Magnets and Blood Flow

Over the last week I have received numerous questions about a recent study (yet to be published, but highly publicized in the press) in which it is claimed that the application of a magnetic field can improve blood flow. Physics World declared in the headline that, “Magnetic fields reduce blood viscosity.” This is not a bad summary of the study, but then the first sentence claims:

Researchers in the US claim that exposing a person to a magnetic field could reduce their risk of a heart attack by streamlining the flow of blood around their body.

Science Magazine ran with the also tame headline of “Magnets Keep Blood Flowing” but also had some problems in the text of their report (which I will get to).

The amount of press attention the study is getting is a bit odd. It’s a small proof-of-concept study looking at the effects of strong magnetic fields on blood flow in vitro. I suspect part of the reason is the same as why so many people have been asking me about it – magnets are frequently marketed with health claims and these claims are often justified by the hand-waving explanation that magnetic fields improve blood flow. The concern is that this small study will be abused by huxsters to sell refrigerator magnets with unfounded health claims.

The history of health claims for magnets goes back as far as knowledge of magnetism itself. In the last decade there appears to have been an upsurge in this old scam – a plethora of products promising to treat arthritis, improve healing, or just give extra energy by placing a magnet over the target area. The magnets used are typically very weak and have a field that barely penetrates the skin, let alone reaching down to the joints or the area of pain.

Further – these products are generally using static magnets. Static magnetic fields would not be expected to have any effect on nerve function or blood flow. It is not surprising, therefore, that the clinical evidence for any efficacy is also negative.

This study is very different, and therefore has no applicability to any magnet product on the market (if it has any applicability at all). Physicists Rongjia Tao Ke Huang took donated blood and then measured its viscosity in a small tube used for that purpose. They then applied a 1.3 Tesla magnetic field to the tube (this is about the strength of the magnetic field used in a typical MRI scanner), with the field aligned with the direction of blood flow, for one minute and found that the viscosity decreased by 20-30%. This effect lasted for about 2 hours.

There are numerous problems with extrapolating from this study to a net clinical effect, and also in the interpretation of the mechanism of the effect. The researchers claim that the effect comes from the red blood cells clumping together, mostly in a line, like box cars on a train. The cells moving together as a train produces less resistance than if they were all bouncing around separately. Further, they tend to flow more down the middle of the tube, reducing friction with the tube wall.

The picture above shows the clumping of the cells. Immediately it seems as if there can be a problem applying this to a person. The glass tube used in the study was larger than the smallest arteries in people. Further, capillaries are only large enough to allow red cells to flow through single file. I would not want my red cells clumping as in the picture above and then trying to squeeze through capillaries. I would not be surprised if the effect on viscosity were reversed for smaller arteries, or even caused serious problems with capillary flow. But I suspect the net effect on blood flow in vivo is negligible, because we have been exposing people to magnetic fields of this strength in MRI scans for a couple decades now without any ill effects.

Another major problem is that the effect only happened when the field was aligned with the (straight) tube. Arteries in a living organism are not straight and are not parallel. They will be traveling every which way in relation to an external field. This will probably be the greatest limiting factor in applying this effect to organisms.

The effect (even in the optimal and contrived conditions of the study) was also short-lived – only two hours. Even if the effect could be achieved in a person, this makes it impractical for any application of routine prevention – such as preventing heart attacks and strokes as was reported in most articles on the study. I could imagine an application to an acute event, such as during a heart attack or stroke, and focused on a single blocked artery that can be aligned with the field. But even then, for the reasons stated above, I doubt the net clinical effect will be significant or necessarily positive.

Regarding mechanism, the Science Magazine article reports:

The magnetic effect, the researchers say, all comes down to hemoglobin, the iron-based protein inside red blood cells. In the same way that iron filings align themselves along the field lines around a bar magnet, so the red blood cells align themselves along the straight field lines of Tao and Huang’s electromagnet.

