Thursday, January 15, 2009

Magnetic Quackery

I was browsing through a book store a few days ago and I came across Kevin Trudeau's line of Natural Cure's They Don't Want You to Know About books (I must have been in the convicted fraudsters section). I usually see Kevin Trudeau on late night TV raving about the benefits of some untested treatment or another that "they" (hey that's me) are hiding from you. He's made millions and the gullibility of the American public is demonstrated by the fact that his books are always on a best seller list. Anyway, I thought I might get a laugh if I saw what's inside. I turn to a random page and what do I see? Magnetic therapy!!! Being an expert in training in real magnetic therapy, I started reading. Alas, it wasn't the 2 Tesla focused rapid brain stimulator that I work with. He was talking about wearing a small magnetic bracelet around your wrist for treating pain (and if I had read further I'm sure he would have said it will cure your heartburn, get rid of that tumor that's been bothering you and make you have a better sex life). This isn't the first time that I've encountered this form of "therapy." Several times when I've told people that I research magnetic brain stimulation, the response has been, "Oh, I know. It's like those magnetic bracelets!"

Well, I'm here to say that this:

does not work.

Let me quickly tell you why. Although our bodies have molecules that could potentially be affected by magnetic fields, biological tissue is amazingly unresponsive to static magnetic fields. The device pictured above (which you could have for a mere $17.95+sh) according to the manufacturer (if we actually believe them) contains 2 x 1000 Gauss static magnets. Magnetic fields aren't additive so let's say we're working with 1000 Gauss (or 0.1 Tesla) - though a JAMA article actually measured their surface field strengths and found them to be more like 30 to 250 Gauss. The problem is that a 0.1 Tesla static magnet (about the strength of the magnet in a small speaker) doesn't do anything to tissue. The magnetic therapy proponents say things like it affects your circulation by interacting with hemoglobin or it stimulates nerves (if they don't first say it aligns your chi). But nonetheless, valuable tax dollars were spent to test the claim that magnetic therapy is a natural cure that we don't want you to know and several studies (here are 4: 1 2 3 4) have found that it's no better than placebo at treating pain (their main use). The reason why magnetic brain stimulation works is that a very large magnetic field (around 2 T) is being delivered over a very short period of time (<250 microseconds). It's this rapidly changing magnetic field that affects biological tissue (induces current). Even then, unless you get it at the right intensity, frequency, target, angle, duration, etc, it has very subtle effects. So, unless the magnet on the bracelet produces a rapidly changing magnetic field (and if it did it would cost way more than $17.95 and would probably not be so portable), it won't do anything to nerves and it won't treat pain.


  1. Yes, but will the bracelets tell you which way is North? Because that could be useful if you get lost in the woods or something.

  2. Come on, that's what hemoglobin is for. I just hold my hands out and see which direction the blood rushes to.