What is the difference between a food allergy, sensitivity, and intolerance?

It's common knowledge that people can react negatively to food.

• Sometimes people start wheezing or break out into hives.
• Sometimes they have an uncomfortable increase in gas and bloating.
• Sometimes they get congestion or swelling.
• Sometimes they get diarrhea, constipation, or even mucus in stools.
• Sometimes they get migraines.

With so many possible symptoms, how do you know whether you have an allergy, a sensitivity, or an intolerance to food?

It's true, all three types of reactions can produce similar symptoms, but via very different biological pathways.

In a nutshell, here are the differences:

1. A food allergy involves IgE antibodies, and typically produces a reaction within 30 minutes of eating.
2. A food sensitivity still involves the immune system, but NOT IgE antibodies, and the reactions are typically more delayed (up to 72 hours after eating).
3. A food intolerance does not involve the immune system at all, and is caused by a lack of appropriate enzymes to digest certain foods.

Food allergies are most common with the "Big 8":

1. Peanuts
2. Tree Nuts
3. Cow's Milk
4. Egg
5. Fish
6. Shellfish
7. Soy
8. Wheat

90% of the time, food-related allergic reactions are caused by one of these foods.

Most people will know right away if they have a food allergy, since they will develop quick symptoms like hives, diarrhea, or trouble breathing. True food allergies are Type I hypersensitivity reactions, involving IgE antibodies and the degranulation of mast cells in connective tissue, like the lungs, skin, and lining of the GI tract.

Food allergies can be diagnosed using a skin-prick test, an IgE blood test, an elimination diet, or in some cases, an oral tolerance challenge.

The best way to handle allergies is to work with an allergy specialist. Typically your food allergens must be avoided indefinitely to avoid symptoms.

In contrast... food sensitivities are more likely to occur with ANY food or chemical.

Yep, even "healthy" foods like lettuce, salmon, or even turmeric! It's also totally possible to be sensitive to chemicals that are added to our foods, like food colorings, caffeine, solanine (in nightshade vegetables), or artificial sweeteners.

Unlike allergies, food sensitivity reactions are often delayed, occurring up to 72 hours after ingestion. They are also triggered by multiple pathways of the immune system (Type III and Type IV hypersensitivity reactions), and DON'T involve IgE antibodies or mast cells.

Instead, they can involve immune complexes with other types of antibodies (IgG or IgM), or no antibodies at all, instead involving antigen presenting cells and T-cells. (For more details the physiology of food sensitivities, read this article.)

Since food sensitivities are not mediated by IgE antibodies & mast cells, traditional allergy testing does NOT test for them.

The most accurate method for food sensitivity testing is MRT, which stands for Mediator Release Test. It's a blood test that measures the magnitude of your body's inflammatory response to foods, via either the Type III or Type IV hypersensitivity pathways.

MRT is great because it doesn't matter exactly which pathway is causing your symptoms (IgG, IgM, T-cells, etc.). MRT tests the amount of pro-inflammatory mediators released, no matter which pathway triggered them, so you can know for sure which foods are likely contributing to (or not contributing to) your food sensitivity symptoms.

The best way to be tested for food sensitivities is through a Certified LEAP Therapist (CLT). CLTs are certified in food sensitivities, the MRT test, and the implementation of the corresponding therapeutic diet, known as LEAP (Lifestyle Eating and Performance). You can find a CLT near you by searching on healthprofs, or, depending on your state's licensure laws, you may be able to work remotely with a CLT (like me!) via telephone or Skype.

Food sensitivities are often a symptom of a deeper root cause, such as gut dysbiosis, infections/parasites, or low stomach acid. They can also be influenced by genetics or triggered by stressful events such as childbirth or serious illness.

However, food sensitivities are typically not permanent, and once the body system is healed, food sensitivities tend to decrease. Many people can eventually resume eating some of the foods they were once sensitive to, even if only in small doses.

Finally, food intolerances do not involve the immune system at all.

Food intolerances are far and away more common than food allergies or sensitivities. In fact, up to 75% of the world's population is lactose intolerant!

Food intolerances occur when the body lacks the correct enzyme to break down a food product.

Lactose intolerance is the most common type of food intolerance, and is caused by the body's natural decrease in the production of the enzyme lactase, which breaks down the milk sugar called lactose.

Without enough of the enzyme lactase, the lactose sugar remains undigested, and passes into the large intestine in its whole form. This increases the osmotic load of the stool, and causes water to rush into the colon. Of course, this then leads to uncomfortable diarrhea. When lactose sugar enters the colon, it is also rapidly fermented by your gut bacteria, producing the tell-tale gas and bloating.

It is also possible to be intolerant to other sugars, such as fructose, but this is much less common. Other types of intolerances include histamine intolerance (when the body cannot properly breakdown histamine in food, causing allergy-like symptoms), and amine intolerance (in aged foods).

While food intolerances are very uncomfortable, they can be treated by avoiding the food you are having trouble digesting, taking appropriate digestive enzymes with meals, or by consuming products that contain pre-digested forms of the intolerant molecule (like Lactaid milk, which contains pre-digested lactose).

If you are having uncomfortable symptoms after consuming foods, I highly recommend working with a Certified LEAP Therapist or other Registered Dietitian who is well-versed in allergies, sensitivities, and intolerances.

If you would like to book a session with me, shoot me an email at erica@ericajulson.com.

All sessions are held virtually, via telephone or skype. I look forward to "meeting" you!

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