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January 06, 2006


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It didn't need any money at all to show that magnet therapy doesn't work. All it needed was for someone to point out that a person, and each constituent part thereof, is not ferro-magnetic (unless includes surgically implanted, or swallowed, steel bits and bobs. If blood, for example, were magnetic (on the basis that it contains a form of iron) then any part of a human body placed in an MRI scanner would explode. The best analogy I've heard was from Dr Ben Goldacre (Bad Science blog) in an inteview, when he asked why anyone visiting a car scrap yard doesn't get yanked up into the sky by the big magnet they use for picking up the scrap vehicles. But public ignorance is there to be exploited for a buck or two, as is well known by all quacks and medical scammers.

Actually, oxygenated haemoglobin is diamagnetic (is slightly repelled by a magnetic field) and deoxygenated haemoglobin is paramagnetic (slightly attracted to magnetic fields) - this is how fMRI can discriminate between oxygenated and unoxygenated (or deoxygenated) blood.

Using this information - and ignoring the knowledge that the overall magnetic attraction of blood cells is effectively nil (if it weren't, MRI's would be fatal) - then we could expect that magnets would attract unoxygenated blood and repell oxygenated blood.

This would create an effect exactly the opposite of what is claimed by the purveyors of "therapeutic" magnets. Oxygenated blood would be repelled from the treated area and deoxygenated blood would be attracted, decreasing tissue oxygenation.

Of course, the magnets used in most "magnet therapy" items are barely magnetic, being similar to refrigerator magents, which are designed to have a very shallow magnetic field (to avoid demagnetizing credit cards).

And, as mentioned before, the magnetic susceptibility of blood is far too low to create any movement of blood even in the intense (1 - 6 Tesla - about 10,000 to 60,000 times the magnetic field of the earth) magnetic fields found in clinical MRI scanners.

But how nice that someone wasted the research time and money to prove what any thinking person would have known from readily available information.


Why is the guy in the photo leaning backwards?

Check out this introduction article on Magnet therapy:
Magnet therapy
* 1 Magnetic therapy’s benefits
* 2 Criticism
* 3 Magnetic products
* 4 Scientific proof

When I saw a post had come from a guy calling himself 'Magnet Therapy', I was expecting to see an angry response from a true-believer, and that the link would go to a site pushing magnet products.

I was very pleasantly surprised to see that the site in question takes a very clear-headed view.

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