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Food Allergies, Sensitivities, Intolerances: Symptoms, Testing, Treatment

woman with food allergies wondering about IgG food sensitivity testing
Dealing with Food Allergies?

Food Allergies? Food Sensitivities? Food Intolerances? What is the Difference?

The Definition of a Food Allergy

A food allergy is an inappropriate immune system response to a food gauged by the production of antibodies to the food. These are also called Type I immediate hypersensitivity reactions. The most severe food allergies can cause a life-threatening response known as anaphylaxis. Anaphylactic reactions can cause a person’s throat to close, airways to constrict, hives, wheezing, nausea, vomiting, diarrhea, swelling under the skin, and low blood pressure.  These reactions usually involve IgE antibodies to food. Celiac disease, which is a severe gluten allergy, involves IgA and IgG antibodies to gliadin, a protein found in wheat and other cereal grains.

The Most Common Food Allergies

The most common triggers of early childhood food allergy are cow’s milk and eggs, which usually cause mild symptoms, limited to the skin (9). Food allergies acquired in infancy typically disappear by early school age.

Other common anaphylactic food allergies are tree nuts, peanuts, shellfish, soy, and wheat.

The Definition of a Food Sensitivity

The term food sensitivity is a non-specific term that is sometimes used to describe milder versions of food allergies. These mild food allergies are typically triggered by IgG antibodies to foods and do not cause life-threatening reactions. The release of IgG antibodies to specific foods is considered common.  So is the formation of antigen-antibody complexes (which form when a food antigen meets an IgG antibody and they bind together). White blood cells called macrophages typically remove these complexes. However, when many antigen-antibody complexes are present, the capacity of the macrophages to remove them may become overwhelmed. Leftover antigen-antibody complexes then deposit in your tissues and release substances that provoke inflammation. This inflammation is much more prevalent if the reactive food remains a regular part of your diet. Regularly consuming the food perpetuates the production of more immune complexes that may trigger inflammation and contribute to a variety of symptoms.

These types of reactions are also called Type III, delayed hypersensitivity reactions (10) as the onset of symptoms is up to 6-12 hours after eating the food or even days later.

List of the Most Common Food Sensitivities

The most common food sensitivities include wheat, gluten, dairy, eggs, almonds, other nuts and seeds, pineapple, and beans.

The Definition of a Food Intolerance

Food intolerances are foods that a person may have difficulty digesting.  This difficulty results in symptoms such as gas, bloating, abdominal pain, and diarrhea. In this instance, a person may lack the appropriate enzymes to digest the food.  Such is the case in lactose intolerance. An enzyme called lactase is required to break down lactose. Lack of this enzyme means that foods containing lactose (dairy products) end up poorly digested in the intestines, where bacteria ferment the lactose. This creates bloating, gas, diarrhea, and abdominal pain.

List of the Most Common Food Intolerances


Lactose is a sugar that is found in milk and dairy products.


Fructose is a sugar that is found in fruit.

Histamine intolerance

Histamine is a chemical compound produced in your body. It is also present in foods, particularly stored or preserved foods. Some people lack an enzyme known as DAO to effectively break down ingested histamine.  This leads to dietary histamine intolerance. For someone with histamine intolerance, the ingestion of foods that contain high amounts of histamine can cause inflammatory symptoms. The symptoms may include headaches, flushing, digestive problems, vertigo, congestion, and fatigue.

To add to the mix and the confusion, there are also foods and food additives that just don’t agree with people and that can trigger headaches or digestion problems, such as MSG, sulfites, lectins, caffeine, nitrites, aspartame, and salicylates.

IgG Food Allergy Symptoms

The symptoms of food sensitivities can include bloating, gas, constipation, diarrhea, abdominal pain, fullness after eating, headaches, migraines, water retention, irritable bowel syndrome, inflammatory bowel disease, and skin conditions like eczema, hives, and acne, among many other symptoms.

Why Test for IgG Food Sensitivities?

There is much research showing that IgG food reactions are quite relevant in certain disease processes, for example, Irritable Bowel Syndrome (1, 18-25), migraines (2), obesity/weight gain (3), atherosclerosis (3), allergies (4,5), eczema (4), urticaria/hives (5), and ulcerative colitis (6). The common underlying mechanism of all of these conditions is inflammation. Removing IgG food sensitivities helps to reduce inflammation and may benefit other inflammatory conditions as well. Medical doctors will check for IgG antibodies to a protein called gliadin when assessing a patient for the most severe form of gluten allergy, Celiac disease.

One particular subset of IgG antibodies, IgG4, has been theorized to help moderate your immune system, improving immune tolerance and reducing inflammation (8). However, this only applies to this specific IgG antibody (IgG4), not to ALL IgG antibodies. 

In fact, a 2017 chart review study found that there are established associations between:

  • autoimmune pancreatitis, AERD, nasal polyps, and eosinophilia and elevated serum IgG4
  • monoclonal gammopathy and hepatitis C with elevated serum IgG1

The authors also found novel associations between Rheumatoid Arthritis and elevated IgG1 and IgG3, hypothyroidism, and IBS and elevated IgG2, and between Celiac disease and elevated IgG4.

