Attractive Health Measures or Magnetic Manure

Magnetic manure

We probably all know at least one person who swears by their magnetic charm bracelet for preventing travel sickness, reducing arthritic pain or even helping them through situations that induce an attack of social anxiety disorder. These bracelets and other devices (some are in the form of headbands, others pendants, blankets, knee braces, shoe inserts, there’s even one you wear in your pants to improve your sex life) use magnets of a similar strength to those that make shopping lists stick to your refrigerator or let your kids spell out rude words without you realising…

…in other words, they’re not very strong and so probably have absolutely no physiological effect whatsoever. So, this $5billion industry founded in ancient Greek mythology is almost on a par with homeopathy for having no real scientific basis. Or is it?

Serious research, being carried out in a serious university laboratory, with serious financial backing recently hit the headlines with proclamations that a short application of a magnetic field to an inflamed joint could somehow improve blood flow and reduce swelling. Thomas Skalak, chairman of biomedical engineering at the University of Virginia and his colleagues lead the field in the area of microcirculation research, the study of blood flow through the body’s tiniest blood vessels. This status presumably helped them secure $875,000 of US taxpayers’ money from the National Institutes of Health’s National Center for Complementary and Alternative Medicine.

Initially, they set out to examine a claim made by the companies that sell “therapeutic” magnets: that these devices somehow increase blood flow. Skalak’s team used magnets of 70 milliTesla (mT) field strength, which is about ten times stronger than a common refrigerator magnet, but still very weak, the magnetic field of an MRI machine, for instance, is up to about 3000 milliTesla (3 T in other words). The researchers measured blood vessel diameter before and after placing the magnets up against lab rats.

They found that the magnets seemingly had a significant effect on blood vessels. Those that had been dilated became narrower and those that were previously constricted widened. Apparently, this implies that the magnetic field could induce vessel relaxation in tissues with constrained blood supply, ultimately increasing blood flow; how the magnet knows which way to stimulate the effect is not known. In a more recent study, the team treated the hind paws of anaesthetized rats with inflammatory agents to simulate tissue injury. Therapeutic magnets were then applied to the swollen paws immediately. The researchers say they say significant reduction in swelling (oedema), although there was no effect if there was any delay between injury and application.

According to Skalak, “The FDA regulates specific claims of medical efficacy, but in general static magnetic fields are viewed as safe.” So, could magnets be used to improve blood flow following muscle injury, say, as many of the headlines surrounding this press release claimed?

Well, what I’d first like to know, is did the researchers use a double-blind control? Did they, for instance, apply non-magnetic objects of equal size, shape and weight and at the same temperature to a second set of inflamed rat hind paws to examine whether those had any effect on blood vessel dilation? Did they have a set of inflamed rats that were not treated at all? How did those groups respond? The research paper on which the press release is based was published online in November 2007 in the American Journal of Physiology and Heart Circulatory Physiology.

Given that one of the major tenets of sports injury treatment is ice and compression could it be that the very act of pressing an object against the inflamed joint simply acted as a compressive heatsink, reducing local temperature of the inflamed region and at the same time temporarily reducing blood flow during the compression?

It’s just a thought, but couldn’t any metallic object of a reasonable size, 10-20 mm would be adequate for a rat paw, act as a cold compress, asks my good friend Stephan Logan. Logan supplies scientific educational equipment, including neodymium rare earth magnets, and points out that these have a field strength of several thousand milliTesla (1.3 T is typical for the standard neo magnet N42) and so has a keen interest in scientific claims made about much weaker magnets, such as those used in the experiments, knowing that a nasty pinch when flesh is trapped between two neo magnets is one of the well-known physiological effects but has nothing to do with mystical field effects

The Virginia press release, and consequently much of the media, claim that since muscle bruising and joint sprains are the most common injuries worldwide, Skalak’s discovery has “significant implications”. He rightly points out that, “If an injury doesn’t swell, it will heal faster – and the person will experience less pain and better mobility.” The extrapolation of the magnetic research to the notion that “magnets could be used in much the same way ice packs and compression are now used for everyday sprains, bumps, and bruises, but with more beneficial results, is not necessarily supported.

Magnets could be used, but where is the evidence that they reduce swelling any more than a conventional cold compress? Indeed, does injecting a rat’s foot with an inflammatory chemical simulate adequately a sprain or strain? The release says, “The ready availability and low cost of this treatment could produce huge gains in worker productivity and quality of life.” That’s a big extrapolation from a small laboratory study to the whole of sports injury medicine. Anyway, if commercialised are these therapeutic magnet ever likely to be as cheap and readily available as a bag of frozen peas? I doubt it.

