Exactly five years ago I wrote here about a study of polio survivors that examined the effect of magnets on experimentally induced pain. Carlos Valbona of Houston's Baylor College of Medicine identified places on polio survivors' bodies that hurt when he pressed. He then caused pain "by firm application of a blunt object" to the painful area, asking subjects to rate the pain on a zero-to-10 scale. Pain was rated as "nine" on average.

Then either a magnet or a non-magnetic pad was placed over the painful area for 45 minutes, and the blunt object was again pressed into the skin. Subjects wearing the magnet rated their pain as a "four" on average while those wearing the non-magnetic pad rated their pain an "eight."

This double-blind, placebo-controlled study is an example of the gold standard of research. Sadly, the media immediately reported that magnets are a "cure for post-polio pain." Pushing a blunt object into the skin does not produce the typical back, neck, limb, muscle or joint pain experienced by at least 75 percent of polio survivors. Without another study, we can't know if magnets decrease, let alone "cure," post-polio pain.

Only a couple of studies have shown that magnets placed over painful areas actually do decrease pain. In 2002, a study of 375 diabetics found that magnets helped with severe (but not mild to moderate) foot pain, decreasing numbness, tingling and burning. Another study of 25 women found that a magnetic mattress pad decreased fibromyalgia pain.

However, eight other studies have shown no effect of magnets placed on painful feet, knees, necks, shoulders, low backs or pelvises. In addition, the 2005 study you read also found no effect of magnetic versus non-magnetic shoe inserts on foot pain in 83 subjects. However, the study did find that 56 percent of those who believed magnets decreased pain were "mostly" or "all better," vs. 26 percent of non-believers.

What this study actually shows is the power of the placebo effect. Typically, in any study of treatment for subjective symptoms, such as fatigue, pain and depression, about 33 percent of subjects who are given a placebo (a "sugar pill" or "sham" treatment) report improvement even though the treatment has no effect.

The placebo effect extends far beyond the use of magnets. The widespread use of herbs and dietary supplements shows that people's belief that a treatment will work can be more powerful than its actual effect. A 2002 National Institutes of Health study found that St. John's Wort was no more effective for treating major depression than placebo. Ginkgo biloba was found to have no beneficial effect on memory, and echinacea does not prevent or treat colds.

What's worse, some substances are more dangerous than helpful. Ephedra was banned as a weight loss drug because it was suspected of causing heart attacks and strokes. Kava, touted for stress-relief, has been banned in Canada and Germany after it was linked to liver damage.

On the farthest end of the placebo effect spectrum are "remedies" that have no side effects, no beneficial effects and may not exist at all. Homeopathic practitioners believe that minute quantities of substances, that in larger doses produce symptoms similar to those the patient is experiencing, are effective in treating disease. Minerals (sulphur, graphite, creosote, sand) and substances extracted from plants (belladonna, aloe) are diluted in liquid, starting with one part in 10, then one in 100, even all the way to one part in a thousand billion! Homeopathic remedies diluted that much may not contain a single molecule of the "remedy." In 2005, 110 studies of homeopathic remedies and traditional medical procedures to treat infections, anesthesia -- even surgery -- were compared. The benefits claimed by homeopathy were, like the effect of magnets, explained by the placebo effect alone.

Sure, it's easier to put a magnet in your shoe, take an herb or a swig of diluted sulphur than it is to listen to your body, slow your lifestyle, use an assistive device and really take care of yourself to treat PPS. But polio survivors must beware of treatments that "work" only because of the placebo effect.