There is a significant problem with the  analogy of hemoglobin to iron filings – iron is ferromagnetic, which means it has a strong response to an external magnetic field (in addition to the ability to retain a magnetic field itself, but this is not as relevant to the current study). The iron in hemoglobin is not ferromagnetic. Ferrohemoglobin (without oxygen attached) is weakly paramagnetic (is attracted to an external magnetic field). So it can align with a strong external magnetic field, but this effect is generally very weak. Oxyhemoglobin is non-magnetic (has a magnetic moment of zero, because it has no free electrons) and therefore does not respond at all to an external magnetic field. So oxygenated blood in arteries would have a very weak to no response to to an external magnetic field due to its hemoglobin.

Red cells themselves may be weakly diamagnetic – meaning they are repulsed by an external magnetic field (this is why a frog levitates over a powerful magnetic field) and this may be the effect that causes the observed clumping.

To reinforce this point, the weak paramagnetic or diamagnetic properties of cells or living tissue require a strong magnetic field to have any effect – like an MRI magnet. The small relatively weak magnets used in products with health claims are orders of magnitude too weak to have any such effect. The hemoglobin gambit (based on the fact that hemoglobin contains an iron atom) collapses under close examination.


It is interesting that a strong magnetic field can have a temporary effect on red blood cells. Whether or not this effect will have any future clinical applications remains to be seen. I doubt it, for all the reasons I explained above, but it’s possible someone may find a clever use for this effect.

The simplistic extrapolation from this contrived and temporary effect to improving blood flow and thereby reducing risk of heart attacks, however, is unjustified and misleading. Further, any attempt to use this study as a justification for clinical claims made for weak permanent magnets is beyond misleading , in the realm of the absurd.

Posted in: Science and Medicine

Leave a Comment (27) ↓

27 thoughts on “Magnets and Blood Flow

  1. windriven says:

    Dr. Novella, what was the point of the original research? Was it purely to assess the impact of large magnetic fields on blood viscosity or was there a larger objective?

  2. daedalus2u says:

    I have not read Professor Tao’s paper, but the images of blood cells clumping do not look like the chaining that happens in a magnetic field. Clumping due a magnetic field generates chains of individual particles which then form a high aspect ratio composite particles with essentially point contacts between them. They do not form clumps such as observed in the figure.

    I left two comments on another thread on SBM about this.

    In my day job ;) before I became involved in nitric oxide research I invented and commercialized electrostatic and magnetic separators. I am extremely familiar with the chaining-type behaviors exhibited by ferromagnetic, paramagnetic and dielectric particles in electric and magnetic fields. The mechanism of chaining in donated blood might be due to magnetic chaining of the paramagnetic deoxygenated blood cells. That cannot be occurring in vivo because blood is not deoxygenated.

    Dr Novella’s analysis is correct, but does not go far enough. Oxyhemoglobin is diamagnetic, that is it has a magnetic susceptibility lower than the plasma it is in. In a magnetic field there would be anti-chaining, that is the field would destabilize chains not make them. A magnet attracts paramagnetic particles only because the magnetic susceptibility of the magnetic particle is higher than that of air and so the energy of the magnetic field is minimized by substituting the paramagnetic material for air. The energy minimization is what provides the driving force for the particles to be attracted. If you substituted a material with a higher magnetic susceptibility for air, then energy would be minimized by expelling the material of lower magnetic susceptibility.

    These chaining effects go as the field squared. Humans and other organisms with hemoglobin have been exposed to much higher fields with no observable effects.

    From the earlier reports I had seen, it was not clear that the only viscosity measurement was in vitro on donor blood. There is no reason to think this is other than artifact and that it has no significance or applicability to in vivo conditions on humans. If there was this kind of effect in vivo it would essentially have to be apparent on individuals who get MRIs. No instances of low blood pressure have been noted. It is likely there are no clinically significant effects from this mechanism.

  3. woo-fu says:

    Transcranial magnetic stimulation is another experimental application in which neurons are the target rather than blood cells. IF TMS works as hypothesized, and that remains to be seen, what would happen neurologically if someone were to experiment with the magnetic fields as described in this post? It seems to me there are simply too many variables to devise an adequate experiment or to understand all the risks.

  4. daedalus – thanks for the extra info. It makes sense that a diamagnetic effect (as opposed to paramagnetic) would produce “anti-chaining” as you describe. I understand your description of diamagnetic – but my lay understanding was that completely non-magnetic material would not be diamagnetic. The reference I cited said that oxyhemoglobin has a magnetic moment of zero – so would it still behave as a diamagnetic material?

