Food has a social component that is essential for every culture and society on our planet. However, food can be both enemies and friends, food intolerance can have a negative impact on our quality of life and can even be fatal in food allergies. When we ask Google, from headache to acne, almost every single disease can be attributed to one food or diet, and usually the cure is also attributed to another food or diet.
The "free of" industry is booming when I first moved to the city I currently live in, if I wanted gluten-free products I should have gone to a pharmacy and with a little luck they would be in the corner and would be together Collect dust These strange herbal candies that your grandmother loved.
Two years later, whole parts of the supermarkets are now devoted to gluten and lactose free products. This is obviously a great thing, especially for people with real diagnosed conditions like celiac disease. Increasing awareness of food-related issues has led many of us to wonder whether headaches / lack of energy / lack of sleep are caused by food intolerance.
There are many people who tell you that the answer is yes and that their advice is usually expensive. This article explains why the IgG antibody food intolerance test is a waste of time and money.
I want to make it very clear that this article is not about whether or not you should test for a suspected food allergy, although I will go into food allergies.
If you suspect that you have a food allergy, contact your doctor. By that I mean a real doctor working in a clinic or hospital, and not a charlatan on the Internet with MD by his name. What I'm going to discuss in this article are the blood tests for food intolerance that are advertised on the internet and in some pharmacies.
What is the test?
The test is fairly simple: you order a test kit online from one of the laboratories that offer the test. As soon as it arrives, take a blood sample and then send it back to the laboratory.
The laboratory tests your blood for IgG antibodies that are specific to a variety of foods, usually in the range of 200 different foods. What I mean by specific is that, for example, if you test your blood against a sample of chicken protein, some of the IgG antibodies bind to that protein, they are "specific" to that protein or food.
Once the laboratory has tested all foods, you will receive a report with the results. Different laboratories may do it differently, but the ones I've seen use a traffic light system.
Red for foods with high levels of IgG binding that should be avoided. Yellow for foods that are "borderline" and should only be eaten in moderation. Finally green for foods that contain little or no IgG, which means you can eat them to your heart's content.
So what's the problem?
It all sounds so easy, take the test and then avoid the red foods. However, there are two rather big problems with this method of food intolerance testing. The first relates to the test procedure and the second to the actual function of the IgG antibody.
Real food intolerances
We'll start with the method and assume that the IgG antibody is involved in food intolerance (which is discussed in the next section).
When I got my allergy certificate at university, we were repeatedly told that the most important part of an allergy diagnosis was the patient's medical history.
Without a detailed medical history, the results of the blood test are not helpful at best. The mere presence of antibodies is not enough to make a diagnosis. There must be a history of symptoms to ensure that you are actually allergic (or intolerant in this case) to a particular food.
Blood test results without a medical history will no longer be helpful. As I said, diagnosis and diagnosis require both symptoms and the presence of antibodies. Only the presence of antibodies (without symptoms) against a certain food protein is called sensitization. 1
When it comes to food allergies, when a person is sensitized to a food but has no allergic symptoms, the last thing they should do is stop eating that particular food.
If they stop eating the food they are sensitized to, it could detract from the immune system's tolerance to allergies, and the next time they come across this food, they may have a reaction. 2
For this reason, it is crucial in immunotherapy that the patient continues to eat the foods he has been allergic to, even if, as so often, he does not like them.
If you come back to a food intolerance and only get a report on hundreds of foods, some of which you have now been told that you cannot eat, it is likely that you will be on an unnecessarily restrictive diet, leading to an increased risk of nutrient deficiency and worse, less leads to gains in the gym.
The IgG antibody
Before we look at antibodies in detail, I think it is important to clarify what allergy and intolerance are, as these words are often used interchangeably and cause confusion.
Both allergies and intolerances are referred to as hypersensitivity, which means that they are reactions to something that a “normal” person would not respond to. An allergy is a hypersensitive reaction that is triggered by the immune system, while an intolerance does not affect the immune system. 3
A good comparison would be lactose intolerance and a real milk allergy. A person with lactose intolerance produces no or insufficient amounts of the enzyme lactase, which helps us to digest sugar lactose. So if she consumes milk, she cannot break down lactose, which causes digestive problems. These problems are not caused by the immune system.
However, you can consume lactose-free milk. In the case of a person allergic to milk, their immune system has raised antibodies to milk proteins. When you consume milk, your immune system attacks it and the person has classic allergy symptoms, itchy rash, swelling and difficulty breathing.
A person allergic to milk could not consume lactose-free milk because it still contains milk proteins. However, you could consume a hydrolyzed or amino acid formula with lactose.
These are made by the B cells of our adaptive immune system. Our immune system consists of two parts, the innate and the adaptive. The innate is fairly simple in that it attacks everything that is not "we".
On the positive side, it is very quick to react. The adaptive immune system reacts a little slower, but has a “memory”, so to speak. The next time it encounters something bad, it will usually be treated before we even notice that we are sick.
