IgG Food Intolerances

There is growing evidence that food-specific IgG antibodies can be linked to many chronic health conditions. It can be normal for our bodies’ defense system to produce some levels of IgG antibodies to specific foods and combine with the proteins of these foods to form complexes, cross the intestinal wall and enter the blood stream. When the immune system is working well, these complexes are removed by macrophages. But if there is an overload or a poor immune system, these complexes can circulate in the blood stream and deposit in different tissues, leading to inflammation.

The diseases and conditions that have been linked to raised levels of food IgG antibodies:

  • Irritable bowel syndrome
  • Inflammatory conditions, arthritis
  • Migraines, headaches
  • Asthma, respiratory
  • Bloating, gas, constipation, diarrhea
  • Tiredness, not feeling well
  • Rashes, eczema
  • Obesity

It can be very difficult to identify the food(s) that are linked to the symptoms. IgG food sensitivities are typically a delayed reaction which means the symptoms may not appear for days, making it hard to identify the foods. Elimination diets are based on guesswork and can take a lot longer to determine which foods are causing the issue.


It is important to understand the role that cross-reactivity plays in the interpretation of results. Cross-reactivity occurs when the immune system reacts to a protein that is similar or identical to a protein of other foods or pollens. These are known as panallergens. If there is a 70% similarity, a cross-reactivity can lead to an increased result, even if the patient has not consumed the particular food. These reactions should not be considered a false positive, as these results may be a reflection of a pattern of clinical sensitivities including the possibility of a pollen sensitivity. Current publications focus on IgE antibodies, but given the relationship between IgE and IgG antibodies, cross reactivities can overlap between the two antibodies. For example, it has been shown that birch pollen can have a cross reactivity with peanut, hazelnut, potato, soy and almonds or foods that contain similar storage proteins, such as peanut, lentil, soy, pea and walnut can have a cross reactivity.

CanAlt IgG Food Intolerance Test

CanAlt’s IgG food intolerance test is a valuable tool to take out the guesswork and help patients to a better quality of life. The test uses microarray based ELISA technology that measures IgG antibody levels to over 200 different foods. The panel includes the foods that are common to food intolerances, such as dairy, eggs, wheat, soybean, and nuts as well as foods that can lead to an insensitivity, but may not be suspected, such as cola nut, rice, sunflower and sesame seeds.

Strict control processes are in place to ensure the quality of the foods used for testing and there is no contamination. The food antigens are applied to a nitrocellulose pad for testing, then reagents are added through a series of steps that result in the development of a fluorescent colour that is proportionate to the amount of IgG antibodies present. Each food is tested in duplicate and each patient test is run with known standards and controls providing confidence in the accuracy of the results.

The report provides quantitative results that can be used to help design an elimination diet. Eliminate the foods with the highest results and start re-introducing the foods with the lower results first.

Allergy or Food Intolerance

It is very important to understand the differences between an allergy and an intolerance. A food allergy is an immune reaction that results in the production of IgE antibodies. The reactions are usually immediate and symptoms can range from rashes, swelling, violent sickness, difficulty breathing and anaphylactic shock.

Food intolerances that are immune related result in the production of IgG antibodies and symptoms are usually not as severe and may not appear for several days.

If you have a food allergy, it is important to continue avoiding that food, regardless of the test results obtained in the Food IgG Intolerance Test. This advice also applies if you have been diagnosed with Celiac disease or any other food related conditions such as lactose intolerance