Updated: Dec 22, 2022
-From the desk of Dr.Brkich
Our clinic gets ongoing calls asking if we do food allergy testing. There is confusion about food allergies, food sensitivities, and food intolerances. Allergies, sensitivities, and intolerances are terms that are often used interchangeably. However, they are not the same. Food allergies are different from food sensitivities and food intolerances. The medical definition of allergy is very specific and precise.
Our immune system protects us from various things such as bacteria, viruses, fungi, parasites, and toxins by producing different kinds of antibodies. Antibodies are also called immunoglobulins. Antibodies and immunoglobulins are terms that can be used interchangeably. All antibodies are immunoglobulins, but not all immunoglobulins are antibodies. For our purposes, that distinction doesn’t matter. Antibodies and immunoglobulins are essentially the same. Not so, however, with allergies, sensitivities, and intolerances. If you experience repeated adverse reactions to something that you eat, you may not be able to tell if it is an allergy or a sensitivity or an intolerance, but they are quite different.
Our immune system makes different types of immunoglobulins. Remember that immunoglobulins and antibodies are the same. The immunoglobulins made by the immune system are Immunoglobulin A (or IgA), Immunoglobulin D (or IgD), Immunoglobulin E (or IgE), Immunoglobulin G (or IgG), and Immunoglobulin M (or IgM).
According to the true definition of allergy, only immunoglobulins of the IgE class can be called allergies. Immune reactions caused by immunoglobulins IgA, or IgD, or IgG, or IgM are not allergies, even though they are triggered by the immune system. Only IgE reactions are classified as allergic reactions.
Immune reactions caused by IgA, IgD, IgG, and IgM immunoglobulins can be called sensitivities, but not allergies. Allergies and sensitivities are both immune system reactions. Allergies are triggered only by Immunoglobulin IgE. Sensitivities can be triggered by any of the other Immunoglobulins, IgA, IgD, IgG, or IgM. The most important and most common immunoglobulin that triggers food sensitivities is IgG. Food sensitivity tests are mostly IgG tests, although specialty laboratories include IgA and IgM in addition to IgG. Allergy tests, on the other hand are always IgE tests.
What if you have a reaction that is not triggered by the immune system at all? It may be a troublesome and life-changing reaction for you, even though the immune system may not be involved. Reactions that are not triggered by any immunoglobulins, neither IgE, IgG, IgA, IgD, or IgM, are not immune reactions. These types of reactions that are not triggered by the immune system are referred to as intolerances. Lactose intolerance, for example, is neither an allergy nor a sensitivity because the immune system is not involved. Lactose intolerance is a digestion issue, not an immune system reaction. Only immune system reactions can be called allergies or sensitivities. If the immune system makes IgE antibodies, it is an allergic reaction. If the immune system makes IgG, or IA, or IgM antibodies it is a food sensitivity reaction. This is an important distinction for understanding testing.
Allergy testing by a medical doctor is usually done via an IgE skin test. If you have no skin reaction to anything that is tested, you will be told that you have no allergies, at least not to the things tested. Even though you may not have any allergies, you may still have sensitivities or intolerances. Having no allergies on a skin test or blood test doesn’t necessarily mean a clean bill of health.
Food allergies, food sensitivities and food intolerances.
Let’s say that you have a life-threatening anaphylactic reaction every time you eat peanuts. That would be an allergic reaction to peanuts. That type of an immune reaction is always triggered by IgE. But, what if, instead of an anaphylactic, life-threatening reaction to peanuts, you get digestive symptoms every time you eat peanuts, such as gas, bloating, cramping, constipation, diarrhea, skin rash, or some other unique symptoms? Even though your skin test may be negative for IgE, you may still have food sensitivities or intolerances, even though you have no allergies.
What are some other differences between a food allergy and a food sensitivity? An allergic reaction, mediated by IgE, can be sudden and severe, and can, in severe cases, cause an anaphylactic reaction which has the potential to kill you if your airway becomes restricted from sudden severe edema of the throat during the course of the IgE reaction. Food sensitivities or intolerances mediated by IgG, IgA, or IgM, (but not IgE), do not cause serious breathing difficulties or anaphylactic reactions but can still cause considerable distress even though they may not be life threatening. If you have an allergy to peanuts you will need to carry an Epi-Pen or have epinephrine close at hand in case you get exposed to peanuts. If you have a food sensitivity to peanuts you may not need to carry an Epi-Pen, unless you also have an IgE allergy to peanuts.