    Woo-fu – TMS uses a dynamic magnetic field. That is why it affects nerve function. Static magnetic fields do not do this – even if they are very strong.

  5. SloFox says:

    Great analysis. Very interesting. VERY preliminary when it comes to clinical applications.

    I would find it more surprising if a press release like this DIDN’T become false justification for some quack magnetic product. My Googling didn’t produce anything just yet but the study already appears on a couple of alt-med websites.


  6. PDManson says:

    Not only have the alt-med sites picked it up, but so has that bastion of sillyness, the Daily Mail

    The article also includes the comment: “Tao said that further studies are needed and that he hopes to ultimately develop this technology into an acceptable therapy to prevent heart disease.”

  7. TsuDhoNimh says:

    But when that freight-train of RBCs hits an artery that is going at right angles to the magnetic field, what then?

    Does it jam the artery? Fall apart?

  8. Zetetic says:

    I wonder if this is just rouleaux artifact like the “Live Blood Cell Analysis” woo-meisters talk about?

  9. daedalus2u says:

    If this person is suggesting the effect he describes will have clinical importance, then this is very likely a deliberate scam (my opinion).

    A vacuum has a magnetic susceptibility of 0 (by definition). There are materials that have a magnetic susceptibility less than 0, things like bismuth, graphite, water. Things that have a magnetic susceptibility greater than 0 are considered to be paramagnetic.

    Materials that are ferromagnetic have a magnetic susceptibility that depends on the field and is many orders of magnitude higher than things that are paramagnetic (in low fields). In ferromagnetic materials the magnetic moments of individual domains get aligned by the magnetic field and add to the magnetization. In high enough fields everything gets aligned and the dependence on the field vanishes and even ferromagnetic materials act as if they were only paramagnetic. This is called “saturation” and the highest saturation field is about 2.4 Tesla in special iron-cobalt alloys.

    Air has a near zero magnetic susceptibility but because O2 is paramagnetic air is slightly paramagnetic. The magnetic chaining effect is due to magnetic susceptibility differences between the objects and the medium that they are in.

    You could get magnetic chaining of something non-magnetic if it was in a fluid that was even less magnetic than it was.

    Hemoglobin is a pretty complex molecule. It consists of a tetramer with 4 hemes and those 4 hemes are somewhat independent. Usually there is what is called cooperativity, so that all four hemes either gain O2 or lose it simultaneously, that is you usually don’t have individual hemoglobin molecules with different numbers of O2 molecules. Magnetic susceptibilities of the different hemoglobin species have been measured and hemoglobin with ferrous iron (Fe+2+) and no O2 is paramagnetic, hemoglobin with ferrous iron coordinated to O2 is diamagnetic (this is oxyhemoglobin), hemoglobin with ferric iron (Fe+3) (methemoglobin) is also paramagnetic and to about the same degree as deoxyhemoglobin. Carboxyhemoglobin (hemoglobin with ferrous iron coordinated to carbon monoxide is like oxyhemoglobin and is diamagnetic.

    The physics of magnetic chaining is pretty simple and pretty well understood. The magnetic properties of hemoglobin in blood are pretty well understood too. That is the entire basis for the BOLD fMRI technique. The magnetic susceptibility of the brain is measured by its effects on the MRI signals, and then the very subtle differential magnetic susceptibility due to differential perfusion of the brain with oxy and deoxyhemoglobin is measured. This is very well understood and has been cross-correlated with oxy and deoxyhemoglobin measurement by optical methods in vivo. They track exactly. The BOLD signal is due to a reduction in magnetic susceptibility from an increase in perfusion due to a displacement of deoxyhemoglobin by the dilation of vessels increasing the perfusion of blood containing oxygenated hemoglobin. (it turns out that dilation is mediated by neurogenic NO, but that is another story ;).

    Part of why BOLD fMRI works is because the skull is pretty rigid, so the volume of blood in the brain stays pretty much the same. If blood vessels dilate in one place, they have to constrict somewhere else such that the total volume of blood in the skull stays the same.

