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I recently got an email from a gentleman who told me I was wrong about many things because I “come from an era of incomplete medical education and information.” He rambled on but had two main points: modern doctors fail to recognize a kind of allergy that defies standard diagnosis and that is the cause of pretty much every health problem, and MSG is a poison that should be banned. He said, “…about 3,500 unsuspecting Americans are dying prematurely of undiagnosed allergies aggravated with FDA approved food poisoning every day in 2018.”

I told him I would be glad to complete my medical education and asked for reliable sources that would properly educate me. He answered, “therein lies the problem. Despite all I’ve heard about medicine and alternative medicine I don’t know of any. About the best I can do for now and have been doing is to suggest the reading of Dr. Coca’s THE PULSE TEST and, much more recently, John Erb’s THE SLOW POISONING OF MANKIND and to learn by doing.”

I’ll leave MSG for a later date; today I’ll discuss Arthur F. Coca’s pulse test for allergies. The full text of Coca’s book is available for free online. I read it. I was not impressed.

The pulse test

Coca’s discovery of the pulse test was prompted by his wife’s experience. She developed angina pectoris and noticed that her attacks of chest pain occurred within minutes of eating certain foods, and that after eating those foods, her pulse always accelerated. Coca deduced that harmful foods could be identified by testing for an increase in pulse rate.

He decided that he had discovered a new kind of “allergy” that explained all these health problems: recurrent headache, nervousness, migraine, dizziness, constipation, canker sores, heartburn, epilepsy, overweight, underweight, irritability, gastric ulcer, abdominal pain, gallbladder pain, gastric pain, nervous and emotional instability (neurasthenia), abnormal tiredness, indigestion (vomiting, gas, nausea), neuralgia, sinusitis, hypertension, hives, heart attacks (angina), asthma, hemorrhoids, psychic depression, diabetes, chest pain, gastrointestinal bleeding, conjunctivitis, nose bleed, and colitis.

He claims to have treated all these conditions successfully by identifying and avoiding the offending foods.

He developed elaborate rules for diagnosis, with no explanation of how he arrived at them. For a baseline, patients are asked to take their pulse 14 times a day at specified times. If the highest count is the same each day and is not over 84, they are probably not allergic. If the maximal count varies more than 2 beats from day to day, they are certainly allergic. Foods are then tested one at a time and if the pulse rises, that means they are allergic to that food. In addition to foods, symptoms can be produced by environmental allergens like tobacco, house dust, fumes, medicines, soap powder, and wood smoke. He notes that there are exceptions to his rules, but he explains them away. For instance, he says sensitivities can be temporarily lost. He is content to accumulate a mass of examples that confirm his hypothesis but doesn’t look for examples that might disconfirm it. He never thinks to ask if there might be any other explanations for his results. He doesn’t take the essential step of testing with a control group.

There are a number of different versions of the Coca test promoted on various alternative medicine websites, using different criteria for how many increased beats per minute (and sometimes even decreased beats!) constitute a positive test. And none provide any credible evidence for the test’s validity.

He provides case histories (anecdotes) of “almost miraculous” resolution of symptoms both in patients he has seen and in patients he has not (hearsay).

He plays the “lone genius” persecution card, saying the establishment is unwilling to even consider his findings and has prevented publication of his results.

Here we go again!

Reading his book was a painful experience for me. I could see step by step how he had made unwarranted assumptions, succumbed to confirmation bias, and deluded himself. I have heard this same story so many times before! Just a few examples: Batmanghelidj and his water cure, Jennifer Daniels and turpentine , a Navy neurologist’s adoption of acupuncture, Upledger’s discovery of craniosacral therapy, Hahnemann’s discovery of homeopathy, Palmer’s discovery of chiropractic, the origins of iridology and ear acupuncture… the list goes on.

The story goes like this:

  1. He observes something and misinterprets it.
  2. He extrapolates from one or a few cases to invent a general principle.
  3. He doesn’t even consider the possibility that he might be wrong.
  4. He doesn’t do any controlled scientific testing.
  5. He proceeds to treat patients. Many get better, perhaps because of the natural course of illness, regression to the mean, placebo effects, or other unrecognized factors, Without doing controlled studies, there is no way of knowing whether the treatment was responsible for the improvement, but he firmly convinces himself that it was.
  6. He is flattered and reinforced by feedback from grateful patients who believe he cured them.
  7. Confirmation bias sets in.
  8. He becomes a true believer.
  9. When others try to point out what is wrong, he refuses to listen; instead, he cries persecution and censorship.

Could there be anything to it?

Coca was born in 1875 and died in 1959, long before today’s understanding of the concept of evidence-based medicine. He thought he had “evidence.” He didn’t recognize that it was flawed. He didn’t understand the requirements of the scientific method, and he never put his beliefs to any kind of a valid scientific test. I don’t judge him too harshly; he was only doing what many other doctors did in his era. But I think it is obvious that he was fooling himself.
The whole idea is implausible. In the first place, the heart rate is naturally variable; in fact, a low heart rate variability (HRV) seems to be associated with adverse health effects including an increased risk of death. Many factors affect the pulse rate, and when patients are aware that a food is being tested, anxiety, excitement, and other factors could affect the pulse rate. There are just too many variables for the pulse test to be a reliable indicator of anything.

Coca never defines what he means by “allergy,” and he offers no explanation for how it could cause all those disparate conditions. There is no plausible mechanism. How could a single cause underlie epilepsy, diabetes, hypertension, migraine, conjunctivitis, colitis, and constipation? Similar claims for “one true cause of all disease,” are ubiquitous and bogus.

Coca’s book was published in 1956. If he was onto something, we could expect to have seen some confirmatory studies in the medical literature over the six decades since he published it. There is nothing.

Conclusion: Not disproven, but not worth testing

If we can’t definitively say pulse testing for “allergies” is bogus, at least we can say it is highly improbable, bordering on the impossible. The only way to determine whether Coca’s hypothesis is valid is to test it properly in controlled studies. In my opinion, authorizing such studies would be a waste of scarce research funds that would be better spent elsewhere.

In the absence of evidence, if patients want to try pulse testing, there’s very little potential for downside. Checking your pulse and experimenting with eliminating specific foods from your diet are relatively harmless. Just be aware that such self-experimentation can lead to false conclusions. That’s why we need science: to keep from fooling ourselves.

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Posted by Harriet Hall

Harriet Hall, MD also known as The SkepDoc, is a retired family physician who writes about pseudoscience and questionable medical practices. She received her BA and MD from the University of Washington, did her internship in the Air Force (the second female ever to do so),  and was the first female graduate of the Air Force family practice residency at Eglin Air Force Base. During a long career as an Air Force physician, she held various positions from flight surgeon to DBMS (Director of Base Medical Services) and did everything from delivering babies to taking the controls of a B-52. She retired with the rank of Colonel.  In 2008 she published her memoirs, Women Aren't Supposed to Fly.