22 thoughts on “Attractive Health Measures or Magnetic Manure”

  1. @adreal The short answer is that the weak magnetic fields these kinds of magnets produce have no physiological effects whatsoever, they do not relieve pain or symptoms of any medical condition. By the way, I deleted your spam link.

  2. Do magnetic therapy products really work? Does the pain really go away?

    I found a company that sells magnetic products and was wondering if anyone had tried these products?

  3. Hi, a number of years ago a friend of mine seen a advert for magets for back pain, the price was £35.00p money back guarantee if they did not work, this was in spain, shortly after he put it on
    he told me it was the first time in years he had been pain free. Now for my story 28/3/09 the pain in my knee is hurting bad i play golf and i am ready to give up, a friend tells me his story
    about the pain he had suffered, and tells me how he cured it. I contacted a company called
    Magnapulse who sent me a knee strap with four large magnets £29.00p + £3.00p del. I have been pain free since, back playing golf and bowls, so who’s kidding who about a plascebo affect
    now it does not cure it, but it sure takes the pain away, and i do not have to wear it all the time.
    Would like to hear your reply.

  4. I would not usually cite the Daily Mail, but an item junking magnet therapy caught my eye today because it mentioned how no one would survive an MRI scan if magnets had the kinds of effects quacks claim, which struck a chord and is pertinent to this discussion even if some of their phrasing is sensationalist –


  5. Thanks Mike for the follow up. You must admit that for every dozen “genuine” alternative (I thought the word was complementary these days) there are a million quacks perveying snake oil and pink medicine. Moreover, many “Western” acupuncturists have tried to disengage their practice from the Chinese tradition because of the mystical associations of chi (life force, energy) etc.

    There is, however, no doubt that the placebo effect works, and yes, you’re probably right that the patient needs to think they are being “treated” in some way. However, even being told that you are receiving a placebo sometimes seems to work. As to the dogs and rats. The dog is a single anecdotal instance of recovery for whatever reason, putatively just a spontaneous remission, who knows? The rats, on the other hand, were in a trial and did not need to know about placebos and magnetism. Indeed, as I’ve said, I reckon the evidence points to a very simple mechanism taking place in the treatment and that is simply the rapid withdrawal of heat from the “injury” site by the thermal conductivity of the metal placed against it.

    Incidentally, I don’t think it’s arrogant of medicine to be healthily skeptical of alternative complementary practices, as I said for every one practice for which there is perhaps some evidence there are a thousand healers and charlatans who are taking money from desperate individuals and offering nothing more than a proverbial shoulder to lean on (which isn’t necessarily all bad, but could be got much cheaper elsewhere).


  6. Hi David,
    The word ‘quack’ is habitually used by the medical establishment whenever they wish to ridicule someone who does not employ their methods or use their chemicals. Would the Norwegian ‘alternative’ therapist, who in the words of his attempted indictment “illegally cured a seriously ill person” be classified as a ‘quack’ or just someone who uses different methods? I’m sure accupuncture was once regarded as ‘quackery’, but it is now seen as being effective for a wide range of complaints. Something which the Chinese could have told us, if only we’d been prepared to listen more and scoff less!

    Whenever something new or different appears, the establishment’s first reaction is to ridicule it, then to subject the newcomer to vilification and attempt to stamp it out, then when it won’t go away to finally embrace it as something they were aware of all along and to claim it as their own. However, I digress slightly…

    Wikipedia has some interesting information on placebos, stating it is associated with the patient’s belief that the form of treatment they are about to receive will work. The variable results from placebos is probably explained by one person’s belief being stronger than another’s. I have seen a programme where a doctor performed a mock knee operation, with full theatre staff, on a man who was at the end of his tether with pain. When interviewed afterwards, the patient stated he could now dance with his wife and live a normal life. The doctor was at first reluctant to carry out this ‘quack’ operation, fearing ridicule by his peers but was himself astounded at the outcome. That is one man who’s mind has grown just a little.

    Which brings us back to rats and dogs. The scientists found a change in the rats, and my neighbour’s dog was greatly improved, by the application of a magnet. For the placebo effect to work, the patient has to be aware that they are being treated and to have faith in the medication/doctor. I’m certain my neighbour would have been kind and comforting to his dog, when he found it could not jump onto his bed, and I’m sure the rats never thought “Ah, this looks like it just might do me some good, for once!” so I argue that the placebo effect is not applicable in these situation, as there was no prior knowledge or anticipation of a successful outcome.

    If the rats or dog did not take a chemical to cause their physiological changes, and a placebo effect seems unlikely, then I agree with you that something else must be going on which we do not fully understand. Do you, or any of the original contributors at the start of this debate, have any idea what effect could be causing these changes?