    In terms of what would happen if a chain of blood cells held together magnetically hit something, this paper:

    Calculates a diffusion velocity of a red blood cell in a magnetic field of 10 T, and a gradient of 1000T/m. These are gigantic fields and field gradients. To get a gradient of 1000T/m you would need a 10 T change over 0.01 meter. Since the highest field you can get continuously is maybe 20 T, a gradient of 1000T that a human would fit inside is simply not achievable. In that very high field and extremely high field gradient, they calculate a diffusion velocity of 27 microns per second for deoxyhemoglobin blood cells. Usual human blood flow velocities are a few mm/second, so adding a velocity component of ~1% should be negligible.

  10. ConspicuousCarl says:

    daedalus2u on 29 Jun 2011 at 9:43 am:

    The mechanism of chaining in donated blood might be due to magnetic chaining of the paramagnetic deoxygenated blood cells. That cannot be occurring in vivo because blood is not deoxygenated.

    So they may have found a way to prevent heart attacks in dead people?

  11. aeauooo says:

    “Currently, the only way to reduce blood viscosity is with drugs like aspirin.”


    “Magnets could prevent heart attacks by thinning the blood as effectively as aspirin

  12. Sullivan says:

    Dr. Novella,

    Two things about this study bother me.

    First, isn’t donated blood given some substance to keep the blood from coagulating? What change did this have on the properties like viscosity of the blood?

    More importantly, diamagnetic and paramagnetic materials generally will not be clumped in no field. At zero magnetic field, they have no net moment. No reason to clump. Either (a) the blood cells are acting magnetically different than regular blood cells, or (more likely) (b) once the cells are clumped in the field, they stay clumped chemically. In other words–they are glued together, not magnetically clumped in the absence of a field.

    There is a point where I would have to disagree with daedalus2u. It is rare in my experience. But, diamagnetic particles could clump. It doesn’t matter that their moments anti-align to a field. They would have moments and they could then attract. Once they have a moment induced, the direction of the field isn’t the factor. The problem is that the moments involved tend to be very small. There just isn’t that much force pulling them together.

    Strong permanent magnets can have magnetic fields as high as 1.3%. Neodymium iron boron, for example, can have remnant inductions of over 1T. So, very near such a magnet’s surface, one would see fields this high.

    Note–1.3T is very possibly the full field of the electromagnet used in the study. I wouldn’t place much importance on that number unless the study authors claim some field dependence.

  13. Sullivan says:

    “Strong permanent magnets can have magnetic fields as high as 1.3%. ”

    Should read “Strong permanent magnets can have magnetic fields as high as 1.3T”

  14. Nikola says:

    I love it when you technical freaks come out of the closet like this;)
    It makes me remember just how much I simply don’t know. Then again I might just say “to hell with it!” and buy a magnetic knee supporter.

  15. diabetic77 says:

    I just read on a CNN health blog the following headline “Could magnets replace aspirin as blood thinners?”….. as you said, this study is being taken WAY out of proportion!!

  16. daedalus2u says:

    Sullivan, donated blood is treated with citrate to chelate the calcium so the blood doesn’t clot. That would have no effect on the magnetic properties.

    I completely agree with you that the magnetic effects are very small.

    My understanding is that he is using a uniform magnetic field, as in the magnet from an MRI machine. Such magnets can have gradients, using a 1.3 T magnet, and a person-sized magnetic gradient, one would get ~ 1 T/m. That gives a product of 1.3 T^2/m, or about 1.3/10,000 the product in the example I gave earlier with a 27 micron/s drift velocity. Or about 27 microns in 2 hours.

    Paramagnetic materials do have induced moments that align with the field, but those moments are quite small, and in the case of deoxygenated blood cells, very small. In paramagnetic materials those moments disappear as soon as the applied field is removed. In diamagnetic materials too, the moments are very small and are anti-parallel to the field and disappear as soon as the field is removed.

    It is only some ferromagnetic materials that can have residual magnetic moments after the applied field is removed. None of the constituents of blood have this property at all. Some organisms do use magnetite (Fe3O4) crystals as magnetic compasses to orient in the Earth’s magnetic field. Those would be aligned and form chains if they were free to move.

    Blood cells could clump together mechanically, but a magnetic field isn’t necessary to do that, and the fields he is using are not enough to cause them to magnetically clump together.

