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Food allergies vs. food sensitivity
There appears to be an upward trend in food allergy and intolerance testing, across the globe, with many naturopaths now even coining the term “food sensitivity” to drive sales of IgG food sensitivity tests within their clinic. These tests claim to identify food intolerances/sensitivities that may be resulting in fatigue, skin issues, weight gain, headaches, congestion, bloating, arthritis, various mental issues, pretty much all non-specific health issues.
Interestingly, the actual data on medically diagnosed food allergies has remained constant, at around 2 - 3%, while the prevalence of adults who ‘believe’ they have a food allergy is up to 25% and rising thanks to these at-home self-testing kits.
A food sensitivity is essentially the same as a food intolerance, they occur when an individual has difficulty digesting a particular food. Food sensitivities can lead to symptoms such as gas, bloating, abdominal pain or diarrhea, and are often dose dependent in that you could eat a small amount with no issue, but increasing doses cause more symptoms.
A food allergy on the other hand, is a medically diagnosed condition that involves the immune system, where a food intolerance/sensitivity does not involve the immune system. A food allergy is a serious condition, even minuscule amounts of a particular food is enough to trigger an immune response resulting in serious symptoms which may even be life threatening, such as anaphylaxis.
At this point we highly recommend avoiding self-diagnosis as this can lead to more problems further along the line, as we will go on to discuss. Rather go and discuss the issues with a medical professional who can refer you to a gastrointestinal specialist.
There are many types of at-home tests that claim to identify food sensitivities, but the research paints a fairly ugly picture when it comes to their reliability and validity. Let us evaluate this research and then hopefully help you re-evaluate your stance when it comes to these tests.
What is a food sensitivity test?
A food sensitivity test is a fingertip blood test that measures an antibody called immunoglobulin-G, referred to as IgG. The IgG antibody is the most abundant antibody in the body, and makes up around 75% of the total antibodies in circulation at any given time. IgG antibodies also have an incredibly long half life, meaning they are present in the circulation for anywhere between 22 and 96 days. Research has clearly, unanimously shown that elevated IgG reflects exposure to a compound.
Alarm bells ringing yet?
Are these tests accurate?
A quote taken directly from a research paper published by the European Academy of Allergy and Clinical Immunology (EAACI): 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.
This paper is not alone in making this conclusion, there is more from the American Academy of Allergy Asthma and Immunology, and many more, including a statement and warning from the British Dietetic Association.
On the other hand, there is a huge lack of research to support the use of IgG as a means of diagnosing intolerance or sensitivity. The only available research fails to provide any real information on what exactly was measured and how the test was conducted, with some papers even relying on research on dogs.
It gets worse…
When researching what a food intolerance actually is and how it is caused it becomes evident that IgG is actually associated with food tolerance, rather than intolerance.
So elevated IgG that you are basing your self-diagnosis on simply tells us that you ate that particular food recently, up to 96 days ago even, and that you actually tolerate that food.
Example, I eat eggs on toast most days for breakfast, my IgG will thus be elevated for these foods, which I then have to eliminate. I am not intolerant to them, IgG just tells me that I have been exposed to them recently.
But, in my frantic state of despair and ill health this diagnosis confirms to me that what I have been doing all along is completely wrong. A confirmation-bias of sorts, further cementing the apparent validity in my mind.
When in actual fact it’s all wrong, all of it.
If you were to visit a medical professional they would test for immunoglobulin-E (IgE), which is another antibody that is released by the body when an actual allergen is detected.
The troubling thing with at-home IgG tests is that levels of IgE are more often than not very, very low when IgG is elevated.
These tests are testing the wrong thing and leading to false diagnosis.
But you’re wrong, I did a test and feel so much better!?
Most, if not all of the research that shows beneficial effects after measuring IgG and then eliminating those foods or food groups follow the same simple steps. The companies that provide these at-home food intolerance tests follow those exact same steps:
- Heavily market their product and prey on your vulnerability, insecurity and lack of knowledge.
- Collect baseline IgG data and then provide a list of foods that you cannot eat
- This elimination diet more often than not includes dairy, gluten containing foods, FODMAPs and maybe some nuts, all of which people with self-reported sensitivities respond well to.