    Mike Jozefiak

    Ps Many thanks David for rescuing and ironing out my original letter from the trash bin!

  7. Mike, I retrieved this comment from the spam filters, i suspect it was the list of drugs that got it caught out by Akismet.

    Anyway, I still don’t think the effect reported in the rats and magnets study has anything to do with placebo. Placebo, as you say, could be a very powerful tool and is exploited very well by quacks and various other practitioners across the globe and has been for many years. To put it in hand-wacing terms, the underlying principle of placebo is essentially the soothing hand of a parent on the fevered brow, surely?

    As to the placebo effect on animals, especially as observed in pets…many kinds of animal kept as pet can detect only too easily their owner’s mood, a trip to the vet with the promise of a healthy pet to come could so easily have a placebo effect on the owner’s downheartedness, which could rub off (literally), olfactarily, or temperamentally on a pet (in particular dogs) and seemingly. I suspect that there is no placebo that you could give a dog that will cure it of a rampant dose of worms though, no matter how good filling the prescription makes the owner feel.


  8. Hi,

    As every doctor, witch or otherwise, knows, the power of belief in the practitioner is 95% of the cure. A case in point is the effect of Voodoo; believe in it and the effects are real enough. Do not believe in it, and Voodo has no effect.

    How do rational, thinking, evidence-based scientists, worshiping only the one true God of science, explain the placebo effect or faith healing? Is it the power of suggestion, the patient’s belief that this treatment will cure them, or perhaps some other effect or force which we do not understand but, nevertheless, by the process of elimination, have to admit must exist? Doctors have for ages given sugared pills, conducted mock operations etc. and some patients have been cured, all to the consternation of the Guardians of the Temple.

    The fact that not all patients are cured, by whichever method is employed, must surely warrent further investigation, if only out of scientific curiosity.

    Something which most people don’t want to admit is that we are not rational beings; we are emotional ones. Anyone who disputes this I would ask to walk on a three inch wide line painted on the floor. Then I would ask them to walk on the same line 30 feet in the air, at which 99% of people would baulk. That is not logic, it is pure emotion.

    It is not the fault of caring doctors, and there are many doctors, scientists and healthcare workers who do care, who enter the business wishing to help people; it is the influence of the multi-billion moolah businesses behind the teaching establishments and doctors mug mats that must be scutinised, the status quo who will go out of business if ‘natural’ practitioners are allowed to flourish.

    No wonder the MHRA (wholly funded by the pharma companies) tried so hard to get herbals classified as drugs! I wonder if anyone has ever made a comparison between the numbers killed by the chemical companies and those killed by evidence-based-over-thousands-of-years practitioners? Has anyone taken the time to read the side effects warning leaflet that accompanies every bottle of prescription drug? This is not to say that all chemicals are bad, but there is surely room for everyone to co-exist in working together to alleviate suffering, and not dismissing things they do not understand, purely because they don’t understand them.

    Many doctors are forgetting their roots, and their roots are just that – roots!


    Mike Jozefiak Guinea Pig

    PS. A Norwegian alternative practitioner was prosecuted by the Norwegian equivalent of the MHRA in 2002 for, I kid you not, “illegally curing a seriously ill person”. His case was thrown out of court. The point being? Who cares how someone is cured, as long as they adhere to the 1st Hippocratic principle ‘First, do no harm’. How many doctors, legislators and chemical companies can honestly say they have not prescribed medicines which have killed or harmed their patients? In case anyone has a short memory, do the words Vioxx, Celebrex, Accutane, Bextra, Ephidra, Meridia, Thalidomide, Ortho Evra, etc, ring any bells? Mote and beam.

  9. Many thanks for the follow up Mike. Anyone else care to comment on what Mike has to say about the putative effects of magnetic fields on health?


    PS I checked the spam filter and cannot see your missing post there, feel free to re-post it and I’ll watch out for it.

  10. Hi David,

    My apologies for not clarifying that the main focus of my comment about placebos was directed at the testimonials concerning various pets/animals that have benefited from magnets, not exclusively the rats. For instance, a neighbour was commenting that his old dog could no longer jump up onto the bed, due to arthritic/joint problems. Two weeks after he fitted his dog with a magnet, he reported that his dog now found no difficiulty leaping up onto the bed. That’s what I mean by “Something must be going on that we don’t understand.”

    The dog certainly had no inkling that he was being treated, probably thinking he was being given a new collar. Hence my question whether you could possibly explain the mechanism that seemed to, if not cure, then sufficiently diminish the dog’s pain enough to allow him to jump up onto his (and mine) favourite platform, the bed!

