Can Magnets Heal?

Blogging on Peer-Reviewed ResearchBelief in the healing power of magnets and magnetic fields has existed since the discovery of magnets several thousand years ago. In the late 18th century, Franz Anton Mesmer, an infamous charlatan, promoted the notion that he could heal with “animal magnetism.” In the 19th century magnetic healers were common – D.D. Palmer was a magnetic healer prior to founding chiropractic. Magnetic devices for everyday aches and pains have been increasingly popular recently, and today they are a multi-billion dollar industry.

Yet the scientific evidence does not, generally, support the use of magnets for specific indications, and the vast majority (if not totality) of claims made for magnetic devices in marketing are either false or unsupported and highly implausible. The media attention given to a recent study of static magnetic fields (SMF) in the treatment of inflammation brings up many important points regarding this disconnect.

A headline from January 7th proclaims: “Healing Value Of Magnets Demonstrated In Biomedical Engineering Study.” This headline is extremely misleading, especially the use of the word “healing.” The article is referring to a study by CE Morris and Thomas Skalak(1) published two months ago in the American Journal of Physiology – Acute Exposure to a Moderate Strength Magnetic Field Reduces Edema Formation in Rats. In the sciencedaily article Skalak is quoted as saying:

“We now hope to implement a series of steps, including private investment partners and eventually a major corporate partner, to realize these very widespread applications that will make a positive difference for human health.”

This optimism, however, is premature, and represents a significant problem with many popular therapies, the extrapolation from preliminary pre-clinical studies to clinical applications in humans. But before I look at this new study in more detail I will review some basic concepts for background.

First, it is important to recognize that not all magnets or magnetic fields are the same. The most significant difference is between pulsating magnetic fields and static magnetic fields. Electricity and magnetism are actually manifestations of the same fundamental force: electromagnetism. This was first recognized when it was discovered that a changing magnetic field can generate and electrical current, and a changing electrical current can generate a magnetic field. A pulsating magnetic field, therefore, is capable of generating an electrical current. Many aspect of cell function and communication involve electrical potentials or currents, and therefore it is plausible – at least from a physical point of view – for a pulsating magnetic field to affect electrical current in tissue and thereby manifest an effect. The best established clinical use of a pulsating magnetic field is in the healing of bone fractures. Although this effect is modest, the evidence so far supports the conclusion that there is a relevant biological response.

Static magnetic fields do not generate electrical current, and therefore any biological or medical evidence dealing with pulsating magnetic fields cannot be applied to SMF. An even more significant problem with SMF as a therapeutic modality is that the strengths of magnets commonly used are very low, probably too low to have any biological effect. Further, magnetic field strength decreases as the square of the distance or even as the cube of the distance from its origin (depending upon the shape and orientation of the magnets). So field strength decreases very quickly with distance.

Most magnetic health products list the magnetic field strength at the core of the magnet, but even 1 cm distance may decrease the field to negligible strength. Therefore, if a magnet is in a bandage or casing the field strength will be significantly decreased at the surface of the skin, and then even further decreased below the skin down to the target tissue. (David Ramey goes into this in more detail in this excellent review article.)

Assessing the biological plausibility of magnetic therapy reveals further difficulties. So far no proposed mechanisms for how a SMF would provide a therapeutic effect have been established. Some common claims include that SMF increases blood circulation, thereby providing more oxygen to the tissue and reducing inflammation, but again this has not been established and there is no known mechanism by which this would occur. When tissue lacks sufficient oxygen it sends out powerful chemical signals to increase blood flow. It is unlikely that a weak SMF would provide a stimulus for vasodilation (increasing blood vessel size) greater than what occurs naturally in the setting of low oxygen. Also, ironically, the claims made in the current study by Skalak is that SMF decreases blood flow to inflamed tissue.

Older claims, that SMF attracts the iron in blood, are easily dismissed because the form of iron in blood is not ferromagnetic. More recent claims that SMF affects the flow of ions in the blood, altering blood flow, are not plausible as the SMF strengths are too low to significantly affect the movement of ions. Still others claim that SMF decreases inflammation, and that is the subject of this recent study.

Skalak’s current study is an extension of prior work in which he demonstrated that, under a SMF, blood vessels that were already constricted would tend to dilate and those that were already dilated would tend to constrict. Therefore, a SMF must have a normalizing effect on blood vessel tone. This study has yet to be properly replicated, and one concern about such results is that they could simply be due to regression to the mean (a normalizing statistical effect).

