Electrodermal screening devices have been sold to Canadian naturopaths for forty years as instant diagnostic machines. Every controlled test of them has failed. Here is what is claimed, what the evidence says, and what regulators have actually done.
A patient sits down. A probe is pressed against a point on a finger or toe. A number appears on a screen. Within twenty minutes the patient is told which of her organs are “stressed,” which forty foods she is “sensitive” to, whether she carries heavy metals, parasites or mould, and which supplements — usually sold on the premises — will correct it.
The instrument is some descendant of electroacupuncture according to Voll (EAV), devised by the German physician Reinhold Voll in the 1950s. Its commercial offspring have carried dozens of names: Vegatest, Vega Expert, Dermatron, Interro, BioMeridian, LISTEN System, Avatar, ZYTO, Asyra, and the EPFX/QXCI/SCIO family. The trade calls them “bioenergetic screening,” “electrodermal screening,” or “meridian stress assessment.”
What every one of them physically measures is the same thing: the electrical resistance of a patch of skin. That reading changes with how hard the operator presses, how long the probe is held, how moist the skin is, and the angle of contact. It carries no information about a liver, a thyroid, a food allergy or a tumour.
| The claim | What the record shows | Verdict |
|---|---|---|
| “It detects energetic imbalance in your organs before disease develops.” | The device records skin electrical resistance at one contact point. That value is dominated by probe pressure, contact time, skin moisture and operator technique. No published work establishes that any organ-specific signal can be recovered from it. The underlying “meridian” model has never been demonstrated to correspond to any anatomical or physiological structure. | No basis |
| “It identifies your food and environmental sensitivities in a single session.” | Tested directly, twice, under blinding. Lewith and colleagues (BMJ, 2001) put 30 volunteers — 15 skin-prick positive, 15 negative — through 54 Vegatest readings each, across three operators and three sessions. The device could not separate the allergic from the non-allergic; no operator performed better than any other; not one participant was consistently classified correctly. Semizzi and colleagues (Clinical & Experimental Allergy, 2002) ran 100 subjects against sealed, randomised vials of allergen, histamine, immunoglobulins and saline, in duplicate. The device could not correctly diagnose respiratory allergy. | Refuted |
| “The right remedy is chosen by testing it in the circuit.” | This is the step the sealed-vial designs were built to test. When the operator cannot see which vial is which, the readings stop tracking the contents. There is no mechanism by which a sealed glass ampoule placed on a metal plate alters skin resistance at a fingertip. | Refuted |
| “It is an FDA-approved device.” | The FDA has permitted some galvanic-skin-response instruments onto the U.S. market as biofeedback devices and ohm meters. That is not clearance as a diagnostic device, and it says nothing about Canadian status. This exact discrepancy is documented in QuackeryWatch's own file on an Ontario complaint, where the practitioner's public web page called the machine “an electronic FDA approved device” while her own patient consent form stated the FDA has not approved EAV for treating any disease and approves it only as a biofeedback device and ohm meter — and that the device was used “for investigational purposes only.” | Misleading |
| “It screens for Lyme, parasites, mould, heavy metals and viral load.” | No validated diagnostic performance exists for any of these indications. The practical consequence is a pipeline: a fabricated positive leads to supplement regimes, “detoxification,” and in the worst cases to chelation therapy — which is the point at which this stops being merely a waste of money. | No basis |
| “Health Canada regulates the sale of devices, not my use of them.” | As a description of the Medical Devices Regulations this is broadly accurate, and it is the defence Canadian practitioners actually run — the College of Naturopaths of Ontario published an anonymised account of a registrant making exactly this argument after admitting the device's Health Canada licence had expired in 2017 and that they had bought it in 2018. But it is not a defence to a college. Advertising and professional standards bind the practitioner regardless of who the device regulations bind. | True but irrelevant |
There is a peculiar and useful piece of Canadian history buried in the citation list.
