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What's the Difference Between a Food Allergy, a Sensitivity, and an Intolerance?

We spoke with a registered dietitian to better understand the difference between these three reactions.
Woman holding bloated stomach belly

Currently, there is a lot of hype around common food allergens—such as peanuts, milk, eggs, and wheat—and how they're rapidly affecting both adults and children worldwide. According to Food Allergy Research and Education, the world's largest non-profit organization that's dedicated to food allergy awareness and advocacy, roughly 15 million Americans have at least one food allergy. About 4 percent of the U.S. adult population has a food allergy, and 8 percent of children have one as well.

To make things even more complicated, there are two other types of reactions that can mimic that of an allergy, when really they occur for different reasons and are not the same type of reaction at all. We spoke with Cynthia Sass, a registered dietitian, to help break down the difference between a food allergy, a sensitivity, and an intolerance.

What is a food allergy?

"With a food allergy, the body's immune system, which normally fights infections, sees a food as an invader," Sass says. "This leads to an immune response, in which chemicals like histamine are released, triggering symptoms such as breathing problems, throat tightness and swelling, hoarseness, coughing, and hives, among others."

Food allergies are not something you want to mess with. Think of someone who says they're allergic to peanuts. Some individuals with this allergy will experience life-threatening symptoms when they ingest foods that contain peanuts or are made from a facility where peanuts are processed, while others experience similar symptoms from just being in the same room as the tree nut. These individuals usually carry EpiPens with them in the event they encounter a food or room where peanuts are present.

Got it. So, what is a food sensitivity?

"A food sensitivity is a non-allergic inflammatory immune response that can lead to a range of symptoms, including fatigue, brain fog, eczema, headaches, joint pain, reflux, depression, fluid retention, and bloating," says Sass. "Sometimes intolerance and sensitivity are used interchangeably, but they really shouldn't be."

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If you've experienced any of these symptoms, consider getting tested to see if you react abnormally to any foods.

Now, what is a food intolerance?

Unlike a food allergy and food sensitivity, a food intolerance is not a response triggered by the immune system, says Sass.

She explains that a person who has an intolerance to lactose, "is missing an enzyme needed to break down the naturally occurring sugar in milk. The undigested sugars are attacked by bacteria, which creates gas buildup and triggers bloating, and sometimes diarrhea."

So why does everyone equate "sensitivity" and "intolerance" with an allergy?

"I think allergy has become a catch-all term, even though technically these responses aren't all allergies," says Sass.

How do you detect each?

Sass says there are several tests to determine if you have a food allergy, sensitivity, or intolerance. Typically, these include several kinds of blood tests. Speak to an allergist about what kind of test is best for you according to your symptoms.

Final verdict: What's the difference between a food allergy, a sensitivity, and an intolerance?

When someone eats something they're allergic to, their immune system sees that particular food as a foreign body and essentially begins attacking itself. Experiencing adverse reactions such as throat tightness, coughing, and hives are indicators of a food allergy.

A food sensitivity is also an immune response. However, the symptoms are not as abrupt or serious. They can cause a range of gastrointestinal discomfort, such as bloating, fatigue, and acid reflux.

Finally, an intolerance occurs when the food cannot be broken down properly, which can cause bloating along with other symptoms.

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Cheyenne Buckingham
Cheyenne Buckingham is the news editor of Eat This, Not That!, specializing in food and drink coverage, and breaking down the science behind the latest health studies and information. Read more
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