Do food intolerance tests actually work?

Yes, food intolerance tests can be effective in identifying foods that cause adverse reactions. These tests measure IgG antibodies in your blood, which indicate sensitivity to specific foods. Independent studies and clinical practice have shown that eliminating foods identified through these tests can lead to significant symptom relief, especially for conditions like bloating, IBS, food realated energy dips and others . However, it's important to interpret results with the guidance of a nutrionist / dietian.

Can my GP do a food intolerance test?

An NHS GP's in the UK doesn't offer food intolerance testing, but verious GP's around the world do offer a blood based food intolerance test to aid symptoms. Alternatively, there are few blood based CE marked home test kits available that can be used with guidance from a nutritonist to interpret the results accurately.

What is the most accurate food intolerance test?

The most accurate food intolerance tests are those that use blood samples to measure IgG 1,2,3 and 4 antibodies against a wide range of foods using microarray technology. ELISA-based tests are considered reliable and provide detailed insights into food sensitivities. These tests are clinically validated and widely used in medical diagnostics for their precision and reliability.

What is the test method?

Our food intolerance tests are done using a blood based method covering IgG 1,2,3,4, the blood sample collection process is done via a pin prick to the finger, it takes around 4-5 large droplets.

Why do food cause an IgG antibodies response?

Generally, foods are broken down during digestion into their component parts e.g. amino acids, glycerides etc. These pass harmlessly through the gut as the gut becomes inflamed (bloated) these proteins enter the bloodstream. This is where they are recognized by the immune system as being ‘foreign’. The immune system responds by making IgG antibodies to these foods.

What is the difference between hair and blood based test?

You can't test immune reactions via a hair sample, and in many cases there have been discrepancies in results when parts of the hair have been coloured/bleached. This has led to inconsistency in the sample tested twice. 

Our IgG 1,2,3,4 blood based testing covers the full range of antibodies responses, this is important, if a particular food elevates any antibodies against it, this means your gut and immune system recognises that food as a threat. This could affect the nutrients absorbed from this particular food and leads to multiple symptoms. For a detailed comparison, visit our Blood vs Hair Strand Testing page.

Do high IgG antibody levels cause symptoms?

When a food causes the body to produce high levels of IgG then these antibodies combine with the protein in the food to form an ‘antigen-antibody complex’. These complexes are usually eliminated by other cells in the immune system. However, if the immune system is overloaded, these insoluble molecules become deposited in tissues within the body, causing chronic inflammation and the subsequent production of symptoms.

Why test for IgG antibodies to foods?

The efficacy of a diet based on the measurement of IgG antibodies specific for food components has been demonstrated in a number of conditions, both in independent studies and clinical practice. Excellent results have been obtained in patients with migraine, IBS and obesity.

What is the lower age limit for testing?

Supply Life's existing policy for a lower age limit on testing for IgG food antibodies is that we do not recommend testing on children under the age of 2 years. We base this on the European Society for Paediatric Gastroenterology, Hepatology, and Nutrition Guidelines for the Diagnosis of Coeliac Disease 2012, which states that there is a possibility of false negative results occurring in infants younger than 2 years of age. This related to the fact that the infant gut is more permeable than that of an adult coupled with immature mucosal immunity that is still in the learning and development stage. We have used this criterion as antibody measurements in Coeliac Disease are comparable to food IgG measurements used in our food intolerance tests. However, we are aware that there are in fact no published guidelines that specifically indicate a minimum age for testing for such IgG antibodies, for example the guidelines for testing for coeliac antibodies indicate that such testing can be performed any time after the introduction of gluten into the diet. Therefore, where such requests are received from a statutory regulated professional the decision of when and what tests to perform will remain the responsibility of the requesting clinician.

What should be considered before testing - Is there any medication that I should avoid when taking a food intolerance test, due to its potential effects upon the results?

Customers should avoid the use of immunosuppressant medication if possible if performing these tests, as they may have an impact upon the results. Please refer to the medication datasheet in the “Support” section for further details.

How does the test work?

Food extracts are 'printed' onto nitrocellulose 'pads'™ on a glass microscope slide, together with calibration standards and controls. A blood sample provided by the patient is diluted and dispensed onto each printed microarray. Food IgG antibodies, if present, bind to the food extracts and the results are measured by a high-resolution scanner, before being calibrated against the standards using the reporting software to give quantitative results. This software then produces a tailor-made printout of the final food IgG antibody result for each food on the requested food panel.

Do you need to full the microvette all the way to the white line?

Although it is advisable to completely fill the tube, a half filled microvette tube should be enough to run the test. If there are any problems with a sample and the lab will let the customer know. However, if you are ordering two tests we can test from one sample if you provide a full microvette.

Do you need to store the blood in the fridge, if not sending the same day?

Yes, it does need to be stored in the fridge with the lid secured if not sending on the same day.

Can I upgrade my test to a larger food panel?

You can upgrade for up to a maximum of 4 weeks from the date that your first sample is received.

What are the sample requirements and test turnaround?

A pin-prick blood sample is required. Results are available within 10 working days.

Does the Supply Life test for all subclasses of IgG antibody or only IgG4?

Our process screens for all IgG subclasses 1-4, with the numbers on the test report representing the total IgG concentration for each food extract in the selected panel.

What is the difference between a food allergy and a food intolerance?

A true food allergy triggers an immune system reaction that can affect multiple organs in the body, leading to a range of symptoms that can be severe or even life-threatening. In contrast, food intolerance typically results in less serious symptoms, often limited to digestive problems.

Both terms relate to adverse physiological responses to particular foods, but the mechanisms differ. Reactions can be immunological (IgE or IgG mediated) or non-immunological, causing immediate (minutes to hours) or delayed (several hours to days) responses. Identifying the specific reactive mechanism is crucial for effective management and dietary interventions to prevent unpleasant or dangerous symptoms.

What are the four symptoms of food intolerance?

The two most common symptoms of food intolerance are:

  • Digestive issues (bloating, gas, diarrhoea, or constipation)
  • Food related energy dips / food coma 

However there other many other symptoms that people have reported 

Need some help?

Speak with one of our clinicians and get personalised advice.
Monday to Friday 9am-4:30pm


Unlock your full potential today

Get your easy to use food intolerance assessment today