In this article, I investigate the scientific evidence behind IgG Food Intolerance Testing to determine if the tests are worthwhile or simply a complete waste of time and money.

A food intolerance is much more common than a food allergy and common symptoms include headaches, fatigue, stomach upset and Irritable Bowel Syndrome (IBS).  The triggers are often substances that naturally occur in foods, arise in food processing method or are added during processing; food additives (MSG) or salicyclates which naturally occur in some foods such as spices.  Enzyme deficiencies e.g. lactose may lead to an intolerance to dairy products.  IBS is bowel condition which can cause abdominal bloating, pain, cramping, constipation and diarrhoea; these symptoms can be also linked with certain foods.  The symptoms of food intolerances are usually delayed, which explains why they are difficult to diagnose.

Food intolerance testing has become increasingly popular in recent years.
A growing number of pharmacies in addition to complimentary therapists and private health clinics offer intolerance testing services directly to the public.These test centres claim that food intolerances are associated with health problems such as chronic fatigue, fibromyalgia, arthritis, sinusitis, skin problems, irritable bowel syndrome and even obesity.

The tests involve taking a small sample of blood to check the levels of IgG antibody (immune system activity) for a range of various foods e.g. shellfish, wheat and nuts.  If IgG antibody levels are elevated for particular foods, the test centres diagnose an intolerance and recommend complete exclusion from the diet to relieve symptoms.  These tests cost €100-€250 approximately depending upon the number of foods tested.

The websites marketing food intolerance testing claim that there is sufficient scientific evidence to prove that these tests are warranted when food intolerance is suspected.  Having examined these studies, many of the trials involved small numbers of people tested twenty years ago,  therefore applications to the general population are dubious. Many of the leading food allergy and intolerance institutes around the world are currently advocating against IgG food intolerance testing.

There appears to be no correlation between high levels of a particular food antibody and the development of symptoms.   High levels after testing only indicate the person has consumed a particular food in the past and the immune system has “acknowledged” this food.  According to The Canadian Society of Allergy and Clinical Immunology, positive test results are to be expected in normal, healthy adults and children. Furthermore, the inappropriate use of this test only increases the likelihood of false diagnoses being made, resulting in unnecessary dietary restrictions and decreased quality of life.

The European Academy of Allergy and Clinical Immunology does not support testing either stating “they should not be performed in case of food-related complaints”  The scientists at the UK House of Lords Science and Technology urge GP’s, pharmacists and charities not to endorse the use of these products until conclusive proof of their efficacy has been established.

Food Exclusion

At present, the “gold standard” method for determining if a food intolerance exists is to follow an elimination or exclusion diet.  The elimination approach helps to pin-pointing the culprit food within 2-8 weeks and it’s the preferred method as recommended by health professionals, Allergy UK’s Intolerance Group and the NICE guidelines for the treatment of Irritable Bowel Syndrome.  Guidance from a health professional such as a Dietitian or Doctor is essential to ensure that the correct type of diet is followed and to avoid any risk of nutrient deficiency in the long-term.

More detailed information and references regarding the lack of scientific evidence behind food allergy / intolerance testing is available upon request.

Article published in the Kilkenny reporter March 2013.