When testing for food sensitivities, we test for IgG1 – IgG4.  Removing foods that may provoke an additional body burden of IgG antibodies makes sense. Critics of this test need to get their facts straight and not selectively take from research to support their bias.

How Are IgG Antibodies Detected?

The type of food sensitivity test used in reputable laboratories is called ELISA testing, which stands for enzyme-linked immunosorbent assay. It is a scientifically recognized methodology that was developed in 1978. It is widely used in conventional medical and hospital labs around the world. ELISA testing is used to test for HIV, Celiac disease, Hepatitis B, and malaria among many other applications in medical laboratories. Other means of checking for food sensitivities have not been scientifically validated. If a lab claims that their unique patented technology (that is not revealed) is better, do be wary. Lymphocyte analysis for food sensitivities has been shown to be less reproducible than ELISA IgG testing.

Those who scoff at IgG food sensitivity testing, have never done it. They have never seen the benefits to people who suffer from rheumatoid arthritis, lupus, asthma, sinus problems, GERD, gallbladder conditions, whole body psoriasis, migraines, irritable bowel syndrome, and many other chronic inflammatory conditions.

Does a position paper prove that IgG food sensitivity testing is invalid? Nope. A position paper by definition is only someone’s opinion, again, someone who has never had experience with this type of testing. So in this instance, an opinion based on ignorance.

What is the Difference Between Peanut-Type Anaphylactic Food Allergies and IgG-mediated Food Sensitivities?

Severe and potentially life-threatening food allergies are typically caused by IgE antibodies. Your immune system has 5 antibodies in its arsenal as weapons against infectious organisms like viruses and bacteria. Peanut-Type allergies are usually caused by IgE antibodies. Allergists will test for these using a Skin Prick test. This test exposes the person to food allergens like peanuts by pricking the skin with them and watching for a reaction. This is a useful method for detecting IgE antibodies to foods.

IgG-mediated food sensitivities are not identified by the Skin Prick test. IgG antibodies are found primarily in the blood, lymph, and intestine. IgG-mediated food sensitivities do not cause life-threatening reactions, but rather “quality of life-threatening” reactions.

If You Eliminate IgG Food Sensitivities, Will You Suffer from Malnutrition? Will it Eliminate Essential Nutrients?

Our naturopathic doctor has extensive training in nutrition. She is well-educated to provide advice on the safe elimination of your food sensitivities. The food IgG sensitivity or food allergy test is used as a means to identify which foods to eliminate as part of an elimination challenge diet. This process of food elimination and reintroduction helps to identify which foods are particularly problematic and which foods may just show up as a result of frequent exposure to them.

Our naturopathic doctor provides nutrition counseling and guidance regarding the replacement of your sensitivities with healthier alternatives for you to ensure a well-rounded, nutrient-rich diet. If something that you are eating inflames your gut, odds are that you are not adequately absorbing the nutrients that this food purports to provide anyway.

What About Just Doing an Elimination Challenge Diet?

This is also a viable option that we offer to our patients. In some instances, it works well to identify problematic foods. We can provide guidance about what foods to eliminate, for how long, what to use in place of those foods to ensure good nutrition and how to go about reintroducing foods and what to watch for when you do.

In other people, elimination just doesn’t work because there is no “safe” food that may be exempt from causing a reaction.  Therefore, it’s hard to determine what to eliminate. For example, on food sensitivity testing the following foods have been identified as food triggers in various patients that I have tested: blueberries, avocado, broccoli, salmon, beef, and almonds. In each of these cases, eliminating this offending food has provided relief to the patient of their symptoms. None of these is a food that I would typically recommend avoiding as part of an elimination diet. In fact, most of them are foods that I would encourage people to eat more of. Also, because of the delay in reaction to foods, it may be something that you ate 6-48 hours before that is causing the symptoms you are experiencing right now.

What about Electrodermal testing, Cytotoxic testing, and Applied Kinesiology food allergy testing?

We do not recommend these types of unproven means of testing for food allergies or sensitivities. Beware of those who do or those who lump science-based IgG food sensitivity testing in with these methods.

What Should You Do if You Have Food Allergies?

If you have severe anaphylactic allergies, you should avoid those foods entirely until your allergist finds that you no longer test positive and gives you the okay to consume them.

With milder food allergies or sensitivities, our ND can guide you in the process of removing them over the short term to give your gut time to heal and let the inflammation calm down.

If you have many food allergies, it may be that your gut wall is not providing a good barrier between your food and your immune system. Increased intestinal permeability is also referred to in the medical literature as “leaky gut syndrome”(17). It has been linked to inflammatory bowel diseases like Crohn’s and Ulcerative Colitis (14, 15), but also to mood disorders like Major Depressive Disease (16) and metabolic syndrome (17).

Our licensed naturopathic doctor will advise you about scientifically proven supplements (11, 12, 13) that help repair your gut and balance your healthy bacteria, along with lifestyle modifications that can also help.

Authored By Dr. Pamela Frank, BSc(Hons), ND, updated Feb. 10, 2022

IgG Food Sensitivity Testing & Leaky Gut References

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