ZYTO: An Electrodermal Diagnostic Device Is Tested and Fails Miserably

ZYTO is a bogus, illegal electrodermal diagnostic device that claims to evaluate organ function and make dietary recommendations. Repeat testing produced results that were wildly inconsistent. The device produces noise, not meaningful information.


Dr. Stephen Barrett, the founder of Quackwatch, had abundant reason to believe the ZYTO electrodermal testing device couldn’t possibly work as claimed, but belief is not enough: science requires evidence from testing. He followed the advice we so often hear: “Don’t knock it until you’ve tried it.” He managed to obtain a ZYTO (The Elite 5.0) and he used it to test himself repeatedly. He reported his results on Quackwatch, in the journal Missouri Medicine (114:238-244, 2017), and in Skeptical Inquirer (41:5, p. 40-45, 2017). This is the first time such a study of an electrodermal diagnostic device has ever been published.

In my opinion, electrodermal testing is bogus. The devices are basically galvanometers that measure skin resistance. Galvanic skin resistance has no relation to diagnosis or treatment of any disease, but practitioners claim to diagnose and treat all diseases, food allergies, nutrient deficiencies, even defective teeth! I have written two previous articles about it: “Fooling Patients with a Computerized Magic Eight Ball,” and “Legal and Regulatory Aspects.” And Dr. Barrett has written an extensive critique on Quackwatch. He says, “The practitioners who use them are either delusional, dishonest, or both.”

Quackwatch lists 43 brands of these EAV (electroacupuncture of Voll) devices. Many of them rely on probes that are touched to specific points on the skin (“acupoints”). Those readings vary with the amount of pressure applied, the condition of the skin, and other factors. The ZYTO device attempts to minimize operator influence by using a cradle that the patients rest their hand on.

What ZYTO claims to do

The company website makes extravagant claims for what it calls “biocommunication” and “innovative decision support technology.” It “helps inform your wellness decisions by providing accurate readings directly from your body.” The patient rests a hand on the cradle, a computer program presents questions in the form of digital signatures, and the body answers directly by changing galvanic skin resistance. The questions might be ones the patient knew about and wanted answered, or they might be “unknown” questions.

  • The testing allegedly can help with all these personal wellness areas: energy, lifestyle, gut health, detoxification, relationships, weight loss, environmental factors, nutrition, performance, anti-aging.
  • The software evaluates 20 body organs to determine if their functioning is “in range” or “out of range.” It tests everything from the pineal to the spleen, from the thymus to the small intestine, from the lung to the pancreas. For the condition of each organ, they have allegedly determined unique digital signatures that are connected through acupuncture meridians.
  • Then it tests various remedies to see which ones show the most coherent responses – which supplements, homeopathic remedies, diet changes, or procedures would restore the “out of range” readings to “in range.”
  • It does a nutritional survey to determine which foods the individual should be eating or avoiding.
  • It generates a multi-page report with colored graphs and charts.
  • Manufacturers submit their products so the company can create a library of their digital signatures to test.
  • Testing can be done remotely by connecting a hand cradle to the client’s computer.

If all this sounds preposterous, that’s because it is.

Dr. Barrett’s results

Dr. Barrett did a total of 43 basic and nutritional scans on himself over a ten-day period. A series of 16 basic scans over four days identified an average of 11 organs that were out of range, but the organs varied from scan to scan, as did the direction (above or below range) and the corrective measures recommended. The organs that were furthest out of range were the adrenal glands (on 4 scans), the small intestine (3), the heart (2), the thymus (2), and various other organs (once each). Only four of the scans found any organs within range.

Dr. Barrett’s tests reported his gallbladder function as positively out of range 4 times, negatively out of range 4 times, and within range 8 times. Interesting, since he doesn’t have a gallbladder! He does have benign prostatic hypertrophy; his prostate failed to show up on one scan, and was reported as positively out of range on 7 scans, negatively out of range on 4, and within range on 8.

