Food Intolerance Tests: Can You Trust Their Results?

Published on: 05/02/2023

I bet at some point we have all considered purchasing food intolerance tests. Diagnosis of IBS can sometimes take up to 7 years and it is estimated 2/3 of cases remain undiagnosed.

Even after diagnosis most sufferers are left trying to manage the condition on their own with minimal help from their doctor or other healthcare professionals. I am sad to say I see this happen way too often. Unquestionably, this leaves individuals with IBS anxious, frustrated and still in search of answers. 

I know from personal experience that IBS symptoms can significantly impair quality of life. My doctor at the time (about 10 years ago) did no tests, declared it was probably IBS and said I should purchase Buscopan. Which I did, however this made no difference to my symptoms whatsoever. My symptoms got progressively worse, so did my anxiety and I became fearful of leaving the house. 

These feelings are common amongst individuals with IBS as studies have shown poorer quality of life, increased anxiety, increased absenteeism at work and a reduction in productivity 1,2,3,4. With such a huge impact on day-to-day life and dissatisfaction with poor healthcare provision it is no wonder that people with IBS look elsewhere for answers!

However, there is a lot of conflicting information online. As a result this makes it very difficult to know what will actually help and what is worth spending your hard earned money on. 

That is where I come in! Through this blog I will look at the most common recommendations touted to be the next IBS cure and summarise the evidence for you! Let’s start with IgG food intolerance tests like the York test. 

What are IgG Food Intolerance tests?

IgG food intolerance tests are blood tests which look for IgG antibodies in your blood. They claim high levels of these antibodies show an intolerance to a specific food.

The Facts

There are numerous companies offering IgG food intolerance tests however current scientific evidence does not support their use. 

Why are food intolerance tests not backed by science?

  1. We make IgG antibodies after long exposure to a specific food 6
  2. Studies have not yet shown a link between the presence of IgG antibodies and symptoms. 
  3. Healthy people with no symptoms also have high levels of IgG antibodies 7
  4. Some studies also argued that high levels of IgG antibodies may actually show tolerance to the food 6

So the evidence shows no link between IgG antibody levels and food intolerance. 

Eliminating foods based on these tests may lead to an unnecessarily restricted diet and possible nutritional inadequacies. A small randomised control trial showed that only 28% of participants noticed an improvement in their symptoms after eliminating foods they had high levels of IgG antibodies for  with 67% noticing no change and 5% noticing worsening in their symptoms. This shows results are variable and inaccurate. As a result, IgG food intolerance tests cannot be recommended to identify food intolerances and healthcare professionals do not recommend them 6,9.

So how can I find out which foods I am intolerant to?

Unfortunately, there is no quick fix for this. If your symptoms are due to an allergic reaction, reliable tests do exist such as skin prick testing and a blood test which looks at IgE antibodies called RAST. 

However the only way to identify an intolerance is to undertake an elimination diet under the guidance of a dietitian who can help guide you in what elimination diet is right for you whilst ensuring a nutritionally balanced diet. Keeping a food and symptom diary may also be effective in identifying any patterns in your diet which may be contributing to your symptoms. Write down what you eat in detail including quantities, and your symptoms including their severity and duration. Be mindful that food may not be the only culprit but how you eat, stress, anxiety, lack of sleep and movement may all play a role.


  1. Drossman, D.A. and W.L. Hasler, Rome IV-Functional GI Disorders: Disorders of Gut-Brain Interaction. Gastroenterology, 2016. 150(6): p. 1257-61.
  2. Agarwal, N. and B.M. Spiegel, The effect of irritable bowel syndrome on health-related quality of life and health care expenditures. Gastroenterol Clin North Am, 2011. 40(1): p. 11-9.
  3. American College of Gastroenterology Task Force on Irritable Bowel, S., et al., An evidence-based position statement on the management of irritable bowel syndrome. Am J Gastroenterol, 2009. 104 Suppl 1: p. S1-35.
  4. Hungin AP, Chang L, Locke GR, et al. Irritable bowel syndrome in the United States: prevalence, symptom patterns and impact. Aliment Pharmacol Ther 2005;21:1365-75.
  5. Knott V, Holtmann G, A. Turnbull D, et al. Abstract: M1253 Patients’ Satisfaction with Specialist Gastroenterologist Consultation for Irritable Bowel Syndrome (IBS)and Health Care Utilisation: Exploring the Role of Patient Expectations, 2009.
  6. Stapel, S.O., et al., Testing for IgG4 against foods is not recommended as a diagnostic tool: EAACI Task Force Report. Allergy, 2008. 63(7): p. 793-6.
  7. Kruszewski J , Raczka A, Klos M, et al. High serum levels of allergen specific IgG-4 (asIgG-4) for common food allergens in healthy blood donors. Arch Immunol Ther Exp 1994;42:259–61.
  8. Atkinson W., Sheldon T.A., Shaath N., Whorwell P.J. (2004) Food elimination based on IgG antibodies in irritable bowel syndrome: a randomised controlled trial. Gut 53: 1459-1464
  9. Teuber S.S and Porch-Curren C (2003) Unproved diagnostic and therapeutic approaches to food allergy and intolerance. Current Opinion in Allergy and Clinical Immunology 3(3): 217-221


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Daniela is a dietitian passionate in helping those with gut issues. 

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