versão On-line ISSN 2078-5135
SAMJ, S. Afr. med. j. vol.98 no.3 Cape Town Mar. 2008
Dr Sharon Kling
To the Editor: Since we are constantly consulted about the reliability and appropriateness of the ALCAT and IgG food allergy tests, we provide the following information for readers of the journal and the public.
The ALCAT and the IgG test claim to have diagnostic value in identifying substances responsible for allergic and intolerance reactions. These tests claim to be more effective than traditional allergy tests, particularly for delayed allergic reactions.
The manufacturers of the ALCAT test argue that orthodox allergy practice does not recognise delayed allergic reactions, when in fact these reactions are universally acknowledged to play a role in up to 30% of the spectrum of allergic reactions! The manufacturers argue that the test is predictive for assessing and diagnosing a variety of conditions such as attention deficit disorder (ADD)/attention deficit hyperactivity disorder (ADHD), autism, allergies, hay fever, asthma, chronic sinusitis, urticaria, candida, autoimmune diseases, obesity, and even poor memory. They claim that the test is 'The world's gold standard' and '... recently cited as the world's number 1 food sensitivity test'.
The ALCAT was evaluated in the Allergy Unit at Groote Schuur Hospital in 1994 by the University of Cape Town's Respiratory and Gastrointestinal Units and the Allergy Clinic at Red Cross Children's Hospital in patients with asthma, eczema and irritable bowel syndrome. Its predictive value was found to be extremely poor and not of benefit in identifying the trigger of the patient's symptoms. There was no improvement in the patients who were followed up by a doctor and a dietician, using the diets recommended by these tests.1,2
Consensus statements released by allergy societies throughout the world as well as the World Allergy Organization do not recommend the use of this test in the evaluation of acute or delayed allergic or intolerance reactions.3-7 Significantly, not a single non-allergy clinical society worldwide has supported the use of the ALCAT. These viewpoints have been reiterated in recent international reviews of allergy diagnostic tests.4-5 It is significant that there are also no peer-reviewed publications or any reasonable studies to support a diagnostic value for the ALCAT.8-10
The second test marketed with insufficient documentation is the IgG test for food allergies, ADD and obesity. There is no published evidence for these claims. Although IgG does play a role in the allergic response, there is no evidence to suggest that it has a diagnostic value in predicting food allergens or other substances that may affect individuals.5 Strong IgG responses have been demonstrated to be a normal physiological response to certain proteins that are frequently ingested under certain circumstances, and are commonly detectable in healthy adult patients and children, independent of the presence or absence of food-related symptoms.11-14
Teuber and Beyer noted: '[The role of IgG] is certainly a question for further research and emphasizes that it is far too early to encourage patients or insurers to spend money on blood test panels that are suited for research, and not clinical applications at this time'.15 It is disconcerting that the marketers of the IgG substantiate the use of their tests with studies that actually argue against the use of the test.16
In our opinion, it is wrong to market tests with little scientific validity. Both the ALCAT and IgG tests for 'panels' of allergens cost patients up to R3 500. We have first-hand knowledge of patients who have been placed in financially compromising situations after paying for such tests, with no relief of their conditions.
Furthermore, testing so many (up to 100) foodstuffs in the 'fixed' panels is neither economical nor useful for diagnosis. As a result, these unproven techniques lead to misleading advice or treatments. We would therefore caution patients and doctors to be fully informed of the sensitivity and specificity of such testing, and to consider the evidence when contemplating such tests.
Allergy Society of South Africa
PO Box 88 Observatory 7935
1. O'Keefe E, Steinman HA, Potter PC, O'Keefe S. Evaluation of the ALCAT test in reactions to food in the Irritable Bowel Syndrome. Poster: South African Gastroenterological Society Annual Congress, October 1993. [ Links ]
2. Pitt A, Bateman ED, Steinman H, Potter PC. Lack of correlation between self-reported food intolerance, food challenge testing and results of the ALCAT system in chronic adult asthmatics (abstract). Current Allergy & Clinical Immunology 1994; 7(3): 7. [ Links ]
3. European Academy of Allergology and Clinical Immunology: Sections-Interest Groups - Allergy Diagnosis - Controversial diagnostic tests. http://www.eaaci.net/site/content.php?l1=91&sel=323 (accessed 6 November 2007). [ Links ]
4. Ortolani C, Bruijnzeel-Koomen C; Bengtsson, U, et al. Controversial aspects of adverse reactions to food. Allergy 1999; 54(1): 27-45. [ Links ]
5. Australasian Society of Clinical Immunology and Allergy: Cow's Milk (dairy) allergy. http://www.medeserv.com.au/ascia/aer/infobulletins/hp_allergy_milk.htm (accessed 6 November 2007). [ Links ]
6. Global Resources In Allergy (GLORIAÂ) - The Diagnosis of Allergic Diseases. http://www.3bel.dote.hu/oktatas2007/eload2007ang/Nekam%20TOK%20eloadas%20Allergy.ppt (accessed 6 November 2007). [ Links ]
7. Potter PC, Mullineux J, Weinberg EG, et al.The ALCAT test - inappropriate in testing for food allergy in clinical practice. S Afr Med J 1992; 81(7): 384. [ Links ]
8. Teuber SS, Porch-Curren C. Unproved diagnostic and therapeutic approaches to food allergy and intolerance. Curr Opin Allergy Clin Immunol 2003; 3(3): 217-221. [ Links ]
9. Niggemann B, Grüber C. Unproven diagnostic procedures in IgE-mediated allergic diseases. Allergy 2004; 59(8): 806-808. [ Links ]
10. Beyer K, Teuber SS. Food allergy diagnostics: scientific and unproven procedures. Curr Opin Allergy Clin Immunol 2005; 5(3): 261-266. [ Links ]
11. Paganelli R, Quinti I, D'Offizi GP et al. Immune-complexes in food allergy, a critical reappraisal. Ann Allergy 1987; 59: 157-161. [ Links ]
12. Tay SS, Clark AT, Deighton J, King Y, Ewan PW. Patterns of immunoglobulin G responses to egg and peanut allergens are distinct: ovalbumin-specific immunoglobulin responses are ubiquitous, but peanut-specific immunoglobulin responses are up-regulated in peanut allergy. Clin Exp Allergy 2007; 37(10): 1512-1518. [ Links ]
13. Enrique E, Pineda F, Malek T, et al. Sublingual immunotherapy for hazelnut food allergy: a randomized, double-blind, placebo-controlled study with a standardized hazelnut extract. J Allergy Clin Immunol 2005; 116: 107-109. [ Links ]
14. ASCIA Position Statement: Unorthodox techniques for the diagnosis and treatment of allergy, asthma and immune disorders. Dr Raymond J. Mullins on behalf of the Education Committee, ASCIA October 2004. http://www.allergy.org.au/pospapers/unorthodox.htm (accessed 6 November 2007). [ Links ]
15. Teuber SS, Beyer K. IgG to foods: a test not ready for prime time. Curr Opin Allergy Clin Immunol 2007; 7(3): 257-258. [ Links ]
16. Sampson HA. Food allergy. Part 1: immunopathogenesis and clinical disorders. J Allergy Clin Immunol 1999; 103(5 Pt 1): 717-728. [ Links ]
Dr Sharon Kling