|Energy medicine - edit|
Magnet therapy, magnetic therapy, or magnotherapy is a pseudoscientific alternative medicine practice involving the use of static magnetic fields. Practitioners claim that subjecting certain parts of the body to magnetostatic fields produced by permanent magnets has beneficial health effects. These physical and biological claims are unproven and no effects on health or healing have been established. Although hemoglobin, the blood protein that carries oxygen, is weakly diamagnetic (when oxygenated) or paramagnetic (when deoxygenated) the magnets used in magnetic therapy are many orders of magnitude too weak to have any measurable effect on blood flow.
Methods of application
Magnet therapy is the application of the magnetic field of electromagnetic devices or permanent static magnets to the body for purported health benefits. Some believers assign different effects based on the orientation of the magnet; under the laws of physics, magnetic poles are symmetric.
Products include magnetic bracelets and jewelry; magnetic straps for wrists, ankles, knees, and the back; shoe insoles; mattresses; magnetic blankets (blankets with magnets woven into the material); magnetic creams; magnetic supplements; plasters/patches and water that has been "magnetized". Application is usually performed by the patient.
Purported mechanisms of action
Perhaps the most common suggested mechanism is that magnets might improve blood flow in underlying tissues. The field surrounding magnet therapy devices is far too weak and falls off with distance far too quickly to appreciably affect hemoglobin, other blood components, muscle tissue, bones, blood vessels, or organs. A 1991 study on humans of static field strengths up to 1 T found no effect on local blood flow. Tissue oxygenation is similarly unaffected. Some practitioners claim that the magnets can restore the body's hypothetical "electromagnetic energy balance", but no such balance is medically recognized. Even in the magnetic fields used in magnetic resonance imaging, which are many times stronger, none of the claimed effects are observed. If the body were meaningfully affected by the weak magnets used in magnet therapy, MRI would be impractical.
Several studies have been conducted in recent years to investigate what role, if any, static magnetic fields may play in health and healing. Unbiased studies of magnetic therapy are problematic, since magnetisation can be easily detected, for instance, by the attraction forces on ferrous (iron-containing) objects; because of this, effective blinding of studies (where neither patients nor assessors know who is receiving treatment versus placebo) is difficult. Incomplete or insufficient blinding tends to exaggerate treatment effects, particularly where any such effects are small. Health claims regarding longevity and cancer treatment are implausible and unsupported by any research. More mundane health claims, most commonly about anecdotal pain relief, also lack any credible proposed mechanism and clinical research is not promising.
Effects of magnet therapy on pain relief beyond non-specific placebo response have not been adequately demonstrated. A 2008 systematic review of magnet therapy for all indications found no evidence of an effect for pain relief. It reported that small sample sizes, inadequate randomization, and difficulty with allocation concealment all tend to bias studies positively and limit the strength of any conclusions. In 2009 the results of a randomized double-blind placebo-controlled crossover trial on the use of magnetic wrist straps (a leather strap with a magnetic insert) for osteoarthritis were published, addressing a gap in the earlier systematic review. This trial showed that magnetic wrist straps are ineffective in the management of pain, stiffness and physical function in osteoarthritis. The authors concluded that "[r]eported benefits are most likely attributable to non-specific placebo effects".
These devices are generally considered safe in themselves, though there can be significant financial and opportunity costs to magnet therapy, especially when treatment or diagnosis are avoided or delayed.
A 2002 U.S. National Science Foundation report on public attitudes and understanding of science noted that magnet therapy is "not at all scientific." A number of vendors make unsupported claims about magnet therapy by using pseudoscientific and new-age language. Such claims are unsupported by the results of scientific and clinical studies.
Marketing of any therapy as effective treatment for any condition is heavily restricted by law in many jurisdictions unless all such claims are scientifically validated. In the United States, for example, U.S. Food and Drug Administration regulations prohibit marketing any magnet therapy product using medical claims, as such claims are unfounded.
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- Magnetic Therapy: Can magnets alleviate pain? by Cecil Adams — The Straight Dope
- Magnetic Therapy: Plausible Attraction? by James D. Livingston — Skeptical Inquirer
- Magnet therapy in the Skeptic's Dictionary by Robert Todd Carroll
- Magnet therapy — editorial in the British Medical Journal
- Magnet Therapy: A Skeptical View by Stephen Barrett — Quackwatch