    If he is doing his experiments in glass, there may be interactions with the glass that cause the cells to clump together. How much shear, how much turbulence, was the viscometer biocompatible or not, these may have influenced the results, and until there is a published paper it is hard to assess his data without knowing how he got it.

    In my opinion, this looks like a scam and not a breakthrough. If he is right, then there is a lot that is fundamentally wrong with our understanding of the effects of magnetic fields on blood and the effects of MRIs on people. He is presenting an extraordinary finding without even ordinary data and the theory he uses to explain what he is reporting doesn’t fit what he is claiming.

    When a physicist tout in vitro findings and claim this “could” be used to treat heart disease as effectively as 100+ year old drugs that have been tested in gigantic trials, my inclination is to think Dunning-Kruger and not breakthrough.

  17. Tell it like it is says:


    Physicists Rongjia Tao Ke Huang claimed that that exposing a person to a magnetic field could reduce their risk of a heart attack by streamlining the flow of blood around their body and researchers at Temple University in Michigan found that a device that uses a magnetic field to thin fuel can have the same effect on human blood (i.e. thin the fuel).

    Would anyone like to purchase a pair of sugar shower curtains I have for sale?

  18. woo-fu says:

    Would anyone like to purchase a pair of sugar shower curtains I have for sale? Sweet!

    @ Steven Novella

    Thanks for clarifying the differences regarding the magnetic applications in TMS and this experiment. I was imagining all kinds of sci-fi scenarios.

  19. Sullivan says:

    “Sullivan, donated blood is treated with citrate to chelate the calcium so the blood doesn’t clot. That would have no effect on the magnetic properties.”

    I wasn’t thinking about the magnetic properties. Rather the viscosity and the surface properties of the blood cells. Can you make the same claims about donated blood as in-vitro blood based on these differences.

    “My understanding is that he is using a uniform magnetic field, as in the magnet from an MRI machine”

    The photo I saw was a standard laboratory electromagnet. The pole pieces were large and flat, so I assume the field was fairly uniform, at least in the measurement space. It is possible that there were gradients in the rest of the fluid circuit.

    Just one geek-correction. Magnetite is a ferrimagnet, not ferromagnet. For the purposes of your discussion, there is no difference.

    “Blood cells could clump together mechanically, but a magnetic field isn’t necessary to do that, and the fields he is using are not enough to cause them to magnetically clump together. ”

    I would assume that there is some sort of surfactant which keeps them from clumping normally. I am very concerned that they remained clumped after the field is reduced.

  20. nybgrus says:

    part of why I love this blog is exemplified here – I can follow the in depth physics, but I could never generate it on my own. However, there is one question I can answer:

    I would assume that there is some sort of surfactant which keeps them from clumping normally. I am very concerned that they remained clumped after the field is reduced

    It isn’t a surfactant, but it is the negative charge on the cell surface, dubbed the Z-potential. Essentially, the protiens et al that cover the surface of the cell membrane are weak acids and thus in the slightly basic serum give off a proton, leaving a negatively charged molecule.

    In inflammatory states, these proteins tend to get covered up with acute phase molecules/proteins which dampen the negative charge, allowing the RBCs to stick together more closely. This is the basis of the erythrocyte sedimentation rate (ESR) lab test. It tells you something is going on, but it could be anything causing an inflammatory state.

    I reckon that even if the magnets could get the RBCs to align and come close to each other, it couldn’t last – the Z-potential must be overcome. So the first hurdle I see is that the magnetic field would have to overcome the electrical repulsion RBC normally have for each other. Then, after removing the field, they would somehow have to stay clumped. If the Z-potential remains intact then they would unclup immediately or never – the latter being because a chemical change gluing them together would have to be going on (to at least some degree). The paper said the effect was for two hours?

    Sorry if I rambled a bit or missed something – it is 6am and I am 3 sips into my coffee :-D

  21. Tell it like it is says:


    @woo-fu BRILLIANT! LOL

    You sound interested. They are trimmed with sugar flowers and have 1.1 Serbian Tesla neodymium magnets in the hemming, spaced 100 angstroms apart. Xcited?

    Interesting fact number 1: A Tesla – a word here which describes the measurement of magnitude of the magnetic field vector necessary to produce a force on a charge (in coulombs) moving perpendicular to the direction of the magnetic field vector with a given velocity, is named after the Serbian Nikola Tesla who was responsible for giving the world the electric power grid.

