IgG stands for Immunoglobulin (type G). Immunoglobulins are a class of proteins that function as antibodies produced by the immune system in response to foreign bodies entering the body. There are several different types of immunoglobulins with IgA, IgE, IgG, IgM being the most well-known.
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, lethargy, bloating, constipation, diarrhoea, flatulence, nausea and irritable bowel syndrome (IBS).
C-reactive protein (CRP) is an acute inflammatory protein produced by the liver in response to inflammation. It is considered a non-specific “marker” for disease and infection. Inflammatory markers are known as acute phase reactants, others include erythrocyte sedimentation rate (ESR) and ferritin. They can be used separately or together to monitor a person’s health.
What is the difference between CRP and hs-CRP?
They both measure the same protein, but hs-CRP (high sensitivity) is a more sensitive test enabling low grade inflammation to be detected. Low grade inflammation may contribute to obesity, insulin resistance, diabetes mellitus, atherosclerotic vascular disease, and other chronic health conditions.
hs-CRP is a tool for assessing low grade inflammation. It is used medically to predict a healthy person’s risk of heart attack or other heart conditions as part of a cardiovascular profile. Those with hs-CRP results in the highest quartile have 2-4 times the risk of developing atherosclerosis compared to those in the lowest quartile. Within a functional medicine approach the test is used as a marker to identify the presence of low-grade inflammation and results can be used to monitor a person’s health establishing the effectiveness of recommended protocols.
Why combine a hs-CRP test with a FoodPrint test?
Combining a hs-CRP test with a FoodPrint test can be a great tool to monitor the success of the recommended IgG elimination diet. We suggest an initial baseline test and a second test 3 months after dietary intervention strategies have been implemented. A reduced second test score may help to indicate the success of the recommended treatment protocol and help to motivate an individual to continue to follow the implemented lifestyle changes.
If the score remains high, or increases, a general practitioner referral may be suggested to establish the cause.
Please see FP200 and hs-CRP for specific questions about each test.
Considerations before taking the test
Can I take the test if I am pregnant?
A food sensitivity test is not recommended during pregnancy as the immune system is suppressed. However, 4-6 weeks after giving birth should be ok.
What is the lower age limit for testing?
Our 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 sensitivity 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 medications may affect the results?
Antibody Therapy, Immunosuppressant, Chemotherapy, Radiotherapy.
This test is not suitable for anyone undergoing treatment for cancer or taking biologic drugs or other immunosuppressants.
Food extracts are 'printed' onto nitrocellulose 'pads'™ on a glass microscope slide, together with calibration standards and controls. A sera or plasma 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 FoodPrint ® 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 re-introduce foods before taking a FoodPrint test? If so, how long for?
In general, we recommend that you follow your normal diet, so that the test will reflect what you usually eat. However, if you have specifically avoided a food, which you are not allergic to, for more than three months e.g., cow's milk, which used to be part of your normal diet and you would like it tested, we would recommend it is reintroduced. The recommendations are to reintroduce the food for 1 week eating a normal portion of that food at least once daily before taking your blood sample. If symptoms occur once the food is re-introduced, we recommend that you discontinue that food and conclude you are still sensitive to it.
NB: If you have a known allergy to any food, coeliac disease or any food intolerance do not reintroduce this food into your diet. Food sensitivity tests do not identify IgE-mediated food allergies or provide information about coeliac disease, enzyme deficiencies such as lactose, histamine, tyramine or alcohol intolerance or indeed other chemical sensitivities, such as reactions to certain food additives.
Food sensitivities are commonly associated with delayed reactions up to 72 hours – why?
It is important to differentiate a food sensitivity (IgG) and a food allergy (IgE).
A classic food allergy, such as a peanut or shellfish allergy, is usually characterised by an immediate and often severe reaction upon exposure to the offending food. Symptoms include sneezing, rashes, skin irritation, swelling of mucosal tissue and fatigue and could potentially be life threatening. Such allergic reactions usually involve IgE antibodies.
Food sensitivity tends to be characterised by a delayed onset of symptoms and often involves the production of IgG antibodies which can lead to the formation of immune complexes and release of inflammatory markers. Symptoms may occur several days after eating the offending food, making it difficult to identify the cause.
If the response to food and drink is immediate, please refer to your doctor or Allergy specialist to rule out a suspected allergy.
Is it possible that I am affected by foods that do not show up in my IgG food test?
Yes - some foods may cause a classic allergic reaction involving the production of IgE antibodies. These will not be detected by any IgG food test. There are also many foods that can cause a reaction in the body without involving the immune system but produce symptoms similar to IgG reactions. For example, amines in chocolate, cheese and red wine may cause migraines; some food additives such as tartrazine can cause hives, rashes and asthma; monosodium glutamate in Chinese dishes can produce sweating and dizziness; ‘Nightshade’ alkaloids in potatoes, tomatoes and peppers may affect the joints. Food intolerance may also be due to a deficiency of a particular enzyme, as in lactose intolerance. You should avoid any foods that you suspect are affecting you adversely.
