Food Sensitivities vs. Allergies: What's the Difference?

There are many ways your 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. – Notch’s medical 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 your immune system and are produced in response to things you 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 your 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 your body, many of which occur hours (or even days) after you’ve ingested a food you’re sensitive to. Because these IgG-stimulated reactions are usually associated with your 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 your 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 don’t necessarily mean the same thing. While we use food sensitivities to specify your body’s IgG response to specific foods, intolerances such as lactose intolerance and bean intolerance generally fall outside of this description.

“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.

“Histamines, lactose intolerance, bean intolerance, lectins and cross-reactivities are all independent of IgG,” he says. “If you try an elimination diet and are still miserable, these are the things to pay attention to.”

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’s a good idea to have a discussion with your doctor about what makes the most sense for you. 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 over the last few years. By using a small sample of your blood to measure your reactivity to certain foods, IgG food sensitivity tests can provide you with valuable information about your body’s response to what you're eating and help guide any potential changes to your diet.

“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.”