I’ll let you in on a secret. Until recently, I had almost exclusively stopped using food sensitivity testing in clinical practice. I will explain the reasons for this in this article, but more importantly, I will explain why I now see the value of food sensitivity testing in 2024.
It all starts with cognitive bias.
We’re all guilty of it.
My political party is better than yours. My god more supreme than yours. Your diet is unhealthier than mine. Notorious B.I.G. is a better rapper than Jay-Z are just a few examples.
Ironically, even thinking that everyone is guilty of cognitive bias is a form of cognitive bias.
There can be many reasons why subjective experiences, such as emotions or individual motivations, can get in the way of objective reality or, in simpler terms, the facts.
Most of the time, this is harmless.
However, when it comes to helping people get better, one of the most dangerous things a practitioner like me can get stuck with is cognitive bias.
In natural medicine it’s hard enough to separate the wheat from the chaff as it is without getting in your own way simultaneously.
It’s not just the emerging field of natural medicine though. A study released in 2018 suggested that cognitive bias is increasingly recognised as a source of medical error.[1]
Exposing bias in my practice is one of the reasons I started writing regularly using as many evidence-based references as possible. I want the people in the Good Mood Flat Tummy community to get the best information possible.
If you want to see an example, I wrote an article in 2021 about what to do after taking antibiotics. It appears probiotics might not be as good as fibre intake for antibiotic recovery (they still help for other things when it comes to antibiotics, so don’t lose it).[2]
Writing that article reminded me of the “I was today years old” memes flying around – an important lesson in getting set in your ways.
If you are new to food sensitivity testing, here is a quick introduction.
Foods can cause different types of minor immune responses. For example, small immune reactions involving IgA, IgE and IgG reactions are common and, more importantly, normal.[3]
In some cases, certain foods can bring about a more pronounced immune response and, consequently, higher levels of these immune cells. These high levels of immunoglobulins can then cause higher levels of inflammation to occur.
These increased levels of immunoglobulins can then cause excitatory effects in systemic immunity via stimulating different parts of the immune system or increases in inflammatory chemicals in a more direct fashion.
For example, whilst small levels of IgG can be normal, higher levels can be pro-inflammatory, which could be a sustaining factor in illnesses with inflammation at their core, such as autoimmune conditions.[4]
The aim of the testing then, broadly, is to test the level of your immune system’s response to these foods, commonly via looking at the IgE and IgG reactions to them.
For many practitioners, these tests can indicate the need to rotate foods in patient’s diet on the basis of their ‘reactivity,’ with a view to influencing the immune system. However, for me, I didn’t seem to see the benefits clinically and earlier last year, whilst studying under Dr Kharrazian, I found another of my long-held cognitive biases challenged – ‘food sensitivity tests are a waste of time and money’.
Let me explain.
In the early days of my practice, I often used IgG food sensitivity testing. In the early days of functional medicine testing (yes, I was there before it was a thing), it was a pillar of our practice and it generally helped people.
Over the years, though, I found two things that, in hindsight, created my cognitive bias about food testing.
The first was the presence of cognitive dissonance in my patients.
Even if patients saw their immune systems showing up as sensitive to particular dietary proteins such as gluten or dairy protein, they weren’t committed to removing it from their diets in a way that would benefit them.
Even if it meant not potentially getting better or at least trying in some situations.
To offset this risk, I always ask people interested in food testing (and still do!) if they were willing to remove the foods from their diet if the results indicated it would be best for them to do so.
Most people said they’d find it difficult and would most likely not be willing to remove foods like gluten one hundred per cent, regardless of the test results. Hence, the waste of time and money I’m referring to.
Secondly, and perhaps more importantly, we got differing results when we tested the same person with different laboratories!
Random results, false negatives and positives all contributed to me trusting the results of the testing less and less.
Over the years, I have had so many of these situations occur that I stopped suggesting food testing as an option.
Fast-forward to my training with Dr. Kharazian, and I learnt something about food testing that explains some of the poor results.
I’m not going to lie I felt somewhat embarrassed about not having encountered this study earlier. The original review was released in 2009.
I’ll summarise the results for you.
Most food sensitivity panels only test for the raw versions of food. Read that again.
Most food sensitivity panels only test for the raw versions of food.
Now, if you were Rocky eating raw eggs, I’d get it. But it seems, at least from this review from Dr Aristo Vojdani, that most foods essentially become more allergenic if they are modified or processed in some way.
This can be as simple as cooking food or using foods as ingredients in cooking, for example, cakes and sauces.
If you don’t believe me, look at some of the data:
This particular study measured the levels of IgE reactions (think the same type of reaction as an allergic response to dust or pollen – not life-threatening in most cases but apparent nonetheless) and their levels of allergenicity compared with their level of processing or cooking.
Some key things to notice here are the differences between cooked and raw eggs and salmon and the huge changes in allergenicity when cooking shrimp (we call them prawns where I come from).
These differentials are across all immune responses, including the commonly checked IgG responses (section A in the chart). Notice in section A the huge change in IgG allergenicity when ingredients that aren’t independently allergenic are combined in a potato salad, for example the chart below:
This can, for someone, either patient or practitioner, have real world consequences. Imagine coming up with no reaction to eggs only to find that you are reactive to the cooked version.
