What Is The Difference Between a Food Allergy And A Food Sensitivity?

Mark Volmer
Apr 14, 2017 · 7 min read

An allergy is not the same as a sensitivity and a sensitivity is not the same as an allergy. They are two different reactions.

Turn on the television or open a newspaper, and you’re likely to find information on food intolerances or allergies. From peanut allergies to celiac disease to lactose intolerance, more and more attention is being paid to these foods effect on our health.

When you drink milk, you get a stuffy nose and a bloated stomach. Do you have a milk allergy? Or, is it a sensitivity/intolerance to milk? How can you tell the difference between an allergy and a sensitivity?

Food allergies, food sensitivities, and food intolerances are often used interchangeably and inappropriately. In fact, there is an active debate in scientific and medical circles as to how to define and use these three terms. The internet has even more conflicting information when it comes to the differences between allergies and sensitivities.

Different types of immune reactions

The main difference between a food allergy and a food sensitivity is the immune system that gets triggered in response to an irritant. For the purpose of this post, we will discuss IgE food allergies and IgG food sensitivities.

IgE food reactions

IgE is a type of antibody that is used when the immune system comes under attack. If you catch a parasite while on vacation, your IgE immune system is what will defend you. Parasites aside, IgE reactions are what occurs in food allergies. There is not an IgE reaction in a food sensitivity.

Have you ever had the skin prick test done by your doctor? It’s a common test done to determine food allergies. This is used to identify your body’s IgE response to particular foods. (1)

In many autoimmune conditions (lupus, rheumatoid arthritis, etc.), IgE levels are shown to be elevated. It is currently thought that the elevation of IgE levels makes the body hypersensitive. This furthers the theory that an autoimmune disease is caused by something in the environment that our body mistakes itself for. (2)

IgG food reactions

IgG is the most common antibody found in our blood. IgG antibodies bind with viruses, bacteria, and fungi; in turn assisting our body in removing these harmful substances. (3)

IgG antibodies are what’s measured in food sensitivity testing. Labs will measure the quantity of IgG antibodies developed for a particular food source. For example, you could create no IgE antibodies to dairy products but you could produce IgG antibodies.

To further complicate matters, there are other antibodies that can be measured for food sensitivities. These include IgM and IgA. In theory, you could not react to dairy with your IgG antibodies. but your IgA antibodies may react.

What is a food allergy?

Do you know someone who has a peanut allergy? That is a food allergy. A food allergy is a full-scale response from your immune system in reaction to a food. In response, the body creates antibodies to fight it. (4)

In food allergies, the symptoms can be quite severe. Anaphylaxis is one of the more well-known symptoms of a severe food allergy. Anaphylaxis is a hyper-reaction of the immune system that can cause restriction of the airways and a severe drop in blood pressure. (5) Thankfully, not everyone with food allergies experiences anaphylaxis. In anaphylaxis, the IgE immune system causes certain cells to release histamine. Histamine is what causes the swelling/inflammation commonly observed in a food allergy.

This underlying mechanism is considerably different from the triggering mechanisms found in food sensitivities. The most common foods implicated in food allergy are peanuts, other nuts, shellfish or foods containing sulfites. (6)

What are the symptoms of a food allergy?

Symptoms of a food allergy can range from mild to severe, and the amount of food necessary to trigger a reaction varies from person-to-person. Symptoms of a food allergy may include: (7)

  • Rash or hives
  • Nausea
  • Cramping or stomach pain
  • Diarrhea
  • Itchy skin
  • Shortness of breath
  • Chest pain
  • Swelling of the airways to the lungs

Anaphylaxis is a very serious and potentially fatal allergic reaction that involves a sudden drop in blood pressure, loss of consciousness, and body system failure.

What is a food sensitivity or intolerance?

A food sensitivity (also known as delayed food allergy) is quite another story. Delayed reactions manifest in many different ways as they can affect any organ system in the body and can take from 45 minutes to several days for symptoms to become apparent. (8) The delayed onset of symptoms and complex physiological mechanisms involved in food sensitivities make them an especially difficult puzzle to try to solve on your own. In fact, food sensitivities often go undiagnosed or misdiagnosed.

