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Do magnets have statistically significant effects on humans?

Some example claims are in the Wikipedia article on Magnet therapy.

Which says:

Practitioners claim that subjecting certain parts of the body to magnetostatic fields produced by permanent magnets has beneficial health effects. These claims are both physically and biologically implausible and no effects on health or healing have been established.

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    In germany, you have to prove the effect if you make marketing for medical devices. Since there aren't magnetic devices which are marketed as medical effective, I conclude, that no such effect could be proven. It would be a big market with the possibility of earning very much money. – user unknown Mar 7 '11 at 19:59
  • If magnets had a significant effect on humans, MRIs would not be as widely used. Just as significant is the fact that most magnetic diagnostics rely on dyes because the body alone doesn't have enough "signal". – jjj Mar 7 '11 at 20:53
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    Our wonderment that magnets exist, and a tendency of some fraction of the population to attribute mystical healing powers to them without evidence, certainly seems to be a noticeable effect of magnets on humans. But perhaps this is not the sort of effect that you are looking for. – Niel de Beaudrap Apr 28 '11 at 15:53
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    I find it amusing that the proponents of the health benefits of magnets often are the same ones who think it is harmful to live under power lines. – JohnFx Aug 8 '11 at 4:46
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    @JohnFx (+1): Perhaps there's a difference in the magnetic output between a consistent magnetic material vs. the magnetism exhibited by power lines carrying AC power (since Alternating Current is constantly switching direction)? You've made a very interesting observation. – Randolf Richardson Aug 28 '11 at 18:59
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While there are studies that have shown some relief of pain, most do not show those results. Given the other factors that could cause false-positives, it seems unlikely that the magnets are the cause.

What the Science Says About Magnets for Pain

Scientific evidence does not support the use of magnets for pain relief.

Preliminary studies looking at different types of pain—such as knee, hip, wrist, foot, back, and pelvic pain—have had mixed results. Some of these studies, including a 2007 clinical trial sponsored by the National Institutes of Health that looked at back pain in a small group of people, have suggested a benefit from using magnets. However, many studies have not been of high quality; they included a small number of participants, were too short, and/or were inadequately controlled. The majority of rigorous trials, however, have found no effect on pain.

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Transcranial Magnetic Stimulation gets used in neuroscience to affect the brain. Klein et al showed in a placebo controlled double blind study that it can be used to treat recurrent major depression.

Abstract

Converging evidence points to hypofunction of the left prefrontal cortex in depression. Repetitive transcranial magnetic stimulation (rTMS) activates neurons near the surface of the brain. We questioned whether daily left prefrontal rTMS might improve mood in depressed subjects and report a pilot study of such treatment in six highly medication-resistant depressed inpatients. Depression scores significantly improved for the group as a whole.

Daily repetitive transcranial magnetic stimulation (rTMS) improves mood in depression by George, Mark S.; Wassermann, Eric M.; Williams, Wendol A.; Callahan, Ann; Ketter, Terence A.; Basser, Peter; Hallett, Mark; Post, Robert M.

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    It is important to point out that TMS uses rapidly changing magnetic fields to induce electric currents in the brain. Many alleged magnet-based therapies use static magnetic fields (i.e. a magnet held close to the body) which would not induce an electric current at all. Very big distinction. – Tim Farley Mar 9 '11 at 15:18
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Magnets can be used to unobtrusively remove small metal parts from human body remained after suffering an injury caused by a near bomb explosion. There's a so called 'magnet trap' developed by Dr. Dusanka Mandic

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    Interesting, but I don't think qualifies as "effect on humans". Removing your loose pocket change or keys is also a notable effect. – dbkk Mar 11 '11 at 18:03
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    @dbkk agree, but let's mention this usage, too – Boris Pavlović Mar 11 '11 at 20:17
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    If we're going to mention this, perhaps cow magnets are also worthy of mention. They're not used for humans, but they do serve a medical purpose, as veterinarian devices, for other animals. – oosterwal Mar 11 '11 at 22:48
  • @oosterwal: I'd better keep my laptop away from cows from now on! =O – Randolf Richardson Aug 28 '11 at 19:02
  • The website seems not to be quite reliable (it also boasts a bunch of other benefits which are not science supported). This answer would really benefit from a better source! – Sklivvz May 6 '12 at 14:50
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MIT neuroscientists published a study which provides evidence that a magnetic field applied to certain portions of the brain can impact morality judgements. If true, that seems to be a clear example of a magnet's noticeable effect on humans.

When we judge an action as morally right or wrong, we rely on our capacity to infer the actor’s mental states (e.g., beliefs, intentions). Here, we test the hypothesis that the right temporoparietal junction (RTPJ), an area involved in mental state reasoning, is necessary for making moral judgments. In two experiments, we used transcranial magnetic stimulation (TMS) to disrupt neural activity in the RTPJ transiently before moral judgment (experiment 1, offline stimulation) and during moral judgment (experiment 2, online stimulation).
In both experiments, TMS to the RTPJ led participants to rely less on the actor’s mental states. A particularly striking effect occurred for attempted harms (e.g., actors who intended but failed to do harm): Relative to TMS to a control site, TMS to the RTPJ caused participants to judge attempted harms as less morally forbidden and more morally permissible. Thus, interfering with activity in the RTPJ disrupts the capacity to use mental states in moral judgment, especially in the case of attempted harms.

Disruption of the right temporoparietal junction with transcranial magnetic stimulation reduces the role of beliefs in moral judgments by Liane Young, Joan Albert Camprodon, Marc Hauser, Alvaro Pascual-Leone, and Rebecca Saxe

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    To repear Tim Farley's excellent comment on another answer, this is not about static magnets, but about rapidly changing magnetic fields. – Oddthinking May 7 '12 at 3:26

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