The Difference Between Food Allergies, Sensitivities, & Intolerances

Headaches. Bloating. Phlegm.

Once we recognize the power of healing our gut, we may start to notice symptoms that have been flying under the radar for years… The next question often is, “Do I have a food allergy? Wait, a food sensitivity? Or could it be a food intolerance?”

Well, which is it? You, like me, may have used the terms interchangeably in the past. However, there is a difference, and thankfully, it’s not as complicated as it seems!

First, A Word On The Immune System

Our guts contain 70% of our immune system. Therefore, the immune system plays a huge role in this discussion of adverse reactions to food. A properly functioning immune system has two tasks:

1. To discern the difference between a foreign substance and the body’s own healthy tissue;
2. Then, to attack and eliminate the foreign substance, whether pathogen (virus, bacteria, parasite, yeast, etc.), food, or chemical.

Although the immune system attacks foreign substances in a variety of ways (see below), one thing remains constant: inflammation.

When a foreign substance invades our bodies, pro-inflammatory chemicals are released. This inflammation halts the spread of pathogens, disposes of the pathogens as the immune system attacks them, and promotes healing. So, you see, inflammation is not inherently a bad thing. Problems arise when the inflammation never fully goes away — which is why it is important to address the underlying cause(s), such as food allergies, sensitivities, and more.

What Are Food Allergies?

Food allergies — also known as immediate hypersensitivity reactions — involve a swift immune response against a food, or food component (usually one or more proteins), that the body thinks is harmful.

When in the presence of this food, certain white blood cells called B lymphocytes produce antibodies. These antibodies attach themselves to the food (a.k.a “invader”) and thereby either mark it for destruction by other parts of the immune system, or neutralize it directly. These antibodies are also known as immunoglobulins, abbreviated Igs.

There are five different classes of immunoglobulins, all performing different tasks. For example, IgA confers passive immunity to breastfeeding infants via breast milk, among other functions. IgE is the antibody most commonly involved in allergic reactions — including food allergies.

Most people don’t react to an allergen when exposed to it for the first time. Instead, they become “sensitized” to it. This means that the body produces IgE antibodies specific to that allergen, which are primed and ready to attack whenever the allergen is next encountered.

At that point, IgE also triggers the release of a pro-inflammatory chemical called histamine, among others. Histamine spreads through the body, causing the symptoms of an allergic reaction (vomiting, diarrhea, asthma, swelling, hives, even anaphylactic shock) within minutes to hours of exposure. The symptoms can be mild or quite severe, normally affecting the gastrointestinal tract, skin, and/or respiratory system.

Finally, parents with food allergies may pass them to their children.

(Source.)

How To Diagnose Food Allergies

There are several ways to diagnose food allergies, including blood tests, skin prick tests, and the oral food challenge (the gold standard of food allergy tests). Furthermore, you can keep a food diary and practice an elimination diet.

In the United States, 90% of all food allergies involve the “big eight” food allergens: peanuts, soybeans, fish, crustacea, milk, eggs, tree nuts, and wheat. However, this list changes depending on the country. Sesame seed is a common allergen in Asia and the Middle East, while celery is highly allergenic in Europe. Perhaps dietary patterns do affect the prevalence of certain allergens!

What Are Food Sensitivities?

Food sensitivities — also known as delayed hypersensitivity reactions because they occur within hours to days of exposure — are sometimes categorized as a subset of food allergies. After all, they involve the immune system as well.

What’s the difference? Food sensitivities are cell-mediated, not IgE-mediated.

Let’s say an individual is sensitive to a few specific foods. When he or she eats these foods, the digestive system breaks them down and they pass into the bloodstream. The immune system recognizes these food particles as foreign, and immunoglobulins such as IgG (sometimes IgM or IgA) activate certain other white blood cells such as T lymphocytes, neutrophils, and macrophages. These white blood cells attack the food particles and release a cascade of pro-inflammatory chemicals, including prostaglandins, interleukins, and even histamine again.