    Interesting fact number 2: Tesla maintained that POWER could be TRANSMITTED through the ether via the natural electromagnetic layers (Appleton, Kennelly-Heaviside, etc.) and carried out an experiment whereby he placed a string of HIS ‘coiled-coil’ lamps (NOT Thomas Edison’s FILAMENT lamp – which only gave 25% of the BRIGHTNESS for a given applied power) in a field – and WITH NO PHYSICAL CONNECTION TO ANYTHING WHATSOEVER – ALL of the lamps ILLUMINATED at FULL BRILLIANCE! Homage is paid to this feat in the film ‘Prestige’ which features David Bowie – who BRILLIANTLY plays the part of Nikola Tesla.

    Interesting fact number 3: The event took place near Niagara Falls (on the American side), and not long after this event took place Tesla ‘disappeared’. There is conjecture as to whether it he was kidnapped and killed by his arch enemy Thomas Edison, who saw himself as Tesla’s Nemesis, or Tesla was seized and later killed by the Russians – who either wanted the secret – or – wanted to KEEP the secret secret secret (yes my grammar is correct – read ‘secretest of secrets’ secret).

    Interesting fact number 4: His secret secret disappeared with him but it was REDISCOVERED in 1996 and devices that exploit the electromagnetic phenomena are NOW available that will power your laptop WITHOUT EVER HAVING TO CONNECT TO ANY POWER SOURCE. Isn’t that WONDERFUL?

    I had best NOT mention a clean, reliable, cost-effective and truly sustainable ‘engine’ powered from the sun, that can be READILY purchased on the open market, and that will provide all the electricity and all of the hot water and heating you or your community would ever need, whilst not contributing ONE JOT to our planet’s carbon emissions. The only hint I will give is to say its sterling stuff.

    Kindest regards


  22. daedalus2u says:

    Sullivan, I saw it mentioned in one of the articles that they used donated blood as the blood source. They don’t use any surfactants in donated blood, only citrate. Any clumping together of these cells seems most likely to be artifact and not due to magnetic effects. The clumps in the picture do not at all look like magnetic chaining. Magnetic chained particles touch at opposite ends of their highest aspect ratio dimension.

    Displacement of magnetic materials due to a magnetic field does not occur in uniform fields. Magnetic particles can align (while diamagnetic particles anti-align), but this alignment is due to a torque, not a displacement. Chaining of magnetic particles occurs because the magnetic particles distort the field and generate a magnetic field gradient due to that distortion. If there is no distortion of the field by the particles (as when the medium and the particles have the same magnetic susceptibility) there is no chaining. The distortion due to very weakly paramagnetic or diamagnetic particles is tiny. There might be chaining of deoxygenated red blood cells, but those are unimportant as far as pressure drop is concerned in vivo because the pressure drop that controls flow is in arterial blood where O2 saturation approaches 100%.

    Red blood cells do have an aspect ratio, so it is conceivable that they could align in a field and simply from that alignment there would be a viscosity change. There would not be much of a change in vessels that are large compared to the blood cell diameter. That alignment would not persist after the field was removed. I don’t think this is the effect.

    There could be a zeta potential effect, not from the magnetic field, but from trace ionic contamination. Poly valent ions (like Al+3) are much more effective at collapsing the double layer.

    The biggest problem with this approach is that “blood thinners”, like aspirin, don’t actually reduce blood viscosity, they prevent clots from forming. It is not at all clear that the effects of aspirin are mediated through changes in blood viscosity (it is probably very likely that they are not).

    I looked and was able to find very little on the effects of aspirin on blood viscosity. Aspirin has lots of changes in clotting time and in time for bleeding to stop. But all of these have only a very small dependence on viscosity.

    In any case, blood flow is controlled locally by vessel diameter, not globally by blood viscosity. Increased blood viscosity can increase blood flow because vessels are active tissue. Shear at the vessel wall causes the release of NO.

