Food allergies & the immune system

Published February 22, 2024

Food allergies and intolerances can present similar symptoms but knowing the difference matters.

What’s the difference between a food allergy and food intolerance? 

The difference is how your body reacts to a certain food¹:

With a food allergy, the immune system wrongly identifies something safe, like food, as harmful. This triggers an immune response within the body that can be dangerous.

With food intolerance, the immune system isn’t involved. The symptoms can be unpleasant but don't pose the risk of a life-threatening reaction, like a food allergy.

Common signs and symptoms of a food allergy¹

• Itching
• Swelling
• Hives
• Vomiting
• Diarrhea
• Wheezing
• Anaphylaxis (pronounced an-uh-fuh-lak-sis)

Common signs and symptoms of food intolerance²

• Vomiting
• Diarrhea
• Upset stomach
• Belly pain
• Gas
• Heartburn
• Headache, migraine

What are the most common food allergies?

Some of the foods that can cause allergic reactions include¹:

• Cow’s milk
• Eggs
• Fish
• Peanuts
• Sesame
• Shellfish
• Soy
• Tree nuts
• Wheat

What’s celiac disease? Is it the same as a wheat allergy?

A wheat allergy is when a person is allergic to wheat. Celiac disease is an autoimmune disorder. In autoimmune disorders, the immune system mistakenly attacks the body's own tissues and organs. In the case of celiac disease, eating gluten makes the body turn against itself, targeting the small intestine. These attacks damage the villi (pronounced vil-eye) that line the small intestine, making it hard for the body to absorb nutrients.⁴

What’s the difference between gluten intolerance and celiac disease?

Gluten intolerance means your body doesn’t handle gluten well, but it’s not the same as celiac disease or a wheat allergy. Celiac disease is an autoimmune condition where eating gluten damages your small intestine. So, while both involve gluten issues, celiac disease can also lead to health issues if not managed with a gluten-free diet.⁵

Can you outgrow food allergies?

In some cases, yes. Some children outgrow their allergies to cow’s milk, egg, soy, and wheat. But allergies to peanuts, tree nuts, fish, and shellfish often last through adulthood. If you develop a food allergy as an adult, you’re less likely to outgrow it. Adult food allergies often stick around for the long haul, but there hasn't been a ton of research on this yet.⁶

Is there a cure for food allergies?

Right now, there’s no cure for food allergies. But researchers are making progress on possible treatments. Please talk with your doctor about potential options.

How are food allergies managed?

Treatment involves strictly avoiding the food(s) you’re allergic to. For people with severe food allergies, this could even include not touching or smelling certain foods and having access to self-administered epinephrine (pronounced eh-puh-nef-rin). Epinephrine is an emergency medication used to treat severe allergic reactions.⁶

What’s the difference between IgE and IgG blood tests?

Let's use shrimp as an example (but this relates to other foods, too). If you’re allergic to shrimp, your immune system sees a protein in shrimp as a problem. When your immune system senses the shrimp protein, it fights back by making special antibodies called immunoglobulin E (pronounced im-mew-no-glob-you-lin E) or IgE for short. These antibodies stick to cells in your skin, lungs, and digestive system.¹ 

Now, let’s say you come across shrimp again. These cells then release chemicals like histamine. This reaction is what causes symptoms like itching, hives, swelling, diarrhea, or even anaphylaxis.¹ 

So, why does knowing this matter?

Food intolerance tests aren't usually recommended for diagnosing food allergies.¹ Allergy tests, on the other hand, check for IgE antibodies—the same ones causing trouble in cells, releasing chemicals, and creating symptoms. Blood tests that look at IgE levels for certain foods help doctors figure out food allergies.¹ Quest’s allergy panels help identify food allergies, not intolerance. 

Since the difference between a food allergy and intolerance is significant, it’s important to team up with a doctor for a treatment plan. Only a doctor can properly diagnose food allergies by considering your symptoms, medical history, and test results.¹

No doctor visit is required to buy your own lab test at questhealth.com. PWNHealth and its affiliates review your purchase to ensure it is medically appropriate before submitting the test order for processing. PWNHealth also reviews your test results and will contact you directly if they require prompt attention. Included in each purchase is the option to discuss your test results with an independent physician; however, you are also encouraged to speak with your primary healthcare provider.