As these pro-inflammatory chemicals travel throughout the body, they produce the symptoms commonly associated with food sensitivities: headaches and/or migraines, eczema, arthritis, irritable bowel syndrome, etc.

Now, what if this individual has leaky gut? In other words, say their intestinal lining is so permeable that it allows macromolecules into the bloodstream before they can be broken down.

Even if the individual didn’t already have food sensitivities, this scenario easily creates them. Intestinal permeability has been linked to celiac disease, type I diabetes, and more.

While it’s true that leaky gut can lead to food sensitivities, it’s also true that food sensitivities left unaddressed may lead to leaky gut. It goes both ways.

(Source, source, source, and source.)

How To Diagnose Food Sensitivities

In addition to elimination diets, the Mediated Release Test (MRT) looks at 130 different foods plus 20 different chemicals and additives to see which ones are causing inflammation, and therefore sensitivity, in individuals.

The IgG test evaluates the presence of food sensitivities as well. However, results aren’t entirely accurate or reproducible from lab to lab. Furthermore, antibodies other than IgG may be involved in the sensitivity instead, and so the presence of IgG would be inconsequential (source and source).

What Are Food Intolerances?

Now, we come to food intolerances, which don’t involve the immune system at all. These result from an inability to digest a certain food(s). In other words, it’s an enzyme issue.

For example, to digest lactose (the disaccharide present in milk), our gut requires the enzyme lactase to break it down into its component parts: two monosaccharides called glucose and galactose. When our digestive systems lack lactase, dairy poses a problem. Lactose can’t be absorbed into the bloodstream as-is, and so it passes into the colon, where it is fermented.

This fermentation of the offending food(s) causes general discomfort such as bloating and cramping, but also contributes to the body’s toxic load and level of inflammation by releasing pro-inflammatory toxins into the bloodstream (source). Notice that food intolerances cause inflammation as well, despite the fact that the immune system doesn’t play a role.

Certain food intolerances known as metabolic food disorders can be passed down genetically from generation to generation.

How To Diagnose Food Intolerances

A simple elimination diet — if done correctly — does the trick.

Also available is the Carroll evaluation, a blood test which checks for an individual’s primary food intolerance. Most food intolerances fall into one of these categories: milk, egg, meat, sugar, fruit, and potato. Many individuals also have a combination of foods they don’t tolerate well within 4 hours of each other, such as fruit + sugar or grain + potato, so this test checks for secondary pairings as well.

Jared Zeff, ND, LAC of Salmon Creek Clinic in Vancouver, WA performs the Carroll evaluation for interested individuals. Simply call his office and request a test kit!

Is It Possible To Heal Food Allergies, Sensitivities, & Intolerances?

It depends…

At the very least, you may be able to put food allergies and sensitivities into remission. The first step is to remove the offending food(s) and then embark on a gut-healing diet such as GAPS. If our bodies are in a constant state of inflammation due to a perpetual barrage of foods they no longer tolerate, healing will not happen. We need to rest, nourish ourselves, and give our guts time to seal properly.

Food intolerances may never go away entirely since they are genetic. It’s possible, however, that some individuals may be able to tolerate the foods again in small amounts and occasionally once they are in better health (source).

Interested in healing your gut and putting food allergies and sensitivities into remission? Check out these resources!

• Allergy-Free Cooking eCourse
• 82 Ways To Heal Your Gut
• 5 Ways To Heal Your Gut That You Probably Haven’t Tried
• Gluten Sensitivity & Sourdough: Is Sourdough Gluten-Free?
• We Healed Food Sensitivities Through Traditional Foods
• How Megan Stevens Healed Her Interstitial Cystitis
• The Gut-Healing GAPS Diet Made Simple (KYF165)
• Let’s Demystify The GAPS Diet

Did you know the difference between food allergies, sensitivities, or intolerances?

Referenced throughout: Modern Nutrition in Health and Disease, 11th edition, pages 1421-1439; Human Anatomy & Physiology, 8th edition, pages 767-799.