Magnetic therapy is hugely popular, grossing about $5 billion yearly world-wide. Most often static therapeutic magnets are encountered in pieces of jewellery, though everything possible where magnets can be placed is available. As the sale and advertisement of magnets is not restricted in any way and testimonies by celebrities on the alleged benefits they have gained from the use of therapeutic magnets are published widely, it is not surprising that many people may think they might be of therapeutic use.
Claims made by the sellers include magnets relieving pain from arthritis, back problems, frozen shoulder, gout, insomnia and migraine headaches. They are also claimed to improve circulation, increase blood oxygen, decrease deposition of cholesterol plaques in blood vessel walls, relax blood vessels through effects on cellular calcium channels, reduce edema or fluid retention, increase endorphins and muscle relaxation. And, of course, no “alternative” therapy would be complete without someone claiming it cures cancer.
Can magnets really do all this? The answer is no. Although hemoglobin does contain iron, it is slightly diamagnetic. Therapeutic magnets are much too weak to have any effect on blood, having a field strength of roughly 0.1-0.4 T (1,000-4,000 G). Even MRI scanner magnetic fields, which are much stronger than any piece of magnet used in magnetic therapy, 1-8 T (10,000-80,000 G), do not affect blood. Good thing too, or nobody would be able to survive a MRI scan as their bodies would explode.
Robert Park, a physics professor from University of Maryland, examined some therapeutic magnets in 1999. One pair he tested came from a $49.95 magnetic therapy kit. They were a little stronger and thicker than the common or garden variety fridge magnet but they failed to hold even ten sheets of 1 mm thick paper on a file cabinet. That means they were too weak to do more than barely penetrate the skin.
One theory behind the alleged magnetic effect on blood circulation the sellers often resort to relies on the Hall effect. According to this theory, the charged particles in blood in a magnetic field would move towards their respective poles. The movement of the particles would be resisted as the particles would be forced to move against their normal flow direction. This migration against resistance would produce heat, causing the veins to dilate. There is one problem with this theory: magnets generate no heat in the tissues. A study published in 2001 found no increase in the tissue temperatures when magnets were applied:
No meaningful thermal effect was observed with any treatment over time, and treatments did not differ from each other. We conclude that flexible therapeutic magnets were not effective for increasing skin or deep temperatures, contradicting one of the fundamental claims made by magnet distributors.
As for the rest of the claims, even the strongest of magnets are not able to influence non-ferrous materials. Cholesterol, C27H46O, does not contain any iron, so any magnetic therapy is unable to have any effect on it.
There have also been studies on the effects of the therapeutic magnets. A double-blinded study, published in 2002, on the effects of magnets on carpal tunnel pain had this to say:
Presenting symptoms including numbness, tingling, burning, and pain did not differ significantly between the 2 groups. There was significant pain reduction across the 45-minute period for both groups. However, test comparisons found no significant differences between the groups for beginning pain, pain at 15 minutes, pain at 30 minutes, or pain at 45 minutes. The use of a magnet for reducing pain attributed to carpal tunnel syndrome was no more effective than use of the placebo device.
A study on magnets for pain relief, published in 2007, concluded:
In conclusion, the evidence does not support the use of static magnets for pain relief, and such magnets therefore cannot be recommended as an effective treatment.
Another study, published in 2009, researched magnetic therapy for osteoarthritis and concluded:
Our results indicate that magnetic and copper bracelets are generally ineffective for managing pain, stiffness and physical function in osteoarthritis. Reported therapeutic benefits are most likely attributable to non-specific placebo effects.
The only effect the so-called therapeutic magnets can have is the placebo effect. While the magnets themselves are harmless – unless their settings contain allergenic materials like nickel in the plating of the bracelet or another piece of jewellery – reliance on them can delay diagnosis as pains and aches can be symptoms of a serious condition.
If, despite all this, you wish to invest in magnetic therapy, my advice would be to buy the cheapest one available. If nothing else, doing so will help to ease the pain felt in the wallet.