The terms food allergy, food sensitivity, and food intolerance are often mistakenly used interchangeably even though they are completely different conditions. Understanding how these conditions differ is critical in securing a proper diagnosis and remedy. 

In this article we will examine the differences between food allergies, sensitivities, and intolerances, highlight the unique symptoms of each, and provide several testing options to help you determine which foods may be sabotaging your health. 

Table of Contents

Understanding the Body's Response

The main difference between food allergies, sensitivities, and intolerances is the body’s response. Food allergies and sensitivities trigger immune system responses, while a food intolerance is primarily the inability to metabolize, digest or absorb a food component.

The severity of each condition varies, as does the symptoms associated with each, and the manner in which they are diagnosed.

Elimination diets are the most inexpensive and accurate method to determine whether food allergies, sensitivities, or intolerances are responsible for certain symptoms, but they require patience, extra vigilance, and disciplined effort.

A simple blood test can be a convenient way to quickly narrow down the list of possible culprits and help expedite the process. 

Immune Response (Allergies & Sensitivities)

Our blood contains immunoglobulins (Ig), which are antibodies that help protect us from dangerous bacteria, viruses, and other threats. When these antibodies detect foreign objects, called “antigens”, in the body, they trigger a protective immune response.

There are five isotypes of antibodies, IgG, IgM, IgA, IgD & IgE, each with different functions and distributions within the body. IgG is the main antibody (70-75%) in the blood, and It is widely distributed within the blood and tissues. Interestingly, it is also the only isotype that can pass through the placenta and be transferred from mother to baby. 

IgE (0.001% or less) is believed to be related to immunity reactions to parasites, and has recently become known as a key factor of allergies. 

Food Allergies

A food allergy is an IgE-mediated immune response that is generally very acute, and may affect many areas of the body, not just the digestive system. A reaction occurs every time a trigger food is ingested, even when only a tiny amount is consumed, and the reaction can sometimes be life threatening.

Food allergies are less common than food sensitivities or intolerances, and the symptoms can vary in severity. People with severe food allergies often carry an epi-pen (epinephrine injection) to provide emergency relief from a severer allergic reaction (anaphylaxis).

Food Allergy Symptoms

  • Anaphylaxis 
  •  Flushed skin or rash
  • Hives
  • Tingling or itchy sensation in the mouth
  •  Face, lip, or tongue swelling
  • Vomiting and/or diarrhea
  • Abdominal cramps
  • Coughing or wheezing
  • Difficulty breathing
  • Dizziness and/or lightheadedness

Testing For Food Allergies

A skin test or blood test may be used to determine if you have a food allergy. In a food allergy skin test, and very small drop of a liquid food extract, one for each food being tested, is placed on the skin. 

The skin is then lightly pricked at each site and then monitored for 15-20 minutes to see if a bump or redness (similar to a mosquito bite) forms at any of the sites. 

A blood test can be used to assess the overall number of IgE antibodies in your blood (total IgE test), or it can be used to measure the level of IgE antibodies in response to a specific allergen (specific IgE test).

You can begin the food allergy testing process with your primary health provider or you can simply request an allergy test directly from a testing agency or lab (no prescription required). You simply place your order online, visit a lab in your area to complete the blood draw, and the results are mailed or emailed to you.

Each company provides a lab locator tool to help you find the nearest lab, and In some instances, rather that visiting a lab, the lab will send a person to your home to conduct the blood draw. 

Online Food Allergy Testing Options

Food Sensitivity

Food sensitivity is an IgG-mediated immune response that is generally isolated to the digestive tract or results in intestinal inflammation. The symptoms may present quickly, within an hour, or they may be delayed up to 48 hours. 

Reactions may not necessarily occur every time the trigger food is consumed, and the trigger food may need to be consumed frequently or in large amounts before a noticeable reaction occurs. An inconsistent, and potentially delayed reaction therefore makes it difficult to determine the identity of the trigger food, especially if there are multiple. 