Based upon this preliminary work, Morris and Skalak conducted a study in which they look at various SMF strengths a in a rat model of inflammation. Two different chemical irritants were used to produce local inflammation in a rat hind paw. The paws were then subjected to SMF of either 10mT (miliTesla), 70mT, or 400mT. What they found is that swelling due to histamine induced inflammation was decreased in the 10mT and 70mT groups, but not400mT, and not in the rats where inflammation was induced by lambda-carrageenan (CA). The effects were only seen if the SMF was applied immediately after inflammation was induced, not prior and not delayed or during peak edema. The authors conclude that this shows a dose and temporal dependent effect of SMF on inflammation, probably due to vasoconstriction reducing blood flow to the inflamed tissue. To their credit they measured the strength of the magnetic fields at the level of the tissue, not the core of the magnet, so field penetration was not an issue. (In fact the authors acknowledge that virtually all magnetic products currently on the market report core SMF strength, which is misleading.)

There are significant problems with this interpretation, however. First, there is not a consistent dose response effect, as the strongest field (400mT) showed no effect. The authors make the post-hoc analysis that there is an upper therapeutic threshold, but this was not predicted by the original hypothesis and there is no known mechanism for such a threshold. The more standard interpretation of such a result is a lack of consistent dose-response. Also, the effect was only seen in the histamine induced inflammation and not CA induced inflammation – again, not predicted by the working hypothesis of the study. If SMF works through vasoconstriction of dilated arteries, as the authors hypothesize, why would the mechanism of inflammation matter? Therefore, these results do not show a consistent or predicted pattern, and could easily be interpreted, if taken together, as a null effect.

The authors also looked at the effects of pharmacologically blocking L-type Ca(2+) channels or nitric oxide (NO) to see if either blocked the effects of the SMF. This is a clever and established way to infer mechanism of action, and they found that the former, but not the latter, did block the effect of decreased inflammation by a SMF. Therefore the authors hypothesize that the SMF may work its effect through calcium channels. But again, random effects cannot adequately be ruled out, given the large number of outcomes that were measured in total.

The study design and results are indeed interesting, and I think that such serious attempts at looking at various aspects of SMF effects, including possible mechanism of action, are constructive. However, these current results are only useful as preliminary data since the results require post-hoc analysis and were not specifically predicted ahead of time. In other words, no reliable conclusions can be drawn from this study until it is replicated to see if the pattern of results hold up. Is there really a 400mT therapeutic threshold, or was this simply a lack of dose-response, and therefore a negative result?

Also, there are significant limitations in applying this study to humans. As the authors recognize, SMF strength decreases significantly with distance. Rat paws are very small, and it is therefore practical to apply a strong SMF at tissue depth. A human joint or limb, however, is significantly larger requiring a much stronger SMF in order to maintain adequate strength at tissue depth. If these results represent a real physiological effect, they may not apply at all to humans or may simply be impractical.

Therefore it is premature to conclude from this study that SMF’s can be applied to treating inflammation in humans, or that there is any specific clinical effect. At best this study requires replication and may point the way toward further research.

The media reporting of this study has been misleading and highlights some of the difficulty in dealing with such research in areas where there is already a vigorous and largely unregulated market. Preliminary and problematic results, such as we have here, are presented by the media as if they were reliable clinical evidence that magnets can “heal.” Such studies are also used to market specific products that differ significantly from the magnets used in the study, and to make clinical claims that cannot be extrapolated from the available data.

1) Morris CE, Skalak TC., Acute Exposure to a Moderate Strength Magnetic Field Reduces Edema Formation in Rats. Am J Physiol Heart Circ Physiol. 2007 Nov 2

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13 thoughts on “Can Magnets Heal?

  1. daedalus2u says:

    A slight correction, nitrous oxide is N2O, nitric oxide is NO. It is nitric oxide NO that is the agent involved in so many different physiological pathways. The normal basal level is less than 10 nM/L, less than 0.3 ppb. That level causes 50% activation of soluble guanylyl cyclase, a major NO target which ultimately leads to vasodilation. NO is paramagnetic, as is O2, O2 is about 2x as paramagnetic (on a molar basis).

    The major uses of nitrous oxide N2O is as a (poor) anaesthetic, as a blowing agent in whipped cream, and as an oxidant in boosting the power of gasoline engine for short periods of time.

    Nitric oxide is too reactive to administer except in a hospital setting with good instrumentation and controls. While NO is non-toxic even at hundreds of ppm, it is easily oxidized by air to form NO2 (nitrogen dioxide) which is toxic at a few ppm. Any use of NO therapeutically (it is pretty much only good for pulmonary hypertension) has to include monitoring for NO2.

    It should be noted that MRI uses very strong large volume DC magnetic fields.

