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What is IgG Food Intolerance Testing?

by Kate Young on Dec 06, 2019

If you’re looking to get food intolerance testing, chances are you’ll have come across a few different methods by now. One way you may have come across is ‘IgG testing’. Sounds official, but what is it? Today we’ll unveil the mystery and explain IgG food intolerance testing, and it’s efficacy.

What is IgG Food Intolerance Testing?

IgG testing uses a sample of either blood to look for food-specific antibodies in response to exposure to foods. The test measures your production of Immunoglobulin G (IgG) antibodies, hence the name ‘IgG Testing’. Immunoglobulins (AKA antibodies) are large, Y-shaped glycoprotein molecules. They’re produced by white blood cells. They act as a significant part of our immune response by recognising and binding to particular antigens, such as bacteria or viruses, and aiding in their destruction. In IgG food intolerance testing, your sample is analysed for food-specific antibodies after exposure to those foods. It is believed that reaching a threshold of IgG antibodies in response to a particular food indicates a food intolerance is present.

Is there Research Backing IgG Testing?

IgG antibody testing has the most published research available compared to other methods such as ALCAT or MRT. Studies have shown that eliminating foods from the diet, guided by IgG tests, can help improve symptoms in people with IBS and migraines. Blood sample IgG testing currently has the most research backing it.

IgG or IgG4 Testing?

There are four subclasses of IgG that can be analysed, IgG1, IgG2, IgG3 and IgG4. At Test Your Intolerance we test only for IgG4 rather than IgG1 or 1-4 as other intolerance testing companies do. This is a massive advantage as testing for only IgG4 leads to a reduced number of false-positives. Out of the four subclasses, IgG1 and IgG4 are the most commonly tested. These are produced in response to food antigens meaning we can identify their intolerances easier, with less irrelevant data. IgG1 antibodies are seen as ‘first responders’, if they struggle in destroying an antigen, they can activate further immune reactions, and can complement cascade and inflammation. This is why we test for IgG4 only, as the IgG1 is a first responder and doesn’t indicate a definitive intolerance.

Can Overindulgence Cause Food Intolerance?

You may be surprised to hear that overindulgence of a single food or food ingredient can actually cause an intolerance to develop. Since IgG1 responds first, it may then initiate a further response. Luckily though, food intolerances aren’t permanent like allergies, and you can potentially reverse the intolerance through time away from the food.

Author: Kate Young, BSc, Lab Manager

Kate Young joined Test Your Intolerance in 2020 after working in private laboratories in Japan for 15 years as a Clinical Bio Scientist and embryologist. As Lab Manager, Kate works on IVDR and GLP accreditation.