One of the main weapons in the arsenal of the adaptive immune system is the antibody (or immunoglobulin). The B cells form different types of antibodies, each with a different role in the immune system. The best known antibody is probably IgE. IgE's original role was to treat parasitic infections, but it is more commonly known as the antibody behind allergic reactions. 4
When the B cell produces an antibody, it is “specific” to a particular protein (a food protein in the case of a food allergy). The next time the antibody encounters this protein, they bind to it and control an immune response.
In the case of IgE, they sit on certain immune cells (mast cells), and when they encounter the specific protein or antigen, they bind to them and cause these cells to release histamine. It is this histamine that causes your typical allergic reactions and why people with allergies usually carry antihistamines with them.
With IgG antibodies there are actually four subclasses of IgG antibodies, IgG1, IgG2 etc., each with slightly different functions. All IgG subclasses are very good at enhancing a process called phagocytosis, in which certain cells of the immune system (macrophages) devour and destroy bacteria.
For example, IgG1 is very good in a process known as ADCC (antibody-dependent cell-mediated cytotoxicity). Here the IgG1 binds to a target cell and immune cells recognize this binding as a signal that this particular cell must be destroyed. 4th
IgG Food Interolence Science
Proponents of the IgG food intolerance test point to the ability of the antibody to activate multiple cells of the immune system as "evidence" that the antibody cannot and does not mediate allergic reactions to food.
However, when we examine the role of IgG4, we see that it is not. In 2012, Norwegian researchers investigated the connection between IgG, IgG4 and IBS (irritable bowel syndrome). IBS is a food-borne disorder with many symptoms of food intolerance, bloating, and changes in bowel habits. An attempt was therefore made to link the disease with IgG antibodies. 5
In the Norwegian study, they compared food-specific IgG and IgG4 antibodies from IBS subjects with healthy, symptom-free subjects. Not only did the researchers find that the IBS group's IgG and IgG4 antibodies did not match their trigger foods (foods that they know made their symptoms worse), but there were no differences in IgG either and IgG4 levels between the IBS and control groups.
What the researchers found was that the higher levels of the antibodies matched foods that both groups ate regularly, in the case of the IBS group, their "safe foods" and in the control group, only foods they ate frequently.
The researchers concluded that IgG and IgG4 antibodies are unlikely to play a role in IBS, and that the presence of these antibodies only reflects diet.6
In other words, the more of something you eat, the more IgG is specific to the food you have. In recent years it has been shown that IgG and especially IgG4 is not only a reflection of a diet, but also a tolerance marker and protects against allergic reactions.
For non-allergic people, we produce IgG4 antibodies (in contrast to IgE) against proteins in order to label them as "safe" and to prevent the possibility of an allergic reaction. This was called the IgG4 / IgE ratio. It has been shown that non-allergic beekeepers have a 1000 times higher IgG4 / IgE ratio than people who are allergic to bee venom. 7
During immunotherapy, allergic people do not gain tolerance by reducing their IgE number, but by increasing their IgG1 and especially IgG4 number. The IgG4 antibodies compete with the IgE antibodies and prevent them from attaching to the mast cells, thus preventing them from causing reactions. 8
Continue with caution
When it comes to food proteins, the IgG antibody, and especially the IgG4 subclass, appears to have anti-inflammatory effects that prevent allergic (and intolerant) reactions in both allergic and non-allergic people.
To paraphrase EAACI (European Academy of Allergy): Testing IgG for food intolerance is "irrelevant" and should not be done. 9
The companies that continue to promote the IgG blood tests either do not fully understand the function of the IgG antibody or sell their product anyway. I really hope it's not the latter.
References
1. Van Ree. R et al. 2014. Allergic sensitization: host immune factors. Clinical and translational allergy. 4:12.
2. James. LK et al. 2011. Long-term tolerance after allergen immunotherapy is associated with selective persistence of blocking antibodies. Journal of Allergy and Clinical Immunology. 127: 509-; 516.
3. Johansson. SGO et al. 2004. Revised Allergy Nomenclature for Global Use: Report of the World Allergy Organization's Nomenclature Review Committee, October 2003. Journal of Allergy and Clinical Immunology. 133 (5): 832-8. 836.
4. Owen. J et al. 2013. Kuby Immunology, 7th edition. Macmillan.
5. Philpott. H et al. 2013. Alternative studies on irritable bowel syndrome. Journal of gastroenterology. 28: 73-77.
6. Ligaarden. S et al. 2012. IgG and IgG4 antibodies in patients with IBS: A case-control study in the general population. BMC gastroenterology. 12: 166.
7. Carballido. JM et al. 1993. T cell epitope specificity in human allergic and non-allergic subjects against bee venom phospholipase A2. Journal of Immunology. 150: 3582-; 3591
8. Bischoff SC & Sellge G. 2014. Food allergy: side effects on food and food additives, 5th edition. Chapter 2: The immunological basis of IgE-mediated reactions. John Wiley & Sons, Ltd.
9th stack. SO et al. 2008. Testing for IgG4 against food is not recommended as a diagnostic tool: EAACI Task Force Report. Allergy. 63: 793-; 796.