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Food Allergy vs. Sensitivity vs. Intolerance: What's The Difference

Woman having a reaction to drinking milk

There are many ways a body can demonstrate an aversion to specific foods, with allergies, sensitivities and intolerances being some of the most common. However, the differences between these ailments aren’t exactly common knowledge. 


“Exposure to food antigens can lead to different kinds of antibody elevations,” says Dr. Chris Meletis, N.D. – US BioTek’s clinical advisor. “While most people know if they have an allergy, food sensitivities can be a little sneakier.” 


What’s the difference between an allergy and a sensitivity? 


IgG and IgE refer to two different types of antibodies, also known as immunoglobulins. These antibodies are part of the immune system and are produced in response to things individuals encounter on a regular basis. While this includes bacteria and viruses, it can also encompass other substances such as foods, dust, dander, pollen and more. 


In general, “true” food allergies are IgE-driven, instigating a relatively immediate response from the immune system. This can result in reactions such as hives, swelling and anaphylaxis. Peanuts, shellfish, soy and dairy products are just a few common foods that are known to trigger IgE reactions.


While food allergies trigger a relatively immediate response from your immune system, food sensitivities can stimulate a variety of reactions in the body, many of which occur hours (or even days) after exposures. Because these IgG-stimulated reactions are usually associated with the gut’s inability to break down certain foods, bloating, stomach pain and other forms of indigestion are all common symptoms. However, eczema, fatigue and joint pain are all relatively common IgG responses as well.  

Since the gut microbiome is constantly changing, food sensitivities sometimes change over time while food allergies generally remain static. Food sensitivities are also commonly associated with other GI-related conditions such as leaky gut, irritable bowel syndrome (IBS) and more.


Is a food intolerance the same as a food sensitivity? 


Though often used interchangeably, these two descriptors are extremely different. While we use food sensitivities to specify your body’s Ig response to specific foods, intolerances such as lactose intolerance fall outside this description. An intolerance is often the bodies inability to tolerate or process the offending food trigger.


“You could still be lactose intolerant even if you come back dairy negative,” says Meletis. In summary, lactose intolerance is your body’s inability to tolerate lactose sugar, he says, which won’t necessarily be detectable on an IgG test.  


 Allergy vs Sensitivity vs Intolerance Summary


  Timing Bodily Response Symptoms
Food Allergy Immediate, usually within minutes to hours  IgE Immune Response Hives, swelling, anaphylaxis
Food Sensitivity Delayed, usually beginning a few days after exposure IgG/IgA/IgG4 Immune Responses Joint pain, digestive distress, brain fog, fatigue, etc.
Food Intolerance Quick, usually within hours Inability to tolerate triggering food Digestive discomfort and/or disarray 


What about diseases like Celiac and Crohn’s? 


Like intolerances, diseases and other immune disorders differ from both allergies and sensitivities. While they might share similar symptoms, the primary difference is in how they’re detected. Celiac disease is a T-cell-mediated immune response, which means neither IgE nor IgG tests are considered a proper method of diagnosis. In most cases, celiac is diagnosed through an endoscopy or serology test.


Similarly, Crohn’s disease is a type of inflammatory bowel disease (IBD) that is typically diagnosed through a series of examinations, including colonoscopies, stool tests, endoscopies and advanced blood tests. 


So where do IgG and IgE testing come into play? 


Since IgE and IgG testing serve completely different purposes, it is necessary to have a good understanding of patient’s symptoms and ailments in order to decide which test is right for them. Since some IgE-triggered reactions can be life-threatening, it’s important to try to rule out food allergies if you can.  


With the rising concern surrounding gut and immune health, food sensitivity tests have grown in popularity. Using a small sample of blood through serum or dried blood spot cards we can measure reactivity on up to 240 foods, herbs, and spices. This can provide valuable information to help guide any potential changes to patients diets.

“IgG is the most abundant immunoglobulin in your body,” says Meletis. “If we’re going to test for IgE, it only makes sense to test for IgG as well.” 




Written by Maggy Lehmicke

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