Food Sensitivity Symptoms

  • Gastrointestinal distress
  •  Stomach pain
  • Bloating
  • Fatigue (feeling tired)
  •  Headaches
  • Migranes

Testing For Food Sensitivities

A simple blood test can be used to measure your body’s IgG immune response to a range of specific foods.  While a food allergy test assesses broad food types, like dairy for instance, food sensitivity tests measure IgG reactivity associated with very specific food items, as well as the level of reactivity associated with each food.

A prescription is not required for a food sensitivity test, and although they can be conducted in a lab, you can also order a test kit, complete the test at home, and send it back for analysis. Your results are then mailed, or emailed to you along with instructions about how to interpret your results. 

Food Sensitivity Test Options

If you have no idea what is causing your digestive distress, a broad food sensitivity test may be the best place to start. 

If you have already narrowed it down to a particular food type, like dairy for instance, there are also some less expensive, and more focused tests available to help identify the specific food items within that category that are causing the greatest reaction. 

At-Home Food Sensitivity Tests

Food Intolerance

As mentioned above, food intolerance is generally the inability to metabolize, digest or absorb a food component, and is often due to the absence of specific enzymes required to break down a particular food component. 

Lactose intolerance for instance, is the body’s inability to digest lactose (sugar in dairy) due to a deficiency of the lactase enzyme.

Food intolerances can be quite common, even more so in those with digestive system disorders such as irritable bowel syndrome (IBS). 

Common food intolerances involve dairy, gluten, food colorings and preservatives, salicylates (natural chemical in some plants), sulfites, caffeine, fructose and FODMAPS.

Fermentable Oligosaccharides, Disaccharides, Monosaccharides & Polyols, or FODMAPS, are short chain carbohydrates that don’t fully digest or absorb in the small intestine. Check out our keto food list for examples of FODMAPS.

Food Intolerance Symptoms

Similar to food sensitivities, the symptoms of a food intolerance may be varied but usually involve the digestive system, and may not present until several hours after a problem food item has been ingested.

When a food component cannot be properly digested, it usually results in a buildup of gas (bloating), a backup in the system (constipation), or a rapid expelling (diarrhea).

Inflammation within the digestive tract also occurs and other symptoms including headaches, fatigue and malaise (a general feeling of being under the weather) may occur.

  •  Bloating
  •  Excess gas
  • Stomach pain
  • Diarrhea
  • Constipation
  • Headache
  • Migraine
  • Fatigue
  • Runny nose
  • Malaise (feeling under the weather)

Testing For Food Intolerance

The Antigen Leukocyte Antibody Test (ALCAT) is a leukocyte (white blood cell – WBC) activation test that analyses direct, immediate, pro-inflammatory responses of the innate immune system (different than antigen-specific immune response mentioned above). 

The process includes exposing white blood cells (WBCs) to foods, herds, spices, chemicals and additives, and the offending food component is identified when changes in the number and size of the WBCs occurs.

The ALCAT test can be used for assessing both food intolerances and food sensitivities because it identifies foods that provoke an inflammatory response which can include both the innate and adaptive (antigen-specific) immune system.

There is however, continued debate over the accuracy and/or reliability of the ALCAT test largely due to its inability to produce results that can be consistently replicated. 

The ALCAT test is also quite expensive which may prevent people from using it as their first approach to identifying a problem food or food component. 

Food Intolerance Test Options

As with the other test options listed in this article a prescription is not required. Test kits can be purchased online and blood draws are either conducted at a lab, or a phlebotomist (blood collection expert) may be able to come to your home.


Food allergies, sensitivities or intolerances can be extremely detrimental to your health but, there are some tools to help you detect which foods may be to blame. 

An elimination diet is the least expensive way to identify problem foods, and a simple blood test can help narrow the list of potential culprits considerably. 

|RELATED| Ditch the Dairy – 10 Signs Dairy Doesn’t Agree With You

Do you have, or suspect you have a food allergy, sensitivity or intolerance? How did you diagnose it? Have you tried one of the tests mentioned above? Please consider sharing your experience by commenting below.

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