For testing purposes, IgG antibody tests are the main tests that are used to test for food sensitivities. IgG is the most common antibody, making up 75% to 80% of all antibodies in the body. A reaction to food is more likely to be an IgG reaction than an IgE reaction, although both are possible. IgG food sensitivity tests are more commonly done than IgE food allergy tests. An IgG food sensitivity blood test can be combined with IgA or IgM by some specialty labs for greater specificity and precision. As a general rule, a food sensitivity test may discover offending foods that you may not be aware of because the reactions may occur long after you have eaten the food. An IgE food allergy blood test may often confirm things you already know because IgE reactions are usually immediate and strong, and therefore you may already be aware of them.
In summary, IgG food sensitivity reactions differ from IgE food allergies. IgE food allergies are immediate and strong reactions that occur within minutes or hours of consuming a food and may include serious reactions such as hives, angioedema, difficulty breathing, and anaphylaxis. IgG food sensitivity reactions, on the other hand, are delayed reactions that may occur hours to days after the food is consumed and the symptoms may not show up for days or even weeks, and in some cases months.
Testing for allergies, food sensitivities, and food intolerances.
IgE allergies are typically tested via the skin. IgE blood allergy tests for foods are available to general practitioners, subject to medical plan restrictions allowing only 5 foods to be tested per year, unless done by a specialist. A full panel of IgE food allergy tests can be done privately by LifeLabs through our clinic. It is my belief that most people already know what foods they are allergic to, because allergic reactions generally occur quickly and can be strong, and are easier to detect with an elimination diet. If a particular food causes immediate and unequivocal adverse symptoms every time you eat it, in my opinion, it may be better to eliminate that food from your diet rather than do a test, especially since you have to eat substantial amounts of that food on a regular basis in order to do the test in the first place. If you don’t eat a certain food for a long enough period of time, you may get a false negative on a test if your immune system may have stopped producing antibodies against that particular food allergen.
Because food sensitivities can be harder to detect than food allergies with an elimination, this is where IgG and IgA food sensitivity testing can be useful.
I believe that food allergies, food sensitivities, and food intolerances are always caused by something that has gone wrong in the body outside of the immune system. At birth, we should have no allergies or sensitivities to any foods. A baby’s immune system learns to develop tolerance to all foods. Loss of oral tolerance to foods occurs when the immune system becomes overwhelmed and dysfunctional due to imbalance elsewhere in the body, leading to a breakdown in the body’s defenses. If we correct the underlying factors that have allowed the immune dysfunction in the first place, the immune response to foods should diminish over time.
The same reasoning applies to food intolerances. If one corrects the underlying digestive dysfunctions, the intolerances should eventually disappear. Eliminating those foods that are eliciting an inappropriate inflammatory response, however, can speed up the healing process, and that is where testing can be beneficial.
Tests for food allergies, food sensitivities, and autoimmune reactions that are available through our clinic:
Blood test for total quantitative immunoglobulins (IgA, IgG, IgE, IgM). The higher your numbers, the higher the number of allergies and sensitivities you have. This test measures the total immunoglobulins in your blood, but doesn’t tell you what you are allergic or sensitive to.
Skin prick test for IgE allergies. This type of test is usually done by an allergy specialist.
Autoimmune blood test for antibodies against the intestinal tight junction barrier. This test confirms “leaky gut”.
Blood test panel for gluten, including all the fractions and metabolites of gluten, not just tissue transglutaminase IgA which is the only test that is done for gluten by family doctors. This test is considerably more comprehensive than a common celiac test.
Blood food sensitivity panel for dairy and other foods that commonly cross-react with gluten.
A blood test panel of an additional 180 foods. You must be eating the foods on a regular basis prior to the test to avoid false negatives.
In addition to food allergies and food sensitivities, we have tests available for autoimmune reactions against various body tissues and organs such as joints, nerves, thyroid gland, pancreas, stomach parietal cells, brain etc.
We can also test for immune system reactions against various bacteria, viruses, fungi, as well as endogenous and exogenous toxins.
If you are interested in finding out what you are allergic or sensitive to, intolerant of, or what tissues or organs your immune system may be attacking and destroying, we can find the most appropriate test for you and provide you with the cost.
Please call our office at 250-561-1700 to set up a time that works for you to discover more about how we can help you or a family member get well.