According to an article in the British Medical Journal, there is no hard evidence regarding the therapeutic properties of the magnetic devices, like bracelets, insoles, wrist and knee bands and even pillows and mattresses.

Producers tout their magnetic trinkets as being extremely efficient for pain relieving, and even as powerful weapons against cancer, but all the studies aimed at confirming these claims are regarded with suspicion by the scientific community.

"Money spent on expensive and unproved magnet therapy might be better spent on evidence based medicine," Professors Leonard Finegold ans Bruce Flamm write in their article.

The magnetic device industry generates worldwide $1 billion, the US being responsible for almost a third of this amount.

The studies should be carried out without the participants knowing that magnets are used, but the two researchers say this is very difficult to achieve, mainly because of the magnets' well-know property of sticking to metallic surfaces.

"Perhaps subjects with magnetic bracelets subconsciously detected a tiny drag when the bracelets were near ferromagnetic surfaces, and this distracted or otherwise influenced the perceived pain."

"Sadly some advertisers even claim that magnets are effective for cancer treatment and for increasing longevity; not surprisingly, these claims are unsupported by data."

Extraordinary claims demand extraordinary evidence. If there is any healing effect of magnets, it is apparently small since published research, both theoretical and experimental, is weighted heavily against any therapeutic benefit, the researchers concluded.