    I believe physiotherapists use electromagnetic devices to speed bone and tissue healing. Whether they can explain how the bodys heals faster under the influence of a magnetic field, albeit alternating, or not, doesn’t seem to prevent them using it, just as we don’t need to know anything about Lenz or Faraday to appreciate that assuming a certain direction of current flow, under the influence of a magnetic field, an electric motor always rotates in a certain direction when we switch it on.

    Just as an aside, did the researchers think of thermally insulating the magnets from the rats’ skins (it wouldn’t have taken much of a gap)? That would show whether the effect is as you suppose, a thermal one. Also, did they try an alternating magnetic polarity?

    I too value scientific research, provided it is done correctly and without axes to grind or the ensuing biased bull**** that often results from commercial-sponsoredship, but even scientists have to sometimes admit they do not understand what is going on, especially concerning the huge influence our brains and thought processes have upon the outcome of treatment for an illness. Can they explain how cancers mysteriously ‘disappear’?



    PS I submitted an earlier comment to the original article, but it seems to have been ‘eaten’ by the system. Should I resubmit?

  11. Mike, I most certainly do have a likely explanation. But, more to the point who said anything about it being a placebo effect? I didn’t mention placebos in the original article, there was no need. The effect is probably very real, but nothing to do with magnetism. The material is most likely simply acting as a heat sink (being thermally conductive and colder than the rats’ skin) it would thus have the same beneficial effect as any other cold compress. Moreover, read Stephan’s comment regarding the type of magnets used. Why wouldn’t an even stronger magnet have more of an effect unless it were something to do with the thermal conductivity of the material itself as opposed to its magnetism?

    Humankind has for generations sought panaceas. Why wouldn’t it? We all want to live long and healthy lives. Magnets as not much stronger than the kind I used in the little graphic at the top of this post are just another example of the kind of this wishful thinking.


  12. Hi David,
    Thanks for explaining the concept of DB trials. I would think it highly unlikely the rats knew they were being exposed to magnets, meaning that there could not have been a placebo effect when the magents were applied to the trauma area. I have seen plenty of testimonials from owners who’s animals have shown improvements following the application of magnets. These animals too could not be showing a placebo effect. Something must be going on that we don’t understand.

    Do you have any likely explanation?



  13. MIke, a more important point, is did the rats sign an ethical consent form prior to being injected with painful inflammatory agents?

    Seriously though, the whole point of a blind placebo-controlled trial is that the subject is unaware of whether they are being given the test therapy or a placebo. Double-blind means that neither the experimenters nor the subjects know.


  14. Hi All,
    My aplogies for missing the original point of the article; whether rats are susceptible to the placebo effect. Did anyone tell the rats they were having magnets applied?


    Mike Jozefiak

  15. Grace, point taken, but I think the use of ice applied to injuries has been studied in reasonable detail. That said, I may be hoisting myself by my own petard if it turns out that the evidence is merely anecdotal (something regular readers will know, I’ve criticised in the past)


  16. Shame – poor little rats.

    Did anyone ever do any double blind clinical trials on the therapeutic effects of bags of frozen peas? Think about it – they wouldn’t be very practical or attractive as bracelets or blankets or shoe inserts – or stuffed down your trousers, boys.

  17. From Stephan Logan via email

    One aspect of this research highlighted by Science Based Medicine which is interesting is that the magnetic effect on the swelling did not seem to happen above 400mT. That gives it away even more I think. It sounds like the low strength magnets were likely steel bar magnets…great heat sinks. The higher power ones would likely have been ferrites (4000 gauss=400mT I believe: ), much less mass…hence even less effective than the frozen peas.


  18. John – thanks for taking the time to comment. You presumably noticed the little graphic I did with fridge magnets ;-) Iron compounds, including haemoglobin, are, of course, not attracted by a bar magnet, a fridge magnet or any kind of therapeutic magnet. Magnetic resonance imaging would be hellishly dangerous if they were.


  19. David,

    I rarely comment. But this requires comment.

    A homeopathic device vendor (a former basketball name of fame) sells all kinds of magnetic “cure” devices, and apparently makes a good living at it. His contention is that since blood contains iron, the magnets obviously affect blood flow, and thus, the “cure”. When, at a gathering, I posed that magnets attract iron, and thus increase blood flow to the region of the magnet (if this is true), and keeps the blood at that location (i.e., restricting flow itself), possibly the magnets are a unhealthy alternative procedure. There was no answer, but he didn’t talk to me anymore that evening and I had to find new persons with which to converse.

    The claims are wild and varying. There is no real science. I think it is all bound up in some kind of mystical hope. I think I will get some praying beads instead.

    Good missive, thanks


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