    A typical field for MRI is ~1 to 1.5 Tesla. 3 Tesla is not uncommon, and there are some units that go as high as 9 Tesla. Some static field effects (such as dielectrophoresis) vary with the field squared. If magnetic fields had dramatic effects on physiology including healing properties I would think a place to look would be following MRI testing.

  2. Stick, C., et al. Do Strong Magnetic Fields in NMR tomography modify tissue perfusion? Nuklearmedizin 154: 326, 1991

    Answer: no.

    (Cited by D. Ramey)

  3. wertys says:

    Harden RN, Remble TA, Houle TT, Long JF, Markov MS, Gallizzi MA.

    Prospective, randomized, single-blind, sham treatment-controlled study of the safety and efficacy of an electromagnetic field device for the treatment of chronic low back pain: a pilot study.
    Pain Pract. 2007 Sep;7(3):248-55.

    This recently appeared in the journal of the World Institute of Pain which has a good record of fairly high standards. I was dismayed at the poor quality of the research presented, which had abundant non sequiturs and other logical fallacies, not to mention a very unreasonably optimistic conclusion based on the rubbish they presented. I have seen a couple of other similar articles in other journals which involve highly sophisticated woo devices which have been built and paid for, and only then does the search for evidence begin. This usually results in the tenuous drawing together of basic science studies to support the post hoc determination of effectiveness. The scientific method obviously works the other way around but once the articles are out there they can be freely cited out of context…

  4. faceman says:

    As an alum’ of U.Va. I read about this study in an e-newsletter that I received from the university. The unfortunate headline hyping of the study by the university is even less accurate than the paper’s conclusions. At least they posted my letter to the editor for some balance. The letter is posted on their site here:

  5. DLC says:

    Can Magnets Heal?
    Short Answer: No.
    Magnets won’t heal you, any more than having someone wave their hands at you will heal you. Sorry, but that’s just how it is.
    I’ve never seen a quality study indicating that magnets (or hand-waving for that matter) has any positive effect.

  6. daedalus2u says:

    While reliable data that magnetic fields somehow do enhance healing would of course “trump” any hypothetical reasoning that they don’t, there has been no hypothesis posed as to how any type of magnetic field could possibly enhance healing.

    It is pretty obvious that healing is an incredibly complex process involving many complex steps under extremely complex feedback control and that feedback control system has evolved to be functional over billions of years.

    Healing is extremely important, and organisms have evolved to heal as fast as they can (consistent with other physiological functions the organism must do to survive). If there were some simple thing organisms could do to heal faster, they would (most likely) have evolved to do so. We may understand a few small steps in the process, but it is quite obvious that the vast majority of the physiology that is going on is not at all well understood.

    If a very complex regulated process is going to be accelerated, we would expect that only another very complex process would be effective at doing so. If there were some “simple” improvement to such a complex process that accelerated it, presumably cells would have evolved to use that process in their physiology already.

    To use a (poor) analogy, if you have a computer that has been highly optimized by many iterations of optimization (analogous to evolution) running with a certain program, can you accelerate the performance of that computer by doing something simple? Such as treat the computer with a magnetic field? Hit it with a hammer? Attach something simple to it? Change the voltage?

    Are magnetic interactions so uniquely powerful that perhaps because cells don’t generate ferromagnetic materials (except for use as compasses so far as we know) magnetic interactions are something that might work if cells did use them? Magnetic interactions are much weaker than interactions that cells do use electrostatic, hydrophobic interactions, and all types of chemical bonding. Do cells have some pre-evolved yet unknown magnetic interactions ready to operate using magnetic field strengths that no cellular ancestor has ever experienced during the whole of evolution? The Earth’s magnetic field has never been as high as 10 mT (so far as is known).

    If cells did utilize magnetic interactions, then it is likely that exposing cells to fields orders of magnitude higher than the maximum normal magnetic field those interactions evolved to function with would be non-physiologic and would cause adverse functionality, not improved functionality.

    In my opinion it would be an extraordinary circumstance if static magnetic fields many times higher than the Earth’s magnetic field had any beneficial and/or healing properties. I would want to see extraordinary evidence.

  7. James Randi says:

    Make that name “Skalak,” not “Shalak…!

  8. Randi – Thanks for the correction. Fixed.

  9. Kimbo Jones says:

    Good idea about MRI, daedalus2u, but let’s not forget about the convenient “threshold” to explain that away.

  10. Calli Arcale says:

    Most magnetic health products list the magnetic field strength at the core of the magnet, but even 1 cm distance may decrease the field to negligible strength.

    The one principle the woos always forget to mention: the inverse square rule. Field strength decreases proportional to the inverse square of the distance. Which means that the wussy magnets sold in a lot of healing bracelets and such probably won’t even damage your credit cards, let alone have any affect on your body.

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