    In blood, cell concentration is a large factor in determining bulk viscosity, and viscosity is ~ linearly related with hematocrit. But affecting viscosity is not the only effect that hemoglobin has. Hemoglobin is also the sink for NO and NO is the major determinant of vessel tone with more NO causing vasodilatation. There is considerable thought that the hypertension of hemolysis is due to free hemoglobin in the blood tying up NO too rapidly and in the boundary layer at the vessel wall where cells are normally excluded. If you lower blood viscosity by hemodilution, you are also increasing the NO concentration at the vessel wall (the product of NO concentration times hematocrit is what stays constant). The positive health effects of hemodilution are probably mostly due to higher NO.

    The concentration of blood cells in blood is is not constant. In capillaries the concentration of cells is much lower than in bulk blood. The shear at the vessel wall drives the cells to the center where they move faster, but also plasma effuses out of the capillaries to comprise the extravascular flow of lymph. It is this extravascular flow that transports dissolved high molecular weight solutes (like glucose and insulin) to cells. Diffusion through cells only delivers O2, NO, and takes up CO2 (pretty much).

    The reduced concentration of cells in capillaries is called the Fahraeus effect.

    To summarize, I think that the blood “thinning” and prevention of heart attacks due to aspirin has nothing to do with blood viscosity. Lowering of blood viscosity artificially via magnetic fields (if it even happens) will probably have no positive effects on vascular health and may (likely) make it worse because it will mess up the normal regulation and will lower the shear mediated generation of NO (which will make vascular disorders worse).

    That this extremely preliminary and not well understood in vitro result based on flawed theories and thinking has gotten so much press is unfortunate. This is why non-scientists don’t understand and don’t trust scientists. Non-experts are held out to be experts even when a modest due diligence would show the ideas to be quite flawed.

    I don’t think that a paper like this would get through peer review in a medical or physiology journal (it shouldn’t). That it gets through peer review at a physics journal is an example of Dunning-Kruger.

  23. nybgrus says:

    d2u: I concur. The “thinning” effects of aspirin are indeed not due to changes in viscosity of the blood. That is a misnomer based upon lay understanding and vernacular of the clotting process.

    Even if the magnets could actually decrease the viscosity of the blood I don’t think it would have any effect (maybe a tiny one that is clinically insignificant) on thrombotic events.

  24. daedalus2u says:

    In thinking more about it, lowering blood viscosity would make heart disease worse by lowering the NO production due to shear.

    Reducing blood viscosity by blood letting might be helpful, but that effect would be mediated by increasing NO levels via hemodilution and not by lowering blood viscosity.

  25. Artour says:

    Heart disease and problems with perfusion or low blood flow in many chronic diseases have simple explanations. One just needs to face hard scientific data related to breathing parameters (minute ventilation rates) in patients with heart disease (diabetes, cancer, and many others). Here are 8 independent studies that demonstrated that heart patients breathe about 2-3 times more air compared to the medical norm:

    Hyperventilation causes alveolar and arterial hypocapnia, while CO2, as some studies reasonably claim is “the most potent known vasodilator”:

    Nitric oxide could be the next one. But since heart patients are often mouth breathers, they miss nasal nitric oxide as well. Or they exercise with mouth breathing and die from heart attacks while running or due to mouth breathing after exercise. Simple basic physiology.

  26. Harriet Hall says:


    You may not have noticed, but no one else on this list subscribes to your beliefs about breathing or accepts that your “hard scientific data” support those beliefs. Are you aware that there is an article on our blog eviscerating the claims for Buteyko’s breathing methods?
    The scientific community is aware of your data and your arguments and is not convinced. You keep citing your own website as “evidence;” we do not accept it as evidence and it is not appropriate to co-opt our comments threads for free advertising. If you are under some delusion that your website is consistent with science-based medicine, you are badly mistaken. Please stop proselytizing but keep reading and perhaps eventually you will understand what science-based medicine means.

  27. daedalus2u says:

    You are badly mistaken about CO2 being a potent vasodilator Nitric oxide is by far a more potent vasodilator than CO2. CO2 levels in blood are 24-30 mM/L. NO levels are sub nanomolar.

    In this paper

    They model vasodilatation from NO, from CO2 and from CO2 plus NO.

    They are using changes in CO2 levels in the 1 mM/L range and NO levels in the 0.1 nM/L range, about 7 orders of magnitude less. Even so, they had to multiply the CO2 dilation effect by 20 to get it to even show up on the graph.

Comments are closed.