What I’ve learnt from 17 years of food intolerance research - Test Your Intolerance

I started work as an IT professional in 1997, quickly working my way up through the ranks from the help desk to server and network support teams, establishing myself as the systems security coordinator, and then transferring into a programming role. But, as time went on, my digestion and skin got worse – I had acne, bloating, constipation, nausea… I couldn’t get to the bottom of what was causing it, and neither could my GP, who could only offer me medications to address the symptoms (and even they didn’t help much!). Eventually, I saw a nutritional therapist privately who did some food intolerance testing with me, and identified a few key triggers – cows milk, hazelnuts, oats, and banana. Ironically, I had this combination of foods in a porridge for breakfast, every morning, thinking I was being super-healthy!

Inspired by the total change that I saw in myself within a few weeks of removing those trigger foods from my diet, I resigned from my programming role in 2006 to become a registered nutritional therapist and immediately started using IgG food intolerance testing to help my clients make informed dietary choices. I’m still using IgG food intolerance tests today and, in this blog, I want to share a few things I’ve learnt in my 17 years of food intolerance testing.

What is an IgG food intolerance test?

IgG (immunoglobulin-G) food intolerance testing looks for protein-based antibodies in the blood, produced by B cells of the immune system and secreted into the bloodstream to circulate. Looking at food-specific IgG antibodies allows us to assess levels of antibodies being produced in response to consumption of specific foods e.g. cows milk, wheat, egg white etc.

How is an IgG food intolerance test done?

IgG testing is done as a blood test. Some labs require a venous blood sample taken from a vein in the arm while others, such as Healthy Stuff, use a small finger prick blood sample. Either method is valid for testing for food-specific IgG antibodies.

Are there any risks to consider when having an IgG food intolerance test done?

The only risk is in having your blood sample taken – either a venous blood draw, or a finger-prick blood draw may result in bruising to the local area, with an increased risk of infection while the area heals. You may feel faint or light-headed when having your blood sample taken. If this has happened to you in the past you’re not alone, it’s called a vasovagal syncope reaction or episode, and is not normally harmful.

What does it mean if IgG levels are raised?

If a food-specific IgG antibody is raised, e.g. cows milk, then it is a sign that you may be intolerant to cows milk proteins and I would recommend removing cows milk dairy products for a trial period of 8 weeks to assess changes in your symptoms.

Do I need to avoid all foods that I make IgG antibodies to?

You don’t necessarily need to avoid all foods that you are showing food-specific IgG antibodies to. If there are large numbers of raised food-specific IgG antibodies, this can correlate with an increase in intestinal hyperpermeability.

If you do have intestinal hyperpermeability, commonly known as leaky gut, then you may get some false positives in your IgG food intolerance results. This is because large amounts of food are leaving the intestines and entering the bloodstream through the leaky gut, and your immune system is quite rightly making antibodies against these foreign bodies in the blood stream. However, you may not be reacting to all of those antibodies. Discussing your test results with a health professional will help you to gain clarity over what foods to avoid and for how long, and how to manage the intestinal hyperpermeability.

What are the limitations of IgG food intolerance testing?

Looking at IgG antibodies to assess for food intolerances and optimise dietary choices is a useful test for many. However, it is not without its limitations. As previously mentioned, false positives are possible in the event of intestinal hyperpermeability. IgG tests are also not suitable for testing for allergies – these can only be identified through specific-IgE antibody testing and a skin prick/patch test which will not show on an IgG test. If in doubt, it is recommended that you discuss your symptoms with a healthcare professional who can then assist you with choosing the most appropriate test for you.

Should I get an IgG food intolerance test done?

Without knowing your full case history it would be impossible for me to say yes or no – this is a conversation for you to have with a healthcare professional who can help you to determine whether testing is appropriate for your specific situation. In the 17 years that I’ve been using food intolerance testing, I know that I’ve found it to be incredibly useful for the vast majority of my clients whilst also working together on other aspects of their health. So much so, that I’ve included it as part of my latest book, on testing for food allergies, intolerances, and sensitivities. If you’re showing symptoms of a food intolerance why not get tested with one of our intolerance tests!