Food Allergy Testing

IgG Food Antibody Testing

In the assessment of food intolerances the two most commonly used options in integrative medicine are elimination diets and IgG4 food antibody testing. Neither are perfect – each has its own advantages and disadvantages – these are compared in the table below.

This type of allergy is sometimes referred to as “hidden” or “delayed”.  If the symptom history suggests possible involvement of food intolerances we recommend undertaking either of these strategies, though sometimes both might be needed.

Elimination Diet

IgG Blood Test

Pros

  • “Free”- though may need several progress consultations
  • High reliability for most commonly reactive foods
  • Tests for non-immune mediated intolerances
  • Minimal effort involved
  • Assesses reactions to 96 foods (plus extras if required)
  • Can also test herbs & spices

Cons

  • Requires commitment & motivation
  • Can take a long time
  • You cannot make other dietary changes during elimination diet
  • Cost (~ $300)
  • Can get false positives & false negatives
  • Must have been eating food in question

As with many tests we don’t recommend using just any lab which offers the test. One noted integrative medicine expert did experiments sending blood to several different labs offering IgG testing. He found results varied significantly and the lab he concluded was the most reliable and consistent was US BioTek. This is the lab we currently use at House of Health. Levels of IgG (Immunoglobulin G) antibodies to specific foods are measured in blood as a measure of immune reactivity to the food in question.

To quote US BioTek:

“IgG antibodies represent the most prevalent class found in the blood. It is produced after reimmunization, or secondary response to antigen. It is the primary mediator of the memory immune response. Often involved in Type III delayed hypersensitivity reactions, IgG forms an immune complex with the allergen. This antibody/antigen complex activates complement (a group of small proteins found circulating in the blood stream that are involved in the release of inflammatory mediators), and enhances phagocytosis by opsonization. The inflammatory process is gradual and may take anywhere from several hours to several days, which is why this type of reaction is termed, delayed. Although immune cells called macrophages dispose of these immune complexes immediately, they only have a finite capacity to do so. Excess antigen may saturate the macrophages capacity resulting in the prolonged circulation of complexes and their deposition into the body tissues. Depending on which tissues are involved, it is thought that these complexes may be implicated in many different conditions/symptoms.”

The IgG test is a useful test, but like other laboratory tests it can give false positives and false negatives.  It is not absolute from 100% accurate. It provides a rough guide and should not be read as definitive findings. Testing negative for a food (e.g. wheat) does not rule out the possibility of intolerance and testing positive for a food does not definitely mean this food is contributing to your symptoms.

If you are outside of Auckland and would like to have this test done please contact us – we will give you instructions on how to do the test.  Once we receive the results we will schedule a telephone appointment  for discussing the results – it is important that all lab results are interpreted by a qualified health care provider, in the context of the clinical situation of the individual.