brings up another point: While patented drugs are great for the bottom line, you can still turn a tidy profit on something that is not patentable (or whose patent has expired). Vitamins and supplements aside, Aspirin still makes quite a lot of money for Bayer, despite the fact that Bayer’s patent on acetylsalicylic acid expired 96 years ago.

I find it troubling that while this commenter is quick to point out the profit motive of major pharmaceutical companies, he or she seems to ignore the fact that the companies who provide these testing services are making boatloads of cash from selling these tests, all without bothering to do all of that pesky science to make sure they actually work.

Because the relationship between chronic health conditions and IgG response and use of IgG test results may not be proven, there is a significant amount of anecdotal evidence of dramatic improvements in health through use of elimination diets and similar.

I’m curious as to why this person is so quick to dismiss the many professional associations in relevant medical and nutritional fields (those qualified to assess the state of the evidence) that have determined that IgG tests are worthless. More details are provided by Scott Gavura over at Science Based Medicine.

As for there being “significant anecdotal evidence” for the efficacy of IgG tests, I’ll simply point out that there also seems to be “significant anecdotal evidence” against the efficacy of IgG tests. (Not to mention actual, non-anecdotal evidence to that effect.) While anecdotes are certainly useful in pointing research in new and potentially fruitful directions, they are not in and of themselves especially useful in determining efficacy.

When you get right down to it, this is an argument about health freedom and informed consent, but everyone isn’t going to be well-informed on every topic all the time. For this reason, I’m of the opinion that health products should be subjected to robust regulation, with emphasis placed on both safety and efficacy (and without dubious exemptions for products marketed as “natural”). There will always be Kevin Trudeaus* and Leonard Coldwells trying to sell nonsense disguised as medicine, and we should be trying to make it as difficult as possible for them to do it.

It’s important to know this testing is unproven, but we all need to inform ourselves before choosing any course of treatment, and make our own informed choices.

I could not agree more.


* Or would the proper plural of “Kevin Trudeau” be “Kevin Trudeaux”? Perhaps “Kevins Trudeau”?

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IgG and “Food Sensitivities”

Cross-posted from Startled Disbelief.

A physician of my acquaintance recently brought this article to my attention. Written by Elaine Chin, a Toronto GP “with a holistic approach to health and wellness management”, it responds to a Globe and Mail article entitled “Tests for food allergies, sensitivities a ‘waste of money,’ doctor says”.

The Globe and Mail article is a good one, and I recommend that you read it, but I’ll summarize it for you here: Naturopaths and other “alternative” medical practitioners are sending their patients to be tested for immunoglobulin G, and suggesting extremely restricted diets based on the results of these tests. But according to allergist Dr. Elana Lavine, these practitioners haven’t established that IgG is indicative of food allergy or sensitivity of any sort: a positive test may be indicative of nothing more than repeated exposure to the food in question, which may mean that your favourite foods are more likely to find themselves on your stomach’s No Fly list.

My wife, who is a dietitian, has been seeing increasing numbers of patients come in with IgG panels, often showing “sensitivities” to just about every dietary staple. She also noted that at least one of the labs that sells IgG testing to the public describes immunoglobulin G as a “cell”, which is a disturbingly elementary error: immunoglobulins are proteins. For more background on IgG testing, I recommend this article by Scott Gavura of Science-Based Pharmacy.

But back to Dr. Chin, who was evidently unimpressed with the Globe and Mail article. On her blog, she writes:

Many of my professional colleagues have a contrasting position. Dr. Shelley Burns (a naturopathic doctor) and I use food testing to detect allergies, intolerances, sensitivities in our practice. We believe that such testing should be done under the supervision of professionals who understand the appropriate use of and know how to interpret the report. As well, the results are critically dependent on the source of lab testing. Only 3 labs in North America have been shown to have reliable and reproducible results – one of them is Rocky Mountain Analytical and their lab partner, US Biotek.

Dr. Chin works with a naturopath. I see.

I have along with Dr. Burns completed more than 100 Food IgG, IgE, and IgA tests in our practices for at least 5 years. I’m not at all certain that Dr. Lavine has worked with these tests and yet she is weighing in.

That’s right: Dr. Lavine, an allergy specialist, may have the necessary medical expertise, but does she have the appropriate personal experience? I think not!

I would also like to note that IgG, IgE, and IgA tests are not at all the same thing, and lumping them all together like that (especially when the article Dr. Chin is discussing was critical of only IgG testing) is indicative of sloppiness unbecoming a physician. Immunoglobulin E is closely associated with type I hypersensitivity (allergy), while immunoglobulin A has been linked to celiac disease.

By contrast, here’s what the American Academy of Allergy, Asthma and Immunology has to say about IgG testing: “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.”

The Australasian Society of Clinical Immunology and Allergy adds:

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. [Emphasis added.]

Back to Chin:

I would be willing at any time to challenge my colleague Dr. Lavine as to our experience with a series of case studies where the testing results have in fact made a difference and reduced the chronic symptoms of migraines, irritable bowel syndrome and asthma.

Case studies to demonstrate efficacy? Really? You wouldn’t want to, I don’t know, use any sort of controls or blinding or anything?

The first two cases to be reviewed will begin with my son and me.

You have got to be kidding. Remind me again: When conducting medical research, are we trying to maximize researcher bias, or eliminate it? Because I’ve lost all confidence that Dr. Chin even knows what bias is.

And then, there are dozens of my clients and their children whose lives have improved as a result of their testing and subsequent appropriate dietary changes.

Post hoc ergo propter hoc. It’s a good thing that there are no well-documented medical effects that may cause inert interventions to be confused for effective ones.

In fact, what is a waste of money are tons and tons of imaging tests which do not diagnose the cause of irritable bowel, the chronic use of steroids medications for unknown triggers for asthma (creating issues such as bone thinning), and loss of work productivity hours due to migraines.

And here is my warning to my physician colleagues. Before you comment in our medical journal, take the time to use the test before providing a professional opinion. Do your homework and due diligence as a scientist. I have done so.

Sure. Because “due diligence” means trying the test for yourself, rather than reviewing the medical literature and the best available scientific evidence. I’m honestly surprised that Dr. Chin didn’t make the “you’re just closed minded” gambit.

This article is almost a parody of itself.

There are legitimate allergies (and other hypersensitivities) that may require extremely restricted diets, and for those experiencing chronic symptoms of unknown origin it can be very heartening to think that they may have found the cause. But don’t waste hundreds of dollars on these tests and turn your diet on its head until IgG proponents have demonstrated that the results of these tests are medically useful.


Addendum: The fine folks at Bad Science Watch have pointed out a few other links of note.

First, the British Dietetic Association does not recommend IgG tests for food intolerance, based on the dearth of evidence:

This blood test looks at IgG antibodies present in the blood. It’s claimed that an increase in IgG to a certain food indicates an intolerance to that food. At present there is no convincing evidence to support this test, and it’s not recommended as a diagnostic tool.

Second, you can find an in-depth discussion of food intolerance (and IgG in specific) in the January 2008 issue of Today’s Dietitian.