Symptoms of food intolerance may be caused by your body having difficulty breaking down or digesting certain foods or food ingredients. An intolerance may also be caused by your body’s reaction to a certain food additive. (9)

Symptoms of food intolerance include: (10)

  • Muscle and joint pain/stiffness
  • Nausea
  • Stomach pain
  • Gas, cramps, and/or bloating
  • Vomiting
  • Heartburn or GERD
  • Diarrhea
  • Headaches
  • Irritability or nervousness

What causes food allergies and sensitivities?

We’re not sure the exact cause of food allergies. Though there is a strong hereditary or genetic connection — food allergies are more prevalent in those with family members that have allergies. Food allergies arise from sensitivity to chemical compounds (proteins) in food. Though we’re unsure why the body reacts to some food proteins and not to others.

Food allergies develop after you are exposed to a food protein that your body thinks is harmful. Remember, your body creates antibodies to anything it believes is foreign or harmful. For example, if you are born with a peanut allergy, the first time you eat peanuts (or, any food containing peanuts), your immune system responds by creating a specific antibody to the peanut protein (called immunoglobulin E or IgE). If you’re to eat peanuts again, it triggers the release of IgE antibodies and other chemicals, including histamine, in an effort to expel the protein “invader” from your body.

The allergy symptoms you have depend on where in the body the histamine is released. (11) If it is released in the ears, nose, and throat, you may have an itchy nose and mouth, or trouble breathing or swallowing. If histamine is released in the skin, you may develop hives or a rash. If histamine is released in the gastrointestinal tract, you likely will develop stomach pains, cramps or diarrhea. Many people experience a combination of symptoms as the food is eaten and digested.

With food intolerances, there are many factors that may contribute to their existence. In the case of lactose intolerance, the person lacks the enzyme needed (lactase), to properly digest the dairy proteins. Other food sensitivities are less clear on why they trigger an immune response. One may have an intolerance or sensitivity to food additives. These include ingredients like chemical dyes, monosodium glutamate (MSG), or artificial sweeteners.

Can you tell the difference between a food allergy and a food sensitivity?

With a food allergy, even one molecule of the offending food’s protein can trigger a response. This will occur every time the food is consumed. People with food allergies are generally advised to avoid the offending foods completely.

Food intolerances often are dose related. People with a food intolerance may not have symptoms unless they eat a large portion of the food or eat the food frequently. (12) If, for example, you have a sensitivity to dairy, having one small bowl of ice cream may not create any symptoms. Though, a night of binging on Ben & Jerry’s may result in a congested nose or an upset stomach.

How are food allergies/sensitivities diagnosed?

With food allergies, some people know exactly what food causes their allergy. They eat peanuts or a product with peanut in it and immediately break out in a rash. Others need a doctor’s help in finding the cause. (13) Dr’s utilize either blood tests or skin tests to determine which foods/substances you are allergic to. In an allergy skin test, a very small drop of a liquid food extract, one for each food, is placed on the skin. The skin is then lightly pricked. This is safe and generally not painful. Within 15 to 20 minutes, a raised bump with redness around it, similar to a mosquito bite, may appear. It shows that you are probably allergic to that food. (14)

There are generally two accepted methods in determining a food sensitivity:

  1. Laboratory testing
  2. Elimination or reset diets

Laboratory tests for food sensitivities measure IgG or IgA antibodies to particular food proteins. Ideally, a lab will test both, as you can have a reaction with IgG but not IgA and vice-versa. Food sensitivities are generally run after a food allergy has been ruled out. For example, if you suspect you react to peanuts, ruling out a peanut allergy should be your first priority. Should the food allergy test show that you are not allergic to peanuts, an investigation into a peanut or legume sensitivity would be worthwhile.

For more information on how to perform an elimination or reset diet, please see this post.

Ok, you now have the information needed to determine if your symptoms are due to a food allergy or a sensitivity.
Let’s hear from you. How did you determine the foods your body best tolerates?


Originally published at Flourish Clinic.

Mark Volmer

Written by

I help those with fatigue naturally reclaim their energy and share their gifts with the world.

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