They're embedded in everything from mattresses to insoles for shoes to wrist bands — but there is no definitive scientific evidence that static magnets can relieve chronic pain, researchers say.

Products that incorporate static magnets are a multibillion-dollar business worldwide, and many chronic pain sufferers are drawn by the promise they hold for alleviating such nagging conditions as arthritis, fibromyalgia and low back discomfort.

The theory from proponents is that a magnetic field increases blood flow, causing increased oxygen, nutrients, hormones and painkilling endorphins to be distributed to tissues in the affected area.

'There is no definite grounds of being absolutely sure that a magnet works or not.'—Dr. Max Pittler, researcher

Researchers at the universities of Exeter and Plymouth in England decided to search the medical literature to determine whether there is any proof magnets can reduce pain.

In their analysis of nine randomized trials comparing products containing magnets with those containing either no magnet or very weak ones, the researchers found that the data did not support the use of magnetic therapy for pain control.

"There is no definite grounds of being absolutely sure that a magnet works or not," lead author Dr. Max Pittler, a complementary medicine specialist, said Monday.

"The evidence does not support the use of static magnets for pain relief, and therefore magnets cannot be recommended as an effective treatment," he said. The analysis is published in Tuesday's Canadian Medical Association Journal.

Clinical trials unable to prove magnets offer benefits

Pittler acknowledged, however, that the findings also mean that magnets could work — but the clinical trials weren't able to prove that. In part, that's because pain measurements are subjective — subjects self-report pain levels — and individual studies in the analysis may have been too small to provide statistically relevant results.

Still, Pittler said, the biggest concern is that people seeking to ease their pain may be buying into — and paying big bucks — for a therapy that may not be effective.

"It is important to realize that this is a situation where there is a huge market out there," he said. "In a situation where you don't have rigorous data … patients are putting their hopes into a magnet and spending a lot of money on it."

He suggested many pain sufferers would be better off taking an over-the-counter painkiller such as ASA or acetaminophen or trying complementary medicine such as acupuncture.

Health Canada considers claims for specific therapeutic benefits of static magnets to be unfounded, a spokeswoman for the federal department said by e-mail Monday. A static magnet promoted for any of these purposes is considered a violation of the Food and Drugs Act or medical devices regulations.

Acupuncture, exercise help ease chronic pain

Commenting on the analysis, naturopath Kieran Cooley agreed that magnets wouldn't be high on the list of possible therapies to treat chronic pain.

'Magnet therapy is definitely a buyer-beware or consumer-beware kind of industry.'—Kieran Cooley, naturopath

"Acupuncture is probably the biggest one. Mild to moderate exercise has actually been shown to have the best effect on pain overall of any sort of therapy you can use, even conventional drugs or over-the-counter pain medications like Advil or Aspirin," said Cooley, a researcher and assistant professor at the Canadian College of Naturopathic Medicine in Toronto.

Yet magnets can't be written off completely until more definitive evidence on their effectiveness or lack of effectiveness is obtained, Cooley conceded. "There are clearly some people [in the British analysis] who are benefiting from the therapy. There are other people who are not benefiting very much and a few people who seem to be getting worse."

"So in that respect, magnet therapy is definitely a buyer-beware or consumer-beware kind of industry."