ALCAT and IgG testing for food allergy, intolerance and other disorders: The Reality!!
As an allergy practice in the valley, we are always asked about the reliability and appropriateness of the ALCAT and IgG food allergy tests. Infact, we see at least, one patient a week bringing this detailed food testing to our office and wondering if they should be practicing this diet of “mild”, “moderate”, “severe” or better yet, “red”, “yellow”, “green” diets. Most recently, I saw a frustrated father who has put his child on this strict diet hoping to treat his recently diagnosed ADHD. I couldn’t even offer a piece of chocolate to the child based on these tests. The manufacturers of ALCAT and the IgG test claim that the tests have diagnostic value in identifying foods responsible for food allergies and intolerance reactions. These tests are available to the public and health care providers, claiming to be more reliable than traditional skin prick tests or serum specific IgE tests. Till date, neither ALCAT nor IgG has published any data supporting their work or any predictive value of these tests in the diagnosis of allergy or intolerances.
The ALCAT test measures cellular swelling or cell lysis when cells are exposed to test substances (e.g. foods) in vitro. The test is supposed to assess the relationship of food causing variety of conditions such as: migraine, headaches, ADHD, autism, depression, anxiety, irritable bowel syndrome, inflammatory bowel disease, eczema, urticaria, Candida, autoimmune diseases, fibromyalgia and chronic fatigue. Research has shown that the ALCAT’s predictive value for these tests is extremely poor and not of benefit in identifying the trigger of the patient’s symptoms. Consensus statements released by Allergy Societies throughout the world (The European Academy of Allergy and Immunology The American Academy of Allergy Asthma and Immunology, The Allergy Society of South African, Australian Allergy Society, The British Society for Allergy and Clinical Immunology etc.) states that these tests do not provide any diagnostic value for any disease based on no peer reviewed publication or research study supporting their value.
Specific IgE test’s diagnostic value have been proven time and again for allergic disorders. Although there is a correlation of IgG and allergic response, there is no evidence to show that it can predict food allergies. IgE specific food testing is available for three decades and has been studied. It is published that IgG responses are a normal physiological response to ingested food proteins and can be commonly detected in healthy adults and children, independent of the presence or absence of food-related symptoms. There is no reliable evidence that measuring IgG antibodies is useful for diagnosing food allergy or intolerance, nor that IgG antibodies cause symptoms. (The only exception here bring the use of gliadin, tranglutaminase and endomysial IgG antibodies in celiac disease.) Conclusion Both the ALCAT and IgG tests for so many foods (upto 100 foods at a time) costs patients a huge amount of money. Furthermore, testing so many foods without obtaining a dietary history of possible associations is neither economical nor useful for diagnosis. These unproven techniques lead to misleading advice or treatments. Hence, its highly unlikely that this would help patients. Isolated claims of “success” provided by the manufacturers should be substantiated by double blind controlled challenge tests using scientific methodology. We, at The Allergy Group, would like to caution public of these tests and these test-based diets till future research can prove any diagnostic or therapeutic value. Learn more about food allergy.
- Allergy2008: 63: 793–796 Ó 2008 The Authors Journal compilation Ó 2008 Blackwell Munksgaard DOI: 10.1111/j.1398-9995.2008.01705.x