Are IgG Food Intolerance Tests reliable?

I bet at some point we have all considered purchasing a food intolerance test. Diagnosis of IBS can sometimes take up to 7 years and it is estimated 2/3 of cases remained 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 too often. This leaves individuals with IBS anxious, frustrated and still on a search for a answers. I know from personal experiences that IBS symptoms can significantly impair quality of life. My doctor at the time (about 7-8 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. As my symptoms got worse, so did my anxiety and fear 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 we look elsewhere for answers 5! However there is so much conflicting information online it can be 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!

What are IgG Food Intolerance tests?

IgG food intolerance tests look at the presence of IgG antibodies in your blood. They claim high levels of these antibodies are indicative of 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. IgG antibodies are produced by the body after long exposure to a specific food 6. Studies have not yet shown a link between the presence of IgG antibodies and clinical presentation of symptoms. High levels of IgG antibodies have also been recorded in healthy individuals with no symptoms 7. Some studies also argued that high levels of IgG antibodies may actually indicate tolerance to the food 6. So far evidence does not show a clear link between IgG antibody levels and food intolerance.

A small randomised control trial undertook IgG tests in a number of individuals with IBS 8. Participants were split in two groups; group 1 were asked to eliminate foods for which they had high levels of IgG antibodies, whereas group 2 were asked to eliminate a similar number of staple foods from their diet such as potato, rice and eggs. Participants followed these diets for 12 weeks. At the end of the study they were asked to reintroduce the foods eliminated. After 12 weeks 28% of participants in group 1 noticed an improvement in their symptoms, 67% noticed no significant change and 5% noticed a worsening in symptoms. In group 2, 17% of participants noticed a significant improvement in symptoms, 71% noticed no change and 12% noticed a worsening in symptoms. After reintroducing foods 56% in group 1 and 67% in group 2 noticed no significant change in their symptoms. So while some participants noticed an improvement the majority did not. Improvement in symptoms could have been to high FODMAP foods being eliminated by some such as wheat and milk. Due to this high degree of variability in results and inaccuracies it cannot be recommended as a diagnostic tool.

Evidence is currently lacking, hence these tests cannot be recommended to diagnose food intolerance 6,9. Eliminating foods based on IgG test results may lead to an unnecessary restriction of foods and possible nutritional inadequacies.

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

Unfortunately there is no quick fix for this. The best way to find out your food intolerances is to keep a food and symptom diary. Write down what you eat in detail including quantities, and your symptoms including their severity and duration. You may start noticing patterns.

I would also recommend seeing a registered dietitian who can help you identify food intolerances whilst ensuring nutritional adequacy. A dietitian trained in the low FODMAP diet can guide you through an elimination and reintroduction diet to help identify food intolerances. Children should not restrict their diets unless under the close supervision of a dietitian.


  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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