In 1997, a paper appeared in the Journal of Alternative and Complementary Medicine reporting that electrodermal testing had discriminated correctly 82% of the time between allergens and non-allergens. Its first author was Dr. Jozef Krop, a Mississauga, Ontario physician. One of his co-authors was George Lewith.
Four years later Lewith published the rigorous version in the BMJ — three operators, three sessions, full blinding — and the effect vanished entirely.
Krop, meanwhile, had been before the Discipline Committee of the College of Physicians and Surgeons of Ontario since 1994. In 1998 the Committee found him guilty of professional misconduct for failing to maintain the standard of practice in the care of six patients. Among the conduct at issue was his use of a Vegatest device to screen patients and to decide how to treat them. On 22 June 1999 he was reprimanded, and conditions were placed on his certificate requiring pre-approval steps before any further use of Vega testing, provocation-neutralisation testing and several other techniques. He appealed; the Divisional Court ruled against him, and leave to appeal to the Court of Appeal was refused. He relinquished his Ontario licence in 2010.
In 2002 Health Canada suspended the medical device licences for four Vega products: the Vegasom (licence 13264), Vega Audiocolor (13267), Vegaselect (13270) and Vegatest Expert (14736). Suspension prohibits the sale or importation of those devices in Canada.
That is a real and consequential action. It is also, as far as the public record goes, close to the end of it — twenty-four years ago, against four product licences, in a market that simply renamed the technology and carried on.
The College of Naturopaths of Ontario has been the regulator since 1 July 2015. Its published discipline outcomes contain no decision naming EAV, electrodermal screening or a Vegatest.
What exists instead is one anonymised account, published in the College's own members' newsletter iNformeD (Fall 2019, “ICRC Corner: Medical devices,” pp. 2–3). A registrant had been the subject of a complaint headed “Illegal scheme to defraud patients using EAV.” The registrant admitted the device's Health Canada licence had expired in 2017 and that they had purchased it in 2018, and argued that Health Canada regulates sale rather than use. The Inquiries, Complaints and Reports Committee also took issue with advertising phrases including “highly accurate assessment” and patients finding “swift and full recovery.”
The outcome was a letter of counsel. A letter of counsel is committee advice. It is not discipline, not a caution, carries no penalty, and appears nowhere on the public register. A member of the public checking that naturopath's listing would see nothing at all.
QuackeryWatch's own file on the Stratford complaint (CONO 18-035) — documented at Dawn Cormier, ND — matches that anonymised account on three verbatim advertising phrases and on the sale-versus-use argument. The College's newsletter states details were altered for confidentiality, so the identification is an inference from the documents held, not a certainty. What is certain is that the matter was never referred to Discipline and no finding of misconduct exists.
Lewith GT, Kenyon JN, Broomfield J, Prescott P, Goddard J, Holgate ST. “Is electrodermal testing as effective as skin prick tests for diagnosing allergies? A double blind, randomised block design study.” BMJ 2001;322(7279):131–4. • Semizzi M, Senna G, Crivellaro M, Rapacioli G, Passalacqua G, Canonica WG, Bellavite P. “A double-blind, placebo-controlled study on the diagnostic accuracy of an electrodermal test in allergic subjects.” Clin Exp Allergy 2002;32(6):928–32. • Krop J, Lewith GT, Gziut W, Rădulescu C. J Altern Complement Med 1997;3:241–8. • Quackwatch, “Regulatory Actions Related to EAV Devices” and “Disciplinary Action against Jozef Krop, M.D.” • College of Physicians and Surgeons of Ontario, public register entry for Dr. Jozef Krop (CPSO #29036), Discipline Committee decision and 22 June 1999 penalty order. • College of Naturopaths of Ontario, iNformeD, Fall 2019, “ICRC Corner: Medical devices,” pp. 2–3. • CONO discipline outcomes page, reviewed July 2026. • Health Canada, Medical Devices Active Licence Listing (MDALL) and Medical Devices Regulations.