Fortunately, there is a test I use in my clinic that covers the modification and processing of foods and their compounds but there are some drawbacks.
First of all, having such clean and diverse panels is expensive and compared to some other food testing in Hong Kong, this test can be almost double the price!
Along with this, the same problems with actually removing the foods or at least rotating the appropriate ones are still present.
My frustrations with food testing are reflected from my patients too, however, there might be answers.
“I got this food test from another ‘fill in the blank’ provider and it shows all these sensitivities to foods I don’t even eat!”
Whilst we have already touched on the fact that some immune response to occur to foods, having multiple random foods pop up on the results can also point to the relationship between your gut and your immune system, specifically something called ‘oral tolerance.’
The concept of oral tolerance deserves an article on its own so rest assured it’s coming. In the case of a food test result that has multiple random foods coming up this might actually show an over reactive component of the immune system instead of a food sensitivity.
To put it simply the immune system loses its ability to differentiate what it should attack and what it shouldn’t and essentially begins to slowly attack everything. [5]
On this basis, your crazy, pointless and random result may in fact offer an important signal towards the state of your gut-based immunity as opposed to a food that needs to be rotated or removed.
The best part about this result is that it can essentially be acted on via dietary and supplementary pathways to improve the immune system’s tolerance with a view to it attacking only the things it should be.
shortcode: [ninja_form id=6]Another example of the immune system getting its targeting wrong is autoimmunity.
And this is another example where the right food test is important. If you are new to lectins, they are a group of naturally occurring proteins in food. On their own they are perfectly normal and can be found across the natural world and not just in our food.[6]
However, for those with an autoimmune condition such as Hashimoto’s disease or Rheumatoid Arthritis, there is emerging evidence suggesting that these naturally occurring proteins can activate the immune system through a process called molecular mimicry or cross reactivity.[7]
This occurs when the lectin protein is not digested effectively and binds to different human tissue such as the gut lining or islet cells in the pancreas, for example. The immune system then creates antibodies to this and attacks like it would any other antigen.
Now there are some practitioners, one in particular who have made their name from recommending everyone remove lectins from their diet, however there are really only a few known to be potentially involved in a situation where the immune system starts to attack itself.
These lectins wheat germ agglutinin (WGA), red kidney bean phytohemagglutinin (PHA), jack bean agglutinin (ConA), peanut agglutinin (PNA), and soybean agglutinin (SBA).[8]
One advantage of the new range of testing is the ability to test for immune reactivity to these specific lectin groups so that both practitioner and patient can isolate specific foods to remove as opposed to the broader lectin removal recommended.
So where is the value in IgG and IgE food sensitivity testing in 2024?
The answer is simple, there are tests for people who are curious and there are tests for people whose diet might actually be making them sick.
Even in these few points in this article, the possibility of false negatives and false positives without the correct interpretation can seem all too easy. However, with the correct testing, which looks at the right things, for example, cooked foods along with their raw versions, we can better use food testing to help where needed, especially in those with autoimmune, mental, and digestive conditions.
Hope this helps x
shortcode: [ninja_form id=4]References
[1] O’Sullivan ED, Schofield SJ. Cognitive bias in clinical medicine. J R Coll Physicians Edinb. 2018;48(3):225-232. doi:10.4997/JRCPE.2018.306
[2] Penumutchu S, Korry BJ, Hewlett K, Belenky P. Fiber supplementation protects from antibiotic-induced gut microbiome dysbiosis by modulating gut redox potential. Nat Commun. 2023;14(1):5161. Published 2023 Aug 24. doi:10.1038/s41467-023-40553-x
[3] Husby S. Normal immune responses to ingested foods. J Pediatr Gastroenterol Nutr. 2000;30 Suppl:S13-S19. doi:10.1097/00005176-200001001-00003
[4] Aschermann S, Lux A, Baerenwaldt A, Biburger M, Nimmerjahn F. The other side of immunoglobulin G: suppressor of inflammation. Clin Exp Immunol. 2010;160(2):161-167. doi:10.1111/j.1365-2249.2009.04081.x
[5] Rezende RM, Weiner HL. Oral tolerance: an updated review. Immunol Lett. 2022;245:29-37. doi:10.1016/j.imlet.2022.03.007
[6] Sharon N. Lectins: past, present and future. Biochem Soc Trans. 2008;36(Pt 6):1457-1460. doi:10.1042/BST0361457
[7] Vojdani A, Afar D, Vojdani E. Reaction of Lectin-Specific Antibody with Human Tissue: Possible Contributions to Autoimmunity. J Immunol Res. 2020;2020:1438957. Published 2020 Feb 11. doi:10.1155/2020/1438957
[8] Vojdani A, Afar D, Vojdani E. Reaction of Lectin-Specific Antibody with Human Tissue: Possible Contributions to Autoimmunity. J Immunol Res. 2020;2020:1438957. Published 2020 Feb 11. doi:10.1155/2020/1438957