- They follow the diet for a few weeks and experience improvements in symptoms.
This is a post hoc fallacy.
Yes, your symptoms may well have improved and that is fantastic.
But perhaps that is because you have now inadvertently improved your diet quality, by focusing on eating better food, with less reliance on processed foods and unconscious snacking.
Now consider the potential health issues you may run into further down the line if you were to maintain this reductionist approach and invalid elimination diet long-term.
Also consider the possible reasons why these symptoms may have improved. As an example, when you consume dairy products calcium soaps are formed naturally in your stomach, you could postulate that this could be confused for symptoms of bloating. These calcium soaps form naturally, in everyone and actually have beneficial effects.
Also do not overlook the power of placebo. Research has shown that the placebo effect, or simply believing that something is effective can produce dramatic results. In clinical studies a placebo has improved migraines, fatigue, depression, increased strength and muscle mass, and so much more.
Simply being told you are intolerant to a food by a respected body (eg. the company), developing a strong belief around that and then avoiding that food can produce remarkable subjective improvements, without any objective change.
More harm than good?
The reductionist approach and elimination diet may be more harmful than you think.
Research has shown that consuming a varied diet, with more than 30 different foods, primarily polyphenol-rich plant foods each week is associated with greater diversity in the microbiome and improved health.
The microbiome by the way, is the huge collection of trillions (if not more) of tiny bacteria that reside in your gut that impact a whole host of things, from digestion to immune function, energy, mood and mental health. Taking care of the microbiome is a very, very good idea.
If you significantly reduce the number and variety of foods you are eating, you could be damaging your microbiome, your health and increasing the likelihood of damaging nutrient deficiencies.
Eliminating dairy products will significantly reduce your calcium intake, heightening your risk of osteoporosis, which is already elevated as a result of hormonal changes during the menopause, as one example. There are many more.
Also consider the fact that eliminating a food or food group will likely down-regulate the body’s production of the various enzymes required to break down those foods, which in turn further worsens your ability to digest them. So eliminating and then reintroducing, perhaps mistakenly at a party, could have some truly horrific side effects.
Look at our evolutionary history, the lactase enzyme is responsible for breaking down the sugar lactose, found primarily in dairy products. The lactase enzyme gene has persisted in countries that continue to consume dairy products past childhood, mainly the Western world. Whereas in Asia the lactase enzyme gene has all but disappeared, so dairy intolerance is highly prevalent in the East, simply because they do not consume dairy products regularly, so the body has adapted and reduced its production of the enzyme required to digest it.
The body adapts to stimuli, quickly and effectively. So removal of foods (stimuli) also impacts the response (enzyme production).
Ok, so what do you suggest I do instead?
If you are experiencing symptoms of gastrointestinal discomfort, bloating, diarrhea or constipation after foods or meals then your first port of call should be your doctor and not Google.
Other options would be to consider the below:
- Believe, and I mean wholeheartedly believe that an inclusive diet is far healthier than an exclusive diet.
- Try following a low FODMAP diet which is scientifically proven to improve symptoms of irritable bowel syndrome.
- Improve gut health by supplementing with a probiotic and consuming probiotic rich foods such as kimchi, sauerkraut and kefir.
- Aim to consume 30 different plant foods each week.
- Consume a rainbow of colorful fruit and vegetables with each meal, to boost your intake of protective polyphenols.
- Consider the quantity of foods you consume and remember that large amounts of anything can result in digestive issues.
Concluding remarks
The at-home food intolerance tests are a scam, based on the current scientific data. They do not help you diagnose food intolerances, they simply tell you that you have recently consumed X food and tolerated it well.
Elimination diets “work” and likely reduce symptoms for a number of reasons, although likely not related to the actual avoidance of that food.
If you have digestive symptoms seek medical advice rather than a quick fix self diagnosis and also remember that the mind is an incredibly powerful tool but do not turn it into a weapon.
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The content in this app is provided as lifestyle recommendations for informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. For any medical concerns, always consult with a healthcare professional. The sources that informed our meal plans and recommendations are available at: reverse.health/research.