He went on to conduct 12 food category tests and 15 individual food assessments. The results were inconsistent. The category tests recommended avoiding:

  • Grains (10 tests out of 12)
  • Nuts and seeds (9 tests out of 12)
  • Fruits and vegetables (8 tests out of 12)
  • Fruits, vegetables and grains (5 tests out of 12)

One recommended only beans/legumes. One recommended only beverages, fish/seafood, meats/poultry, and spices/seasonings. One recommended only sugars/sweeteners! If clients were to follow ZYTO recommendations, there is a good possibility they would be dangerously malnourished.

The individual food assessment results were also wildly inconsistent. The same food could be positive (recommended) on one test and negative (not recommended) on a repeat test a few minutes later. Pineapple and red potatoes were among the top negative foods on 7 tests and among the top positive foods on 3 tests.

Dr. Barrett applied a statistical test and confirmed that the results did not differ from random. In other words, they were noise, not meaningful data. He points out that to demonstrate that a device can measure something, it must be repeatedly tested to evaluate its accuracy and consistency. The ZYTO company has not done any such tests. To demonstrate that the device can detect organ pathology, patients with disease would have to be tested against a control group without disease. ZYTO has not done any such tests. To demonstrate that a recommended corrective remedy or action improves outcomes, people who are treated would have to be compared to people who are not. ZYTO has not done any such tests.


ZYTO has FDA clearance, but only as a galvanic skin measurement device. It does not have FDA approval as a diagnostic device. The FDA has warned the company that selling or marketing it as a diagnostic device is illegal and that it was making unallowable claims; some of their software was recalled.  Users of the device often attempt to weasel out by claiming that it is not a medical or diagnostic device and instead calling it something like a “general wellness device” or a “biocommunication” device, and using non-diagnostic language like “out of range.” But a rose by any other name is still a rose. Customers are clearly led to believe that they are being diagnosed and treated.

Electrodermal diagnostic devices cannot be legally marketed in the US, and importation is banned. Regulatory actions have included confiscation of devices, criminal prosecutions, and professional licensing board actions. But there has been no systematic or effective effort to eliminate them, and they are still being widely used by various licensed and unlicensed practitioners.

Conclusion: Not only pseudoscientific but illegal

In my opinion, based on my research, electrodermal diagnosis is not based on reality but on a ridiculous hodgepodge of half-baked ideas borrowed from acupuncture, homeopathy, and so-called “energy medicine.” The claims are preposterous; there isn’t the slightest shred of science to support them. And thanks to Dr. Barrett we now have clear evidence that the results they produce are wildly inconsistent and clinically meaningless, and the recommendations are potentially dangerous. These abuses could be stopped by enforcing existing laws. These devices and the associated software should be removed from the market to protect consumers. Practitioners using the devices should be prosecuted.

Note: as I was writing this, I received an email from someone who had been tested with a related device, the Asyra. She had gone to Simply Health in Jackson Hole, Wyoming, where she saw Jennifer Nelson-Hawks, whose bio bills her as an iridologist and a “board-certified holistic health physician” but does not mention any medical training beyond “Certified Medical Assistant.” Asyra testing showed she had the “energetic signature for Lyme’s Disease” which was “concerning” although she “probably didn’t have the full-blown disease,” and she was told to take vitamin C to support her immune system, see a naturopath, and return for a follow-up with the Asyra tester in a month. She suffered a week of anxiety and panic, desperately contacting her GP and others for advice. She found my SBM article on electrodermal testing and contacted me to ask what I would do in her position, whether I would do anything to report the practitioner or her business. I encouraged her to report her experience to all the relevant authorities and to try to get her money back, since it was obtained under false pretenses. This is just one example of the harm done by users of these devices.

This article was originally published in the Science-Based Medicine Blog.

Dr. Hall is a contributing editor to both Skeptic magazine and the Skeptical Inquirer. She is a weekly contributor to the Science-Based Medicine Blog and is one of its editors. She has also contributed to Quackwatch and to a number of other respected journals and publications. She is the author of Women Aren’t Supposed to Fly: The Memoirs of a Female Flight Surgeon and co-author of the textbook, Consumer Health: A Guide to Intelligent Decisions.

Scroll to top